JP6929676B2 - Tip resistance estimation system, fluid injection combined press-fitting construction system, and tip resistance estimation method - Google Patents

Description

The present invention relates to a tip resistance estimation system for estimating tip resistance by a press input measured during press fitting of a pile, a press-fitting construction system with fluid injection, and a tip resistance estimation method.

Conventionally, the press-fitting method in which piles such as steel sheet piles and steel pipe piles are statically penetrated into the ground by pressure input has been mainly used in urban areas because of its advantages such as low vibration and low noise and no need for temporary construction. Such a press-fitting method also includes a water jet combined press-fitting method. In the water jet combined press-fitting method, the tip resistance and peripheral surface resistance can be reduced by injecting water as a fluid toward the ground around the pile, which is effective even on the ground with large tip resistance and peripheral surface resistance. (See, for example, Patent Documents 1 and 2). In the construction by these press-fitting methods, the construction method and the like are generally planned based on the results of the preliminary ground survey. In the case of a plan based on this ground survey, there are many cases where the construction does not proceed as planned due to encountering ground conditions different from the survey results during the construction work.
On the other hand, the pressure input can be measured during the press fitting of the pile. The pressure input information includes tip resistance, peripheral surface resistance, and inter-joint resistance, and if these information can be separated by some method, it will lead to more efficient construction and estimation of ground information. .. In particular, it is considered effective to separate the tip resistance from the above information.

As a method of extracting the tip resistance from the pressure input, a method of attaching a measuring instrument such as a load meter to the tip of the pile as in the cone penetration test (CPT) is described in Non-Patent Document 1, for example.
Further, Patent Document 3 describes a geological estimation method and a geological estimation system for estimating tip resistance without attaching a measuring instrument to a pile by utilizing an operation called "punching" during press-fitting work.
Further, Patent Document 4 discloses a method and an estimation system for estimating the tip resistance of a rotating pile, which estimates the tip resistance from information on pressure input and torque during rotational press-fitting.

Japanese Unexamined Patent Publication No. 2000-54382 Japanese Unexamined Patent Publication No. 2017-25653 Japanese Unexamined Patent Publication No. 2014-177826 Japanese Unexamined Patent Publication No. 2015-017493

"Study on soil classification and conversion N value based on PPT data" Yukihiro Ishihara, Nanase Ogawa, Saburo Kinoshita, Kozo Tagaya, Japanese Geotechnical Society, Recent Sounding Technology and Ground Evaluation Symposium No. 143, Proceedings pp.85-90, 2009

However, the conventional method for estimating the tip resistance of a pile during press fitting has the following problems.
That is, providing a measuring instrument such as a load cell at the tip of the pile as in Non-Patent Document 1 is an additional cost such as the cost of the measuring instrument itself and the cost of adding the pile tip structure for providing the measuring instrument to the pile. Costs are incurred.
In addition, to use such a pile at a construction site, it is necessary to press-fit a pile equipped with a measuring instrument and then pull it out, and it is troublesome to bring the measuring device to the site and connect the measuring device to the measuring device. There was room for improvement in that respect because of the time-consuming work involved.

Further, in the estimation method shown in Patent Document 3 that utilizes the operation of "punching" during press-fitting construction, it is not necessary to introduce a costly measuring instrument, but the estimated values are discrete in the depth direction. There was a problem that it was not suitable for detecting thin layers and confirming the bearing capacity at the completion of press fitting.

Further, the method using the pressure input and the torque during the rotational press-fitting as shown in Patent Document 4 can extract continuous information in the depth direction, but requires not only the pressure input but also the torque as an input condition. Therefore, there is a problem that it cannot be applied in the case of press-fitting without rotating.

In particular, in the press-fitting method using a water jet as shown in Patent Document 1, there is a problem that the tip resistance cannot be accurately estimated only by the pressure input because the action of the fluid injected from the nozzle also occurs.

The present invention has been made in view of the above-mentioned problems, and in the fluid injection combined press-fitting method in which the pile is press-fitted while injecting the fluid into the ground around the pile, no additional construction cost and working time are generated. It is an object of the present invention to provide a tip resistance estimation system, a fluid injection combined press-fitting construction system, and a tip resistance estimation method capable of continuously and accurately estimating the tip resistance during press-fitting in the depth direction.

In order to achieve the above object, the tip resistance estimation system according to the present invention uses a fluid injection combined press-fitting method in which the pile is press-fitted while injecting fluid toward the ground around the pile. A fluid parameter that calculates the fluid parameter value, which is a value calculated based on the measured value, using the measured value related to the fluid supplied around the pile in the tip resistance estimation system for obtaining the tip resistance. Value calculation unit and
Based on the fluid parameter value calculated by the fluid parameter value calculation unit and the pressure input of the pile obtained at each depth, press-fitting is performed by the tip resistance at each depth and the fluid injection at each depth. It is characterized by including a resistance degree calculation unit for calculating the peripheral surface resistance, which is a value per unit area of the peripheral surface resistance acting between the peripheral surface of the pile and the ground.

Further, the fluid injection combined press-fitting construction system according to the present invention is a fluid injection combined press-fitting construction in which the pile is press-fitted while injecting fluid toward the ground around the pile by a press-fitting device using the above-mentioned tip resistance estimation system. In the system, the press-fitting device includes a depth measuring means capable of sequentially measuring the depth of the pile tip, a pressure input measuring means capable of sequentially measuring the pressure input of the pile, and a soil length in the pipe of the pile. An in-pipe soil length measuring means and a fluid measuring means capable of measuring measured values related to the fluid supplied around the pile are provided, and the depth, pressure input, in-pipe soil length and the area around the pile measured by each means are provided. The tip resistance is determined based on the measured value of the fluid supplied to the vehicle.

