JPH06185051A - Rock anchor construction method and rock anchor - Google Patents

Abstract

PURPOSE:To form an anchor head in specified size simply by a grout material press-fitted to a rock anchor such as a rock bolt while reinforcing the ground and a bedrock in the periphery of the anchor head, and increase pull-out resistance by improving adhesion with the periphery of the anchor head. CONSTITUTION:The impregnating hole 8 of a grout material is penetrated longitudinally into an inserting hole 2 bored to the ground and a bedrock, a rock anchor body 1, to which a bag body 3 for forming an anchor head communicated with the impregnating hole is annexed, is inserted, and the grout material is press-fitted from the impregnating hole, thus expanding the bag body. The grout material is flowed out to a periphery through the pores of the bag body, thus forming a diameter-expanding grout lump for the anchor head to a rock anchor body while reinforcing the periphery of the diameter-expanding grout lump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rock anchor construction method and a lock anchor used for stabilizing various soils such as soft earth and sand, soft rocks and hard rocks, and slopes and tunnels composed of rocks. Is.

[0002]

2. Description of the Related Art Conventionally, in civil engineering work, a lock anchor method using lock bolts has been widely used in order to stabilize slopes such as rocks and slopes and grounds and rocks of tunnels. There is. However, especially in the case of soft earth and sand, etc., the strength of the ground itself is small, so that the pull-out resistance of the expected size may not be obtained when implementing this rock anchor method. Moreover, the softer the ground forming the slope is, the larger the earth pressure acting on the back of the slope becomes. Therefore, the conventional rock bolts cannot often cope with the back surface earth pressure. For this reason,
Under such conditions, the earth anchor construction method and rigid retaining walls such as L-shaped and inverted T-shaped have been frequently used. In this case, it is conceivable to increase the fixing length by increasing the total length of the lock bolts or the like to obtain the necessary pull-out resistance, but this involves the problem that the construction is difficult and costs a lot.

Therefore, as another method, it has been considered to form an anchor head on the lock bolt to increase the pull-out resistance force. As a means for that, an explosive action of explosives forms a space for the anchor head in the ground. It has been proposed to use this space to form an anchor head. However, the use of explosives has many problems of safety and regulation, and there is a problem that they are not generally available technical means.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the situation of the prior art as described above, and an anchor head having a large volume can be easily formed on a lock anchor such as a lock bolt. The lock anchor construction method and lock anchor are designed not only for soft slopes but also for soft rock and hard rock to improve the pullout resistance by strengthening and adhering the surroundings of the anchor head. It is intended to be provided.

[0005]

In order to achieve the above-mentioned object, the present invention forms an anchor head which penetrates an injection hole of a grout material through an insertion hole formed in the ground or rock and which communicates with the injection hole. Inserting a lock anchor body provided with a bag for use, and press-fitting the grout material through the injection hole to expand the bag body and allow the grout material to flow out through the pores of the bag body to the surroundings. Thus, a technical means of forming a diameter-expanded grout nodule for an anchor head on the lock anchor body and strengthening the periphery of the diameter-expanded grout nodule is adopted.

[0006]

