JPS609170B2 - How to detect the strength of the original ground - Google Patents

Description

Detailed Description of the Invention The present invention detects the strength of the original ground in the penetration process of a method of constructing sand piles, etc. in soft ground using a hollow pipe with a sand discharge and vertical consolidation member at the lower end. The purpose is to provide a new means of detecting the strength of the original ground using hollow pipes for construction such as sand piles.

In the above construction method, a hollow pipe is first penetrated into soft ground to a predetermined depth, and then, while the hollow pipe is pulled out, a forced vertical motion mechanism is used to operate the sand discharge and vertical compaction member to create sand piles, etc. However, in the present invention, the hollow tube is penetrated without operating the forced vertical movement mechanism in the penetration step,
At this time, the penetration resistance value acting on the tip of the sand etc. discharge/compaction member is detected, and the strength of the original ground is detected based on this detected value.

The present invention is based on the same principle as the detection of ground strength using a static penetration tester, and is based on the penetration resistance that acts on the tip of a member for discharging sand and vertically compacting when a hollow pipe for constructing sand piles etc. penetrates. The ground strength is detected from the detected value of the penetration resistance value by utilizing the correlation between the value and the ground strength (for example, the N value).

The present invention will be explained below based on the drawings. Figure 1 shows an example of a hollow pipe for constructing sand piles, etc. In the figure, 1 indicates a hollow pipe;
2 is an outer pipe, 3 is a sand discharger and cotton compacting member, 4 is a forced vertical movement mechanism, 5 is a pile material input hopper, 6 is a penetration machine, 7 is an air valve, 8 is an air supply pipe, 9 is an exhaust pipe, 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.

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

When carrying out the present invention, when penetrating a hollow pipe for creating sand piles, etc., it is necessary to set the switching valve 16 to the neutral position and carry out the penetration with the piston 12 stopped in the normal position, or to perform the penetration with the piston 12 near the lower end of the hydraulic cylinder 11, the piston rod 13
It is preferable that the lower end of the sand discharge/compaction member 3 attached to the tip of the outer tube 2 be approximately flush with the lower end of the outer tube 2. If this is done, only the lower end of the sand discharge/compaction member 3 will be exposed. However, it is in the same manner as a double-tube static penetration testing machine.

As the hollow tube 1 penetrates, the piston 12 is pushed upward by the penetration resistance of the ground soil acting on the tip of the sand etc. discharge/compaction member 3, and a back pressure corresponding to the penetration resistance value is applied to the upper part of the piston 12. This is detected by the pressure sensor 21 provided on the hydraulic pipe blade 4, and this detected value is sent as an electrical signal to the meter 22.
Send it to t and record it.

If the switching valve 16 is set to the neutral position, the hydraulic line 1 will be closed, but if the switching valve 16 is of the Subur type, it will not be completely locked due to fluid leakage from the spool. It is preferable that the hydraulic line 14 is provided with a pilot-operated check valve 23 as shown.

This check valve 23 has a conventionally well-known operation, and completely blocks the flow of liquid in the direction of arrow A unless pressure is applied to the pilot pipe 24.

Note that instead of this check valve 23, a counterbalance valve may be provided at the same position. In order to know the strength of the original ground from the penetration resistance value detected by the pressure sensor 21, for example, test the penetration resistance value at multiple points in the construction area using hollow pipes for construction, such as sand piles, and test the original ground by a standard penetration test. The intensity may be detected separately, a correlation diagram between the two may be created, and this may be utilized. As is clear from the above description, in the present invention, a hollow pipe for constructing sand piles etc. can be moved into the ground without operating the forced vertical movement mechanism of the sand discharge and compaction section provided at the lower end of the hollow pipe. In the process of penetrating the sand pile, the penetration resistance value acting on the tip of the sand discharge and compaction section is detected, and the strength of the original ground is detected based on this detected value. Not only is it very convenient to be able to know the strength of the original ground at each depth during the work, but it is also very convenient because the detection results obtained during the penetration process can be immediately utilized in the next reclamation process. convenient.

By implementing the present invention, it is possible to expect construction work such as sand piles that is adapted to the soil properties of the original ground.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a hollow pipe for constructing sand piles, etc., and FIG. 2 is an explanatory diagram of an embodiment of the present invention. In addition, in the drawings, 1: Hollow pipe, 2: Outer pipe, 3: Sand discharge and vertical consolidation member, 4: Forced vertical movement mechanism. Section 1 Column Section 2 Figure

Claims (1)

[Claims] 1. In the process of penetrating a hollow pipe for sand pile construction into the ground without operating the forced vertical movement mechanism of the sand discharge and compaction member installed at the lower end, the sand discharge and compaction member A method for detecting the strength of the original ground, characterized by detecting a penetration resistance value acting on the tip and detecting the strength of the original ground based on this detected value.