JP3798281B2 - Ground survey method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a ground survey method.
[0002]
[Prior art]
  In the prior art, a method called “standard penetration test” is generally used as a method for investigating the ground formation before placing piles.
  The pile is designed based on the N value obtained by this “standard penetration test” and a construction plan is made.
  The N value is the number of drops required to drop a hammer with a mass of 63.5 kg from a height of 75 cm and allow a sampler attached to the tip of a rod having a pile diameter of about 100 mm to penetrate 30 cm into the ground.
  Measurement of the N value is usually performed at 1 m intervals in the depth direction. That is, 30 centimeters are measured and 70 centimeters penetrate without being measured.
[0003]
  Another investigation method is the cone penetration test. The cone penetration test is a method in which the vertical strength is applied from the top of the rod and pressed into the ground, and the press load is measured to check the ground strength.
[0004]
[Problems to be solved by the invention]
  The data obtained by the above-described conventional research method has the following drawbacks.
  The “standard penetration test” is a piecewise piece of data with no continuity obtained by dropping or hitting, so there is a large variation in information and the accuracy is poor. For this reason, when the construction content is based on rotary press-fit steel pipe piles, since the ground survey data is data information based on the drop penetration method, the construction method and survey data do not necessarily match, and the design of rotary press-fit piles (pile There was a problem that the length, thickness of the steel pipe, thickness, excavation blades, open-ended piles, closed-ended piles, etc., and whether or not the roots were solidified) could not be accurately and accurately matched to the ground. .
  Moreover, when performing a standard penetration test, a hole is dug by boring and N value is measured at a predetermined depth. In other words, the work of digging a boring hole and the work of measuring the N value cannot be done at the same time. It was. Accordingly, the deeper the borehole, the longer the time required for N value measurement, and the greater the depth, the longer the inspection time, such as the rod lifting and re-penetration work.
[0005]
  Unlike the standard penetration test, the “cone penetration test” can continuously check the ground strength. However, the testable depth is relatively shallow, and application becomes impossible when the depth of the test ground increases. That is, the necessary pushing force becomes large at a large depth, and the machine becomes large in size, and when a large pushing force is applied, the rod bends or buckles.
[0006]
  When the soft layer and the intermediate layer are multi-layered, the variation of the N value is particularly large, and the construction of the rotary press-fit type steel pipe pile based only on the measurement data may cause trouble during the construction. Had.
  Moreover, when there is an unexpected formation in the N-value unmeasured part, stable construction may not be realized. For example, as shown in FIG. 1, when there is a thin soft layer in the middle of the reached support layer and the thin soft layer is in 70 centimeters where the N value is not measured, the existence information of the thin soft layer is obtained. It will not be obtained, and pile design and pile driving will be performed in which the hard layer above the soft layer is set (determined) as the pile stop site (assumed support layer based on the N value). That is, the constructed pile foundation becomes unstable with a soft layer below, and there is a possibility that the support force expected in the design cannot be obtained.
  In addition, if the existence of a thin soft layer is found during construction, it is necessary to temporarily suspend the construction and change the pile length, which causes new problems such as extension of construction period and cost increase. .
[0007]
  That is, in such a conventional technique, it is difficult to accurately determine the support layer.
  Usually, standard penetration tests (measurement of N value) are performed only on several sites on one building site. And the support layer level (depth) is determined from the measurement result (N value) of the several places, and the support layer level of the whole site is assumed by connecting each depth smoothly.
  However, according to the construction of the rotary press-fit steel pipe pile that the inventors have carried out so far, there is often a difference between the support layer level assumed from the N value and the support layer level determined from the construction torque of the pile. I know. Moreover, in some cases, it has been found that there is a difference of ± 5 m. This means that the support layer level in the premises has unevenness that cannot be determined by several standard penetration tests, and it is impossible to assume a precise support layer level simply by linking the support layer level with N values smoothly. ing.
  During construction, if it is found that there is a difference between the expected support layer level and the actual support layer level, it is necessary to change the pile length at that time, leading to extension of construction period and cost increase.
  In order to accurately determine the support layer level, it is necessary to increase the number of positions where the standard penetration test is performed. However, as described above, since the borehole and N value measurement are performed separately, the standard penetration test requires a lot of time. And cost and time loss increase.
[0008]
  The present invention has been made in view of the above-described problems of the prior art, and the object thereof is to obtain precise continuous ground property data even at a large depth in a shorter investigation time. It is in providing the possible ground investigation method and ground investigation apparatus.
[0009]
[Means for Solving the Problems]
  In order to achieve the above-mentioned object, the present invention is as follows.
<Invention of the ground investigation method according to claim 1>
In the ground survey method, which is to continuously measure the rotational load and the tip depth of the rod when a rod having a drilling blade at the tip is rotationally pressed into the ground,By measuring the rotational load at the time of press-fitting with the rod head and measuring the rotational load at the time of reverse rotation and pulling out, the rotational load acting on the rod shaft is separated, and only the rotational load acting on the rod tip It is characterized by calculating.
  The rotation load means measures the "rotational load" when the rod rotation drive means is an electric motor, and measures changes in current and voltage values that vary depending on the load, and if it is a hydraulic motor, measures the change in hydraulic value. Obtained by conversion. However, the measurement items are not limited to these.
[0010]
<Invention of the ground investigation method according to claim 2>
  The invention according to claim 1 is characterized in that a large diameter portion is formed on the outer periphery of the rod.
[0011]
<Invention of ground investigation method according to claim 3>
  3. The load measuring hand according to claim 1, wherein the rotational load is provided on a rotating means side for rotating the rod.In stepsIt is made to measure more.
[0012]
<EmbodimentInvention of the ground investigation method described in <1>
  In the embodiment, by measuring the rotational load at the time of press-fitting with the rod head and measuring the rotational load at the time of reverse rotation and pulling out, the rotational load acting on the rod shaft portion is separated and acting on the rod tip portion. Only the rotational load to be calculated is calculated.
[0013]
<Claim4Invention of the ground investigation method described in <1>
  In any one of Claims 1-3In the described invention, when calculating only the rotational load acting on the rod tip, the following mathematical formula is used.
