JPH08326054A - Execution method of ground anchor and cutoff device in drilling casing - Google Patents

Abstract

PURPOSE: To conduct the separation recovery operation of a drilling casing smoothly and safely by using a cutoff plunger in the drilling casing having a high cutoff function and performing cutoff treatment in the drilling casing. CONSTITUTION: A cutoff device 15 is passed through the small bore section of the joint section 18 of a drilling casing 5 on the outer circumference of a pressure pipe 17, but the cutoff device 15 is mounted so as to be stopped at the stepped section of the small bore section to water pressure to be applied and cut off water. The cutoff device 15 is inserted into the drilling casing 5, and the drilling casing is drawn out by length, in which the joint section is exposed, under the state, in which the pressure pipe 17 is borne by a holding jig. The exposed joint section is separated, the drilling casing 5 is extracted and recovered, and an injection material is pressed and injected. Accordingly, the re-swelling operation of the holding jig in the extraction process of the drilling casing 5 is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a ground anchor, which is constructed mainly at a position deeper than the groundwater level, and a water stop device in a drilling casing used for carrying out the construction method.

[0002]

2. Description of the Related Art When constructing a ground anchor at a position deeper than the groundwater level, there are the following problems. During drilling, as shown in FIG. 14, the earth and sand a together with the groundwater flow out from the hole mouth, disturbing the ground around the drilling hole or causing an accident in which the surrounding ground sinks. In the figure, e is a retaining wall. w is the water level of groundwater. When the pressure of the groundwater is large, the inside of the drilling casing b as shown in FIG. 15 is shown when the cement milk c is injected after the drilling, the anchor member d is inserted, and the drilling casing b is collected. There is a phenomenon in which groundwater and earth and sand flow into the material and the injected material n (cement milk) is diluted or pushed back, an anchor body of a predetermined quality and shape is not formed, and an anchor proof strength cannot be secured. When the boring casing b is completely removed, FIG.
As shown in, a phenomenon occurs in which a large amount of earth and sand a flows out around the hole mouth.

It is considered that the above-mentioned phenomenon causes a depression of the surrounding ground and a large decrease in the bearing capacity of the ground anchor, which is a serious problem. Conventionally, the following construction methods have been proposed to solve the above problems that occur when constructing a ground anchor at a position deeper than the groundwater level. First, with respect to the above problem, as shown in FIG. 17, the boring casing b having the bit f with a check valve is used for excavation. Further, as shown in FIG. 18, a mouth pipe h was installed together with the water blocking packing g, and as shown in FIGS. 19A and 19B, the mouth pipe h was subjected to a water stopping treatment with a packing k of rubber or the like. For example, a water-stop box m is installed. According to these methods, when a large amount of earth and sand is discharged during drilling or when cement milk is injected,
It is possible to prevent the inflow of groundwater and earth and sand into the inside of the drill casing when the anchor member is inserted.

In order to solve the above problems, a method of inserting a water stop plunger (water stop device) into the holed casing to stop the water (JP-B-5-29729, JP-A-6-12895).
No. 3 gazette) is proposed. In addition, with respect to the above problems, a method of injecting a grout quick-setting agent into the mouth (Japanese Patent Publication No. 5-29729), a method of stopping water by a water stop device attached to a water stop wall, etc. have been proposed. There is.

[0005]

[Problems to be Solved by the Invention]
As disclosed in Japanese Laid-Open Patent Publication No. 29729, etc., a method of inserting a water blocking plunger (water blocking device) into a drilled casing to stop water is performed by using a ground water pressure (pressurized water pressure) with a high water blocking plunger or an anchor. It cannot resist the pressure of cement milk injected during construction, and if left unattended, it will be pushed out of the drilling casing. For this reason, a holding jig for fixing the water stopping plunger is used, but this holding jig requires a refilling work when the drill casing is collected. The remounting work of the holding jig is a very difficult work because it is necessary to refill the fixing jig while resisting the groundwater pressure during the refilling.

Therefore, an object of the present invention is to use a water stop device (water stop plunger device) in a drilling casing which is simple in refilling work and exhibits a high water stop function, and this water stop device. It is an object of the present invention to provide a method for constructing a ground anchor, which can perform water-stopping treatment in a drilling casing and perform the work of separating and collecting the drilling casing in a procedural, efficient and safe manner.

