JP2002004276A - Natural ground reinforcing earth construction method using large diameter rock bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct an anchor body with a high strength and a high quality which is adaptable for a wide range of geological structure and capable of concentrating and simplifying a construction works and enhancing the construction efficiency and accelerating the economical promotion. SOLUTION: A double bit (5) formed separably of an outer bit (3) and an inner bit (4) is attached to the tip of a casing rod (1). A core member (2) and an injection hose (5) are set in the casing rod (1) in advance. After bed rock is drilled to a specified depth, a grouting material is charged from the injection hose into the drilled hole. The double bit is separated when pulling up the casing rod (1). The inner bit (4) and the core member (2) are left in the drilled hole, in the natural ground reinforcing earth construction method using a large diameter rock bolt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavation earth retaining method for civil engineering work, a temporary earth retaining method for excavation, a method of reinforcing earth slopes using a large-diameter rock bolt for strengthening against rainwater and earthquakes and reinforcing structures. The present invention relates to a high-quality, efficient, and economical construction method and apparatus.

[0002]

2. Description of the Related Art There are the following conventional reinforcing earth construction methods in which an anchor bolt is inserted into a perforated ground, a grout material such as cement milk is injected into the perforated ground, and the anchor bolt is fixed in the ground by hardening of the grout material.

(1) A single pipe rock bolt type construction method in which a single diameter small diameter anchor body of usually 5 m or less is constructed using a core material of 25 mm or less by a small diameter single pipe drilling method of 60 mm or less by a pneumatic drifter. It has been known. The construction of this anchor body is performed in five steps: drilling → rod withdrawal → insertion hose insertion → grout material injection → core material insertion. The injection hose is inserted after drilling the injection hose and the core material is also grouted. Is inserted after the injection of

(2) A 90 mm medium bore double pipe drilling system using a hydraulic rotary percussion drill is used.
There is a double-pipe lock bolt method in which a short medium-diameter anchor body of usually 7 m or less is constructed using a core material of 5 mm or less.
Construction of this anchor body is performed in six steps: drilling → casing rod pullout → injection hose insertion → grout material injection → core material insertion → inner rod pullout. The core material is also inserted after the grout material is injected.

[0005] (3) In addition, using a hydraulic or pneumatic rotary percussion drill with a medium-bore single pipe system of 50 to 65 mm in diameter, leaving a drilling rod of 25 to 33 mm as a core material in the drilling hole, usually 6 m or less There is a self-drilling rod bolt type construction method to build a short medium diameter anchor body. The construction of this anchor body is performed in a two-step procedure of drilling → grout material injection, the injection pipe line uses a drilling rod, and this method is to install rock bolts on collapsed ground This is a method of leaving the rod and bit as they are without removing them after drilling.

(4) Further, a short large-diameter anchor body of usually 9 m or less is constructed using a core material of 19-51 mm by a large-diameter double pipe drilling method of 90-135 mm using a hydraulic rotary percussion drill. This is the method of construction. Construction of this anchor body is performed in six steps of drilling → inner rod withdrawal → injection hose insertion → grout material injection → core material insertion → casing rod withdrawal, and the injection pipe is inserted after drilling the injection hose, There is a method of inserting the core material after the grout material is injected and the like.

[0007]

The following items can be cited as conditions to be satisfied by the ground reinforcement method. 1) It can be applied to a wide range of geology. For example, the target geology needs to correspond to soft ground, hard ground, collapsible ground and the ground where these are combined, and all of them. In addition, by applying a single construction method to various types of ground, it is possible to consolidate and simplify construction types, and to promote efficiency and economy of construction.

[0008] 2) The anchor body has a large proof strength. When the anchor strength is large, the number of anchors required for ground reinforcement can be reduced, thereby shortening the construction period and reducing the construction cost. Determining factors of the anchoring force of the anchor body are the frictional force of the peripheral surface between the anchor body and the ground, the adhesion force between the anchor body and the core material, and the tensile strength of the core material.In order to increase the proof stress of the anchor body, It is necessary to increase the construction diameter of the anchor body and lengthen the anchor body, and to configure the strength and the core material of the anchor body so as to conform to this.

3) The quality of the anchor body is ensured.
Determining factors for the quality of the anchor body are the shape of the anchor body, the positional relationship between the anchor body and the core material, and the strength of the anchor body.A predetermined shape is ensured, and the core material is placed near the center of the cross section of the anchor body. In addition, it is necessary to ensure that the cement milk having a predetermined composition is filled.

4) Efficient construction is possible. By adopting a method that can easily and quickly perform the procedure for constructing the anchor body, efficient construction can be performed, and the construction period can be shortened and the construction cost can be reduced.