      Tt = Tb + Tf (1)
        Tt: Rotational load on the rod head during rotary press-fitting
        Tb: Rod end rotation load
        Tf: Rotational load due to friction of rod shaft
    Tt ′ = Tb ′ + Tf ′ = αTb + βTf (2)
        Tt ': rotational load when pulling out with reverse rotation
        Tb ': Rotational load at the tip of the rod pile that acts when pulling out with reverse rotation
        Tf ': due to the friction of the rod shaft acting when pulling out in reverse rotation
                  Rotational load
        α = Tb ′ / Tb
        β = Tf ′ / Tf
            (The α and β are obtained by accumulating experiments.)
    From (1) and (2),
        Tb = (Tt′−βTt) / (α−β)
[0014]
<Invention of the ground investigation method according to claim 5>
In the invention of any one of claims 1 to 4, including artificially made model ground with known propertiesVarious experiments with rotary blades inserted into various experimental grounds with known properties, and based on various data obtained by the experiments,Claim 4The ground strength and the supporting force of the pile are estimated from the rotational load value (Tb) of the rod tip.
  If the rotational load Tb of the tip blade portion can be obtained, the N value of the ground can be estimated from that value, and the bearing force can be calculated.
  Or the value of Tb can be used as the strength of the ground, and the supporting force can be estimated from Tb.
[0015]
<Claim6Invention of the ground investigation method described in <1>
  Claims 1 to5In the invention according to any one of the above, the rod is open-ended hollow, the rod is rotationally press-fitted into the ground, the rotary press-fitting of the rod is stopped at the soil sampling position, the soil sampling jig is inserted into the rod, Thus, the tip soil that has entered the hollow portion of the rod or the soil below the tip of the rod is collected.
  “To make the rod hollow at the open end” is for inserting a soil collecting jig into the rod. At the time of rotary press-fitting, cover the tip of the rod, stop rotary press-fitting at the tip soil collection position, remove the tip lid, insert a soil sampling jig, and then enter the rod hollow part Take a soil sample. After that, attach the lid to the tip again and repeat the rotary press-fitting, stopping, removing the lid, collecting soil, and attaching the lid.
[0016]
<Claim7Invention of the ground investigation method described in <1>
  Claims 1 to6In the invention according to any one of the above, the vertical force acting on the rod is automatically measured simultaneously with the automatic measurement of the rotational load of the rod.
[0017]
  Depending on the ground conditions and construction conditions, vertical force may be applied to the tip of the rod. In such a case, if the vertical force is measured and recorded, and the ground strength considering the influence of the vertical force is converted, a more accurate ground survey becomes possible. The influence of the vertical force on the load is clarified by the prior application (Japanese Patent Laid-Open No. 2000-80650, Japanese Patent Laid-Open No. 2000-80649) of the present inventors.
[0018]
<Claim8Invention of the ground investigation method described in <1>
  Claim7Using the rotational load and vertical force of the rod measured in the ground survey method described in, the rotational load is converted into torque and then(3)A ground survey method characterized by estimating an N value of a ground to be surveyed by a formula.
N = (T + b · L · Dp) / (a · Dpm(3)
Here, N: N value of ground, Dp: Pile diameter, T: Torque (converted from rotational load), L: Vertical force, a, b, m: Coefficient and index
[0019]
<Reference formInvention of Ground Survey Device>
  It consists of a rod with a drilling blade at the tip and load measuring means for measuring rotational load, which is installed in an appropriate part of this rod or provided on the rotating means side for rotating the rod. The rotational load when the rod is rotationally press-fitted into the ground is continuously measured by the load measuring means.
  “Provided in the rotational load measuring means on the rod rotating means side” is obtained by detecting changes in the load of the rod rotating means (such as an increase in hydraulic pressure or current value) corresponding to the height of the load. Things are also within the technical scope.
  There are various types of “excavation blades” such as a single excavation blade, a plurality of excavation blades, a spiral one, and a flat plate attached obliquely.
[0020]
<Reference formInvention of the ground investigation device described in <1>
  Reference formThe present invention is characterized in that a large diameter portion is formed on the outer periphery of the rod.
[0021]
<Reference formInvention of the ground investigation device described in <1>
Each reference formIn this invention, load measuring means for measuring the rotational load acting on the rod tip portion is provided in the vicinity of the rod tip.
  The “load measuring means” is composed of a load meter provided in the vicinity of the tip of the rod, and a load measuring means having a transmitting means for transmitting measured measurement data.
[0022]
<Reference formInvention of Ground Survey Device>
Reference form aboveIn any one of the inventions, the rod has an open end hollow, and is provided with a soil collecting jig, and at the soil collecting position of the rotary press-fitted ground, the tip soil that has entered the hollow portion of the rod or the soil below the tip of the rod is the soil. A sampling jig is inserted and sampled from the upper end of the hollow part.
[0023]
<Reference formInvention of Ground Survey Device>
Any of the above reference formsThe invention is characterized in that the excavation blade portion at the tip of the rod can be replaced.
[0024]
<Reference formInvention of Ground Survey Device>
Of the above reference formIn the invention,The excavation blade portion attached to the rod tip is configured to be replaceable, and the short rod tip portion attached to the excavation blade has a larger diameter than the upper rod..
[0025]
<Reference formInvention of Ground Survey Device>
Of the above reference formIn the invention,The excavation blade portion at the tip of the rod is configured to be exchangeable, the short rod tip portion that the excavation blade is attached to has a larger diameter than the upper rod, and the rod tip portion to which the short rod that the excavation blade attaches is connected Characterized by the same diameter as that of the short rod
[0026]
<Reference formInvention of Ground Survey Device>
  Of the above reference formIn the invention, a detachable connecting portion for connecting the rods is provided at an end portion of each rod.
[0027]
<Reference formInvention of Ground Survey Device>
  Of the above reference formThe invention is characterized in that a depth measuring means for measuring the depth of the rod tip and a vertical force measuring means for measuring a vertical force acting on the rod are provided simultaneously with the measurement of the rod rotational load.
[0028]
<Reference formInvention of Ground Survey Device>
  Of the above reference formIn the invention, the large-diameter portion is formed by welding a steel ring to the outer periphery of the rod.
[0029]
<Reference formInvention of Ground Survey Device>
  Of the above reference formIn the invention, the large-diameter portion is formed by making the connecting portion of the rod larger in diameter than the other portions.