[0007]

[Means for Solving the Problems] As a means for solving the above-mentioned problems of the prior art, the method of constructing a ground anchor according to claim 1 is such that a hole for anchor construction is dug and cut by a drilling casing. After drilling, the grout is filled into the drilling casing, the anchor member is further inserted into the drilling casing, and then while pulling out the drilling casing, pressure injection of the injection material is performed within the range of the fixing length, and finally In a method of constructing a ground anchor that performs water-stopping treatment and curing with a mouth packer, prior to the withdrawing step of the drilling casing, a pressure pipe is provided in the central portion and a small diameter portion of the joint portion of the drilling casing is provided on the outer periphery. It has a packing that can pass through the hole drilling hole and reaches the stepped part formed by the small diameter part against the water pressure in the drilled casing and exhibits a water blocking function. The water device is inserted and installed in the hollow portion of the outer end portion of the hole making casing, and a holding jig for holding and supporting the pressure pipe by taking a reaction force to the fixed system is provided. With the pressurizing pipe supported, pull out the hole drilling casing to a length such that at least one joint part is exposed, and for the hole drilling casing, separate the exposed joint part and collect it. It is characterized in that the casing is pulled out and the injection material is injected under pressure.

The pressure pipe according to claim 1 has a joint portion at a position closer to the front side than the position where the pressure jig is held by the holding jig, and the pressure pipe is placed at the position of the joint portion when the holding jig is resized. After cutting, the holed casing is separated and collected. Next, the water stop device in the drilling casing according to claim 3 is provided with a pressurizing pipe in the central portion, and the outer periphery of the pressurizing pipe is passed through a small diameter portion of the joint portion of the drilling casing. With respect to the pressurized water pressure in the drilled casing, it has an outer diameter packing that stops at the step formed by the small diameter portion and exerts a water blocking function. It is characterized in that the pressurizing pipe is grasped and supported by a holding jig which is inserted into the hollow portion of the drilled casing and has a reaction force to the fixed system.

[0009]

In the withdrawal process of the hole-drilling casing, the water stop device uses the pressing pipe with the pressing jig with a force larger than the sliding frictional resistance generated between the packing and the inner surface of the hole-drilling casing when the hole-drilling casing is withdrawn. Be supported. Therefore, according to the extraction of the drilled casing, the packing of the water blocking device is relatively advanced as it advances in the hollow portion of the drilled casing, and finally passes through the small diameter portion formed in the joint portion of the drilled casing. To do.

At this stage, the withdrawal of the drilled casing is temporarily stopped, and one drilled casing exposed to the outside of the hole is separated and collected at the joint portion. The holding jig that will be a hindrance during the work will be replaced. If the force that grips and supports the pressure pipe is released when changing the holding jig, naturally the water blocking device (packing) is likely to be pushed out of the hole due to the pressure of the water inside the drilling casing. . However, although the packing may move back a little, as shown in FIG. 8, the packing stops at the front side of the step formed by the small diameter portion of the joint portion of the drilling casing, becomes stable, and the position is sufficient. Demonstrate a good water-stopping function.

Therefore, the operator can safely and safely carry out the work of refilling the holding jig and separating and recovering the drilled casing without worrying about the accident of the water stop device popping out. . By the way, the results of the test for confirming the water stopping effect in the hole-cutting casing of the water stopping device are shown in FIG.
3 and Tables 1 and 2. In the test, as shown in FIG. 13, water pressure is applied from one end side to the inside of the hole-drilling casing b by the water supply pump p, and the water-stop device (water-stop plunger) attached to the inside of the hole-drilling casing b from the other end side is stopped. The water quality was investigated. In the test, the water stoppage test was carried out by moving the water stoppage device in the holed casing by the jack j while the water pressure was applied, and in particular overcoming the joint part y. In FIG. 13, reference numeral r is a holding jig, t is a drive pipe, and u is a pressure pipe.

