JPS6149449B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a soil testing device, and particularly to a soil testing device suitable for measuring the strength of relatively soft ground.

Methods for measuring the strength of the ground at the current location include standard penetration tests, cone tests, and vane tests. The standard penetration test is a test method specified by JIS, and is a dynamic penetration test using a boring hole, a boring rod, and dropping a steel hammer. For this reason, only very rough measurements can be obtained in the soft layer. Furthermore, since the weight of rods and steel hammers is large, the rods often scuttle in ultra-soft layers, making it impossible to measure their strength.

On the other hand, the cone test is a static penetration test using a load, and can measure the strength of the ground in a more practical way, but it cannot penetrate hard layers. If there is a soft layer below a hard layer, it is necessary to excavate the hard layer by boring etc. and then take measurements again with a cone, but the ground is complex and there are many layers that the cone cannot penetrate. If they are present, the work becomes extremely labor-intensive, and there is also concern that the hole wall may collapse, often forcing the measurement to be stopped. Continuous measurement with a cone is possible when there is no intervening hard layer, but
There is also a limit to the depth of measurement due to increased friction between the soil and the rod.

Due to these technical problems and costs, ground investigations usually involve measuring the strength only by boring and standard penetration tests, and the strength of soft layers cannot be measured. The current situation is that it is a rough one.

This invention was made in view of the current situation, and allows static penetration tests to be easily performed even when there are many hard layers, and also to be accurate even when the measurement depth is deep. The purpose of this design is to provide a soil testing device that can obtain accurate measured values.

The soil testing device of the present invention is a static penetration testing device that uses a boring hole and a boring rod, and is designed to be inserted into the boring rod and fixed at the tip of the cone during measurement. The penetrating force is converted into an electrical signal by a strain meter installed at the tip of the device, which is then transmitted via a cable so that it can be measured on the ground. The load at the time of cone penetration is applied by a boring rod and a boring machine, and the hard layer is excavated by this boring rod. Therefore, it is easily possible to perform continuous strength tests even when the ground is complex, and the measured values obtained are extremely accurate.

Hereinafter, a detailed explanation will be given based on illustrated embodiments.

Fig. 1 is a sectional view showing the entire soil testing device of the present invention, Fig. 2 is a perspective view showing the part where the engaging claw is attached, with the engaging claw closed, and Fig. 3 is the attached part of the engaging claw. FIG. 4 is an enlarged cross-sectional view showing the mounting portion of the strain meter, and FIG. 5 is a view showing the mounting portion of the strain meter in the direction of arrow A in FIG. 4.

As shown in the figure, the soil testing device of this invention is
A boring rod 1 that penetrates into the soil is provided with a step 2 on its inner diameter surface, and an operating body 4 is slidably connected to a main body 3 that is inserted into the boring rod 1. Engagement pawls 5a and 5b are provided which open and close according to the sliding movement of the actuating body 4,
A soil test piece 9 is attached to the tip of the main body 3 via rods 7 and 8 equipped with strain gauges 6a and 6b, and the actuating body 4 of the above device suspended from the upper end of the boring rod 1 is attached to the cable 10. The engaging claws 5a, 5b are configured to be able to engage and disengage from the step 2 by sliding.

The boring rod 1 has a crown 11 and a core tube 12 attached to the tip via joints 13a, 13b, and a plurality of pipes 14a, 14b...
are connected by a joint 15a.
The step 2 is formed at the connection portion between the pipe 14a and the joint 15a. The main body 3 and the actuating body 4 have outer diameters that allow them to be inserted into the boring rod 1 with a suitable clearance, and the tip of the inserted main body comes into contact with a step 29 provided in the joint 13b. It stops. A sliding rod 16 is formed on the operating body 4, and this sliding rod 16 slides into a hole 17 formed in the main body 3. 18 is the current projection formed at the tip of the sliding rod 16, and 19 is a circumferential groove formed at the end of the hole 17.

At the upper end of the main body 3 (left side in the figure) are pins 20a, 2.
Engaging claws 5a and 5b are pivotally connected by 0b,
The upper ends of the engaging claws 5a, 5b and the actuating body 4 are connected by links 21a, 21b. 2
Reference numerals 2a and 22b are leaf springs that urge the engaging claws 5a and 5b outward, and 23 is a stop that is screwed onto the operating body 4 and grips the cable 10.

