JPH07107264B2 - Underground continuous wall method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction method for constructing a continuous wall in the ground, and more particularly to a construction method for a continuous underground wall suitable for collapsible ground.

[0002]

2. Description of the Related Art Conventionally, in order to construct a continuous wall in collapsible ground, a hollow drilling rod having a cutter at its tip is generally used, and water or muddy water (bentonite, etc.) is fed from the tip of the drilling rod. While making a hole, the hole is made by rotating the hole making rod, and after making the hole making rod, a grout (cement, mortar, etc.) is made to come out from the tip of the hole making rod, and muddy water is replaced by the grout to form a columnar shape. A method has been adopted in which the fixing layer is repeatedly formed at a predetermined pitch so that the fixing layers overlap each other. According to such a construction method, since the ground is prevented from collapsing due to the pressure of water or muddy water during drilling, the columnar wall can be stably formed.

However, in the case of a highly collapsible ground containing a large amount of boulders and gravel, it is difficult to suppress the collapse of the boulders and gravel only by the pressure of the water or muddy water. In such a case, For example, insert the drilling rod into the casing made of steel pipe, rotate the casing and the drilling rod concentrically to perform drilling, and after drilling, inject the grout into the casing while pulling up the drilling rod, I had no choice but to adopt the troublesome construction method of pulling the casing out of the ground later.

By the way, recently, as a ground reinforcement method, as shown in FIG. 4, a relatively small diameter (100 to 300
(mm) steel pipe pile 2 and then a pair of elastically deformable swelling bodies (made of rubber) 3a in the steel pipe pile 2
, First, the bulging body 3a is bulged at the deepest insertion position to form a closed pressure chamber 4 in the pipe 2, and then the pressure chamber 4 is introduced into the pressure chamber 4 through a supply pipe 5 connected to the injector 3. The grout is pressure-fed, the check valve 6 provided on the steel pipe pile 2 is opened by the pressure of the grout to discharge the grout to the outside of the steel pipe pile, and the fixing layer 7 is formed around the steel pipe pile 2 () and injected. The above-mentioned operation is repeated while pulling up the machine 3 to gradually expand the fixing layer 7 upward (), and a construction method has been put into practical use (see, for example, JP-A-3-208986).

According to the above ground reinforcement method, since grout is injected under pressure into the ground around the steel pipe pile 2, a strong anchoring layer 7 having a sufficient thickness is formed around the steel pipe pile 2 to form a steel pipe. The pullout resistance of the pile 2 increases, and it becomes extremely useful as an anchor for reinforcing the inner wall of the tunnel A as shown in FIG. 5, for example, and its use has already been achieved. Therefore, it is also possible to construct a continuous wall by repeating this ground reinforcement construction method so that the fixing layers 7 wrap each other and repeating the fixation layers 7 so as to wrap each other.
In this case, the steel pipe pile 2 functions as a protective wall for preventing the ground from collapsing, and it becomes possible to construct a continuous wall stably and with high efficiency targeting the highly collapsible ground.

[0006]

However, when the ground stabilization method in which the grout is injected under pressure is simply used for the construction of the continuous wall, the steel pipe piles 2 are sewn together because the fixing layers 7 are lapped with each other. It has to be driven at a comparatively small pitch, so when trying to construct a long continuous wall, a huge number of steel pipes with poor machinability are required, and it is very difficult to drill holes for mounting check valves. Takes the labor and time of
Along with the high cost of the steel pipe itself, a significant increase in cost burden cannot be avoided.

[0007] The present invention has been made in view of the above background, and an object thereof is to improve the ground reinforcement construction method for injecting grout under pressure to improve the applicability to continuous wall construction, Therefore, it is to establish an underground continuous wall construction method that can construct a continuous wall with stable and high efficiency and low cost for the highly collapsible ground.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above problems and submerges the pipe into the ground while drilling a slightly wider area than the pipe with the excavator, and the submergence. The second step of pulling up the excavator from the pipe made, insert the injector into the pipe, while feeding the injector at a predetermined pitch in the axial direction of the pipe, feed grout to the injector at each feed position, The third step of opening a check valve provided in the pipe by the pressure of the grout to discharge the grout to the outside of the pipe to form a columnar fixing layer around the pipe, It is characterized in that the three steps are repeated at a predetermined pitch so that the fixing layers overlap each other.

