JP2871264B2 - Process control method of ground improvement work using jet jet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to construct a solid body such as a pillar in the ground by jetting an improved liquid jet jet containing a solidifying material such as cement into the ground and mixing and stirring it while shaving off surrounding soil. And construction management methods for ground improvement works.

[0002]

2. Description of the Related Art As shown in FIG. 5, a ground improvement method using a jet jet is shown in FIG. 5 in which an injection pipe 1 for an improved liquid jet is erected from the ground at a predetermined depth, and an improved liquid jet 2 of a cement slurry is injected from the tip of the pipe. At the same time, the surrounding earth and sand are scraped off and mixed and stirred to form a columnar solidified body 3 in the ground. Conventionally, in order to control the process of this improvement work, as shown in FIG.
During the construction, the vibration applied by the jet 2 of the improved liquid jet is sensed by the accelerometer 5 to detect the arrival of the improved liquid, and thereby determine the shape of the solidified body 3 formed by the improved liquid. Was.

[0003] In addition, processes have been managed by human experience based on values such as the injection amount and injection pressure of the improving liquid, and the finished product has been judged.

[0004]

According to the conventional method for managing a process using a rod, when the jet of the improving liquid comes close to the rod because it is under the ground, the improving liquid is used to detect the vibration of the whole earth and sand. The arrival of the jet cannot be measured accurately. For this reason, it was difficult to know the exact construction result in the construction process. In addition, the magnitude of the vibration also changed depending on the difference in the ground conditions, and a quantitative judgment could not be made. Since the arrival position of the improved liquid jet can be detected only in the plane dimension, the depth direction has to be estimated indirectly from the insertion depth of the injection pipe. In the method in which a person judges based on values such as the injection amount and the injection pressure, large variations occur due to ground conditions and the ability of the person, resulting in low reliability.

The present invention has been made in view of the above problems. The purpose is to control the process by detecting the arrival point of the improvement liquid three-dimensionally and accurately in real time at the time of construction, at the position of the plane and the depth, and accurately determining the shape of the consolidated body. It is to propose a process management method of ground improvement work using jet jet which can be done.

[0006]

This process control method is used in ground improvement work in which a jet grout containing a solidified material is sprayed into the ground to scrape off surrounding earth and sand, and mixed to form a solidified body in the ground. An optical fiber stands vertically in the ground around the jet grout injection pipe, irradiates light from the upper end of the optical fiber, receives light reflected from the tip surface, and cuts the optical fiber tip by the jet grout jet from the time from irradiation to light reception An object of the present invention is to solve the problem by a configuration in which a position is obtained and a jet grout reaching position is detected.

In this management method, an optical fiber made of glass or plastic is placed at a plurality of positions in a work area, and the position of the cut optical fiber is detected by an improved liquid jet, and the remaining cut optical fiber is further detected. Detect length. This measurement data is processed in real time to grasp the arrival point of the improved liquid jet under construction in three dimensions of the plane position and the depth, and to feed it back to the construction process to manage the process.

FIG. 1 shows an example of this management method. .. 6-n are erected vertically at n points in the ground surrounding the injection pipe 1 of the improved liquid jet inserted into the ground, and the upper end thereof is optically switched. Via a detector 7 to a fault point detector 8 and a personal computer 9.

As shown in FIG. 2, for example, as shown in FIG. 2, the optical fiber 6 is set at predetermined intervals in four orthogonal radiation directions and one radiation direction centering on the injection tube 1 and vertically extends at a predetermined depth.

The fault locator 8 irradiates the optical fiber 6 with light, receives the light reflected at the tip, and measures the time from irradiation to light reception. The personal computer 9 performs arithmetic processing on data from the fault point locator.

