JPS6147948B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an underwater boring method in which a boring device is supported by a single support pipe, and this support pipe is erected underwater to inspect, test, and sample the ground. be.

Conventionally, during underwater boring, towers were generally used to load or mount and support the boring equipment from the viewpoint of stability.
In some cases, they were difficult to install, limiting their use and making them impractical.

Therefore, in recent years, single support pipes have been used instead of towers, as they are easy to install and have little to do with the shape of the ground, are hardly affected by tidal currents, and are easy to install. In fact, this single support pipe has made underwater boring easier to perform in a wide range of locations, but due to the structure of the single support pipe, there are problems with accurate testing and sample collection of the surface ground. has occurred.

That is, as shown in Fig. 1, the boring device a includes a casing pipe 2 fitted in the cylinder of a support pipe 1 that acts as a retainer, and a rod for drilling that is inserted through the casing pipe 2 and is able to move up and down and rotate freely. It consists of a drilling rod 3 to which a core tube for collecting soil samples or a sampling tube for collecting ground samples is attached at a timely manner, and a rotation and lifting drive unit for this testing rod. It is now set up vertically.

Therefore, during underwater boring, the support pipe must be able to stably support the boring equipment so that the drilling rod can accurately drill, test, and sample the specified ground. must be erected.

Therefore, conventionally, as shown in Fig. 1, a support pipe 1 in which branch pipes are connected to a predetermined length according to the water depth, etc. is driven perpendicularly into a predetermined water bottom ground cylinder to an appropriate depth, and the support pipe 1a is erected. The support frame 4, which has been pre-attached to the lower part of the support pipe 1, is placed on the water bottom ground, and a plurality of anchor wires 5, one end of which is tied to the upper part of the support pipe 1, are extended radially, and the free ends of the anchors 5a are attached to the ground. A and support pipe 1
It was once stable.

The workbench 6 is attached to the upper end of the support pipe 1 erected as described above, and then the casing pipe 2, the drilling rod elevating and lowering, the rotation drive unit, and the drilling rod 3 are installed.
Install etc. When performing underwater boring, a core tube and a collection tube are alternately screwed to the lower end of the test rod 3 according to the purpose, and the test rod is driven, and the core tube is rotated and lowered to rotate the hole and drive the test rod. Therefore, samples were collected up to a predetermined depth by repeatedly testing soil materials and collecting samples using a sampling tube that penetrated into the ground.
By the way, in order to obtain accurate soil test results for this test and sample collection, it is important that the soil be in its natural state and undisturbed. However, in the conventional construction method, the support pipe itself is first driven into the surface layer of the underwater ground to an appropriate depth in order to stably erect the support pipe, so although there is no disturbance in the ground below the support pipe driving depth, the support Considerable disturbance had occurred in the surface ground where the pipe was driven. For this reason, it was possible to accurately test and sample the ground below the driven support pipe, but the natural conditions of the surface ground where the support pipe was driven were disrupted, making accurate testing and sample collection impossible.

In view of the above-mentioned drawbacks of the conventional art, the present invention has been made to improve the conventional drawbacks.
The purpose of the present invention is to provide an underwater boring method that allows accurate testing and sample collection without disturbing the surface ground of the part where the support pipe is driven, and which also ensures stable installation of the support pipe. It is something to do.

An example of turning according to the present invention will be described below with reference to FIG.

First, the support pipe 1 with the casing pipe 2 inside is plunged into the water, its lower end is placed on the underwater ground, and the support pipe 1 is erected by being held by the support frame 4, pulled and held by the anchor wire, etc. Set up This allows the support pipe to be supported vertically, albeit somewhat unstablely. In this case, the drilling rod 3
A sampling tube 7 is attached to the tube (see Fig. 2A).
Note that the support pipe may be isolated from the ground by locking its lower part to the support frame. Next, the sampling tube 7 at the lower end is penetrated into the surface layer A' of the ground A by a specified amount by striking the test rod 3, and a test and a sample are taken (as shown by the solid line in FIG. 2B). After sampling, lift the sampling cylinder together with the test drilling rod to the top of the workbench 6.
Take out the collected sample from the tube and store it as a sample. Then, the core tube 8 etc. is screwed onto the lower end of the test rod, and the test rod is lowered to the bottom of the underwater hole again, rotated, raised and lowered, and excavated to the depth for the next test and sample collection, after which the core tube is removed from the rod. Then, screw the sample collection cylinder onto the rod again and perform the next new test and sample collection together with the rod. By repeating this process, the depth will be increased sequentially as shown by the chain lines in the drawing, and the ground in each area will be tested and samples taken. The support pipe 1 is stably installed by driving the support pipe into the surface ground that has been sampled to a depth necessary for self-supporting stability (see Figure 2 C). As a result, the support pipe 1 is placed in the same support state as conventional driving support, and is firmly supported in a vertical position. By this method of erecting support pipes, the surface layer of the ground can be tested and sampled in multiple parts, and the tests and samples can be accurately carried out in each part. In addition, sampling of deep layers after driving the support pipe can be carried out by alternately using core tubes and sampling tubes as in the conventional method, and thereby testing and sampling of deep ground can be carried out accurately.

As can be seen from the above description, in the present invention, the support pipe is first placed on or isolated from the underwater ground, held vertically with a support frame, anchor wire, etc., and then inserted into the support pipe to be raised and lowered and rotated. Test and sample soil materials on the surface layer of the ground using the sampling tube at the tip of the freely adjustable test rod, drive and fix the support pipe to the depth of the sample taken above, and then sequentially test and collect the soil materials below the support pipe. The method is characterized in that testing and sample collection are carried out in a state where the surface layer of the ground is not disturbed.

Since the present invention performs turning in this way, it is possible to test and sample the surface layer of the underwater ground before driving the support pipe, and it is possible to perform tests and sample collection as accurately as the sampling of the ground below the driven support pipe. Even if the support pipe is initially placed on the underwater ground or isolated, it must be held vertically by support frames, anchor wires, etc. to the extent that it does not interfere with the initial testing and sample collection. , Since it is securely and firmly supported after driving, testing and sample collection can be carried out smoothly from beginning to end.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of the installed state of the boring device used in the present invention, and FIGS. 2A, B, and C are schematic front views of the main parts showing the implementation procedure of the present invention according to the turning order. be. 1...Support pipe, 3...Testing rod, 4...
Support frame, 5... Anchor wire, a... Boring device, A... Underwater ground, A'... Surface layer of the ground.

Claims (1)

[Claims] 1. In a construction method in which a boring device is supported by a single support pipe and the support pipe is erected underwater to perform boring for geological surveys, the support pipe is first placed or isolated on the underwater ground and then placed on a support stand. frame,
Inspect soil materials on the surface layer of the ground using a sampling tube at the tip of a test rod, which is held vertically with an anchor wire, etc., and inserted into a support pipe so that it can be raised and lowered and rotated freely.
After collecting as a test and inspection sample, the above inspection,
Start by driving and fixing the support pipe by setting the depth at which the support pipe can be stably erected to the tested depth.
Next is the underwater boring method, which is characterized by sequentially inspecting, testing, and sampling the ground below the support pipe.