Analysis of the prior art in view of these conditions reveals that the single-tube rock bolt method described in (1) of the prior art has a small diameter, a small excavation hole, a small anchor body strength, and a loose sand layer or gravel. When drilling a collapsible soil such as a soil layer and a cobblestone layer, there is no measure to prevent collapse of the hole wall after the rod is pulled out because it is a single pipe drilling. Since the cross section cannot be secured, there is a problem that it is difficult to construct a target anchor body.

Further, the double pipe rock bolt system described in the above (2) is not usually applied to hard rock due to the power of the drilling machine. In addition, the hole diameter is small, the drilling length is small, and the anchor body proof stress is small. Further, there is a large difference between the hole diameter and the core material diameter, and some means is required to dispose the core material at the center of the cross section of the anchor body in order to insert the core material after the hole is drilled.

The self-drilling rock bolt system described in the above (3) is not usually used for hard rock due to the relationship between the power of the drilling machine and the economy, and has a small diameter and a small drilling hole, a small anchor body proof stress. Since the grout material is injected with the drilling rod remaining after drilling, the slime treatment may become unstable.

Further, in the large-diameter lock bolt system described in the above (4), since the difference between the hole diameter and the core material diameter is large, the core material is inserted after the hole is drilled. Therefore, there is a problem that requires some means.
Further, since the anchor body is built through the six-step construction procedure, there is a problem in efficient construction.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a ground reinforcement capable of coping with all the grounds such as a soft ground, a hard ground, a collapsible ground and a composite ground thereof. It provides a construction method.

The present invention provides a double bit consisting of an outer bit for drilling in which the tip of the casing rod is attached to the casing rod itself, and an inner bit for drilling which is attached to the tip of a core material previously mounted in the casing rod. Form. The inner bit for drilling is disconnected when the casing rod and the out bit of the casing rod are released when the casing rod is pulled out, and is provided so as to be able to remain in the drilled hole together with the core material. Further, a grout material injection hose is attached to the core material previously mounted in the casing rod, and when the core material penetrates, the casing rod,
Also, after pulling up the casing rod, leave the inner bit for drilling remaining at the tip of the hole so that it is located near the center of the cross-section of the built anchor body, and place a spacer at an arbitrary point in the core material at the middle of the hole. Attach.

[0017] Then, using a hydraulic percussion drill hammer, as described above, the casing rod formed with a double bit at the tip end penetrates into the soil layer or to a predetermined depth of the bedrock, and then provided in the core material. The grout material is injected from the injection hose, and the grout material is filled into the drilled hole while extruding the slime from the tip of the hole toward the opening of the hole, and the outer hole for drilling at the tip of the casing rod when the casing rod is pulled out. The connection between the bit and the inner bit for drilling is released, and the casing rod is pulled out while leaving the inner bit for drilling and the core material in the drilled hole, and the anchor body composed of the grout material and the core material is placed in the ground. It is a ground reinforcement method using large rock bolts.

The casing rod used in the method of the present invention has an outer diameter of 90 to 216 mm, and the core material has a nominal diameter of 19 to 51 mm. In addition, a steel rod such as a deformed or fully threaded steel rod is used as the core material.

Since the present invention is configured as described above, the following operational effects can be obtained. 1) Since a high-output (up to 100 kW) hydraulic rotary percussion drill, which cannot be used in the conventional ground reinforcement method, is used as a drilling machine, it can be used for hard rock and cobblestone-mixed soil layers.

2) Since a large-diameter drill bit and a casing rod are used, and a high-output hydraulic rotary percussion drill is used, a construction diameter (up to 225 mm) and a construction length (10 m) not available in conventional lock bolts. ) The above anchor body can be constructed, and the strength of the anchor body can be increased.

3) By the penetration of the casing rod, the collapse of the hole wall at the time of drilling and grouting can be prevented,
The anchor body can be held in a predetermined shape. Furthermore, since the grout material of the cement milk is injected while eliminating the slime in the hole after the drilling, the slime can be prevented from being mixed into the cement milk, and further, the inner bit for the drilling is left and a spacer is provided. Therefore, the core member can be reliably positioned near the center of the cross section of the anchor body, so that the quality of the anchor body can be ensured.

4) Since the shock absorbing device is mounted on the extension rod portion of the hydraulic rotary percussion drill hammer, the impact energy at the time of drilling is transmitted to the core material previously arranged in the casing rod. Fatigue can be suppressed.

In constructing the anchor body, a core material and an injection hose are previously arranged in the casing rod and drilled. After the drilling is completed, a grout material is injected into the casing rod to cut the core material and the inner bit for excavation. Since it is a method of pulling out while leaving it in the hole, the construction procedure of the anchor body can be saved,
Efficient construction can be performed.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a view showing a procedure of a ground reinforcement method of the present invention, and FIG. 2 is a view showing a core material used in this method. In FIG. 2, 1 is an outer diameter of 90 mm.
216 mm casing rod, and a double bit 5 is formed by an outer bit 3 for drilling at the tip and an inner bit 4 for drilling provided at the tip of the core material 2 previously mounted at the center of the cross section in the casing rod 1. Form.