[0030]
<Reference formInvention of Ground Survey Device>
  Reference formIn the invention, the rod shaft portion is covered with a sheath tube,PileIt is characterized in that the rotational load at the rod tip can be measured by receiving and separating the peripheral frictional resistance received at the time of penetration with a sheath tube and measuring the rotational load applied to the head of the rod on the rotating means side.
  The rod body and the sheath tube are coupled and fixed at appropriate locations by a coupling and fixing means such as a bolt.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described with reference to the drawings.
<referenceForm 1>
  FIG. 1 is a comparison diagram of the ground measurement method of the prior art and the ground measurement method of the present invention, and FIG.referenceIt is an example of the whole schematic diagram of the ground investigation apparatus of form 1.
  In FIG. 1, according to the ground investigation method of the present invention, the rotational load value at the time of rotational press-fitting of a rod with blades at the tip is measured, so that the rotational load can be continuously measured as shown in the figure. It becomes possible. At this time, it is desirable to automatically record the rod tip depth at the same time, but the length of the press-fitted rod may be manually recorded on the ground and collated with the load data.
[0032]
  For example, in the case of the N value measurement of the prior art of FIG. 1, when a thin soft layer existing in the N value non-measurement portion (70 cm) is between the hard layer and the support layer, this thin soft layer cannot be detected. .
  For this reason, in this case, in the prior art, the upper part of the hard layer is assumed as an assumed support layer based on the N value, the length of the steel pipe pile is designed, and the construction is performed using the assumed support layer based on the N value as the support layer. .
  The hard layer shown in Fig. 1 corresponds to the assumed support layer based on the N value, but if a pile is constructed using this layer as the support layer, there is a soft layer at the lower end of the pile, so the support force required for the design may not be exhibited. There is sex.
  On the contrary,referenceIn the ground measurement method of the invention, since a thin flexible layer can be detected with high accuracy, the steel pipe pile is designed and constructed with the upper portion of the thick support layer below the flexible layer as the stop position.
  of course,referenceThe direction investigated by the invention provides accurate information for construction of other construction piles such as cast-in-place concrete piles and PHC piles.
  AlsoreferenceAccording to the invention, since penetration and load measurement are simultaneously performed, measurement in a short time (ground survey) is possible, and more surveys can be performed at low cost. In the ground where the level difference of the support layer is large, it is possible to investigate all pile positions.
[0033]
  referenceIn the ground survey in the invention, the reliability of the survey data is ensured by reducing the total rotational load at the time of rotary press-fitting of the rod and accurately increasing / decreasing the rotational load detected according to the properties of the corresponding ground. Is important for. Figure 2 shows changes in rotational load (rotational load is measured from changes in hydraulic pressure on the rotating means) when a rod with a drilling blade at the tip of the rod is used for ground survey. The change in rotational load when using a drilling blade with a large-diameter portion formed at regular intervals on the outer circumference of the rod for ground survey is set to ○, and the tip of the rod is made larger in diameter than the upper rod portion. The change in rotational load is shown as x when a large diameter rod tip is provided with excavation blades and a large diameter portion is formed on the outer periphery of the rod is used for ground investigation.
[0034]
  In view of what is shown in FIG. 2, when the large-diameter portion is formed on the outer periphery of the rod, the former is more rotated at the time of press-fitting than the latter than when the large-diameter portion is not formed on the outer periphery of the rod. As the load decreases, it can be understood that the detected rotational load accurately increases and decreases corresponding to the known ground properties. Further, by forming a large-diameter portion on the outer periphery of the rod and making the tip end portion of the rod to which the excavation blades are attached have a larger diameter than the upper rod portion, the rotational load at the time of rotational press-fitting is further reduced. This result is because the large-diameter portion of the rod and the large-diameter portion of the rod tip portion reduce the circumferential friction of the rod. One means for forming a large-diameter portion on the outer periphery of the rod is to make a steel member such as a reinforcing bar into a ring shape and fix it to the outer periphery of the rod by welding. In order to detect the resistance of the rod tip more accurately, load measuring means may be provided at the tip of the rod.
[0035]
  referenceAs shown in FIG. 3, the ground survey device 1 of the form 1 has the rod 2 having a diameter of about 50 mm with the spiral excavation blade 9 attached to the tip portion or the excavation blade 9 attached to the tip portion, and the outer periphery thereof. The rod 2 having a diameter of about 50 mm formed with the large diameter portion 100, the rod rotating means 3 comprising a rotary press-fitting device for rotationally press-fitting the rod 2, and the hydraulic pressure and voltage value of the rotary press-fitting device act on the rod. It consists of a load measuring device 4 that detects the load being applied. In this way, the load acting on the rod 2 is measured by the output of the rotary press-fitting device.referenceForm 1 uses a small-diameter rod, so the rotary press-fitting device often uses a small leader type or a crane, and is small and more compact, which is effective in terms of work efficiency and cost.
  belowReference orIn the description of the embodiment, it has been described above.referenceThe same reference numerals are given to the same components as those of the embodiment, and the description thereof is omitted.
[0036]
<referenceForm 2>
  FIG. 4 illustrates the present invention.referenceIt is a whole schematic diagram of the ground investigation device of form 2.
The ground surveying device 1 has a rod 2 having a diameter of about 100 mm with a drilling blade 9 attached to the tip, or a rod diameter in which the drilling blade 9 is attached to the tip and a large diameter portion 100 is formed on the outer periphery at regular intervals. A rod 2 having a thickness of about 100 mm, a rod rotating means 3 comprising a rotary press-fitting device for rotationally press-fitting the rod 2, a rotation built in the vicinity of the tip of the rod 2, a load meter for vertical force, and measurement It comprises a load measuring means 4 having a transmitting means for transmitting measurement data, and a load data reception processing device 5 for receiving (measuring / outputting) the measurement data from the load measuring means 4. As described above, the rotational load changes according to the ground strength, but the vertical force may remain constant depending on the penetration state of the rod, and the pushing force or the pulling force may be applied. It is desirable to measure rotational load, vertical force and depth simultaneously.
