JPS6340885B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a grouting method for injecting cement milk into rock to prevent rock collapse and seepage flow.

In conventional grouting methods, it has been completely impossible to simultaneously grout multiple grout holes with cement using a single grout pump. This is due to the fact that cement milk is a fluid with sedimentation properties. In other words, when cement milk of a predetermined concentration is discharged from one grout pump and injected into many grout holes at the same time, due to the difference in flow path resistance and press-in resistance at each grout position, When , the flow velocity changes greatly. As a result, a phenomenon occurs in which the concentration of cement milk varies greatly depending on the location. In other words, at the point where the resistance is greatest, the flow slows down, cement particles settle, the concentration of cement milk decreases, and the cement particles tend to settle, resulting in clogging, and in some cases, recovery is impossible. This is because condensation may progress.

However, when a floating substance is used as a coagulant rather than a settling fluid such as cement milk, or when a two-component coagulant is separately conveyed to the vicinity of the grout holes and mixed, it is necessary to simultaneously fill multiple grout holes. It is also possible to grout. For example, JP-A-48-
Publication No. 89508 discloses such a simultaneous grouting method. In this construction method, two liquids are pumped into the vicinity of the grout hole through separate pipes, and the two liquids are brought together in the vicinity of the grout inlet.

The object of the present invention is to develop a technique that allows a single grouting pump to successfully grout a large number of grouting holes at the same time even when cement milk, which is a settling fluid, is used alone. In other words, when multiple grout holes are drilled, cement milk corresponding to the characteristics of the rock mass can be injected into each grout hole at the same time, making it easier to reduce seepage flow within the rock mass than before, and effective even at spring locations. The purpose of this work is to provide a grouting method that makes it easier to strengthen rock and saves labor in terms of workability.

The present inventors have developed a grouting method that can effectively achieve these objectives, and have named it the multi-hole simultaneous grouting method since no comparable grouting method has been found in the past.

The grouting method of the present invention is a grouting method in which cement milk is pressurized from a grout pump into a large number of grout holes drilled into the rock, in which a branch pipe is arranged from a main pipe to each of the plurality of grout holes, and each branch pipe is connected to the main pipe. Connecting the branch pipes so as to have a rising angle, forming the main pipe endlessly, and interposing a circulation pump therein to form the main pipe into a circulation path,
The discharge side end of a grout pump for feeding cement milk from the mixer is connected to the circulation path, and the cement milk that is continuously circulated through the main pipe is created with a natural concentration gradient through the branch pipe having the rising angle. The method is characterized in that cement milk is press-fitted into each grout hole while forming the grout hole. The natural concentration gradient here is that under low pressure, the water inside the branch pipe is clear, but when the pressure becomes high and a flow is generated from the branch pipe toward the bedrock, the turbid water due to cement particles begins to rise, and the flow is interrupted. This means that the concentration adjustment function works naturally, where when the flow is slow, the concentration is low, and when the flow is fast, the concentration is within the main pipe.

According to this multi-hole simultaneous grouting method, the interior of the main pipe, branch pipes, and grout holes are always kept unblocked, so cement milk is applied to the internal voids of the rock (whether it is matrix-based or crack-based). The grout flow rate and concentration are automatically adjusted while freely selecting the locations where grout is needed, filling those voids with cement, stopping water flow within the cracks, and solidifying the rock. In particular, it has become possible to grout areas that are difficult to apply high pressure to, such as rock or loose areas where grouting was impossible due to significant leakage of cement milk.

Hereinafter, the grouting method of the present invention will be specifically explained according to the embodiments shown in the drawings.

FIG. 1 shows a system diagram of the present invention, in which a large number of grout holes a _i , b _i , c _i are bored at various locations in the side wall A, ceiling B, and floor C of the tunnel. An example is shown in which cement milk is simultaneously injected into a _i , b _i , and c _i . The main parts of the injection equipment used in this multi-hole simultaneous grouting method are composed of a main pipe 1, a branch pipe 2, a circulation pump 3, a pressure pump (grout pump) 4, and a mixer 5.

The main pipe 1 is arranged almost horizontally unless there is a space restriction, and a large number of upward riser pipes 6 are attached to the pipe wall. The details of this are shown in FIG. 2, and this riser pipe 6 is designed to maintain a relationship in which the cement milk in the main pipe 1 flows upward from the main pipe 1 when the main pipe 1 is installed almost horizontally. It is installed with an upward corner. This upward angle (angle from the horizontal plane) should be as close to 90 degrees as possible. One of the characteristics of the construction method of the present invention is that the branched flow of cement milk from the main pipe 1 is distributed with a rising angle. According to numerous tests carried out by the present inventors, it has been found that distributing with this rising angle plays an extremely important role in automatically adjusting the concentration and preventing blockage in the pipe.

The branch pipe 2 is connected to each grout hole from the riser pipe 6.
It is a conduit leading to the injection tube 7 of a _i , b _i , c _i ,
In practice, it is preferable to use flexible pipes. Regarding this branch pipe 2 facility, riser pipe 6
Care should be taken not to create a U-shaped tube up to the injection tube 7 by raising it as steeply as possible. For example, even if the grout hole is located lower than the position of the main pipe 1, first raise it as much as possible from the main pipe 1 and guide it downwardly to the injection tube without creating a U-shaped pipe.