In the present invention, the excavator is only required to be able to drill a region slightly larger than the pipe, for example, one equipped with an eccentric extension bit at the tip (TUBE manufactured by Sandvik Co.).
X), or one having a swingable rotary cutter at its tip can be used. As the pipe made of the above-mentioned general-purpose plastic, for example, a polyvinyl chloride pipe, a polyethylene pipe, a polypropylene pipe or the like can be used.
Further, in the present invention, as the grout, in addition to general-purpose cement, mortar, etc., cellulose-based,
It is possible to use those to which an inseparable admixture in water containing a water-soluble polymer such as acrylic is added.

[0010]

In the underground continuous wall construction method configured as described above, since the drilling machine drills a slightly wider area than the pipe,
The pipe can be submerged in the ground by its own weight or by applying a slight external force, and therefore, the pipe having special strength is not required, and the use of general-purpose plastic is enabled. The use of the pipe made of general-purpose plastic not only makes the hole for mounting the check valve extremely simple, but also makes it more advantageous in price compared with the steel pipe and significantly reduces the cost burden. Further, when a grout to which an inseparable admixture in water is added is used, the water-stopping property of the constructed continuous wall is improved.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the ground stabilization method according to the present invention in the order of steps. In this embodiment, a polyvinyl chloride pipe 11 provided with a plurality of check valves 10 is prepared. First, an eccentric expansion bit 12 is provided at the tip of the pipe 11.
A drilling rod (excavator) 13 having a hole is inserted, and by rotating the drilling rod 13, that is, by rotating the eccentric expansion bit 12, the pipe is gradually submerged in the ground while drilling a slightly wider area than the pipe 11. ), After sinking the pipe 11 to a predetermined depth, the eccentric expansion bit 12 is pulled up together with the drilling rod 13 (). During drilling with the eccentric expansion bit 12,
Since the pipe 11 functions as a protective wall that prevents the ground from collapsing, stable drilling can be performed with high efficiency even when the ground is highly disintegrating and contains many boulders and gravel. Further, the eccentric expansion bit 12 is attached to the pipe 11 by the boring rod 13.
Since the eccentric expansion bit 12 drills a slightly wider area than the pipe 11, the pipe 11 sinks into the ground by its own weight or by applying a slight external force. Even if the one made of vinyl is used, no strength problem occurs.

Next, the injector 15 having a pair of elastically deformable bulges 14 is inserted into the pipe 11, and the bulges 14 are first bulged at the deepest insertion position to bulge the pipe 11. A closed pressure chamber 16 is formed therein, and thereafter, a grout to which an inseparable admixture in water is added is pressure-fed into the pressure chamber 16 through a supply pipe 17 connected to the injector 15. The pressure of the grout causes the pipe 11 to move. The check valve 10 provided on the pipe is opened to discharge the grout to the outside of the pipe 11, a columnar fixing layer 18 is formed around the pipe 11 (), and then the injector 15 is pulled up at a predetermined pitch. Repeat the above operation at the pulling position,
The fixing layer 18 is gradually expanded upward ().

When the fixing layer 18 having a predetermined length is formed around the tube 11 as described above, the tube 11 in the fixing layer is formed.
Then, the next tube is submerged in the ground by a procedure similar to the above with a predetermined distance, and a new fixing layer is formed around the next tube using the injector 15 in the procedure similar to the above. This time,
The sinking position of the next tube is determined so that the next fixing layer wraps the previously formed fixing layer 18. By repeating the above steps while wrapping the fixing layers on each other in this manner, the pipes 1 are formed at a predetermined pitch as shown in FIG.
A continuous wall 19 in which 1 is buried is constructed. Note that FIG.
Although the continuous wall 19 expanded in one direction is shown in FIG. 1, it is needless to say that if the formation of the fixing layer 18 is expanded two-dimensionally in the horizontal direction, a continuous wall having an arbitrary expansion can be constructed.

However, since the pipe 11 made of polyvinyl chloride is used, the hole drilling for mounting the check valve 10 is extremely simple as compared with the conventional case where a steel pipe is used. In addition, it will be advantageous in terms of price and reduce construction costs as much as possible. Moreover, since the pipe 11 has a lower strength than a steel pipe, even if, for example, the once constructed continuous wall 19 has to be dismantled, its excavation or destruction will be easy, and the time required for re-construction will increase. The cost and cost are reduced as much as possible. Further, particularly in the present embodiment, since the one to which the underwater non-separating admixture is added is used as the grout, the water blocking property of the continuous wall 19 is improved, and the reliability as the water blocking wall is significantly enhanced.