As a measurement procedure, prior to the injection of the improved liquid jet, a reflected light pulse returning from the tip surface of the optical fiber is received as an initial value of the optical fiber installed in the ground, and the time from irradiation to light reception (t ₀₎ ) Is measured (FIG. 3 (a)). Next, after the injection of the improved liquid jet is started, a reflected light pulse from the distal end face of the optical fiber cut by the improved liquid jet is received, and the time (t ₁ ) from light irradiation to light reception is measured (FIG. 3). (b)). Then, the propagation velocity is obtained from the refractive index of the used optical fiber and the frequency of the light which have been input to the personal computer in advance.
The length l (ell) of the cut optical fiber is

[0012]

(Equation 1)

The arrival position of the improved liquid jet is detected from the length of the optical fiber. In this way, by measuring the change in the reflected light pulse, it is possible to detect that the improved liquid jet has reached the optical fiber installation position, which is the check point, and the depth of the point currently being constructed can be determined from the reflected light pulse position change. Can be measured in real time.

The number of optical fiber installation points can be freely selected from several to several tens. The optical fiber 6 and the fault locator 8 are directly connected to each other, or several are used. Alternatively, as shown in FIG. Optical fibers can be used.

The measured data is displayed on a computer in real time, and the arrival point of the improved liquid jet is displayed in a three-dimensional display, a plane position display, a depth for each installed optical fiber, and the like. This information is fed back to the construction process to manage and construct the process, form a solid body of a desired shape, and improve the ground. The measurement data is stored in a recording device such as a floppy disk, and is displayed in a three-dimensional display or a planar display as shown in FIG.

FIG. 4 shows four points A, B, C, and D in four radial directions orthogonal to the injection pipe 1 and A at equal intervals in the A direction.
Optical fibers are installed at -1, A-2, A-3, and A-4 positions to detect the arrival of the improvement liquid, and the results are displayed three-dimensionally at depth levels a, b, c, d, e, and f. FIG. 4 is an explanatory diagram for determining the shape of a solidified body.

[0017]

According to the process control method of the ground improvement work, the pre-installed optical fiber is detected to be cut by the improvement liquid jet and the arrival of the improvement liquid is detected. Can be grasped reliably. The depth position can be accurately determined from the length of the cut optical fiber. During the construction, the arrival position of the improved liquid can be displayed in three dimensions in real time, and the shape of the solidified body can be determined. Information on the improved liquid arrival position, three-dimensional shape, etc. obtained in real time is fed back to the construction process, the moving speed of the injection pipe is adjusted, etc., the process is controlled, and the desired solidified body is formed without defects. Ground improvement can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a partial cross section of a method for managing a process of ground improvement work according to the present invention.

FIG. 2A is a plan view showing an installation position of an optical fiber, and FIG.
Is a longitudinal sectional view.

FIG. 3 is a time-light ratio graph showing (b) a time t ₀ until a reflected light pulse is received by the optical fiber before cutting, and (b) a time t ₁ until a reflected light pulse is received by the optical fiber after cutting.

FIG. 4 (a) is an explanatory diagram of an installation position and a depth of an optical fiber for three-dimensionally displaying the shape of a solidified body.

FIG. 5 is an explanatory diagram showing a partial cross section of a ground improvement work using a jet jet.

FIG. 6 is an explanatory diagram of a conventional method for managing a process of ground improvement work.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Injection pipe, 2 ... Improved liquid jet, 3 ... Solidified body, 4 ... Rod, 5 ... Accelerometer, 6 ... Optical fiber, 7 ... Optical switch, 8 ... Obstacle point detector, 9 ... Personal computer.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masayuki Miura 2-9-1-1, Tobita-Shi, Chofu-shi, Tokyo Kashima Construction Co., Ltd. (72) Inventor Junichi Hirai 2-191-1, Tobita-Shi, Chofu-shi, Tokyo No. Kashima Construction Co., Ltd. (56) References JP-A-57-213 (JP, A) JP-A-55-9958 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB Name) E02D 3/12 101 E02D 3/12 102

Claims (1)

(57) [Claims] An improved liquid jet containing a solidifying material is sprayed into the ground to remove surrounding soil and mix to form a solidified body in the ground. A vertical optical fiber is erected, and light is radiated from the upper end of the optical fiber to receive the reflected light from the distal end surface. A process control method for ground improvement work using a jet jet, characterized by detecting an arrival position.