JPS606413B2 - Sand pile construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sand pile construction method used for soft ground improvement work.

In order to construct sand piles with a diameter larger than the diameter of the hollow pipe using a hollow pipe for sand pile construction in soft ground, conventionally, the hollow pipe is penetrated to a predetermined depth in the soft ground, and then Sand is supplied into this hollow tube, the hollow tube is pulled upward by a suitable length, the sand inside the tube is discharged into the gap created below the tube, and then the hollow tube is re-penetrated to compact the discharged sand and surround it. In addition to the so-called composer method, which is a construction method in which the operation cycle of expanding the volume into the ground is repeated sequentially upward, sand is supplied into a hollow pipe that penetrates to a predetermined depth in the soft ground, and the hollow pipe is pulled upward. A construction method is also used in which the sand inside the tube is forcibly discharged from the lower end of the tube into the soft ground using a vibrating body, a screw, a vertically operating extrusion mechanism, etc. installed inside the hollow tube.

In the above-mentioned conventional construction method, a large amount of energy is required to operate the hollow pipe, especially in order to construct a sand pile whose diameter is considerably larger than the diameter of the hollow pipe using a large-diameter hollow pipe. Additionally, dry sand with as low a water content as possible was generally used as the sand supplied to the hollow tube in order to ensure smooth discharge from the bottom end of the tube. In order to save the operating energy of the hollow tube in the above-mentioned conventional construction method and to eliminate the disadvantage of increasing costs required for using dry sand, "sand to be supplied to the hollow tube" is used in the upward drawing process of the hollow tube. Using hydrated sand with a water content near saturation, this hydrated sand is kept in a fluid state by vibration etc. in a hollow tube.
The pressure of the hydrated sand in the hollow tube at the lower end of the tube is controlled to be greater than the passive pressure of the soft ground at the lower end of the tube, and the hydrated sand in the hollow tube is discharged from the lower end of the tube to create a sand pile with a diameter larger than the diameter of the hollow tube. The present applicant developed a sand pile construction method based on a new technical idea, and published it as ``Sand Pile Construction Method'' in Special Iso No. 52-39543 (Japanese Patent Application Laid-open No. 53-125309). In implementing this construction method, ``Compared to the conventional construction method, a hollow pipe with a relatively simple structure is used to save the operating energy required to construct sand piles with a diameter larger than the diameter of the hollow pipe in soft ground. It was possible to shorten the time and reduce the cost of sand used. Based on the experience of constructing new sand piles using the above-mentioned water-added sand, the construction method of the present invention is based on the experience of constructing sand piles using the above-mentioned water-added sand. The idea was to supply hydrated sand into the hollow pipe during the penetrating process and discharge it from the bottom end of the pipe, making it ideal for creating sand piles with a diameter larger than the hollow pipe diameter, especially sand piles with a large diameter. This makes it possible to further save operating energy and construction time for L hollow tubes.

In other words, "The sand pile construction method of the first invention of the present invention is a soft ground improvement method in which a large number of sand piles are constructed in the ground using a hollow pipe for sand pile construction. While the hollow tube 1 is penetrating the soft ground 2 to a predetermined depth, hydrated sand 3 with a water content near saturation is supplied into the hollow tube blade, and the hydrated sand 3 is caused to vibrate inside the hollow tube 1. While maintaining the fluidized state, the pressure of the hydrated sand 3 in the hollow tube 1 at the lower end of the tube is controlled to be greater than the pressure of the passive soil of the soft ground 2 at the lower end of the tube, and the hydrated sand 3 in the hollow tube 1 is controlled at the lower end of the tube. A layer of hydrated sand 4 is formed around the outer periphery of the penetrated hollow tube.
was created, and then, while the hollow tube 1 was being drawn upward, the above-mentioned hydrated sand 3 supplied into the hollow tube 1 was left below the tube, so that the diameter was expanded from the diameter of the hollow tube 1. This method is characterized by constructing sand piles in soft ground.

