JPS58213922A - Landslide preventive work for soft ground of slope - Google Patents

Abstract

PURPOSE:To economically prevent the landslide of the ground in a short time by a method in which pipe wedges are driven into the landslide portion of sloped soft ground on rock-bed, the surrounding ground of the pipe wedges is solidified, and ground water around the pipe wedges is discharged to the ground's surface. CONSTITUTION:Plural pipe wedges 3 are set with rods in the boundary area between soft ground 2 distributed on sloped rock-bed 1 and the rock-bed 1 and a water-permeable structure 8 through which water around the pipe wedges 3 is discharged to the ground's surface is provided from the boundary of the soft ground 2 to the ground's surface. Then, the soft ground in and aroung the boundary of the soft ground 2 is solidified around the pipe wedges 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for preventing ground failure that occurs in soft ground on a slope where unconsolidated soft ground is distributed in contact with consolidated rock.

In general, in the ground condition of a slope where unconsolidated soft ground is distributed in contact with the consolidated bedrock, Kfi permeation and groundwater may occur at the boundary of the ground or in the soft ground during rain or snow melting. When water flows down to form underground water with multiple scales and multifaceted structures, there are many cases in which disasters such as ground failure and ground failure occur with these boundaries serving as failure surfaces.

When we examine the locations where the above ground collapses and ground failures occur, we find that they frequently occur on slopes ranging from flatlands to mountains, and are often caused by groundwater conditions in addition to the above ground conditions. There are many (accepted).

Therefore, the conventional countermeasure methods for preventing the occurrence of ground collapse and ground failure in soft ground on slopes include (a) replacement method of replacing a part of the soft ground layer, (b) pile driving method,
0 → Various countermeasure construction methods are used, such as pile driving method and drainage polling by drilling holes in the horizontal direction to drain drainage water, but all of the above construction methods do not work if the soft ground is 5 to 10 meters thick or more. In cases where it is widely distributed, it is technically impossible to use it directly without any kind of ground preparation.
This is economically difficult, especially with the pile driving method, which requires longer piles as the soft layer becomes thicker. It is extremely difficult to secure a foothold for the construction machine and carry out temporary construction work.Even if long piles could be driven hot, the ground would be soft Depending on the groundwater conditions, the soft soil in the ground becomes muddy and tends to slip through between the two piles, reducing the deterrent effect of the driven piles.

However, if ground improvement is used as a countermeasure for these problems, even if an attempt is made to improve the soft ground by ±7, if the ground slopes and obstructs the flow of groundwater into the ground, there is a risk of term ups occurring behind the ground, which can be dangerous. situation? It's okay to invite.

First, in order to effectively drain water from a groundwater aquifer with a multifaceted structure, a small number of holes limited to the horizontal direction will not necessarily drain water sufficiently, and unless drilling is done by drilling multiple holes. Adequate drainage 7 lines 7. ．． It is difficult to do so. In particular, after the first hole is drilled by drainage poling, there is a space that is easily filled with soil and sand that flows in. Generally, a perforated PVC pipe is inserted, but after a long period of time, it gradually becomes clear. It is inevitable that the water capacity will be lost and the drainage function will deteriorate.

However, the basis of measures to prevent the occurrence of ground collapse and ground failure on soft ground on slopes is to effectively implement underground drainage. The method is to replace the tiles with water-permeable filler instead of creating spaces that will serve as drainage holes by drilling holes, etc. It would be most desirable as a countermeasure against the above-mentioned ground failure and ground failure if drainage facilities could be constructed with a structure that expands and is interconnected vertically at the full depth reaching the bedrock layer.

This invention solves the above-mentioned drawbacks and problems of the conventional construction methods.One, it is a disaster prevention construction method that prevents ground failure and ground failure that occur on soft ground on slopes, and the other is , restore the ground damaged by the disaster as soon as possible 1
For the purpose of the second construction method, the first step is to install a pipe wedge in a predetermined area centered on the boundary between the bedrock and soft ground on a slope where soft ground is distributed on the bedrock for consolidation. Then, the above pipe wedge is installed to remove the groundwater that causes ground failure in the soft ground outside the target ground, and the third step is to drain the water (filtered water into a drainage channel for pore water). The second step involves injecting the water-permeable unsolidified composition into the ground to form a drainage network in the rice field, and then injecting the solidifying composition into the pipe (with the rust as the core). The present invention provides a method for preventing ground failure that occurs in soft ground on a slope, which is obtained by continuously constructing a third process of improving and strengthening the pipe wedge at seven points around the pipe wedge.

Hereinafter, the construction method according to the present invention will be described in detail with reference to the attached drawings.

First, in the t6-E step according to the present invention, as shown in FIG. In order to integrate the soft ground 2 by suturing it together, pipe wedges 3 as shown in FIGS. 2 and 3 are installed only in a necessary predetermined area.

In general, in soft ground with a slant as shown in Figure 1, there are many cases where clean groundwater flows down mainly to the interface between bedrock 1 and soft ground 2, and the line a-a' or b-b ' line is the ground failure plane or expected ground failure direction.

In the conventional technology, long piles had to be driven to the depth required by the design using a large construction machine, but with the construction method of the present invention, a small polling machine with a self-propelled function is used. A pipe that is easy to use and move (can be moved to the installation point of the rust 6), made of a material whose stability has been considered in advance in the design, and a pipe with the necessary strength (by adding the rod 4 to the rust, In this case, the length of the pipe wedge 3 is the length of the range where ground failure is likely to occur, or the range where ground failure has occurred. In order to connect the rod 4 to the pipe (wedge 3), the upper end of the pipe wedge 3 should be
This is accomplished by forming a single fixing pin 5 fixed to the rod 4 at the lower end connection portion of the rod 4 and fitting it into the T engagement groove 4a.