Further, in the tip resistance estimation method according to the present invention, the tip resistance of the ground at the tip of the pile to be press-fitted by the fluid injection combined press-fitting method in which the pile is press-fitted while injecting fluid toward the ground around the pile is obtained. A fluid parameter value calculation step for calculating a fluid parameter value, which is a value calculated based on the measured value, using a measured value related to the fluid supplied around the pile, which is a method for estimating the tip resistance. Based on the fluid parameter value calculated in the fluid parameter value calculation step and the pressure input of the pile obtained at each depth, press-fitting is performed by the tip resistance at each depth and the fluid injection at each depth. It is characterized by including a resistance degree calculation step for calculating the peripheral surface resistance degree, which is a value per unit area of the peripheral surface resistance acting between the peripheral surface of the pile and the ground.

In the present invention, the tip resistance and the peripheral surface resistance at each depth can be calculated based on the calculated fluid parameter value and the pressure input of the pile obtained at each depth.
In this case, since a measuring instrument such as a load cell used in the conventional technology is not required, the construction cost generated by using the measuring instrument without changing the shape of the pile and the construction procedure adopted in the normal press-fitting construction. The tip resistance can be easily and continuously known in the depth direction without increasing the construction period. As a result, for example, by associating the tip resistance degree with the ground information such as soil classification and N value in advance and creating a database, it can be obtained from the press input information obtained by normal press-fitting construction by the arithmetic processing of the above-mentioned estimation method. Based on the tip resistance, the N value and soil classification can be easily estimated from the database.
Further, in the present invention, it is possible to obtain a continuous tip resistance degree in the depth direction from the start of press-fitting to the completion of press-fitting by the combined use of fluid injection, and it is possible to accumulate the processing data. Then, based on the data of the tip resistance, the bearing capacity of the pile after the press-fitting is completed can be estimated.

Further, in the tip resistance estimation system according to the present invention, the resistance calculation unit is based on the fluid parameter value calculated by the fluid parameter value calculation unit and the tip resistance calculated in advance at each depth. The peripheral surface resistance calculation unit that calculates the peripheral surface resistance of the pile that is press-fitted by combined fluid injection, and the tip resistance by subtracting the peripheral surface resistance obtained by the peripheral surface resistance calculation unit from the pressure input of the obtained pile. May be provided with a tip resistance calculation unit that calculates the tip resistance and obtains the tip resistance based on the tip resistance and the fluid parameter value calculated by the fluid parameter value calculation unit.

Further, in the tip resistance estimation method according to the present invention, in the resistance calculation step, the fluid parameter value calculated in the fluid parameter value calculation step and the tip resistance calculated in advance at each depth are used. The tip resistance is obtained by subtracting the peripheral resistance obtained in the peripheral resistance calculation step from the peripheral resistance calculation step for obtaining the peripheral resistance of the pile press-fitted by fluid injection and the pressure input of the obtained pile. May be provided with a tip resistance calculation step of calculating the tip resistance and obtaining the tip resistance based on the tip resistance and the fluid parameter value calculated in the fluid parameter value calculation step.

In the present invention, the peripheral surface resistance of the pile press-fitted by the combined use of fluid injection can be obtained from the calculated fluid parameter value and the tip resistance strength obtained in advance at each depth, and the obtained pile can be obtained. The tip resistance can be calculated by subtracting the obtained peripheral surface resistance from the pressure input, and the tip resistance can be obtained based on the tip resistance and the calculated fluid parameter value.

Further, in the tip resistance estimation system according to the present invention, the peripheral surface resistance calculation unit uses the tip resistance calculated in advance at each depth to obtain the peripheral resistance at each depth. Based on the fluid parameter value calculated by the fluid parameter value calculation unit with respect to the value obtained by integrating the peripheral resistance calculation unit and the peripheral resistance calculation unit obtained by the peripheral resistance calculation unit. It may be provided with an integrating unit for obtaining the peripheral surface resistance by reducing the value corresponding to the peripheral surface resistance reduction by the consideration value.

Further, in the method for estimating the tip resistance according to the present invention, in the peripheral surface resistance calculation step, the peripheral surface resistance at each depth for which the tip resistance is obtained is obtained from the tip resistance obtained in advance at each depth. Based on the fluid parameter value calculated in the fluid parameter value calculation step with respect to the value obtained by integrating the peripheral resistance calculation step and the peripheral resistance calculation step obtained in the peripheral resistance calculation step. It may be provided with an integration step of obtaining the peripheral surface resistance by reducing the value corresponding to the peripheral surface resistance reduction by the consideration value.

In the present invention, the peripheral surface resistance at each depth for which the tip resistance is obtained is determined from the tip resistance obtained in advance at each depth and the fluid parameter value for the fluid injected into the ground around the pile. The peripheral surface resistance is calculated, and the peripheral surface resistance is integrated by the integrating unit and reduced by the consideration value equivalent to the peripheral surface resistance reduction by the fluid parameter value to obtain the peripheral surface resistance. Based on the pressure input information of the obtained pile, the tip resistance can be obtained based on the tip resistance calculated by subtracting the obtained peripheral resistance and the fluid parameter value. In other words, by continuously measuring the depth, pressure input, soil length in the pipe, fluid parameter value, etc. measured during press-fitting construction, these measurement data can be obtained from the peripheral surface resistance calculation unit, integration unit, and tip resistance. The tip resistance during press-fitting can be continuously estimated in the depth direction in consideration of the influence of the fluid injection on the tip resistance and the peripheral surface resistance of the fluid by taking it into the force calculation unit and performing the calculation processing according to the above procedure. ..