As the core material 2, a steel rod such as a deformed steel rod having a nominal diameter of 19 to 51 mm or a fully threaded steel rod is used. In the embodiment, a fully threaded steel rod is used. An injection hose 6 for discharging the grout material C is attached to the core material 2. The double bit 5 is connected to the casing rod 1 by a disconnecting device 8 described later.
And the casing rod thus configured is attached to the rotary percussion drill 30.
Digs into the soil layer or the rock G.
(Fig. 1 (A))

On the way, the core material 2 and the injection hose 6 are added if necessary (FIG. 1 (B)), and the diameter is 100 to 22 at a predetermined depth.
When the drilling of the hole of 5 mm is completed, a grout material, for example, cement milk C is filled into the drilling from the tip portion through the injection hose 6 attached to the core material 2. (Fig. 1 (C))

The connection between the inner bit 4 of the double bit 5 and the outer bit 3 for drilling the casing rod 1 is released by operation at the opening, and the casing rod 1 is pulled up. (FIG. 1 (D)) When the casing rod is pulled up, the inner bit 4 for drilling and the core material 2 are left in the drilling H and become the core material of the anchor body A (FIG. 1 (E)).

FIG. 3 is a perspective view showing the structure of the core material.
Has an end nut 9 as one of connecting and releasing members of the double bit 5 at the end, and a grouting material injection hose 6 is attached to the shaft by a hose fixing band 7. A spring-loaded spacer 10 for arranging the core material on the shaft body of the core material 2 at the center of the cross section in the casing rod.
Where 11 is a joint coupler and 21 is a nut. Then, the core material 2 configured as described above is mounted and placed in the casing rod 1 in advance.

The double bit decoupling device of the present invention will be described with reference to FIGS. 4 to 6, a tip nut 9 is provided at a tip of a core material 2 to be mounted in a casing rod 1 having a drill bit outer bit 3 screwed to the tip. Also, the inner bit 4 is projected from the inside of the tip of the casing rod 1, the inner bit 4 and the outer bit 3 are connected by the bit connecting pin 12 and the spring 13, and the tip of the bit connecting pin is connected to the tip of the core 2. It is supported by the nut 9.

The tip nut 9 contacts the inner wall 4b of the inner bit 4, and presses and supports the inner bit 4 in the direction of the blade 4a. A rear end 4c of the inner bit 4 is provided with a space 14 for one tip nut 9, and a rear end 4d of the inner bit 4 is provided with a cap 1 for preventing the tip nut 9 from falling off the inner bit 4.
5 is attached.

Referring to FIG. 7, the operation of releasing the connection of the double bit 5 will be described. As shown in FIG. 7 (A), after the casing rod is penetrated and excavated to a predetermined depth of the ground using a hydraulic rotary percussion drill hammer 30, the core material is When the grout material C is filled into the hole H from the injection hose 6 attached to the hole 2 and the casing rod is pulled up, the core material 2 is pulled up by the operation space at the hole opening portion by the moving space 14 of the tip nut 9. 7B, the inner wall 4b of the inner bit 4
The tip connecting nut 12 and the spring 13, which have been supported by the connecting nut 12, come off and the connection with the outer bit is released. Then, as shown in FIG. 7 (C), the inner bit 4 and the core
The casing rod 1 is pulled up while being left inside.

FIGS. 8 and 9 are a structural diagram and an operational state diagram of the spacer according to the third aspect. FIG.
The core material 2 previously mounted on the casing rod 1
One end of the coupling coupler to the shaft 2a of
With the injection hose 6 through the fixing band 7 of
At the other end, a spacer stator 16 that pivotally supports the spacer movable element 17 so as to be able to be turned up and down, a coil spring 18 for urging the spacer movable element 17 in the horizontal direction, a pressing plate 19 and a spacer supporting a washer 20 with a nut 21 are attached. It consists of

When the core member 2 with the spacer 22 configured as described above is inserted into the casing rod 1, FIG.
As shown in (A), the tip of the spacer mover 17 of the spacer 22 is pressed against the inner wall of the casing rod, and the core 2 is maintained at the center position of the casing rod 1. In this state, excavation and grouting are completed, and the casing rod 1 is moved to the position shown in FIG.
(B), the spacer mover 17 slides in contact with the inner wall of the casing. As shown in FIGS. 9C and 9D, when the spacer mover 17 escapes from the inner wall of the casing rod, it rotates in the horizontal direction by the action of the coil spring 18 and contacts the wall surface of the excavation hole H to build a core material. It can be arranged in the vicinity of the center of the cross section of the anchor body that has been set.