Next, the sand pile construction method of the second invention of the present invention is a soft ground improvement method in which a large number of sand piles are constructed in the ground using a hollow pipe for sand pile construction, as shown in FIG. , hollow tube 1
While penetrating into the soft ground 2 at a predetermined depth, hydrated sand 3 with a moisture content near saturation is supplied into the hollow tube 1, and the hydrated sand 3 is
is maintained in a fluid state within the hollow tube 1 by vibration or the like, and the pressure of the hydrated sand 3 at the lower end of the tube is controlled to be greater than the passive soil pressure of the soft ground 2 at the lower end of the tube. The hydrated sand 3 inside the tube is discharged from the lower end of the tube in a controlled manner, and a hydrated sand layer 4 is formed around the outer periphery of the hollow tube 1 that has penetrated.
``Then, while the hollow tube 1 is being drawn upward, the above-mentioned water-hydrated sand 3 is supplied into the hollow tube 1, and the water-added sand 3 is maintained in a fluid state in the same manner as described above, and the hollow tube 1 is The pressure at the lower end of the hydrated sand 3 in the tube 1 is changed to the hydrated sand layer 4 at the lower end of the tube.
By controlling the diameter to be larger than the passive soil strength of the soft ground 2 received through the pipe and discharging the hydrated sand 3 in the hollow pipe 1 in a controlled amount from the lower end of the pipe, the diameter was expanded to a greater extent than the diameter of the hollow pipe 1. This method is characterized by constructing sand piles 5' in soft ground. The present invention will be described in detail below. First, the first invention will be explained with reference to FIG.

As shown in Figures a to d of the first floor plan, while a vibrating pile driver 6 with a hollow pipe 1 for sand pile construction attached to the top of the pipe is penetrating soft ground 2 to a predetermined depth according to the design, the hollow When hydrated sand 3 with a water content near saturation is supplied into the pipe 1 from the supply port 7 at the top of the pipe, the hydrated sand 3 in the pipe is placed in a fluid state by vibration, so it behaves like a fluid. . Therefore, if the pressure of the hydrated sand 3 at the lower end of the pipe is controlled to be greater than the worker pressure of the soft ground 2 at the lower end of the pipe, and the hydrated sand 3 is supplied into the pipe as the hollow pipe 1 penetrates, the hydrated sand 3 inside the pipe is The sand 3 is continuously discharged from the lower end of the pipe into the soft ground 2,
A hydrated sand layer 4 is created around the outer periphery of the hollow tube 1 that has penetrated. That is, as shown in Fig. d of Fig. 1, when the hollow pipe 1 is penetrated to a predetermined depth in the soft ground 2, the hollow pipe 1 is inserted into the sand pile whose diameter has expanded from the diameter of the hollow pipe 1. It will be like this.

Therefore, in the above-mentioned control of the conditions of the hydrated sand 3 at the lower end of the pipe and the passive soil ridge of the surrounding soft ground 2, hollow soil is This is possible by controlling the length of the hydrated sand 3 that is sequentially supplied into the tube 1. Furthermore, if necessary, compressed air can be fed into the tube from the pneumatic inlet 8 at the top of the tube as shown in the drawings, and the pressure of the hydrated sand 3 at the lower end of the tube can be assisted by the air pressure. Next, regarding the state shown in Fig. d of Fig. 1, when the hollow pipe 1 is pulled upward while moving the vibrating pile driver 6, as shown in Figs. 3 is left below the pipe, and when the hollow pipe 1 penetrates, it is integrated with the hydrated sand layer 4 created on the outer periphery of the hollow pipe 1 to create a sand pile 5 whose diameter is larger than the diameter of the hollow pipe 1. Ru.

In addition, in the state shown in FIG. d of FIG. 1, that is, in the state where the hollow pipe 1 has penetrated the soft ground 2 to a predetermined depth, the sand length of the hydrated sand 3 in the hollow pipe 1 is as shown in the figure. Normally, the sand is supplied up to the penetration length of the hollow tube 1, but if the sand length is lower than the penetration length of the tube, the hydrated sand 3 is supplied up to the penetration length of the tube before pulling out the hollow tube 1. It is meant to compensate. or,
A hydrated sand layer 4 formed on the outer periphery of the hollow tube 1 when it penetrates.
The desired thickness is related to the expansion of the diameter of the sand pile 5 to be constructed, and the thickness is controlled by appropriately controlling the flow rate of the supplied hydrated sand 3 and the penetration speed of the hollow pipe 1. It is possible by doing. Next, hydrated sand 3 is added to the hollow pipe 1 for sand pile construction.
As illustrated in FIG.
In addition to supplying water from 0, a water supply pipe 11 is also connected to the hopper 9.
Alternatively, as illustrated in FIG. 7, a sand and water mixer (
It may also be possible to connect a water discharge sand supply pipe 12 that pressure-feeds the water-added sand 3 from a source (not shown).