Further, in the tip resistance estimation system according to the present invention, the peripheral surface resistance calculation unit corrects the tip resistance calculated in advance at each depth based on the change according to the distance from the pile tip. Then, the peripheral surface resistance may be calculated.

In this case, in the peripheral surface resistance calculation unit, for example, according to a general bearing capacity formula, a change according to the distance from the pile tip is added to the tip resistance obtained in advance at each depth. The peripheral surface resistance can be calculated by making corrections.

Further, in the tip resistance estimation system according to the present invention, the peripheral surface resistance calculation unit obtains the tip resistance in advance at each depth based on the index indicating the blocked state of the pile tip obtained in advance. The force may be corrected to calculate the peripheral resistance.

In the present invention, the peripheral surface resistance calculation unit corrects the tip resistance obtained in advance at each depth by adding information indicating the blocked state of the pile tip, for example, according to a general bearing capacity formula. It is possible to calculate the peripheral resistance.

According to the tip resistance estimation system, the fluid injection combined press-fitting construction system, and the tip resistance estimation method of the present invention, the fluid injection combined press-fitting method in which the pile is press-fitted while injecting fluid into the ground around the pile is additional. It is possible to estimate the tip resistance during press-fitting continuously and accurately in the depth direction without incurring construction costs and working hours. Therefore, the estimated tip resistance can be used for geological information and estimation of bearing capacity.

It is a figure which shows an example of the outline of press-fitting construction using the tip resistance degree estimation system by embodiment of this invention. It is a figure which showed the outline about the force in the axial direction in a pile. It is a block diagram which shows the structure of the tip resistance degree estimation system.

Hereinafter, the tip resistance estimation system, the water jet combined press-fitting construction system, and the tip resistance estimation method according to the embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the tip resistance estimation system 1 according to the present embodiment raises and lowers the chuck holding the pile 4 while injecting water as a fluid onto the ground at the tip of the pile 4 as the ground around the pile 4. This is a system using a well-known water jet combined press-fitting device 2 that repeatedly press-fits the pile 4 into the ground, and connects the computer 3 to the press-fitting device 2 wirelessly or by wire so as to communicate with the press-fitting device 2. This is a system that calculates the tip resistance degree by the computer 3 that has acquired the information. Then, the ground information of the press-fitting construction location of the pile 4 is estimated based on the tip resistance degree calculated by the tip resistance degree estimation system 1.
That is, in the present embodiment, a press-fitting construction system is configured in which the pile 4 is press-fitted by the press-fitting device 2 using the tip resistance estimation system 1.

The pile 4 will be described as a steel sheet pile having a C-shaped cross section in the present embodiment, but the pile 4 is not limited thereto. For example, the pile 4 includes a steel pipe sheet pile, a steel pipe pile, a concrete pile, and the like. Further, in the case of a steel pipe pile, the press-fitting device 2 may be used to apply a press-fitting force while applying a rotational force around the shaft.

The press-fitting device 2 includes a press-fitting machine main body 5 that includes a chuck that grips the pile 4 and press-fits the pile 4, and a water jet supply device 6. The water jet supply device 6 is connected to a nozzle 7 attached to the tip of the pile 4, a hose 8 extending from the nozzle 7 to the ground via the base end of the pile 4, and the hose 8 to suck water from the water source. A pump unit 9 for supplying the hose 8 is provided. The nozzle 7 is detachably attached to the pile 4 by a lock mechanism 7a fixed in advance to the tip of the pile 4, and can move forward and backward with respect to the ground together with the pile 4. The hose 8 is connected to the nozzle 7 and extends to the ground along the pile 4, and is wound on a reel 5a provided on the press-fitting machine main body 5 with a nozzle-side hose 8a and a nozzle-side hose 8a via the reel 5a. It is provided with a ground-side hose 8b that is connected and connected to the pump unit 9. Further, the pump unit 9 is a fluid measuring means for measuring a measured value related to the fluid parameter value R, a flow meter 9a for measuring the flow rate of water supplied to the ground hose 8b, and a pressure of water supplied to the ground hose 8b. It is provided with a pressure gauge 9b for measuring. As an example, in the present embodiment, the fluid parameter value R is calculated based on the supply flow rate A measured by the flow meter 9a and the supply pressure P measured by the pressure gauge 9b. When the hose 8 extending from the pump unit 9 is branched in the middle and supplied to a plurality of nozzles 7, a flow meter or a pressure gauge should be installed at a position one-to-one with each nozzle 7 after the branch. Is desirable. Further, the means for measuring the flow rate and pressure is not limited to those directly measured by an instrument, and parameters related to the flow rate and pressure may be measured and calculated from the parameters. Specifically, for example, when the volumetric efficiency of the pump unit 9 is known, the rotation speed of the pump and the reciprocating number of the piston are measured, and the volumetric efficiency is integrated with the rotation speed to calculate the calculated value. The flow rate value may be obtained as.

As shown in FIG. 2, the pile 4 is press-fitted into the ground while applying the press-fitting F. At this time, the water jet supply device 6 injects water W as a fluid from the nozzle 7 toward the tip of the pile 4, so that the ground at the tip of the pile 4 is the tip of the ground itself in the absence of water W due to the water W. Apparently, the tip resistance is lower than the resistance. Further, the water W jetted from the nozzle 7 permeates the ground around the tip of the pile 4, and also permeates the ground on the side of the pile 4 and rises onto the ground along the pile 4. The rising water W'reduces the peripheral friction between the pile 4 and the ground, which apparently reduces the peripheral resistance as well as the peripheral resistance of the ground itself in the absence of water W. By injecting the water W toward the tip of the pile 4 by the water jet supply device 6 in this way, the pile 4 can be press-fitted into the ground with a smaller pressure input F than in the case where the water W is not injected. The information input from the press-fitting device 2 to the computer 3 at the time of press-fitting the pile 4 includes the depth z at the tip of the pile 4, the press-fitting input F, the soil length h in the pipe, and the supply flow rate A and the supply constituting the fluid parameter value R. The pressure P is measured by the depth measuring means 21, the pressure input measuring means 22, the in-pipe soil length measuring means 23, the flow meter 9a, and the pressure gauge 9b, respectively. In the above description, water W is injected as a fluid, but the present invention is not limited to this, and a gas such as air may be injected depending on, for example, the site environment, or a liquid other than water may be injected. Alternatively, a mixture of gas and liquid may be injected.