An excavation bit 6 is fixed to the tip of the pipe wedge 6, and reinforcing reinforcing bars 7 are appropriately set and inserted inside.

Next, in the second step that is carried out following the first step, six pipe wedges are installed at the boundary between the bedrock 1 and the soft ground 2, or in order to exclude groundwater flowing through the soft ground 2.
By injecting/constructing the ground into a predetermined area around this area using an injection liquid made of a water-permeable unsolidified composition, a plurality of plate-shaped water-permeable structures 8 formed in a substantially vertical direction are formed. 1 will be given.

The permeable structure 8 functions as a drainage channel for the groundwater flowing through the soft ground 2 at the boundary between the ground I and the ground, and also as a drainage channel for pore water that is dewatered in the third step described below. .

Here, the characteristics of the injection liquid made of the above-mentioned unsolidified composition are that it remains viscous while being dispersed in a network in a predetermined area during ground injection, and maintains the minimum required fluidity during injection. ,
After the permeable structure 6, which is a net-like drainage system, is formed in the planned area, only the additional material is removed in order to prevent the fluid added material in the unsolidified composition from interfering with drainage. An additional material is selected to prevent it from flowing out together with groundwater in as short a time as possible and impairing the drainage function of the injection material itself, and which does not cause pollution even if it mixes with groundwater. In other words, as a result of various experiments, the unsolidified composition used in the present invention has a particle size of 0.2 to 0 as the main component of the composition.
．． Using sand with a weight distribution of 80 mm or more and having a weight quarter of 80 cm or more, starch, cellulose, etc. are added as auxiliary compositions to provide the required minimum fluidity during pouring. The easily decomposable polymer colloid organic material and water are added, and the mixing ratio of each is sand, auxiliary composition: water = 1: 0.002 to 0.004:
It is best to set it between 0.563 and 0786.

Furthermore, in the third step, which is carried out following the second step, the pipe (rust 3) is installed and fixed in the first step, and the unsolidified composition is injected in the second step to form the net-like water permeable structure 8. After forming - the pipe wedge 6 and the permeable structure 8;
A reinforcing structure 9 is formed by intensively injecting an injection liquid made of an assimilating composition around the area, and a pipe wedge 5 is installed to improve and strengthen the soft ground in this area. By organically performing the three processes from the first process to the third process, the final result is rock 1 and soft ground 2. It is sewn together to create a ground structure that is both strong and hydraulically stable.

Hereinafter, the three steps from the first step to the third step of the construction method according to the present invention will be explained in detail based on FIGS.

In the figure, Fig. 4 (a) shows the first step according to the present invention, in which the pipe (the wedge 6 is installed so as to be connected to the bedrock 1 and the soft ground 2), and then in the second step, the pipe wedge is A plate-shaped water-permeable structure is formed in a vertical direction by performing ground injection (IV) of a water-permeable unsolidified composition in a predetermined area around the installation. As shown in FIG.
The soft ground in the area where the pipe wedge has been installed will be improved and strengthened, and then the rod 4 above the pipe wedge 6 will be separated and removed. Figure 4 (]→ is an explanatory diagram showing the state of ground drainage and pipes (improved and strengthened around the rust) using the construction method according to the present invention, where the soft ground 2 is sutured to the bedrock 1 by the pipe wedge 3. At the same time, the surrounding area of this pipe (Sabiro and ground drainage) is reinforced with an assimilated composition to form a reinforced structure 90, and the surrounding area of this reinforced structure 90 is a water permeable structure 8 made of a water permeable unsolidified composition. Therefore, underground water can be effectively drained.

As explained in detail above, according to the construction method of this invention,
The ability to prevent ground failures that occur in soft and weak ground on slopes in a short time and economically. It should be able to withstand loads and concentrated loads, prevent ground collapse, and quickly restore ground that has been destroyed by a disaster.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the present invention, showing the state of improvement of soft ground on a slope. Figure 6 is a perspective view showing the connected state of Figure 2, and Figure 4 is a sectional view explaining the process according to the present invention. 1... Rock, 2... Soft ground. , 6... Pipe wedge, 4... Rod, 5... Fixed pin, 6... Bit, 7... Reinforcement bar, 8... Water permeable structure, ?-
...Reinforced structure. Patent applicant Yuichi Takahashi

Claims (1)

[Claims] tll A first step of installing a pipe wedge in a predetermined range around the boundary between the bedrock and the soft ground on a slope where soft ground is distributed on solidified bedrock; A drainage network is formed in the soft ground where wedges are installed to remove groundwater that can cause ground failure out of the target ground, and to serve as a drainage channel for pore water that will be dehydrated by ground injection in the third step. The second step involves injecting the water-permeable unsolidified composition into the ground, and pouring the assimilating composition into the pipe around the pipe wedge installed above (by injecting the assimilating composition around the pipe wedge into the ground). A method for preventing ground failure that occurs in soft ground on a slope, characterized in that the third step is to improve and strengthen the soft ground on the slope. (2) The third step to improve and strengthen the soft ground. In the second step,
The water-permeable unsolidified composition injected into soft ground to form a drainage network consists of sand, starch, and cellulose, which has a particle size distribution of between 0.2yn+n and 05-05-0, and has a weight fraction of 80% or more. It consists of an auxiliary composition consisting of an easily decomposable high-molecular colloidal organic substance such as, and one cup of water to liquefy the sand and the auxiliary composition, and the proportions of the sand, auxiliary composition, and water are as follows: 1: 0.002-0004: 056-0786 The method for preventing ground failure occurring in soft ground on a slope as claimed in claim 1.