FIG. 10 is a structural view of a shock absorber according to claim 4, wherein a spring 24 and a washer 25 are arranged in an extension rod 23 which inserts and supports a shaft portion of the core member 2 on the opening side. It is configured to support the end 2b. With such a configuration, it is possible to suppress the impact energy applied to the core material 2 at the time of drilling, suppress the fatigue of the core material, and build an anchor body of good quality.

[0035]

According to the method of the present invention, a large-diameter anchor body having a larger anchoring force than conventional lock bolts can be constructed, and quick construction can be performed as compared with the double pipe drilling method. At the same time, a large-diameter anchor body can be constructed on a hard soil layer, a cobblestone-mixed soil layer, and a bedrock where it is difficult to construct a large diameter by the stirring and mixing method. In addition, the quality, work efficiency and economy of the structure are improved as compared with the prior art.

Further, according to the present invention, the applicable range of the soil reinforcement method can be expanded by expanding the geology to be applied to hard ground or hard rock. Compared to the conventional ground reinforcement method, it is more efficient and economical, and because it is possible to build a high-strength and high-quality anchor body, it is possible to make the conventional design economical. However, the range of application of the ground reinforcement method will be expanded to those where other methods have been applied.

According to the present invention, since a high yield strength, high quality, efficient and economical anchor body can be obtained, the present invention can be applied as an alternative construction method for reducing the number of lock bolts used in the conventional tunnel support method and saving labor. Can be

According to the present invention, since an anchor body having a high proof strength can be obtained, it is possible to increase a resistance and a supporting force against overturning or sliding of an abutment or a pier. The function and effect that can be applied can be expected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a construction procedure of a ground reinforcement method according to the present invention.

FIG. 2 is a structural view of an anchor construction member used in the method of the present invention.

FIG. 3 is a structural diagram of a concentric material.

FIG. 4 is a structural diagram of a double bit used in the method of the present invention.

FIG. 5 is a front view of the same double bit.

FIG. 6 is a diagram showing a main part of the above.

FIG. 7 is a diagram showing a procedure for decoupling double bits according to the first embodiment;

FIG. 8 is a structural view of a spacer used in the method of the present invention.

FIG. 9 is a view showing an operation state of the spacer according to the embodiment.

FIG. 10 is a structural view of a shock absorber used in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing rod 2 Core material 3 Outer bit 4 Inner bit 5 Double bit 6 Injection hose 8 Connection release device 9 Tip nut 10 Spacer 30 Percussion drill hammer A Anchor body G Rock H Drilling C Grout material

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ichiro Sakaguchi 2-17-4 Yanagibashi, Taito-ku, Tokyo Inside Onoda Chemiko Co., Ltd. ) Inventor Masaichi Fujita 2-6-13 Tajiri, Ichikawa-shi, Chiba F-term (reference) 2D041 GA01 GC07 GC14 2D044 EA01

Claims (4)

[Claims] 1. An underground anchor method in which a ground is drilled, an anchor bolt is inserted into the hole, and a grout material is injected, and the anchor bolt is fixed in the ground by hardening of the grout material. Inside the casing rod provided at the tip, a core material having an inner bit for drilling at the tip is mounted in advance, and the inner bit for drilling provided on the core material is mounted inside the tip of the casing rod, and the casing is mounted. After forming a double bit with an outer bit for drilling at the tip of the rod, and drilling the double bit through the casing rod to a predetermined depth in the ground using a hydraulic rotary percussion drill hammer,
The grout material is filled into the drilled hole while extruding slime from the hole tip to the hole opening from the injection hose provided in the core material, and the outer bit for drilling and the inner hole for drilling are withdrawn when the casing rod is pulled out. Disengaging the connection with the bit, pulling out the casing rod while leaving the inner bit for drilling and the core material in the drilling, forming an anchor body consisting of grout material and the core material in the ground. Earth reinforcement method using large diameter rock bolts. 2. The casing rod has an outer diameter of 90 to 21 mm.
2. A soil reinforcement method using a large-diameter rock bolt according to claim 1, wherein the core material is a steel rod such as a deformed or fully threaded steel rod having a nominal diameter of 19 to 51 mm and a core material of 19 to 51 mm. 3. The large diameter lock according to claim 1, wherein an inner bit for drilling and a spacer for positioning the core material near the center of the cross section of the casing rod are mounted at predetermined positions on the core material. Ground reinforcement method using bolts. 4. The soil reinforcement method using a large-diameter lock bolt according to claim 1, wherein a buffer device is provided on an extension rod of the hydraulic rotary percussion drill hammer.