Here, the injection machine 15 has a structure as shown in FIG. 3 as an example. In the figure, 21
Is an injection pipe connected to the supply pipe 17, and the pair of bulging bodies 14 are arranged around the injection pipe 21. Each swelling body 14 is made of a rubber tube, and both ends of the swelling body 14 are connected to each other via a tubular connector 22 and a plug 23.
Supported by. The plugs 23 on both ends of the bulge 14 are
One (upper side in the figure) is fitted to the injection pipe 21, while the other is slidably fitted to the injection pipe 21. A sealed fluid chamber 24 is formed between the inner peripheral surface of the bulging body 14 and the outer peripheral surface of the injection pipe 21.
4 includes a flow path 25 provided in one plug 23 and the flow path 2
A pressure fluid such as air, water, oil or the like is supplied from a fluid source (not shown) through a pipe 26 connected to 5. The flow path 2 provided in the other plug 23 is provided between the fluid chamber 24 and the fluid chamber (not shown) in the lower bulging body.
7 and the flexible hose 28. Further, a plurality of discharge ports 29 are provided in the portion of the injection pipe 21 located between the pair of bulges 14.

In the injector 15 constructed as described above, when the pressure fluid is supplied to the fluid chamber 24 through the pipe 26 at a predetermined position in the pipe 11, the bulging body 14 expands,
At the same time, the other (lower side in the figure) plug 23 that slidably fits into the injection pipe 21 is pulled toward the upper side plug, and the pair of swelling bodies 14 largely expand and stick to the inner surface of the pipe 11. As a result, the position of the injector 15 is fixed.
Then, under this condition, the injection pipe 2 is supplied through the supply pipe 17.
When the grout is pumped into the inside of the pipe 1, the grout is supplied into the pressure chamber 16 through the discharge port 29 provided in the injection pipe 21, and is further discharged to the outside of the pipe 11 by opening the check valve 10 provided in the pipe 11. It

The present invention does not limit the structure of the injector 15, but instead of the structure in which the bulging body 14 is expanded by the internal pressure, the bulging body 14 is compressed in the axial direction by, for example, a cylinder. The structure can be bulged.
Further, in the above-described embodiment, the twin barrel type in which the pressure chamber 16 is formed by the pair of bulging bodies 14 is used as the injecting machine 15. However, as this injecting machine, for example, only the upper bulging body is used. It is also possible to use a single-body type provided, and in this case, it is possible to form a continuous wall in which the inside of the pipe is reinforced by repeating the injection from the lower side to the upper side while filling the inside of the pipe with the grout. it can.

[0019]

As described above in detail, according to the underground continuous wall construction method of the present invention, it is of course possible to construct a continuous wall stably and with high efficiency targeting collapsible ground. By using a pipe made of general-purpose plastic, it is possible to significantly reduce the construction cost compared to the case of using a steel pipe, and its utility value is great. Further, when a grout to which an inseparable admixture in water is added is used, the water-stopping property of the constructed continuous wall is improved, and the reliability as the water-stopping wall is significantly increased.

[Brief description of drawings]

FIG. 1 is a schematic view showing an underground continuous wall construction method according to the present invention in the order of steps.

FIG. 2 is a perspective view schematically showing the form of a continuous wall constructed according to the present invention.

FIG. 3 is a sectional view showing an example of the structure of an injector used in the present invention.

FIG. 4 is a schematic view showing a conventional ground reinforcement method in the order of steps.

FIG. 5 is a schematic diagram showing a usage mode of a conventional ground reinforcement method.

[Explanation of symbols]

 10 Check Valve 11 Pipe 12 Eccentric Expansion Bit 13 Drilling Rod 14 Bulging Body 15 Injector 17 Grout Supply Pipe 18 Fixing Layer 19 Continuous Wall

Claims (2)

[Claims] 1. A first step of inserting an excavator into a pipe made of general-purpose plastic, and submerging the pipe into the ground while drilling a region slightly wider than the pipe by the excavator, and the submerged pipe. From the second step of pulling up the excavator from the above, and inserting the injector into the pipe, while feeding the injector at a predetermined pitch in the axial direction of the pipe, the grout is pressure-fed to the injector at each feed position. A third step of forming a columnar fixing layer around the pipe by opening a check valve provided in the pipe by pressure to discharge grout to the outside of the pipe. The continuous underground wall construction method characterized in that the fixing layers are repeatedly performed at a predetermined pitch so as to wrap each other. 2. The underground continuous wall construction method according to claim 1, wherein a grout to which an inseparable admixture in water is added is used.