As shown in FIG. 3, the depth measuring means 21 for measuring the depth z at the tip of the pile 4 is configured by providing the press-fitting device 2 with a stroke sensor for detecting the press-fitting stroke by the press-fitting device 2.
The pressure input measuring means 22 for measuring the pressure input F uses a hydraulic sensor that detects the oil pressure of the hydraulic drive unit of the press-fitting device 2 and measures the pile 4 as a pressure input value for press-fitting into the ground.
As the in-pipe soil length measuring means 23 for measuring the in-pipe soil length h, for example, a commonly used wire-type stroke sensor or an encoder is used to determine the amount of wire drawn out when the weight is lowered in the pile 4 and reaches the in-pipe soil. The press-fitting device 2 is provided with a measuring device or the like.
Then, the depth z, the press-fitting device F, the soil length h in the pipe, the supply flow rate A, and the supply pressure P are measured by the press-fitting device 2, and these measured values z, F, h, A, and P are transferred from the press-fitting device 2 to the computer 3. It is configured to be entered.

The computer 3 includes a CPU that executes various arithmetic processes and the like, which will be described later, and a storage unit and the like that store various control programs and data executed by the CPU.
The above-mentioned measured values (depth z, pressure input F, in-pipe soil length h, supply flow rate A, supply pressure P) input to the computer 3 are time-series data continuously measured in the process of press-fitting the pile 4. Yes, they are mutually compatible. Then, in the computer 3, time-series data of the depth z, the pressure input F, the soil length h in the pipe, the supply flow rate A, and the supply pressure P are stored in the attached storage device.

As shown in FIG. 3, the tip resistance estimation system 1 has a circumference at each depth shallower than the depth from the tip resistance estimated in advance at each depth shallower than the depth (each intermediate depth described later). The peripheral surface resistance calculation unit 11 for calculating the surface resistance, the integrating unit 12 for calculating the peripheral resistance by integrating the peripheral resistance calculated by the peripheral resistance calculation unit 11, and the integrating unit 12 obtained at the depth. The depth is calculated by subtracting the peripheral resistance obtained by the integrating unit 12 from the pressure input F to calculate the tip resistance at the depth, and dividing this by the tip cross-sectional area considering the blocked state of the pile tip at the depth. The tip resistance calculation unit 13 for obtaining the tip resistance in the above, and the fluid parameter value calculation unit 14 for obtaining the fluid parameter value R based on the supply flow rate A and the supply pressure P are provided. In the present embodiment showing an example, the fluid parameter value R calculated by the peripheral surface resistance calculation unit 11 and the integration unit 12 by the fluid parameter value calculation unit 14, and the tip resistance calculated in advance at each depth. Therefore, the peripheral surface resistance calculation unit for obtaining the peripheral surface resistance of the pile press-fitted by the combined use of the water jet is configured. Further, in the present embodiment showing an example, the peripheral surface resistance calculation unit composed of the peripheral surface resistance calculation unit 11 and the integration unit 12 and the tip resistance calculation unit 13 calculate with the fluid parameter value calculation unit 14. Based on the obtained fluid parameter value R and the pressure input F of the pile obtained at each depth, a resistance degree calculation unit for calculating the tip resistance degree and the peripheral surface resistance degree at each depth is configured.
Here, the peripheral surface resistance calculation unit 11 calculates the peripheral surface resistance based on the change according to the distance from the pile tip according to a general bearing capacity formula as described later.

Then, CPU of the computer 3, the peripheral surface described above resistance calculation unit 11, the integrating unit 12, and the tip resistive force calculation unit 13 includes a fluid parameter value calculating section 1 4, the depth z, the press-fitting force F, the tube soil length h, It functions as a calculation means for calculating the tip resistance based on the time-series data of the supply flow rate A and the supply pressure P.

The fluid parameter value calculation unit 14 inputs the supply flow rate A and the supply pressure P acquired from the flow meter 9a and the pressure gauge 9b into the relational expression composed of the preset supply flow rate A and the supply pressure P, and inputs the fluid parameter. Calculate the value R. The fluid parameter value R is a value representing the energy of water W, which is a fluid supplied from the pump unit 9 and injected from the nozzle 7. Here, when the supply pressure P is used as the pressure, the pressure in the vicinity of the nozzle 7 is lower than the supply pressure P by the pressure loss, so the calculation is performed in consideration of the pressure loss from the pressure gauge 9b to the nozzle 7. Is desirable. The fluid parameter value R may be calculated using either the supply flow rate A or the supply pressure P. Further, the fluid parameter value calculation unit 14 may output the acquired values such as the flow rate and the pressure as the fluid parameter value R which is the calculation result as it is. In addition, measured values other than the supply flow rate A and the supply pressure P, for example, the injection flow rate / injection speed / injection pressure from the nozzle 7, the flow rate / pressure in the middle of piping from the pump unit 9 to the nozzle 7, the rotation speed in the pump unit 9 and the like. The number of reciprocations of the pump, the amount of discharged water flowing upward from the tip of the pile 4 along the peripheral surface, and the amount of discharged water discharged onto the ground may be used. Further, the fluid parameter value R is used for the calculation related to the tip resistance and the peripheral surface resistance, which will be described later, but the fluid parameter value used for the tip surface resistance and the fluid parameter value used for the peripheral surface resistance may be different from each other. For example, when the injection energy greatly contributes to the tip resistance, it is obtained based on the supply pressure P, the injection speed, the injection pressure, etc., and for the peripheral surface resistance, the water W flowing on the peripheral surface rather than the injection energy When the amount contributes significantly, the supply flow rate A, the amount of discharged water, or the like may be used.