In addition, in FIGS. 6 and 7 above, 13 indicates a degassing prevention valve plate. The sand pile construction method of the first invention of the present invention is as follows:
This is carried out as described above, and when constructing the sand pile 5 whose diameter is larger than the diameter of the hollow pipe 1, the sand is discharged from the lower end of the pipe into the soft ground 2 and this sand is further expanded laterally. This is done by controlling the pressure of the hydrated sand 3 supplied into the hollow pipe 1 at the lower end of the pipe to be greater than the passive soil pressure of the soft ground 2 at the lower end of the pipe, and it is different from the drawing of the hollow pipe 1 in the conventional construction method. Since it does not require the operating energy of the hollow tube 1 that repeats the cycle of re-penetration, or the operating energy of the vibrating body, screw, vertical movement extrusion mechanism, etc. installed in the hollow tube, the operating energy is lower than that of conventional construction methods. It is possible to create sand piles with an enlarged diameter.

In addition, it is easy to operate by penetrating the hollow tube 1 of a simple structure to a predetermined depth and pulling it upward, which saves construction time. It has the advantage of being less expensive than using . The effects of the present invention described above are based on the above-mentioned Tokuwaki 52-39 Oni No. 3 "Sand pile construction method" using hydrated sand developed by the applicant.
However, in this construction method, while the hollow pipe 1 is penetrating the soft ground 2 to a predetermined depth, it only prevents soil from entering the pipe from the lower end of the pipe, and the pipe The hydrated sand 3 is not discharged from the lower end.

In contrast, the present invention, in the process of penetrating the soft ground 2 of the hollow tube 1 to a predetermined depth, combines hydrated sand 3 into the hollow tube 1 and discharges it from the lower end of the tube. hollow tube 1
A hydrated sand layer 4 corresponding to the part whose diameter is larger than the diameter of the hollow tube 1 is created in advance on the outer periphery of the hollow tube 1, and the process of pulling out the hollow tube 1 is simply pulling out the hollow tube 1 upward. Only the operation is required, and the operation inside the hollow tube 1 is simpler and easier, and the construction efficiency can be further improved. Next, referring to FIG. 2, a second aspect of the present invention will be explained.

As shown in Figures a to d in Figure 2 in this second invention construction method, the step of penetrating the hollow tube 1 to a predetermined depth into the soft ground 2 is the same as in the first invention described above. Therefore, in the construction method of the second invention, as shown in FIG.
In the upward drawing process, as well as the penetrating process,
The hydrated sand 3 is supplied to the hollow tube 1 and discharged from the lower end of the tube, and the hydrated sand layer 4 formed on the outer periphery of the hollow tube 1 is pushed out laterally to reduce the diameter of the hollow tube 1. This is to create a sand pile 5' with a larger diameter. In addition, hollow tube 1
The diameter of the hydrated sand layer 4 can be further enlarged during drawing by appropriately controlling the flow rate of the supplied hydrated sand 3 and the drawing speed of the hollow tube 1, as described above. The method for constructing sand piles according to the second aspect of the present invention is carried out as described above, and makes it easier to construct sand piles 5' having a larger diameter than the method according to the first aspect. be. That is, in the second invention, the hydrated sand 3 is discharged into the soft ground 2 from the lower end of the pipe in both the process of penetrating the hollow pipe 1 to a predetermined depth in the soft ground and the process of pulling it upward. , a large amount of hydrated sand 3 can be supplied during the operation time of penetrating and withdrawing the hollow tube 1, and the hydrated sand 3 can be supplied without difficulty, and the sand pile 5 with an extremely large required diameter can be supplied.
′ can be created reliably and efficiently. Furthermore, as illustrated in FIG. It is also possible to discharge an appropriate amount of the water-added sand 3 from the pipe submachine only at the above-mentioned location and use it to repair this section.