The rod 2 has a tip 6 having a digging blade 9 and a load measuring rod member 8 having a hollow portion 7 for transmitting a radio wave in which load measuring means 4 is detachably attached to the tip 6. It consists of a connecting rod material 10 having a hollow portion 7 that is detachably connected to the rod material 8 with load meter. Although FIG. 10 shows the large-diameter portion 100 formed by a steel ring, the large-diameter portion 100 may be attached only to the tip portion 6 depending on the ground conditions. Moreover, the large diameter part 100 of a rod may be unnecessary.
[0037]
  FIG. 5 illustrates the present invention.referenceIt is a perspective view which shows the structure of the rod of a ground investigation apparatus of the form 2, and a front-end | tip part.
  At the upper end of the tip 6, the rod 8 with load meter and the connecting rod 10, there are groove portions 13, 13 facing the projecting portions 11, 11 facing each other, and a connection fixing pin 15 (not shown) opened in the projecting portions 11, 11. The connection part 17 which consists of the pin hole 16 which inserts a volt | bolt) is provided, and the connection of the same structure (direction is uneven | corrugated is reverse) which meshes with the connection part 17 in the lower end of the rod 8 with a load meter and the connection rod 10. Is provided. Each rod member can be easily connected and disconnected.
[0038]
  The diameter of the rod is arbitrary, but if the diameter is too large, the necessary construction equipment becomes large and too large for ground surveys, so a diameter of about 100 mm or less is desirable. With such a diameter, the rotational load necessary for ground penetration is often about 2 to 3 tm or less, and construction equipment can be small.
  In order to directly measure the tip load, a load meter may be installed on the tip blade portion or the shaft portion in the vicinity of the tip blade portion.
  In this example, the excavation blade at the tip of the rod has a spiral shape whose diameter is about twice the rod diameter.
[0039]
  From the load measuring means 4, the measurement data is transmitted by radio waves to the receiving antenna 20 through the hollow portion 7.
  In addition to this, the transmission method of the measurement data to the load data reception processing device 5 is one using an electric wire, one using ultrasonic waves or a laser beam, one that flows as an electric signal through the rod and detects it from the rod, There are various methods, such as detecting what flows in the ground.
  A load sensing unit (not shown) of the load measuring means 4 includes a method of detecting a change in voltage and current due to pressure by sandwiching a pressure sensor between the engaging protrusions 11 and 11, and twisting of the rod. There are methods such as by sensing.
[0040]
  As described above, the load measuring means is based on detecting a change in voltage value or current value that changes depending on the load of the rod rotating means in the first embodiment.referenceNot only the load meter provided in the rod tip portion of the form 2 but also various ones such as a load rotating meter attached to the rod rotating means.
  In addition, there are various methods such as a rod rotating means using a rotating means supported and guided by a column so that it can be moved up and down, and a tubebing device.
[0041]
  Further, the rod tip portion 6 ′ shown in FIG. 6 is a case where the diameter of the portion where the excavation blade 9 ′ at the tip of the rod is attached is larger than the diameter of the upper rod.
  With such a configuration, since a thick hole can be made at the tip, the effect of friction between the peripheral side surface of the upper rod and the ground is reduced, and the effect of improving the measurement accuracy of the rotational load at the tip can be obtained. . When the influence of friction can be made sufficiently small by making the tip diameter larger than the rod diameter, the large diameter portion 100 of the rod may be unnecessary.
  Even in such a configuration, it is possible to easily replace the excavation blade portion where the rod tip portion is heavily worn with a new one.
  Regarding the connection structure, the case where the rod diameter is increased is the same as the case of the same thickness.
[0042]
  The rod 21 shown in FIG. 7 has a connecting female portion 23 having a large diameter at one end and a connecting male portion 22 that fits the connecting female portion 23 at the other end. By connecting a plurality of the rods, the connecting portion of the rod has a larger diameter than the other rod portions, and a large diameter portion is formed at regular intervals on the outer periphery of the rod. With such a configuration, the strength of the connecting portion increases, the large diameter portion formed on the outer periphery of the rod reduces the influence of friction with the ground around the rod, reduces the rotational load, and reduces the rotational load. The effect that the measurement accuracy is improved is obtained.
[0043]
  In the structure shown in FIG. 8, the excavation blade portion at the tip of the rod is configured to be replaceable, and the short rod tip portion 6 ′ to which the excavation blade 9 is attached has a larger diameter than the upper rod. By making the tip portion 23 'of the rod 21' to which the short rod 6 'to be attached has the same diameter as that of the short rod 6', a thick hole can be made at the tip portion, and the peripheral side surface of the upper rod and the ground As a result, the measurement accuracy of the rotational load at the tip is improved, and the strength of the rod tip can be increased.
[0044]
<referenceEmbodiment 3> FIG.referenceIt is a perspective view which shows the connection structure of the rods of the ground investigation apparatus of the form 3.
  One rod 24 has a connecting male portion 22 formed of a hexagonal column projection at one end, and an end portion of the other rod 25 has a connecting female portion 23 into which the connecting male portion 22 is fitted. Reference numerals 16 and 26 denote a pin hole and a pin fitting groove into which the connection fixing pin 15 is fitted.
[0045]
<referenceForm 4>
  FIG. 10 shows the present invention.referenceIt is a perspective view which shows the connection structure of the piles of the ground investigation apparatus of the form 4.
  The connecting rod 27 forms a connecting male part 28 composed of a cylindrical protrusion at the end of one rod 30, and forms a connecting female part to which the connecting male part fits at the end of the other rod 31, The connecting male portion 28 is provided with two inverted T-shaped grooves 32 at two opposing positions, and the connecting female portion 29 is provided with a protrusion 33 that fits into the groove 32 from the top and moves laterally so as not to come off. Is provided.
[0046]
<referenceForm 5>
  FIG. 11 shows the present invention.referenceIt is a structural diagram of the ground survey device of form 5.
  The ground investigation device 57 stores the investigation rod 42 having the excavation blade 41 at the tip in the sheath tube 44, and a flat table 45 is provided on the upper portion of the excavation blade 41, and the flat table 45 and the tip of the sheath tube 44 are in contact with each other. It is formed so that a slight gap is formed, and the mutual position is maintained between the sheath tube and the rod by an O-ring or a bearing 43 as appropriate without any force transmission between the rod and the sheath tube. Yes.
[0047]
  FIG. 12 is a perspective view showing a connecting portion of the sheath tube.