Next, the tip resistance estimation method for estimating the tip resistance using the tip resistance estimation system 1, that is, the calculation procedure in the CPU of the computer 3 will be specifically described.
First, in the peripheral surface resistance calculation unit 11, when the pile tip at a depth slightly shallower than the depth (the immediately preceding depth) reaches the relevant depth, the calculation is performed at each depth (each intermediate depth) up to the immediately preceding depth. From the obtained tip resistance, the peripheral resistance at each intermediate depth is calculated based on the depth difference between the depth and each intermediate depth using a bearing capacity formula or the like described later (peripheral resistance calculation step). In addition, "each intermediate depth" corresponds to the above-mentioned "each depth".
At this time, the tip resistance and the peripheral surface resistance when the pile tip depth is zero (ground surface) are set to known quantities (usually both are zero).

Next, the integrating unit 12 integrates the peripheral surface resistance at each intermediate depth calculated by the above-mentioned peripheral surface resistance calculation step at each intermediate depth up to the immediately preceding depth, thereby integrating the peripheral surface resistance at the immediately preceding depth. Calculate the value. Further, the integrating unit 12 calculates the peripheral surface resistance by subtracting the consideration value corresponding to the peripheral surface resistance reduction obtained based on the fluid parameter value calculated at the depth from the peripheral surface resistance integrated value (integration). Process). Here, since the peripheral surface resistance in the minute depth section is approximately zero, the peripheral surface resistance at the depth is calculated assuming that the peripheral surface resistance at the immediately preceding depth is equal to the peripheral surface resistance at the relevant depth. Further, the consideration value corresponding to the reduction of the peripheral surface resistance may be multiplied as the reduction rate. Here, the values corresponding to the reduction of peripheral surface resistance are the pressure input when water W is injected from the nozzle 7 at each depth or a representative depth provided at regular intervals during the main press-fitting construction, and from the nozzle 7. It is possible to measure the pressure input in a state where the injection of water W is stopped and the amount of water discharged onto the ground along the pile 4 is reduced to a steady state, and the pressure input is obtained based on the difference between these pressure inputs. can. Alternatively, when the press-fitting of the pile 4 is stopped by measuring the measured values related to the water W such as the supply flow rate and the supply pressure at the time of press-fitting the pile 4 at each depth or a representative depth provided at regular intervals during the main press-fitting work. Can also be obtained by measuring the same measured values and based on the difference between these measured values. Further, the integration of the force-insertion force data by water jet combination as previously tested construction, with integrated pressure input data not use a water jet, as possible out be predetermined based on the difference of these pressure input data. Further, the calculation may be performed based on the geological data carried out in advance.

Next, in the tip resistance force calculation unit 13, the tip resistance at the depth is subtracted from the peripheral surface resistance at the depth calculated in the integration process based on the information of the pressure input F of the pile 4 measured during the press-fitting work. Is calculated. Further, the apparent tip resistance at the depth is calculated by dividing the calculated tip resistance at the depth by the tip cross-sectional area at the depth in consideration of the blocked state. Then, the actual tip resistance of the ground is calculated and acquired by adding a consideration value corresponding to the reduction of the tip resistance to the apparent tip resistance (tip resistance calculation step). That is, since the peripheral surface resistance in the minute depth section can be ignored, the peripheral surface resistance estimated by the integrating unit 12 is regarded as the peripheral surface resistance at the relevant depth, which is subtracted from the pressure input at the relevant depth, and further, the actual tip of the ground. The tip resistance at the depth is estimated by considering the amount reduced by water W rather than the resistance. In addition, the consideration value corresponding to the reduction of the tip resistance may be divided as the reduction rate. Here, the consideration value corresponding to the reduction of the tip resistance is the pressure input when water W is injected from the nozzle 7 at each depth or the representative depth provided at regular intervals during the main press-fitting construction, and the pressure input from the nozzle 7. The pressure input in a state where the injection of water W is stopped and the amount of water discharged onto the ground along the pile 4 is reduced to a steady state can be measured and obtained based on the difference between these pressure inputs. .. Alternatively, when the press-fitting of the pile 4 is stopped by measuring the measured values related to the water W such as the supply flow rate and the supply pressure at the time of press-fitting the pile 4 at each depth or a representative depth provided at regular intervals during the main press-fitting work. Can also be obtained by measuring the same measured values and based on the difference between these measured values. Further, the integration of the force-insertion force data by water jet combination as previously tested construction, with integrated pressure input data not use a water jet, as possible out be predetermined based on the difference of these pressure input data. Further, the calculation may be performed based on the geological data carried out in advance.

Then, in the above-mentioned arithmetic processing process, the press-fitting device 2 sequentially measures the depth z as the press-fitting progress of the pile 4, and sequentially measures the press-fitting input F as the depth z increases.
Every time the time series data of the depth z, the press input F, the soil length h in the pipe, the supply flow rate A and the supply pressure P accumulated in the computer 3 is updated while the press fitting of the pile 4 is in progress, the pile 4 is newly reached. calculating the tip resistance drag degree of the tip position may be calculated most of the data string of the tip resistance value corresponding to the change of the depth z during press-fitting. Then, during the press-fitting, at least the time series data of the depth z, the press-fitting input F, the soil length h in the pipe, the supply flow rate A and the supply pressure P are recorded, and the pile 4 is being press-fitted or after the press-fitting work is completed. At any time, the computer 3 executes the calculation of the tip resistance.