A rod 7 is fixed at the tip of the main body 3, and resistance wire strain gauges 6a, 6 are connected between the rods 7 and 8.
A dynamometer 24 having a diameter of 1.b is interposed, and a soil test piece 9 is attached to the tip of the rod 8. Although the illustrated soil test piece 9 is a cone test piece, a vane test piece may be installed instead of the cone test piece 9. To rotate the vane test piece, the lower part of the main body 3 (right side in the figure) should be a hexagonal column, and the inside of the joint 13b should be a hexagonal hole so that the rotation of the boring rod 1 is transmitted to the main body 3. good. The electric wire 28 drawn out from the resistance wire strain gauges 6a, 6b passes through the hollow hole 25 provided through the rod 7, the main body 3, and the operating body 4, passes through the cable 10, and is drawn out to the ground surface. 26 is a cover provided to protect the dynamometer 24.

Next, the procedure and operation when conducting a soil test using the apparatus configured as described above will be explained. First, the boring rod 1 is inserted into the soil to a desired depth by known means, and after cleaning the inside of the hole, the boring rod 1 is pulled up beyond the protruding length of the cone 9 from the crown 11, and the water swivel is turned off. remove. Next, the measuring device 27 consisting of the main body 3 or the soil test piece 9 is inserted into the boring tube 1 and lowered to the tip of the boring tube 1 by the cable 10. While the measuring device 27 is suspended by the cable 10, the links 21a, 21b are moved by the engaging claws 5a, 5 due to the weight of the main body 3, rods 7, 8, etc.
b is held in the closed state shown in FIG. Measuring device 2
7 reaches the lower end of the boring rod 1, and when the tip of the main body 3 and the joint 13b come into contact, the engaging claws 5a, 5
b is brought into the open state shown in the third figure by the urging force of the leaf springs 22a, 22b and the weight of the actuating body 4. In this state, the boring rod 1 and the measuring device 27
By lowering or rotating the boring rod 1 in this locked state, the soil test piece 9 can be penetrated into the soil or rotated in the soil. At this time, the soil resistance acting on the soil test piece 9 is the strain meter 6
a and 6b into an electrical signal, and by measuring this electrical signal, the strength of the soil at the relevant depth is measured. Next, when the cable 10 is pulled up, the engagement pawl 5 is
a and 5b are closed, the boring rod 1 and the measuring device 27 are disengaged, and only the measuring device 27 can be pulled up, so the boring rod 1 is inserted to the next measurement depth and the above operation is performed. By repeating this, it is possible to sequentially measure the strength of the soil at each desired depth. In addition, since the force acting on the soil test piece 9 is measured by the strain gauges 6a and 6b installed near the test piece 9, the weight of the boring rod 1 and the frictional force of the soil acting on it are measured values. It is possible to obtain extremely accurate measurement values without affecting the Since the measuring device 27 is inserted into the boring rod 1 and attached to its tip, there is no need to remove the drilling rod 1, core tube 12, and crown 11 when starting the test, and the test can be performed as is. This allows the work to be done quickly. This also means that the water level in the hole does not fluctuate as the boring rod 1 moves up and down, making it difficult for the hole wall to collapse or the test ground to be disturbed, making it possible to obtain more accurate measured values.

As described above, according to the soil testing device of the present invention, it is possible to perform a static penetration test extremely easily and quickly even when the ground is complex, and the strength of the ground can be measured extremely accurately. It has a certain effect.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the entire soil testing device of the present invention, Fig. 2 is a perspective view showing the part where the engaging claw is attached, with the engaging claw closed, and Fig. 3 is the attached part of the engaging claw. FIG. 4 is an enlarged cross-sectional view showing the mounting portion of the strain meter, and FIG. 5 is a view showing the mounting portion of the strain meter in the direction of arrow A in FIG. 4. In the figure, 1 is a boring rod, 2 is a step, 3 is a main body, 4 is an operating body, 5a, 5b are engagement claws, 6a,
6b is a strain meter, 7 and 8 are rods, 9 is a soil test piece,
10 is a cable, 16 is a sliding rod, 17 is a hole, 20a,
20b is a pin, 21a and 21b are links, 22
a and 22b are leaf springs, 24 is a dynamometer, 25 is a hollow hole, and 28 is an electric wire.

Claims (1)

[Claims] 1. A boring rod that penetrates into the soil has a step formed on its inner diameter surface, and an operating body is slidably connected to the main body inserted into the boring rod, and the sliding movement of this operating body is A soil test piece is attached to the tip of the main body via a rod equipped with a strain gauge, and the actuating body of the device suspended from the top of the boring rod is connected to the rod. A soil testing device characterized in that the engaging pawl is configured to be freely engageable and detachable from the step by sliding it.