JPS6156730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves inserting a casing pipe for an inclinometer into a borehole and measuring the liquefaction outside of the casing pipe when measuring the amount of movement of strata over time in the horizontal direction with high precision. This invention relates to a grouting method for fixing a casing pipe to the ground by filling and solidifying the grout material.

It is known to insert an inclinometer probe into a casing pipe fixed to the ground and to sequentially measure the inclination of the casing pipe while pulling the inclinometer probe up, thereby obtaining data regarding the continuous inclination angle over the entire borehole. This technology can be used, for example, for landslide investigation, safety management of cut slopes, measurement of lateral flow due to embankment, deformation due to pile driving and grouting,
It is used for measuring deformation of retaining walls and seawalls, safety management for deep excavations, measuring deformation of foundation piles, measuring deformation in horizontal pile loading tests, and tracking research on ground deformation.

In this case, it is essential to form a complete grout in the gap between the borehole wall and the casing pipe so that the deformation of the ground is correctly transmitted to the casing pipe. As shown in FIG. 1, one conventional method is to first drill a borehole 1 (A in the same figure), and then attach a grouting hose 3 to the outer wall of a bottomed casing pipe 2 using vinyl tape 4 or the like. Insert the casing pipe 2 to the bottom of the hole while filling it with fresh water 5 to prevent it from floating up (Figure B). Then, use a pump etc. to grout from the end of the grouting hose on the ground side. There is a method in which the grout 7 is injected from the lower end of the casing pipe 2 to remove muddy water (C in the same figure), and the casing pipe 2 is fixed to the ground by solidifying the grout material 7 (D in the same figure).

Another method that has been used in the past is
As shown in Figure 2, first a borehole 1 is drilled (A in the figure), and then a bottomed casing pipe 2 is drilled.
Insert the casing pipe 2 to the bottom of the hole while filling it with clean water to prevent it from floating up (B in the same figure), lower the grouting pipe 8 between the casing pipe 2 and the hole wall (C in the same figure), and grout. The material 7 is injected from the bottom of the hole to fill it (D in the same figure), and the grouting pipe 8 is
There is a method in which the casing pipe 2 is brought into close contact with the ground using grout (Fig. E).

However, in these conventional methods, since the grouting hose and the grouting pipe are located outside the casing pipe, it is necessary to drill a bore hole with a hole diameter much larger than the outer diameter of the casing pipe. Casing pipe is usually 50-80mm
Because it is inserted into a hole with a diameter of about 10 to several tens of meters deep, drilling a borehole with a large diameter requires large-scale equipment and a large amount of grout material. There are also drawbacks. Furthermore, the first
In the method shown in the figure, the work of fixing the grouting hose to the casing pipe is complicated and takes a lot of time, and in the method shown in Fig. 2, the grouting pipe is inserted between the casing pipe and the hole wall. There are disadvantages such as the work is complicated and takes a lot of time.

When burying a pipe or the like using a borehole or the like, it is important to bury a pipe or the like in the borehole using a structure as simple as possible because the internal state of the borehole cannot be seen. Particularly in geological formations where sand or gravel layers are distributed, there is a risk of collapse of the hole wall, so a simple structure is desired. Also, it is not good from an economic point of view to drill a hole larger than necessary.

The purpose of the present invention is to overcome the above-mentioned drawbacks of the prior art, and to provide a method for grouting a casing for an inclinometer, which requires the diameter of a borehole to be drilled to be as small as possible, and which is easy to operate, reliable, and highly reliable. It is about providing.

The present invention will be explained in detail below. FIG. 3 is an explanatory diagram showing one embodiment of the present invention. First, a borehole 11 is drilled (see A in the same figure). The depth of the borehole 11 varies depending on the measurement application, but the depth is several to
It is several tens of meters. This point is similar to the conventional technique, but a notable difference from the conventional technique is that the pore diameter may be much smaller than the conventional technique. The casing pipe 12 of the inclinometer is inserted into the borehole 11 (see B in the same figure). This casing pipe is different from the conventional one in that its lower end is open, and a sealing gasket 20 is attached to the inside near the lower end. Since the lower end of the casing pipe 12 is open, the casing pipe 12 can be smoothly inserted into the hole without floating up. Next, a casing head 21 is attached to the upper end of the casing pipe 12.
is installed, and the grouting material 7 is injected into the casing pipe 12 from there. The injected grout material is discharged from the lower end opening of the casing pipe 12, removing the muddy water in the hole and filling most of the hole with the grout material (see C in the same figure). Thereafter, the piston 22 is inserted into the casing pipe 12 (see D in the same figure). A sealing gasket made of rubber or the like is attached to the piston 22, and the sealing gasket is in sliding contact with the inner surface of the casing pipe 12 to maintain airtightness. Furthermore, to prevent the piston from floating due to the difference between the specific gravity of muddy water and fresh water, the piston is designed so that it can slide downward but cannot move upward.
A plate spring is attached to the top of the piston, which is always open outward and whose tip presses against the inside of the casing pipe.When an upward force is applied to the piston, this piston acts as a wedge and moves the piston upward. It has a check valve designed to prevent it from happening. . Fresh water is forced into the upper end of the casing pipe 12 and the piston 22 is pushed down. The piston 22 pushes down the grout material while cleaning the inner surface of the casing pipe 12, and eventually stops at the sealing gasket 20 at the lower end of the casing pipe (see E in the same figure). It can be easily determined that the piston 22 has reached the lower end of the casing pipe 12 because the water supply pressure suddenly increases when it hits the gasket 20. As described above, since the piston 22 has a structure that does not move upward, it remains in that position even if the water pressure is removed, thereby preventing the grout material from flowing back into the casing pipe 12. In addition to the structure of the check valve described in this example, there are other types such as a ball clamp type, and the check valve is not limited to a check valve having a plate spring structure. Also,
If such a check piston is not used, the piston may be held at a constant position while the water pressure is kept high. In any case, by maintaining such a state, the grout material solidifies, and the casing pipe 12 can be brought into close contact with the ground.

Since the present invention is a grouting method for a casing pipe for an inclinometer in a borehole constructed as described above, the diameter of the borehole to be drilled need only be slightly larger than the outer diameter of the casing pipe, which is better than the conventional case. It is very economical as it can be much smaller, and since only the casing pipe needs to be inserted into the borehole, compared to the conventional method, there are cases where the casing pipe cannot be inserted due to collapse of the hole wall etc. In addition, when inserting a casing pipe, there is no need for the conventional work of pouring water or fixing a grouting hose, so the insertion work can be done quickly and easily. It can produce excellent effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the prior art, FIG. 2 is an explanatory diagram showing another example of the prior art, and FIG. 3 is an explanatory diagram showing an embodiment of the present invention. 1, 11... Bore hole, 2, 12... Casing pipe, 20... Seal packing, 22
……piston.

Claims (1)

[Claims] 1 In a grouting method in which a casing pipe for an inclinometer is inserted into a borehole, the gap between the casing pipe and the wall of the borehole is filled and solidified with grout material, and the casing pipe is fixed to the ground, the lower end of the casing pipe is The casing pipe is open and a sealing gasket is attached to the inner side near the lower end. After the casing pipe is inserted into the borehole, grout is injected from the upper end of the casing pipe, and the grout material is injected from the lower end opening of the casing pipe. The grout is discharged into the hole to fill the hole, and then a piston is inserted into the casing pipe, and fresh water is forced into the upper end of the casing pipe to push the piston down until it reaches the sealing gasket, and in that state. A method for grouting an inclinometer casing in a hole, the method comprising solidifying a grouting material.