  The sheath tube 44 has a connection portion 48 that connects the sheath tubes at substantially the same site as the pile connection portion 22 of the investigation rod 42.
  The connecting portion 48 is a mesh-type connection with an uneven end, and is provided with protrusion rings 49, 49 on the outer side, and has two ring fitting grooves 50 in which the protrusion rings 49 are fitted in a mating structure. The cover 52 and the bolt 46 are connected and fixed.
  On the upper part of the flat table 45, an adapter 53 for preventing the sheath tube 44 from blurring and preventing sediment from entering is fixed.
  By adopting a sheath tube type, the rotational resistance (load) of the tip (blade) can be reduced by measuring the load on the rod head or the rod rotating means without providing the rotational load measuring means at the tip. Will be measured.
[0048]
  The investigation rod 42 is rotationally press-fitted by a rotational press-fitting means 59 connected to a rotational load measuring means (not shown) for continuously measuring the rotational load value, and the sheath tube 44 is rotationally press-fitted by the rotary press-fitting means 60. Both rotary press-fitting means 59 and 60 are set so as to rotate synchronously, and the rod 42 and the sheath tube 44 are rotationally press-fitted together without shifting.
[0049]
<referenceForm6>
  FIG. 13 shows the present invention.referenceIt is a construction procedure figure which shows the ground investigation method of the form 6.
(B) Survey rod rotation press-fitting rotation load measurement process
  The open end opening / closing means 68 provided with a tip closing member 67 at the tip of the operating rod 66 was inserted from the top of the check rod 65 to close the open end. Rotate and press into the soil collection site.
  The rotational load value of the investigation rod 65 is continuously measured during rotational press-fitting by a rotational load measuring means (not shown).
(B) Opening end opening / closing means removal step
  When the pile tip reaches the soil collecting place, the rotary press-fitting is stopped, the open end opening / closing means 68 is taken out, and the investigation rod 65 is brought into the open end state.
[0050]
(C) Soil collection process
  A pipe-shaped soil sampling tube 69 is inserted into the survey rod 65 from above, and the soil 70 that has entered the rod from the ground at the tip of the survey rod 65 is taken into the soil sampling tube 69.
  When the necessary amount of soil 70 has been taken in, the soil collection tube 69 is pulled up to the ground and the soil 70 is collected.
(D) Re-examination rod rotation press-fitting rotation load measurement process
  The open end opening / closing means 68 is inserted into the soil collection pipe 69, and the open end is closed and the rotational load value measurement is performed until the next soil collection site is closed.
A predetermined soil 70n ·· is collected by repeating the steps (a) to (d).
[0051]
<referenceForm 7>
  FIG. 14 shows the present invention.referenceIt is a conceptual diagram which shows the ground investigation method of the form 7.
  The investigation rod 65 is stopped in a state where it reaches the support layer, and a weight 75 whose weight is known is placed on the investigation rod 65 to perform a loading test.
  There are various loading test methods, but the illustrated one applies a load 75 on the survey rod 65, reads the settling of the survey rod 65 by the indicating member 73 and the scale 74, and estimates the actual bearing force. To do.
  Based on the data obtained in this way, it can be reflected in the construction plan of the main pile.
[0052]
  The conventional ground survey was to investigate only a part of the burial site of this pile because of the time and cost of the survey. For this reason, at the stage of actual construction, it was often found that the bearing capacity of the piles varied and it had an adverse effect on the structure.
  In this respect, the present invention is quick to investigate,referenceCollecting soil of form 6, andreferenceIt is easy to carry out at most parts of the planned site for embedding the pile, such as the loading test of Form 7, and enables a highly reliable ground survey.
[0053]
<Embodiment1>
  Embodiment1Using the numerical value obtained by measuring the rotational load at the rod head and measuring the rotational load at the time of reverse rotation and pulling out, the rotational load acting on the rod shaft is separated by the mathematical formula, and the rod tip Only the rotational load acting on the part is calculated.
  If the rotational load on the rod head during rotary press-fitting is Tt
    Tt = Tb + Tf (1)
        Tt: Rotational load on the rod head during rotary press-fitting
        Tb: Rod end rotation load
        Tf: Rotational load due to friction of rod shaft
    If the rotational load when pulling out in reverse is Tt '
    Tt ′ = Tb ′ + Tf ′ = αTb + βTf (2)
        Tt ': rotational load when pulling out with reverse rotation
        Tb ': The rod tip (blade part) acting when pulling out in reverse rotation
                  Rotational load
        Tf ': due to the friction of the rod shaft acting when pulling out in reverse rotation
                  Rotational load
        α− = Tb ′ / Tb
        β = Tf ′ / Tf
            (The α and β are obtained by accumulating experiments.)
      From (1) and (2),
        Tb = (Tt′−βTt) / (α−β)
  The rotational load (Tb) at the rod tip can be obtained.
[0054]
  The inventor of the present application has already filed a patent application (Japanese Patent Application No. 2000-272639), and in the patent application, the ground obtained by ground investigation in the construction method of the rotary press-fit steel pipe pile provided with a spiral blade at the tip and rotationally press-fitted into the ground From the strength (N value), the torque value required at the time of construction is calculated by the following equation, and the construction method of the rotary press-fit steel pipe pile is clarified.
Tt = a ・ N ・ Dp^m-B, Lt, Dp (4)
(Here, Tt: Torque, Dp: Pile diameter, Lt: Overload, N: N value, a, b, m: Coefficient and index)
In addition, in the detailed description of the aforementioned patent application,
m = 2 to 3, a = α / X1, b = Y1 / X1
α: Coefficient of friction between ground and blades (steel plate)
  X1 = 2π · atr / {(2/3 + i) α · π + g} (5)
  Y1 = atr (i · α · π + g) / {(2/3 + i) α · π + g} (6)
  atr: Transmission rate of the torque Tt and the upper load Lt to the lower end of the pile
  i = {2 (h³-1)} / {3 (h²-1)}
  (H: blade diameter ratio (= Dw / Dp), Dp: pile diameter, Dw: blade diameter, g: ratio of pitch of spiral blade to pile diameter (= P / Dp), P: start and end of spiral blade Open)
  Expression (3) shown in claim 9 of the present application is obtained by modifying the above expression (4) into a form of N =.