The water shut-off device was passed through the joint portion y of the hole-drilling casing b once to confirm that the rubber packing had no abnormality, and then was reset in the hole-drilling casing b. When water pressure is applied to the inside of the hole drilling casing beyond the first hole drilling casing joint, 5 kg
Water stopping was confirmed up to a water pressure of f / cm ² . Next, the water pressure inside the hole-drilling casing was lowered once, and the hole-drilling casing was pulled out so that the water stop device entered the hole-drilling casing joint, and water pressure was applied, and a water-stoppage of 8 kgf / cm ² or more was recognized. . The test according to the same procedure was performed until the joint y of the drilled casing was crossed 20 times, 5 kgf / cm ² in the drilled casing and 8 kg in the casing joint.
Water stoppage of f / cm ² or more was confirmed.

In the construction of one ground anchor, up to 20 drilled casings (30 m in total length of the casing) can be added at the maximum, and as a result of this test, the water stopping device has a necessary and sufficient water stopping ability and durability. It can be said that it has been confirmed to work. By the way, the attached Table 1 shows the confirmation of water leakage (water blocking) by visual inspection for the drilled casing in the above test, and Table 2 shows the result of water blocking confirmation of the joint portion (step). . In Table 1 and Table 2, "reaction force required" indicates that it is necessary to apply a reaction force by a pressing jig to the pressure pipe of the water stop device.

[0014]

EXAMPLES Next, examples of the present invention shown in FIGS. 1 to 12 will be described. 1 to 5 and 9 to 12 show essential process diagrams of a method of constructing a ground anchor under a high pressure groundwater pressure below the groundwater level. First, FIG. 1 shows a stage in which the base plate 2 and the lower bracket 3 are attached to the mountain retaining wall 1 in accordance with the driving position of the ground anchor. FIG. 2 shows a step of mounting a water stop box 4 on the lower bracket 3 and installing a drilling machine (not shown), and further inserting a drilling casing 5 into the water stop box 4 to dig a hole for anchor construction. Is shown. Drilling is performed with a drilling casing with a check valve bit (see FIG. 17). The drilling water and the drilling soil are discharged through the drain valve 4 a of the water shut-off box 4. A water stop shutter 7 and an outer swivel 8 are installed in advance on the outer periphery of the hole-drilling casing 5 via a reaction force stand 6 between the hole stop casing 4 and the water stop box 4.

In FIG. 3, after completing the drilling to a predetermined depth, the drain valve 4a in the water shut-off box 4 is closed, the jack 9 for pulling out the drilling casing is attached, and then the grout hose is placed in the drilling casing 5. It shows the step of putting 11 and injecting and filling grout (cement milk) 10. Next, FIG. 4 shows a stage in which the anchor member 12 is inserted into the hole casing 5 (cement milk 10). A mouth packer 13 and a wire packer 14 are attached to the anchor member 12 in advance.

FIG. 5 shows a pressurizing pipe 17 with a water stopping device 15 (water stopping plunger) in the pipe at the outer end of the hole-drilling casing 5.
It shows a stage in which the pressing jig 16 is set by inserting and setting. As shown in detail in FIGS. 6 and 8, the water shut-off device 15 is provided on the outer periphery of the pressurizing pipe 17 with the drilled casing 5
Is slightly smaller than the inner diameter of the hole drilling casing, and a plurality of packings having a diameter slightly larger than the small diameter portion of the joint portion 18 of the casing (hard water-stop rubber discs) 15a ...
It is configured such that b are sandwiched in between and gathered at a little interval, and are fixed by a rubber mount 15c. When the water blocking device 15 is inserted into the hollow portion of the holed casing 5, the outer peripheral edge of the packing 15a is slightly deformed as illustrated in FIG. The packing 15a reaches the stepped portion 18a formed by the small diameter portion of the casing joint portion 18 when receiving the pressurized water pressure from the left side to the right side in FIG.
It resists the high pressure water pressure inside the hole-drilling casing and exerts a water stop function. As shown in FIG. 7, a pouring port 20 that is opened and closed by a check valve 19 is provided at the tip of the pressurizing pipe 17. Therefore, the cement milk does not flow back through the pressure pipe when pulling out the drill casing 5. The outer end of the pressurizing pipe 17 is connected to an injection material press-fitting pump (not shown). The pressurizing pipe 17 is also provided with a detachable joint portion 21 at a position on the front side of the position (the position of the gripping tool 16a in FIG. 5) gripped and supported by the pressing jig 16, It is easy to change the place. In this embodiment, the holding jig 16 for fixing the positions of the water stop device 15 and the pressure pipe 17 is a gripping tool 16 for holding and supporting the head of the pressure pipe 17.
The steel rod 16 is attached between a and a handle 16b provided on the jack 9 for pulling out. This is because when the jack 9 for pulling out is used to pull out the drilling casing 5, the water blocking device 15 is pushed into the drilling casing of the next stage (specifically, the position of the water blocking device 15 is fixed and the drilling casing 5 is This is to enable work. It will be apparent from the above-described experimental results that the water stopping device 15 exhibits a high water stopping performance even when the water stopping device 15 moves in the hole forming casing 5. .