In addition, as illustrated in Fig. 4, in the second invention, when an irregularity in the thickness of the hydrated sand layer 3 occurs, the hydrated sand 3 is discharged from the lower end of the tube while the ``hollow tube'' is being pulled out to correct the diameter. greatly expanded sand pile 5
′, it is also possible to increase or decrease the amount of hydrated sand 3 discharged at the irregular locations by an appropriate amount to create a sand pile 5′ with a uniform diameter and a greatly enlarged diameter as shown in Figure g. Also, as illustrated in FIG. This can also be done by controlling the sand length of the hydrated sand 3, but it is easier and faster to control by increasing or decreasing the air pressure that assists the pressure of the hydrated sand at the lower end of the tube by compressed air fed into the hollow tube. As mentioned above, the sand pile construction method of the present invention uses a hollow pipe with a relatively simple structure to construct a sand pile with a diameter larger than that of the hollow pipe in soft ground compared to the conventional method. It has the excellent advantage that it can be constructed easily, quickly and economically with little operating energy, and that the diameter of the sand pile can be easily controlled.

[Brief explanation of drawings]

The attached drawings illustrate the present invention with examples.
FIG. 1 is an explanatory diagram sequentially showing the construction method of the first invention of the present invention, and FIG. 2 is an explanatory diagram sequentially showing the construction method of the second invention of the invention. Next, FIGS. 3 to 5 are explanatory views showing examples of adjusting the sand pile diameter according to the second invention. Next, FIGS. 6 and 7 are sectional views showing an embodiment of the main part of a hollow pipe for constructing sand piles used in the present invention. Noble...Hollow pipe, 2...Soft ground, 3...Drained sand, 4...Hydrated sand layer, 5
...Sand piles with enlarged diameters, 5'...Sand piles with greatly enlarged diameters, 6...Vibratory pile drivers too?・・・・・・Supplementary port, 8... Pneumatic inlet 9... Hopper, 10...
Bucket, 11...Water supply pipe, 12...Hydrated sand supply pipe also 13..."Degassing prevention valve plate. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] 1. In a soft ground improvement method in which a large number of sand piles are constructed in the ground using hollow pipes for sand pile construction, while the hollow pipe is being penetrated to a predetermined depth in the soft ground, inside the hollow pipe The hydrated sand is supplied with a moisture content near saturation, and the hydrated sand is kept in a fluid state by vibration etc. in the hollow tube, and the pressure of the hydrated sand at the lower end of the hollow tube is reduced by the passive soil of the soft ground at the lower end of the tube. The hydrated sand in the hollow tube is discharged in a controlled amount from the lower end of the tube to create a hydrated sand layer around the outer periphery of the penetrated hollow tube, and then, while the hollow tube is being pulled upward, A sand pile construction method characterized in that a sand pile with a diameter larger than the diameter of the hollow pipe is created in soft ground by leaving the above-mentioned hydrated sand supplied into the hollow pipe below the pipe. 2. In a soft ground improvement method in which a large number of sand piles are constructed in the ground using hollow pipes during construction of sand piles, while the hollow pipes are being penetrated to a predetermined depth in the soft ground, the moisture content in the hollow pipes is close to saturation. In addition to supplying the hydrated sand and maintaining the hydrated sand in a fluid state in the hollow tube by vibration etc., the pressure of the hydrated sand in the hollow tube at the lower end of the tube is controlled to be greater than the passive earth pressure of the soft ground at the lower end of the tube. Then, the hydrated sand in the hollow tube is discharged in a controlled amount from the lower end of the tube to create a layer of hydrated sand around the outer periphery of the hollow tube that has penetrated, and then, while the hollow tube is being pulled upward, the above-mentioned hydrated sand is discharged into the hollow tube. Supplying sand and maintaining the hydrated sand in a fluid state as described above, and controlling the pressure of the hydrated sand in the hollow tube at the lower end of the tube to be greater than the passive earth pressure of the soft ground that is received via the hydrated sand layer at the lower end of the tube. A sand pile construction method characterized in that a sand pile with a diameter larger than the diameter of the hollow pipe is created in soft ground by discharging a controlled amount of hydrated sand inside the hollow pipe from the lower end of the pipe.