JPS609169B2 - How to detect soil texture - Google Patents

Description

Detailed Description of the Invention The present invention improves geotechnical properties in the construction process of a construction method in which sand piles, etc. are constructed in soft ground using a hollow pipe with a sand discharge and vertical consolidation section provided at the lower end. It is related to detection technology and aims to provide a new means of detecting the ± nature of the original ground using hollow pipes for construction such as sand piles.

In the above-mentioned construction process, the sand etc. discharge/vertical compaction member is operated by a forced vertical movement mechanism to discharge and vertically compact the sand etc. in the hollow pipe. The pushing force of the forced vertical movement mechanism is detected just before the working distance when lowering the village reaches the set stroke, and the ground quality (for example, ground strength) is detected based on this detected value.

The present invention will be explained below with reference to the drawings.

Fig. 1 shows an example of a hollow pipe for constructing sand piles, etc. In the figure, 1 is a hollow pipe, 2 is an outer pipe, 3 is a sand discharge/compaction member, and 4 is a forced vertical movement mechanism. , 5 is a pile material input hopper, 6 is a penetrator, 7 is an air valve, 8 is an air supply pipe, 9 is an exhaust pipe, and 10 is an exhaust valve.

Since the method of constructing sand piles and the like in soft ground using this hollow pipe for constructing sand piles and the like is well known, a description thereof will be omitted.

Figure 2 shows a hydraulic piston as the forced vertical movement mechanism 4. 1 is an explanatory diagram of an embodiment of the present invention when a cylinder device is used, and in the diagram, 11 is a hydraulic cylinder, 12 is a piston,
13 is a piston rod, 14, 15 are hydraulic pipes, 14', 1
5'' is a hydraulic hose, 14'' and 15'' are hydraulic pipes, 16 is a switching valve, 17 is a pump, 18 is a motor, and 19 is a tank.

By operating the switching valve 16, the piston 12 reciprocates between the upper limit position X' and the lower limit position Y'. goes back and forth between x and Y.

Of course, the distance from X' to Y is equal to the distance from X-Y, and this distance is the setting stroke in the present invention. Normally, the entire stroke length of the hydraulic cylinder 1 is the set stroke, but in some cases, as shown in Figure 3,
Normally, the piston 12 is moved between X,' and Y', but if necessary, the movement may be changed to between x2' and Y' or between X3' and Y'.

In this case, X'→Y(X,→Y), X2'→Y(X2
→Y) and X3'→Y' (X3→Y) are set strokes separately. The working hydraulic pressure when the piston 12 is lowered is detected by two pressure sensors installed in the hydraulic line 14'', and this hydraulic pressure is detected during the movement of the piston 12 by the set stroke, for example, as shown in FIG. Change.

Near A, the tip of the sand discharge/compaction member 3 is connected to the outer pipe 2.
The fluid pressure around this area includes a large amount of loss due to the silo effect. Further, B is the stroke end Y' of the piston 12, and the hydraulic pressure at B is equal to the operating pressure of the leaf valve 21 provided in the hydraulic pressure circuit. In the present invention, "immediately before the working distance of the sand discharge and compaction unit reaches the set stroke" means when the piston 12 has moved to C, and at this time Is the lower end of the stiffening member 3 on the same plane as the lower end of the outer tube 2?
Or it has become more prominent.

Next, the present invention will be specifically explained with reference to FIG. The flowmeter 22 installed in the hydraulic line 15'' emits a pulse signal corresponding to the flow rate per unit time, and this pulse signal is integrated over time in the meter 23, and the flowmeter 22 is measured from the start of operation to that point. The number of pulses corresponding to the amount of liquid that has passed through the installation point is calculated, and this is output as a voltage and enters the meter 24.

The set voltage Vs set by the meter 25 is input to the meter 24, and the voltage from the meter 23 and VS are compared here, and when the two become equal, a signal is sent to the meter 26.
On the other hand, the liquid pressure detected moment by moment by the liquid pressure sensor 20 is converted into voltage and sent to the meter 26, and the meter 26 is connected to the meter 24.
The voltage Vp from the hydraulic pressure sensor 20 at the time when the signal is sent from is stored.

This voltage Vp is further sent to a control instrument 27 and a recording instrument 28. If the set voltage Vs is set to a value corresponding to the amount of fluid required for the piston 12 to move up to C in FIG. 4, the working fluid pressure of the piston 12 at this point can be detected from the voltage Vp.

Then, by multiplying this working hydraulic pressure by the cross-sectional area of the cylinder 11, the pushing force F of the sand etc. discharge/compaction member 3 is determined. This pushing force F is equal to the final reaction force of the sand pile during construction, and the soil quality of the surrounding ground surrounding the sand pile can be determined based on this pushing force F. Below, we will briefly explain how to detect the ground strength. do.

The worker pressure 〇 at the lower end depth Z of the hollow tube 1 is.

=7Z+2CHere, 7: Unit volume weight of the ground engineer C: It is expressed as soil strength, but during sand pile construction, pressurized air is supplied from the air supply pipe 8 to the inside of the hollow pipe 1, which is approximately equal to ↑Z. If you apply pressure.

: It becomes 2C.

Therefore, by detecting the cross-sectional area of the sand pile under construction using conventionally known means, and applying the triaxial compression theory using this detected value and the detected value of the pushing force F, C, that is, the ground strength, is detected. can do.

Note that the present invention is not limited to the embodiment described based on FIG. Of course, this need not be done in terms of liquid volume. For example, when installing an instruction cylinder device on the ground that moves similarly to the drive cylinder device that operates the sand discharge and compaction section (see Japanese Patent Application Laid-open No. 50-88477), the instruction cylinder device A limit switch is installed in front of the indicator rod (piston rod), and just before the piston of the drive cylinder device reaches the set stroke, the indicator rod contacts the limit switch and issues a signal. Alternatively, in the device described in Japanese Utility Model Publication No. 56-51077, which has a proximity switch mechanism adjacent to the drive device, the indicated value of a stroke detector provided on the output side of the potentiometer circuit. Return the voltage to meter 2
4 may be input.

As is clear from the above description, the present invention operates a sand discharge/compaction member provided at the lower end of a hollow pipe for constructing sand piles, etc. by a forced vertical movement mechanism to discharge sand, etc. inside the hollow pipe. In the process of vertical compaction, the pushing force of the forced vertical movement mechanism is detected just before the working distance of the sand discharge and cotton compaction member reaches the set stroke, and the geotechnical properties are determined based on this detected value. Therefore, it is not only possible to accurately grasp the geotechnical characteristics of the construction site, but also it is easy to immediately reflect the results in the construction work.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a hollow pipe for creating sand piles, etc. Fig. 2 is an explanatory diagram of an embodiment of the present invention, Fig. 3 is an explanatory diagram of the set stroke, and Fig. 4 is a diagram showing the working distance of the piston and the fluid flow. It is a relationship diagram with pressure. In addition, in the figure, 1... hollow pipe, 2... outer pipe, 3... sand discharge and compaction member, 4...
...Forced vertical movement mechanism. Sickle 1 Ugly Spot 2 Number 3 Figure 4

Claims (1)

[Claims] 1. In the process of discharging and compacting sand, etc. from inside the hollow pipe by operating the sand discharge/compaction member installed at the lower end of the hollow pipe for creating sand piles etc. using a forced vertical movement mechanism, the sand discharge/compaction member is A method for detecting soil properties of the ground, characterized in that the pushing force of a forced vertical movement mechanism is detected just before the working distance of a compaction member reaches a set stroke when descending, and the soil properties of the ground are determined based on this detected value.