  Since Formula (4) is for the construction management of a pile, it is considered that the torque and the overload (vertical load in the present invention) use the measured value at the pile head position as a standard. However, the present invention includes both the case where the rotational load (torque) and the vertical force are measured near the rod head and the case where it is directly measured at the rod tip.
When the torque and the vertical force are measured near the rod head, the coefficient in the equation (3) may be obtained by the equations (5) and (6).
  When measuring the torque and the vertical force at the rod tip, the term of the transmission rate is unnecessary, and the equations (5) and (6) may be changed to the following equations (7) and (8).
  X1 = 2π / {(2/3 + i) α · π + g} (7)
  Y1 = (i · α · π + g) / {(2/3 + i) α · π + g} (8)
  Further, when the influence of the vertical force is relatively small, it may be calculated as “L = 0” or “L = fixed load placed on the top of the rod such as a motor”.
[0055]
    Furthermore, this embodiment performs various experiments by rotating and pressing experimental piles into various experimental grounds with known properties (including artificially created model grounds with known properties). Various data are collected and analyzed through experiments, and based on the results, the ground strength and pile support force are estimated from the rotational load value (Tb) at the tip.
  (1) If the rotational load Tb of the tip blade portion can be obtained, the N value of the ground is estimated from the value, and the support force is calculated.
  Conventionally, the value of Tb in the ground where the N value is measured is measured, and the correlation between the N value and Tb is obtained. However, many researchers have already pointed out that the N value itself is very variable data.
[0056]
  (2) The value of Tb is used as the strength of the ground, and the supporting force is estimated from Tb.
  Tb itself is more reliable as ground resistance, and the correlation with bearing capacity can be clarified by accumulating data.
  Since Tb is static data or continuous data, the ground strength can be measured with higher accuracy than the N value.
  As described above, the relationship between Tb and bearing force is obtained by collecting data by experiments using model ground (artificially created ground with known properties).
  According to this method, it is not necessary to provide a special measuring mechanism for the investigation rod, and high-accuracy data can be acquired by an easy method of continuously measuring the rotational load of the rotary press-fitting means.
  The ground strength and pile support force can be estimated from the estimated rotational load of the tip blade.
[0057]
【The invention's effect】
  Since the present invention is configured as described above, the following effects can be obtained.
<Effect of the first invention (ground investigation method)>
  Rotating load and rod tip depth are continuously measured when a rod equipped with a drilling blade on the rod tip side is rotationally pressed into the ground. It continues and produces the effect that high-precision ground information can be obtained.
  In particular, since the investigation method is the same as the method of construction of rotary press-fit type steel pipe piles, the design and construction of rotary press-fit type steel pipe piles that are accurate, high-precision, and without worry are realized.
  For example, as shown in FIG. 1, even if there is a thin soft layer between the hard layer and the support layer, the number of flexible layers, intermediate layers, and hard layers that can accurately grasp the presence and thickness thereof. Even in the existing ground, the thickness and properties of those formations can be grasped with high accuracy, and appropriate measures can be taken, and defects in the prior art can be eliminated.
[0058]
Also, there is no operation of lifting and re-penetrating the rod, and the penetration with piles with excavation blades is better intrusion than the drilling of the standard penetration test, so depending on the ground conditions, the depth of 50m As is clear from the fact that, according to the present invention, it took 3 to 3 hours to complete the standard penetration test, the survey time was greatly shortened. Play.
  In addition, since the blades have the action of pulling the shaft part because the tip blades exert a propulsive force, they are not penetrated only by the pushing force from the pile head, so the pushing force (compression) acting on the rod is cone Smaller than penetration test. As a result, the rod does not buckle even at a large depth, and a large depth survey can be carried out efficiently and safely.
[0059]
<Effect of the second invention (ground investigation method)>
  By providing a drilling blade on the rod tip side and forming one or more stages of ring-shaped protrusions on the outer periphery, the rotational load and the tip depth of the rod are continuously measured when the investigation rod is rotationally pressed into the ground. Therefore, it is possible to measure continuously and accurately by reducing the rotational load at the time of rotary press-fitting, and accurately matching the corresponding ground properties with the detected rotational load. There is an effect that the ground information can be obtained.
[0060]
<Effect of the third invention (ground investigation method)>
  In addition to the effect of the first invention, when the rotational load is measured by the load measuring means provided on the rod rotating means side for rotating the rod, there is an effect that the apparatus can be made simple and inexpensive. In addition, the load acting on the rod end is not measured directly, but is converted into the load from the hydraulic pressure or current rotating the auger, so the value is the load due to the rod end load + rod peripheral friction. However, according to the experimental results of the inventors of the present application, the load caused by friction generated during construction is relatively small, and depending on the soil conditions, the load is 80% at the rod tip even if the rod length is about 60 m. I was communicating. Therefore, the strength of the rod tip ground can be sufficiently sensed even with the load measured by the load measuring means provided on the rod rotating means side. However, depending on the ground conditions (such as when there is an intermediate layer in the middle), the influence of friction cannot be ignored. In such a case, the influence of friction can be reduced by forming a large diameter portion in the rod shaft portion.
[0061]
<Effects of reference invention (ground survey method)>
  rotationIn the case where the load is measured by a load measuring means provided on the rod tip side, there is an effect that the rotational load acting on the rod tip (excavation blade) can be measured with higher accuracy.
  That is, it is possible to measure only the properties of the ground without being affected by the friction between the rod shaft portion and the ground. It means grasping accurate information of the ground layer.
[0062]
<Effects of the first, fourth and fifth inventions (ground investigation method)>
  Measure the forward rotation load value at the time of positive rotation press-fitting (drilling rotation) of the rod and the reverse rotation load value at the time of reverse rotation of the rod (at the time of pulling out rotation), and use various experimental grounds with known properties in advance. The forward rotation load value of the excavation blades can be obtained with the calculated coefficient, enabling measurement using only the rotational load measurement means on the ground, and no need for complicated equipment, so that the ground data can be grasped in a short time. Can be achieved, and the cost can be reduced.
  In addition, in order to obtain | require by calculation the rotational load Tb which acts on a rod front-end | tip (excavation blade) from normal rotation load value, reverse rotation load value, and coefficient (alpha) and (beta), it is possible by the formula mentioned above.