The computer 3 stores the calculation result of the tip resistance degree in the attached storage device. The calculation result of the tip resistance degree is in the form of a data string of the tip resistance value according to the graphed change of the depth z, and includes the tip resistance value at the final depth of the pile 4.
Further, the computer 3 displays the calculation result on the display device 31 (see FIG. 1).

Next, an example of a function (supporting force equation) for calculating the tip resistance degree q _{b (z) will be described.}
Equation (1) is a formulation of a method for estimating the tip resistance (tip resistance degree qb (z)) from the pressure input F.
That is, the tip resistance at the depth z is estimated by numerically solving the equation (1) by the arithmetic procedure executed by the CPU of the computer 3 described above.
Hereinafter, the equation (1) for estimating the tip resistance degree qb (z) will be specifically described.

As shown in FIG. 2, the press-fitting input F (z) during press-fitting is considered to be composed of a tip component (represented by a subscript b) and a peripheral surface component (represented by a subscript S). Each resistance when the pile tip is at the depth z is expressed as Qb (z) and Qs (z), and the pressure input F (z) is expressed by equations (2) to (7).

Here, in Eqs. (2) to (7), F (z), Qb (z), Qs (z), qb (z), and h (z) are the pressure input, tip resistance, and circumference at the depth z, respectively. Surface resistance, tip resistance, and soil length in the pipe, a is a coefficient representing the reduction of soil stress around the pile tip, b is a coefficient representing the effect of blockage, and c is a coefficient representing frictional fatigue (reduction of peripheral resistance). The coefficient, l is the distance from the tip of the pile, Lp is the circumference of the pile, Do is the outer diameter of the pile, and Din is the inner diameter of the pile. In Eq. (4), max (l / Do, 2) ^c represents the degree to which the resistance changes as the relative distance between the piles changes.
Further, Ab and eff are the tip cross-sectional areas of the pile considering the blocked state and are represented by the equation (5), and Ar and eff are the area ratios of the pile considering the blocked state and are expressed by the equation (6). It is represented. That is, Ar, eff, Ab, and eff are determined by the soil length and the penetration length in the pile. IFR is an index indicating a completely blocked state, IFR = 0 represents a completely blocked state, and IFR = 1 represents a completely non-blocked state.

The tip resistance qb (z) is a value per unit area of the tip resistance Qb (z). The normal force generated in the minute area dA on the tip surface is expressed as qb · dA, and the frictional force generated in the minute area dA on the tip surface of the pile when the pile is rotated is obtained by multiplying qb · dA by the friction coefficient. It is a stake. When this friction coefficient is tan δ, that is, when the above friction force is qb · dA · tan δ, δ is the wall surface friction angle.

Then, the tip resistance degree qb (z) is derived from the relational expression (8) from the above-mentioned relational expression (2) and (3).
Further, since the increment of the peripheral surface resistance Qs can be regarded as zero with respect to the minute depth increment δz, the equation (9) can be obtained.

Then, the above-mentioned equation (1) is derived from the relational expression between the above equations (4) and (9), and this equation (1) is applied as a function of the tip resistance. That is, the tip resistance degree qb (z) can be obtained by numerically solving the equation (1) in consideration of the boundary condition qb (0) = 0.
At this time, a sufficient result can be obtained even if an appropriate constant is set for the wall surface friction angle δ for each site and the wall friction angle δ is implemented as a constant.

Here, in the equation (1), in the present embodiment, the deduction value corresponding to the reduction of the peripheral surface resistance by the fluid parameter value is subtracted from the integrated value in the term of the peripheral surface resistance. Further, the value obtained by subtracting the peripheral surface resistance from the pressure input F (z) is divided by the closed tip areas Ab and eff, and the consideration value corresponding to the tip resistance reduction is added. Not limited to this, the apparent peripheral surface resistance may be calculated by subtracting the deduction value equivalent to the peripheral surface resistance reduction and integrated, or a coefficient c representing frictional fatigue (reduction of peripheral surface resistance). It may be possible to reflect the amount equivalent to the reduction of peripheral surface resistance. Further, with respect to the consideration value corresponding to the reduction of the tip resistance, the consideration value may be added to the pressure input F (z), or the reduction rate may be divided.

As described above, in the tip resistance estimation system, the water jet combined press-fitting construction system, and the tip resistance estimation method according to the present embodiment, as shown in FIG. 3, the depth z and the press-fitting F measured during the press-fitting construction are performed. By continuously measuring the soil length h in the pipe, the supply flow rate A, the supply pressure P, etc., these measurement data are taken into the peripheral surface resistance calculation unit 11, the integration unit 12, and the tip resistance calculation unit 13. By performing the arithmetic processing according to the above procedure, the tip resistance during press fitting can be continuously estimated in the depth direction in consideration of the influence of the water jet.
In this case, since a measuring instrument such as a load cell used in the conventional technology is not required, the construction cost generated by using the measuring instrument without changing the shape of the pile and the construction procedure adopted in the normal press-fitting construction. The tip resistance can be easily and continuously known in the depth direction without increasing the construction period.

As a result, for example, by associating the tip resistance degree with the ground information such as soil classification and N value in advance and creating a database, it is obtained from the information of the press input F obtained by normal press-fitting construction by the arithmetic processing of the above-mentioned estimation method. Based on the obtained tip resistance, the N value and soil classification can be easily estimated from the database.