Next, in FIG. 9, in order to surely generate the frictional resistance between the cement milk 10 in the fixing length portion of the ground anchor and the ground, every time the drilling casing of the fixing length portion is pulled out by a predetermined length (about 3 m), shows a step of performing a pressurized injection of cement milk ^{(3kg / cm 2 ~5kg / cm} 2 about pressure) through the pressure pipe 17. Even with respect to the pressure at the time of pressure injection, by using the water stop device 15, there is no outflow of cement milk due to pressurization, and reliable pressure injection can be performed.

FIG. 10 shows a stage in which the drilling casing of the free length portion is further pulled out after the procedure (drawing of the drilling casing and pressure injection) of FIG. 9 is repeated in the fixed length portion of the ground anchor. Even when the drilling casing is pulled out, if the water pressure at the tip of the drilling casing is high, the cement milk in the drilling casing will be pushed up or mixed with groundwater, and the injectant (cement milk) will be diluted. However, since the water stop device 15 completely prevents the movement of groundwater, such inconvenience does not occur at all. FIG. 10 also shows that the shutter in the water shut-down box 4 is compressed against the wire packer 14 previously installed near the head of the anchor member 12 with only the last one drilling casing 5 left. And the backflow of the cement milk is prevented at the ostium at this time.

After that, the last hole-drilling casing 5 is pulled out and collected, and the casing pulling jack 9 and outer swivel 8 which have been used as shown in FIG. 11 are removed. FIG. 11 also shows a stage in which grout is pressure-injected into the mouth packer 13 to perform a water-stop treatment for preventing backflow of groundwater and cement milk from the drill hole.

Further, FIG. 12 shows a stage in which the last water stop shutter 7 and the water stop box 4 are also removed, and only the lower bracket 3 is left. After that, the anchor is cured, and the anchor is tensioned and fixed in the usual manner. The above-described embodiment is an example of the diagonal anchor, but the same configuration and procedure are carried out in the case of a vertical (vertical) anchor adopted for preventing the structure from rising, and the same operational effect is obtained. Can be obtained.

[0021]

According to the method of constructing a ground anchor according to claim 1, which employs the water stopping treatment in the hole-drilling casing according to the invention of claim 3, the construction of a ground anchor at a depth below the groundwater level is achieved. , Especially the remounting work of the pressing jig is extremely easy in the process of extracting the holed casing,
The work of separating and recovering the drilled casing can be carried out efficiently and safely in a procedural manner.

In addition, the water shut-off device according to the third aspect of the present invention is provided with another water pressure countermeasure method (for example, a drill hole casing with a check valve, a wire packer and a water shut shutter, a mouth packer, etc.).
When used in combination with the ground anchor, it prevents the outflow of groundwater and sediment other than drilling water and drilling earth and sand, and adds an anchoring long part that plays an important role in demonstrating the yield strength of the ground anchor in the entire construction process of the ground anchor. The pressure injection can be reliably performed with good workability.

[0023] As a result, a special reshuffling procedure for the construction of ground anchors for earth retaining for deep-depth excavation in the ground having a high groundwater level and vertical anchors used for preventing floating of structures, etc. Without it, it can be done efficiently and safely.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mounting stage of a base plate at an early stage of construction of a ground anchor.

FIG. 2 is a sectional view showing a stage of drilling.

FIG. 3 is a cross-sectional view showing a step of injecting an injection material.

FIG. 4 is a cross-sectional view showing a step of inserting an anchor member.

FIG. 5 is a cross-sectional view showing a stage where a water stop device is installed.