  If the forward rotation load value Tb of the excavation blade is obtained, the N value of the ground can be estimated from that value, and the bearing force can be calculated. Or the value of Tb can be used as the strength of the ground, and the supporting force can be estimated from Tb. Tb itself is more reliable as a ground load, and the correlation with the supporting force can be clarified by accumulating data. Since Tb is static data or continuous data, it has an effect that the ground strength can be measured more accurately than the N value.
[0063]
  In addition, since the mechanism of the small-diameter rod for ground investigation is the same as that of the large-diameter rotary press-fit steel pipe pile, the “investigation data” according to the invention of the present invention of the small-diameter rod is referred to as “geologic data” described later By using it as comprehensive data combined with `` test data '', it can be used as important data for guaranteeing the bearing capacity of large-diameter main piles or making a construction plan, and it can prevent construction loss etc. Play.
[0064]
<6thEffects of the Invention (Ground Survey Method)>
  Since the characteristic data of the stratum can be obtained from the soil collected at each depth of the stratum, the effect of making the construction of this pile more accurate can be achieved.
[0065]
<7th and 8thEffects of the Invention (Ground Survey Method)>
  Since the depth data and vertical force data of the rod tip can be obtained, the relationship between the forward rotation load value and the depth can be accurately measured. This makes it possible to clearly show the relationship between depth and ground strength.
In addition, by measuring and recording the vertical force, it is converted into a ground strength considering the influence of the vertical force, and it is possible to perform a more accurate ground survey. Moreover, in this ground investigation method, as shown in Embodiment 7, since the settlement data of the rod to the ground due to loading on the rod can be obtained, the possibility of settlement of the main pile is accurately predicted. It is possible to form a highly reliable support pile group with a stable support force by construction with less loss suitable for each ground.
  Since the mechanism of the small-diameter rod for ground investigation is the same as that of the large-diameter rotary press-fit steel pipe pile, the load test and construction data of the small-diameter rod can be used to guarantee the bearing capacity of the large-diameter main pile or to make a construction plan. It can be used as important data. Until now, there was only about drilling data and soil test data before construction, so the level of support layer was not uniform or the workability change due to the strata not expressed in N value was not known, so the piles at the time of construction Although the length has been adjusted and the workability has changed unexpectedly, this problem is solved by the present invention.
[0066]
<referenceEffect of Invention (Ground Survey Device)>
  A ground surveying device comprising a rod having an excavating blade at the tip and a load measuring means for measuring a rotational load provided in an appropriate part of the rod or provided on a rotating means side for rotating the rod. Thus, the rotational load when the rod is rotationally press-fitted into the ground can be continuously measured by the load measuring means, and there is an effect that precise ground survey data can be obtained.
[0067]
<referenceEffect of Invention (Ground Survey Device)>
  Load for measuring rotational load, provided with a drilling vane at the tip and a large-diameter portion on the outer periphery, and at the appropriate part of the rod or on the rotating means side that rotates the rod It is a ground survey device consisting of measuring means, and it is possible to continuously measure the rotational load when the rod is rotationally press-fitted into the ground with the load measuring means, and the rotary press-fitting is performed by the large-diameter portion of the outer periphery of the rod. The rotational load at the time is reduced, and the detected rotational load changes accurately in accordance with the properties of the ground, so that precise ground survey data can be obtained.
[0068]
<referenceEffect of Invention (Ground Survey Device)>
  Load measuring means for measuring the rotational load acting on the rod tip is installed near the rod tip (tip blade or shaft near the tip blade), eliminating the load caused by rod circumferential friction. Thus, the tip load can be directly and accurately measured.
[0069]
<referenceEffect of Invention (Ground Survey Device)>
  Since the ground investigation device has a hollow rod at the open end and is equipped with a soil collecting jig, it is possible to obtain characteristic data of the formation from the soil collected at each depth of the formation.
[0070]
<referenceEffect of Invention (Ground Survey Device)>
  Since the rod tip can be replaced, it is possible to use excavated blades with severe wear by replacing them with new ones, and the same survey rod can be used to obtain accurate survey data continuously. Play.
[0071]
<referenceEffect of Invention (Ground Survey Device)>
  By making the diameter of the rod large only at the tip, it is possible to make a hole larger than the upper rod in the ground, so that the influence of friction around the rod can be reduced and the tip load can be measured more accurately. Become.
[0072]
<referenceEffect of Invention (Ground Survey Device)>
  A hole larger than the upper rod can be drilled in the ground by making the short rod with which the excavation blades are attached and the tip of the rod to which the short rod is connected larger than the upper rod part. The tip load can be measured with higher accuracy, and the strength of the connecting portion is increased.
[0073]
<referenceEffect of Invention (Ground Survey Device)>
  Since it is a ground surveying device that has a detachable connecting part for connecting rods at the end of each rod, the rods can be connected easily, eliminating the field welding work and connecting work time Is shortened, and the workability is greatly improved.
[0074]
<referenceEffect of Invention (Ground Survey Device)>
  The ground survey device is equipped with a depth measuring means that measures the depth of the rod tip and a vertical force measuring means that measures the vertical force acting on the rod simultaneously with the measurement of the rod rotation load, so it has excellent effects. Play.
[0075]
<referenceEffect of Invention (Ground Survey Device)>
  Rotating load that is detected by reducing the rotational load at the time of rotational press-fitting by the large diameter part of the outer periphery of the rod by forming a large diameter part by welding a steel ring in the form of a ring of rebar etc. on the outer periphery of the rod Changes accurately according to the properties of the ground, and there is an effect that precise ground survey data can be obtained.
[0076]
<referenceEffect of Invention (Ground Survey Device)>
  By making the connecting part of the rod larger in diameter than the other part, a large diameter part is formed on the outer periphery of the rod, the large diameter part on the outer periphery of the rod reduces the rotational load at the time of rotary press-fitting, and the detected rotational load is the ground It changes accurately according to the properties of the ground, and precise ground survey data can be obtained, and further, the strength of the connecting portion is increased.
[0077]
<referenceEffect of Invention (Ground Survey Device)>
Since the rod shaft part of the rod is covered with a sheath tube so that the rod shaft part is not affected by the ground, it is a ground investigation device configured to measure the rotational load value of the excavating blade at the tip of the rod. The effect is that the properties can be measured with high accuracy.