Further, in the present embodiment, the degree of tip resistance continuous in the depth direction from the start of press-fitting to the completion of press-fitting can be obtained, and the processing data can be accumulated. Then, based on the data of the tip resistance, the bearing capacity of the pile 4 after the press-fitting is completed can be estimated.

As described above, in the tip resistance estimation system, the water jet combined press-fitting construction system, and the tip resistance estimation method of the present embodiment, the press-fitting is performed by the combined use of the water jet without incurring additional construction cost and working time. The tip resistance can be estimated continuously and accurately in the depth direction. Therefore, the estimated tip resistance can be used for geological information and estimation of bearing capacity.

Although the embodiments of the tip resistance estimation system, the press-fitting construction system, and the tip resistance estimation method according to the present invention have been described above, the present invention is not limited to the above embodiments and deviates from the gist thereof. It can be changed as appropriate as long as it does not.

For example, in the present embodiment, only press-fitting work is targeted for construction, but rotary press-fitting can also be targeted for construction. In the case of rotary press-fitting, the torque due to the rotation of the press-fitting device is also calculated as input information, so that the tip resistance can be estimated with higher accuracy.

Further, in the above-described embodiment, in the peripheral surface resistance calculation step, the tip resistance used by the peripheral resistance calculation unit 11 to calculate the peripheral resistance is a depth slightly shallower than the depth (the immediately preceding depth). When the tip of the pile at) reaches the depth, the tip resistance calculated at each depth (each intermediate depth) up to the immediately preceding depth is adopted. Then, the peripheral surface resistance calculation unit 11 of the present embodiment corrects the tip resistance calculated in advance at each depth in consideration of the information indicating the blocked state of the pile tip obtained in advance. In addition to calculating the surface resistance, the peripheral resistance calculation unit calculates the peripheral resistance by correcting the tip resistance in consideration of the change according to the distance from the tip of the pile. However, it is not limited to these corrections.
That is, the estimation system may not perform both the correction based on the information indicating the blockage state and the correction based on the change according to the distance from the pile tip in the peripheral surface resistance calculation unit. A system that makes one of the corrections may be used. Alternatively, it is also possible to use another correction method to correct the tip resistance and calculate the peripheral resistance.
_{That is, the function (supporting force formula) for calculating the tip resistance degree q b} (z) shown in the above-described embodiment is an example, and an estimation method using another bearing capacity formula is also possible.

Further, in the above embodiment, it has been described that the soil quality for each depth of the ground into which the pile 4 is press-fitted does not affect the consideration value corresponding to the reduction of peripheral surface resistance based on the fluid parameter value, but the present invention is not limited to this. For example, even if the sand layer and the clay layer have the same fluid parameter value, they may have different consideration values. Further, when the lower layer is a highly permeable sand layer, the water W flowing upward from the tip of the pile 4 easily permeates, so that the flow rate of the water W flowing upward is smaller in the upper layer than the sand layer. Therefore, even if the fluid parameter values are the same, the influence of the consideration value may be set to be low. The same applies to the tip resistance, and the consideration value corresponding to the tip resistance reduction based on the fluid parameter value may differ depending on whether the ground is a sand layer or a clay layer.

Further, the press-fitting device is not limited to the one using a press-fitting device that takes a reaction force from an existing pile and press-fits the pile into the ground. For example, the reaction force of the press-fitting device may be taken from the weight or the existing structure. Further, in the above embodiment, the water W by the water jet is sprayed toward the ground at the tip of the pile 4, but the present invention is not limited to this, and in the pile 4, any of the ground around the pile 4 is used. At least one of the tip resistance and the peripheral surface resistance may be reduced by injecting the water into the portion. For example, in the case of a steel pipe pile or the like, the pile may be injected from the peripheral surface of the pile in the outward or inward direction in the radial direction.

In addition, it is possible to replace the components in the above-described embodiment with well-known components as appropriate without departing from the spirit of the present invention.

1 Tip resistance estimation system 2 Press-fitting device 3 Computer 4 Pile 9a Flow meter 9b Pressure gauge 11 Peripheral resistance calculation unit 12 Integration unit 13 Tip resistance calculation unit 14 Fluid parameter value calculation unit 21 Depth measurement means 22 Pressure input measurement means 23 In-pipe soil length measuring means W water (fluid)

Claims (11)