FIG. 6 is a front view of the water stop device.

FIG. 7 is a cross-sectional view of a check valve mechanism at the tip of a pressure pipe.

FIG. 8 is a cross-sectional view showing an installed state of the water stop device.

FIG. 9 is a cross-sectional view showing a stage of pressure injection of an injection material in ground anchor construction.

FIG. 10 is a cross-sectional view of a stage where water stop processing is performed by operating a water stop shutter.

FIG. 11 is a cross-sectional view of a stage where the mouth packer is inflated to perform the water stop treatment.

FIG. 12 is a cross-sectional view at a stage where all the equipment is removed.

FIG. 13 is a front view of a water stop performance test device for a water stop device.

FIG. 14 is an explanatory diagram showing a situation of sediment outflow from a hole mouth.

FIG. 15 is an explanatory view showing a situation of inflow of groundwater and earth and sand into a holed casing.

FIG. 16 is an explanatory diagram showing an outflow of earth and sand around the hole mouth when removing the hole making casing.

FIG. 17 is an explanatory view showing a hole drilling situation by a hole drilling casing having a check valve bit at its tip.

FIG. 18 is an explanatory diagram showing an installation example of a mouth pipe.

19A and 19B are explanatory views showing an installation example of the water shut-off box.

[Explanation of symbols]

 5 Drilling casing 10 Grout (cement milk) 12 Anchor member 13 Mouth packer 15 Water stoppage device 15a Packing 16 Holding jig 17 Pressurizing pipe 18 Joint part 18a Step part 21 Joint part

[Table 1]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Yamamoto 1-18-22 Nishiki, Naka-ku, Nagoya City Takenaka Corporation Nagoya Branch (72) Inventor Kazuhiko Tanimura 1-18-22 Nishiki, Naka-ku, Nagoya No. Takenaka Corporation Nagoya Branch (72) Inventor Takeshi Sakamaki 1-44 Kanda Jinbocho, Chiyoda-ku, Tokyo Structural work Co., Ltd. (72) Inventor Kazutoshi Kuratomi 1-44 Kanda Jimbo-cho, Chiyoda-ku, Tokyo Within the corporation

Claims (3)

[Claims] 1. A hole for anchor construction is dug by a hole-drilling casing, after the hole is drilled, grout is filled into the hole-drilled casing, an anchor member is further inserted into the hole-drilled casing, and then the hole-drilled casing is pulled out. However, in the method of constructing a ground anchor that performs pressure injection of the injection material in the range of the fixing long portion and finally performs water-stopping treatment by the mouth packer to perform curing, prior to the drawing step of the drilled casing, the central portion A pressurizing pipe is provided on the outer periphery to allow passage through the small diameter portion of the joint portion of the hole drilling casing, and for pressured water pressure in the hole drilling casing, it reaches a step formed by the small diameter portion. A water blocking device having a packing that exhibits a water blocking function is inserted into the hollow portion of the outer end portion of the holed casing and installed, and a reaction force is applied to the fixed system to grip the pressure pipe. A pressing jig for supporting is provided, and the hole drilling casing is pulled out by a length such that at least one joint portion is exposed in a state where the pressure pipe is supported by the pressing jig, and the hole punching casing removes the exposed joint portion. A method for constructing a ground anchor, which is characterized by separating and recovering, and repeating the same steps below to perform extraction of the drilled casing and pressure injection of the injection material. 2. The pressurizing pipe according to claim 1 has a joint portion at a position closer to the front side than a position where it is gripped by a holding jig, and presses at the position of the joint portion when the holding jig is rearranged. A method for constructing a ground anchor, characterized by separating and recovering a drilled casing after dividing a pipe. 3. A pressurizing pipe is provided at a central portion, and the pressurizing pipe can pass through a small diameter portion of a joint portion of the boring casing on the outer periphery of the pressuring pipe to prevent water pressure in the boring casing. Is equipped with a packing of an outer diameter that reaches a step formed by the small-diameter portion and exhibits a water-stop function.
For the ground anchor construction, wherein the packing is inserted into the hollow portion of the drilling casing together with the pressure pipe, and the pressure pipe is gripped and supported by a holding jig that has a reaction force to the fixed system. Water stop device for drilling casing.