[Brief description of the drawings]
FIG. 1 is a comparison diagram of a conventional ground measurement method and a ground measurement method of the present invention.
FIG. 2 is a comparison diagram of ground measurement methods when the rod shape of the present invention is changed.
FIG. 3 of the present inventionreferenceThe whole schematic diagram of the ground investigation device of form 1.
FIG. 4 of the present inventionreferenceThe whole schematic diagram of the ground investigation device of form 2.
FIG. 5 shows the present invention.referenceThe perspective view which shows the structure of the rod of a ground investigation apparatus of form 2, and a rod front-end | tip part.
FIG. 6 of the present inventionreferenceThe perspective view which shows the structure at the time of making the diameter of the rod front-end | tip part of form 2 thick.
[Fig. 7] of the present invention.referenceThe figure which shows the structure which makes the connection part of the rod which is a form larger diameter than another part.
[Fig. 8] of the present inventionreferenceThe figure which shows the structure which made the connection part of the rod front-end | tip which is a form large diameter.
FIG. 9 shows the present invention.referenceThe perspective view which shows the connection structure of the piles of the ground investigation apparatus of the form 3. FIG.
FIG. 10 shows the present invention.referenceThe perspective view which shows the connection structure of the piles of the ground investigation apparatus of the form 4.
FIG. 11 shows the present invention.referenceThe structure figure of the ground investigation apparatus of form 5.
FIG. 12 shows the present invention.referenceThe perspective view which shows the connection part of the sheath pipe of form 5
FIG. 13 shows the present invention.referenceThe construction procedure figure which shows the ground investigation method of form 6.
FIG. 14 shows the present invention.referenceThe conceptual diagram which shows the ground investigation method of form 7.
[Explanation of symbols]
    1 ... Ground survey device
    2 ... Rod
    3. Rod rotating means
    4. Load measuring means
    5. Load data reception processing device
    6 ... Rod end
    6 '... ・ Large rod end
    7: Hollow part
    8 ... Rod with load meter
    9 ... Excavation blade
    9 '・ ・ ・ ・ Drilling blade with large diameter
  10 ... Connecting rod material
  11 ... Projection
  13 ... Groove
  16 ... pin hole
  17 ... Connecting part
  19 ... For storage
  20 ... Receiving antenna
  21 ... Rod
  22 ... Linked male part
  23 ... Connected female part
  24 ... Rod material with load meter
  26 ... Pin fitting groove
  25 ... Connecting rod material
  27 ... Rod
  28 ...... Linked male part
  29 ...... Connecting female part
  30 ... Rod material with load meter
  31 ... Connecting rod material
  32 ... Groove
  33 ... Protrusions
  40: Ground survey device
  41 ... Drilling blade
  42 ... Survey rod
  43 ... O-ring or bearing
  44 …… Sheath tube
  45 ... Flat stand
  47 ... Rotary press-fitting means
  48 ... Connection part
  49 ... Projection ring
  50 ... Ring fitting groove
  52 .. Connecting cover
  53 ... Adapter
  54 ... Connecting pin
  55 ... Screw hole
  57 .. Ground survey device
  58 ... Bolt
  59... Rotary press-fitting means
  60... Rotary press-fitting means
  61 ... Screw hole
  64 ... excavation blade
  65: Survey rod
  66 .. Operation bar
  67... Tip closing member
  68... Opening end opening / closing means
  69 …… Soil collection pipe
  70 ... Sat
  73... Needle member
  74 ... Scale plate
  75 ... Weight
  100 ··· Large diameter part

Claims (8)

In the ground survey method that continuously measures the rotational load and the tip depth of the rod when a rod with excavating blades at the tip is rotationally press-fitted into the ground, the rotational load at the time of press-fitting with the rod head is measured. A ground survey characterized by measuring the rotational load when it is measured and rotating backward and pulling it out to separate the rotational load acting on the rod shaft and calculating only the rotational load acting on the rod tip Method.   2. The ground investigation method according to claim 1, wherein a large-diameter portion is formed on an outer periphery of the rod. The rotational load, ground survey method of claim 1 or 2, wherein the composed so as to more measured load measurement hand stage provided on the rotating means side for rotating the rod. The ground investigation method according to any one of claims 1 to 3, wherein in calculating only the rotational load acting on the rod tip, the following mathematical formula is used.
Tt = Tb + Tf (1)
Tt: Rotational load on the rod head during rotary press-fitting Tb: Rotational load on the rod tip Tf: Rotational load due to friction on the rod shaft Tt ′ = Tb ′ + Tf ′ = αTb + βTf (2)
Tt ': Rotational load at the time of reverse rotation and pulling out Tb': Rotational load at the tip of the rod pile that acts when pulling out in the reverse direction Tf ': Rotational load due to friction of the rod shaft portion acting at the time of reverse rotation and pulling out α = Tb ′ / Tb
β = Tf ′ / Tf (The α and β are obtained by accumulating experiments.)
From (1) and (2),
Tb = (Tt′−βTt) / (α−β) Etc. and has a variety of experimental locations Release of Aware properties including a model ground of known properties that have been prepared artificially, performs various experiments to rotate pressing the vaned rod, various obtained by the experiment The ground investigation method according to any one of claims 1 to 4 , wherein the ground strength and the supporting force of the pile are estimated from the rotational load value (Tb) of the rod tip portion according to claim 4 based on the data. . The rod is open-ended hollow, the rod is rotationally press-fitted into the ground, the rotary press-fitting of the rod is stopped at the soil sampling position, the soil sampling jig is inserted into the rod, and the tip that has entered the rod hollow portion by the soil sampling jig The ground investigation method according to any one of claims 1 to 5 , wherein soil or soil below the rod tip is collected. The ground survey method according to any one of claims 1 to 6 , wherein the vertical force acting on the rod is automatically measured simultaneously with the automatic measurement of the rod rotation load. Using the rotational load and vertical force of the rod measured in the ground investigation method according to claim 7 and converting the rotational load into torque, estimating the N value of the investigation target ground by the following equation (3): Characteristic ground survey method.
N = (T + b · L · Dp) / (a · Dp ^m ) (3)
Here, N: N value of ground, Dp: Pile diameter, T: Torque (converted from rotational load), L: Vertical force, a, b, m: Coefficient and index

Images