It is a tip resistance estimation system that obtains the tip resistance of the ground at the tip of the pile that is press-fitted by the fluid injection combined press-fitting method that press-fits the pile while injecting fluid toward the ground around the pile.
A fluid parameter value calculation unit that calculates a fluid parameter value, which is a value calculated based on the measured value, using the measured value related to the fluid supplied around the pile.
Based on the fluid parameter value calculated by the fluid parameter value calculation unit and the pressure input of the pile obtained at each depth, press-fitting is performed by the tip resistance at each depth and the fluid injection at each depth. A resistance calculation unit that calculates the peripheral resistance, which is a value per unit area of the peripheral resistance acting between the peripheral surface of the pile and the ground.
Advanced resistance estimation system equipped with. The resistance calculation unit is based on the fluid parameter value calculated by the fluid parameter value calculation unit and the tip resistance calculated in advance at each depth, and the peripheral resistance of the pile press-fitted by the combined fluid injection. Peripheral resistance calculation unit to find
The tip resistance is calculated by subtracting the peripheral resistance obtained by the peripheral resistance calculation unit from the pressure input of the obtained pile, and the tip resistance and the fluid parameter value calculated by the fluid parameter value calculation unit are calculated. The tip resistance calculation unit that calculates the tip resistance based on
The tip resistance estimation system according to claim 1, further comprising. The peripheral surface resistance calculation unit includes a peripheral surface resistance calculation unit that calculates the peripheral surface resistance at each depth for which the tip resistance is calculated from the tip resistance calculated in advance at each depth.
The value obtained by integrating the peripheral surface resistance calculated by the peripheral resistance calculation unit is reduced by the consideration value corresponding to the peripheral resistance reduction by the fluid parameter value calculated by the fluid parameter value calculation unit. The advanced resistance estimation system according to claim 2, further comprising an integrating unit for obtaining peripheral resistance. The peripheral surface resistance calculation unit is characterized in that the peripheral surface resistance is calculated by correcting the tip resistance calculated in advance at each depth based on the change according to the distance from the pile tip. The advanced resistance estimation system according to claim 3. The peripheral surface resistance calculation unit calculates the peripheral resistance by correcting the tip resistance calculated in advance at each depth based on the index indicating the blocked state of the pile tip obtained in advance. The tip resistance estimation system according to claim 3 or 4. The integrating unit is a measured value of the pressure input when the fluid injection is used together and when the fluid injection is stopped, and a measured value related to the fluid supplied to the periphery of the pile when the pile is press-fitted and when the pile is press-fitted and stopped. Consideration value equivalent to the reduction of peripheral surface resistance using the measured value of the pressure input when the fluid injection is used together and when the fluid injection is stopped, or the result of the geological survey conducted in advance in the test construction conducted. Seeking more,
The tip resistance calculation unit is a measured value of the pressure input when the fluid injection is used together and when the fluid injection is stopped, and a measured value related to the fluid supplied to the periphery of the pile when the pile is press-fitted and when the pile is press-fitted and stopped. , Using the measured values of the pressure input when the fluid injection is used together and when the fluid injection is stopped, or the result of the geological survey conducted in advance, the amount equivalent to the reduction of the tip resistance is used. The tip resistance estimation system according to any one of claims 3 to 5, further comprising obtaining a consideration value. It is a fluid injection combined press-fitting construction system that press-fits the pile while injecting fluid toward the ground around the pile by the press-fitting device using the tip resistance estimation system according to any one of claims 1 to 6. hand,
The press-fitting device includes a depth measuring means capable of sequentially measuring the depth of the pile tip, a pressure input measuring means capable of sequentially measuring the pressure input of the pile, and a pipe soil length measuring means capable of sequentially measuring the in-pipe soil length of the pile. And a fluid measuring means capable of measuring the measured value related to the fluid supplied around the pile is provided.
A fluid injection combined press-fitting construction system characterized in that the tip resistance is obtained based on the measured values of the depth, the pressure input, the soil length in the pipe, and the fluid supplied around the pile measured by each of the means. .. It is a tip resistance estimation method for determining the tip resistance of the ground at the tip of the pile to be press-fitted by the fluid injection combined press-fitting method in which the pile is press-fitted while injecting fluid toward the ground around the pile.
A fluid parameter value calculation step for calculating a fluid parameter value, which is a value calculated based on the measured value, using the measured value related to the fluid supplied around the pile.
Based on the fluid parameter value calculated in the fluid parameter value calculation step and the pressure input of the pile obtained at each depth, press-fitting is performed by the tip resistance at each depth and the fluid injection at each depth. The tip resistance is characterized by comprising a resistance degree calculation step for calculating the peripheral surface resistance degree, which is a value per unit area of the peripheral surface resistance acting between the peripheral surface of the pile and the ground. Strength estimation method. In the resistance degree calculation step, the peripheral surface resistance of the pile press-fitted by the combined fluid injection from the fluid parameter value calculated in the fluid parameter value calculation step and the tip resistance strength obtained in advance at each depth. Peripheral resistance calculation process to find
The tip resistance is calculated by subtracting the peripheral resistance obtained in the peripheral resistance calculation step from the pressure input of the obtained pile, and the tip resistance and the fluid parameter value calculated in the fluid parameter value calculation step are calculated. The tip resistance calculation process to obtain the tip resistance based on
The tip resistance degree estimation method according to claim 8 , wherein the tip resistance degree is estimated. The peripheral surface resistance calculation step includes a peripheral surface resistance calculation step of calculating the peripheral surface resistance at each depth for which the tip resistance is obtained from the tip resistance calculated in advance at each depth, and the peripheral resistance calculation step. The value obtained by integrating the peripheral surface resistance calculated in the surface resistance calculation process is reduced by the consideration value corresponding to the peripheral resistance reduction by the fluid parameter value calculated in the fluid parameter value calculation process. The tip resistance estimation method according to claim 9 , further comprising an integration step for obtaining peripheral resistance. In the peripheral surface resistance calculation step, the measured value of the pressure input when the fluid injection is used together and when the fluid injection is stopped together, and the measured value related to the fluid supplied to the periphery of the pile when the pile is press-fitted and when the pile is press-fitted and stopped. Using the measured values of the pressure input when the fluid injection is used together and when the fluid injection is stopped, or the result of the geological survey conducted in advance, the amount equivalent to the reduction of the peripheral surface resistance is used. Equipped with a calculation process equivalent to the reduction of peripheral surface resistance to obtain the consideration value of
In the tip resistance calculation step, the measured value of the pressure input when the fluid injection is used together and when the fluid injection is stopped, and the measured value related to the fluid supplied to the periphery of the pile when the pile is press-fitted and when the pile is press-fitted and stopped. Consideration of tip resistance reduction by using the measured values of pressure input when the fluid injection is used together and when the fluid injection is stopped, or the result of the geological survey conducted in advance. The tip resistance estimation method according to claim 10, further comprising a calculation step corresponding to reduction of tip resistance for obtaining a value.

Images