Typical examples of the injection tube 7 are shown in FIGS. 3 and 4, and the injection tube 7 is inserted into the grout holes a _i , b _i , c _i made by boring so that its tip is open. For example, it is fixed with a mouth patcher 8 made of cement. At that time, in places where grout holes a _i and b _i are bored upward, such as in side wall A and ceiling B, this injection tube 7 is inserted shallowly into the grout hole and fixed. In section C, if the grout holes a _i and c _i are horizontal or inclined downward, this injection tube 7
It is best to insert it deep into the grout hole. In a typical example, the stronger the downward slope, the higher the
As shown in the figure, for vertically downward grout holes, insert the long injection tube 7' so that the tip of the injection tube 7' opens near the bottom of the grout hole, and pour cement milk toward the bottom of the grout hole. It is best to press it in from the bottom and blow it out from the bottom. In this case, as shown in FIG. 4, a pipe 9 with a valve 10 attached is buried at the mouth of the grout hole so that the inside of the grout hole can be washed with water when the work is interrupted. This prevents occlusion of the lower end of the tube.

In addition to such a pipe configuration, it is extremely important to circulate cement milk within the main pipe 1 by the circulation pump 3 in order to succeed in this multi-hole simultaneous grouting method. In other words, the main pipe 1 is configured to be endless, and the circulation pump 3 is interposed therein. This circulation pipe is supplied with cement milk from a mixer 5 under pressure by a pressure pump 4 which is a grout pump. In other words, each grout hole a _i ,
Regardless of the injection state of b _i and c _i , it is important to continue to flow cement milk into the main pipe 1 at a high flow rate during this grouting work. The cement milk supplied from the mixer 5 has a cement to water ratio of 1:1, although it varies depending on the nature of the rock.
to 1:20.

The multi-hole simultaneous grouting method of the present invention enables simultaneous grouting of multiple grout holes using a single grout pump, which was considered impossible with conventional methods, and allows for flexible grouting of cracks in the rock. It has been found that a phenomenon occurs in which cement milk is injected and filled while automatically adjusting the concentration and flow rate according to the conditions of the crack. This phenomenon of free selection of cracks and automatic adjustment of concentration and flow rate to the desired advantage can be achieved in the absence of the above-mentioned requirements for upright branches from the main pipe, circulation pipes, and also for downward grout holes. If the requirement for bottom blowing is missing, it will not be satisfied. In the case of the method of the present invention, no matter what state (over-system or leakage system) or situation the cracks in the rock leading to each grout hole are in, the inside of the main pipe, branch pipes, and grout holes are always kept unblocked. If maintained, the cement milk circulating in the main pipe will cause turbulent flow or boiling phenomenon (floating state of cement particles) at the rise of the branch pipe, and turbulent flow or sliding flow will occur in the cracks, causing cracks. This forms a flow that becomes less concentrated toward the tip. This low-concentration milk then takes the lead and gradually guides the high-concentration milk to fill the cracks leading to the free surface, forming a partially accumulating flow.

In carrying out the present invention, the pressure of the cement milk that is injected into the system by the pressure pump 4 (grout pump) is not raised to an unnecessarily high pressure as in the conventional grouting method, but rather starts from a low pressure and removes cracks etc. The pressure naturally becomes high as it fills. For example, when starting grouting, it is preferable to use a low pressure of 5 kg/cm ² and a cement/water ratio as low as 1/10 to 1/20, and gradually increase the pressure as grouting progresses. In addition, it is preferable to continue with a low concentration of cement unless there is a special reason. Shortly after starting this injection, spring water or dripping water can be seen on exposed rock walls and permeability test holes. Eventually, this spring water becomes cloudy and leakage of cement milk is observed, but once the void within the bedrock is filled with cement milk in the desired condition, these phenomena stop, and the grouting is almost complete. It is determined that

According to the present invention, in civil engineering and mining work that requires strengthening the rock mass and suppressing seepage flow within the rock mass, cement milk is simultaneously injected from multiple grout holes to simultaneously fill the entire area of the rock mass from the surface layer to the deep layer. Not only can it be filled with grouting, it is not only advantageous in its operation, but the filling layer that is formed is dense and detailed, and it exhibits effects that cannot be achieved with conventional grouting methods.
It can greatly contribute to disaster prevention, etc.

[Brief explanation of the drawing]

Figure 1 is a system diagram of the method of the present invention, Figure 2 is a cross-sectional view of the main pipe, Figure 3 is a cross-sectional view of the grout hole, and Figure 4 is a cross-sectional view of the grout hole.
The figure is another cross-sectional view of the grout hole. 1... Main pipe, 2... Branch pipe, 3... Circulation pump,
4...Pressure pump (grout pump), 5...Mixer, 6...Rise pipe, 7...Injection tube,
7'... Injection tube (long injection tube for bottom blowing), 8... Packer, 9... Washing tube, 10
……valve.

Claims (1)

[Scope of Claims] 1. In a grouting method in which cement milk is pressurized from a grout pump into a large number of grout holes drilled into the rock, a branch pipe is arranged from a main pipe to each of the plurality of grout holes, and each branch pipe is connected to the main pipe. The branch pipes are connected so as to have a rising angle, the main pipe is formed endlessly, and a circulation pump is interposed therein to form the main pipe into a circulation path, and a grout pump for feeding cement milk from the mixer is formed. The discharge side end is connected to the circulation path, and the circulating cement milk connected to the main pipe is forced into each grout hole while forming a natural concentration gradient through the branch pipe having the rising angle. A multi-hole simultaneous grouting method characterized by: 2. The construction method according to claim 1, wherein a bottom-blowing tube for injection is provided in the horizontal and downward grout holes. 3. The construction method according to claim 1 or 2, wherein a pipe equipped with a valve is installed alongside the injection pipe at the grout hole opening.