As a result of the adoption of the above technical means, due to the expansion of the bag body attached to the lock anchor body, the surroundings undergo plastic deformation when the ground is soft, or have a certain strength or more like rock. In this case, an expanded diameter grout nodule, that is, an anchor head is formed in a state of being in close contact with the inner surface shape of the insertion hole. In addition, the grout material flows out from the pores of the bag body, fills the voids around the bag body, or enters the surrounding ground or rocks such as cracks or gaps and solidifies. Further, by selecting the injection pressure of the grout material according to the ground condition, the degree of anchor head formation can be controlled, and the pullout resistance of the lock anchor can be managed by measuring the injection pressure. These strengthen the ground or rock around the anchor head and improve the adhesion to the surroundings of the anchor head, so that they together greatly increase the pull-out resistance. Moreover, the water-cement ratio at the time of solidification of the grout material is reduced by the degassing and dehydrating functions of the pores of the bag body, so that an anchor head having high strength can be promptly obtained. Further, it becomes possible to increase the water-cement ratio at the time of pouring grout to give an appropriate fluidity.
If the bag body is configured to be locally destroyed by a predetermined pressure higher than the inflation pressure of the bag body, by applying the predetermined pressure after the inflation action of the bag body is completed, the bag body is locally destroyed. It is also possible to cause a large amount of destruction and secondarily flow out a large amount of grout material through the opening.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are schematic views showing a construction state of an embodiment of the present invention. FIG. 1 shows a construction state on a slope and FIG. 2 shows a construction state on a roof such as a tunnel. . In the figure, reference numeral 1 denotes a lock anchor body, which is inserted into an insertion hole 2 which is previously formed at a predetermined position of the ground or rock by a known appropriate means. An injection hole, which will be described later, is vertically penetrated through the lock anchor 1, and the bag body 3 is inflated by press-fitting a grout material into the bag body 3 attached to the distal end portion through the injection hole at a predetermined pressure. While the wall of the insertion hole 2 is pressed, the grout material filling the bag body 3 is solidified to form an anchor head. When the bag 3 is inflated and the target ground is soft, the surrounding ground is plastically deformed. Further, the bag body 3 has appropriate pores, and the grout material flows out through the pores and the bag body 3
It fills the voids around, and enters into the cracks and gaps in the surrounding ground and rock to solidify. When the grout material flows out from the pores, a part of the pores may be broken due to stress concentration around the pores.
In the figure, 4 is an insertion reinforcing cone that guides while protecting the bag body 3 when inserting the lock anchor body 1 into the insertion hole 2, 5 is a screw portion, 6 is a tightening nut, and 7 is a washer. . Further, FIG. 2A shows a temporary construction state based on the connection between the anchor head formed in the bag body 3 and the ground or rock, and FIG. 2B shows the anchor head and the ground or rock. The figure shows a permanent construction state in which both foundations are used for both the connection and the connection between the outer peripheral surface of the lock anchor body 1 itself on the base end side of the anchor head and the ground or rock.

Next, each embodiment will be specifically described with reference to FIGS. FIG. 3 shows an example for temporary installation. (A) shows a state in which the lock anchor body 1 is inserted into the insertion hole 2 formed in the ground or rock, and (B) shows the lock anchor body 1 through the longitudinal direction. It shows a state where the grout material is press-fitted into the bag body 3 through the injection hole 8 and the bag body 3 is inflated. In the figure, 9 and 10 are discharge ports formed at the tip of the injection hole 8 and communicate with the inside of the bag body 3. The opening area of the discharge port 10 is set to be larger than that of the discharge port 9 and promotes the inflow to the distal end side of the bag body 3, thereby achieving a balance in order to average the inflow. In addition, a concave portion 11 is formed on the outer peripheral surface of the lock anchor body 1 to increase the pullout resistance force. The bag body 3 is attached to the tip of the lock anchor body 1 so as to cover the discharge ports 9 and 10, and is configured to be inflated by the inflow of grout material. FIG. 4 shows an example thereof, and in this example, a long fiber non-woven fabric made of aramid fiber or polyester fiber having a fold 12 as shown is used. The bag 3 has pores (not shown) through which the grout material can flow out.
Needless to say, the pores may be the pores that the material of the bag body 3 such as cloth has, or may be the pores that are formed after the fact. In short, when the bag body 3 is inflated, part of the grout material can flow out through the pores, and at the same time, the pressure in the bag body 3 rises to a predetermined inflation pressure due to the outflow resistance, and the bag body 3 is inflated. Any material having an opening area capable of expanding 3 may be used. The bag 3 is the bag 3
It is also possible that the pores are broken and the grout material is allowed to flow out after the internal pressure has reached a predetermined pressure. As shown in FIG. 3, the bag body 3 is attached to the lock anchor body 1 by fastening both ends using fastening bands 13, 14 and the like.

However, when the grout material is injected through the injection hole 8, the portion of the fold 12 is expanded, and the bag body 3 is inflated as shown in FIG. 3 (B). The grout material filled in the bag body 3 is then solidified to form an expanded diameter grout nodule to form an anchor head. At that time, a part of the grout material flows out through the pores of the bag body 3 to fill the voids around the bag body or to the cracks or gaps in the surrounding ground or rock. It enters and solidifies to further strengthen the surrounding ground and rock, and at the same time, improves the adhesion of the anchor head to the surroundings to increase the pull-out resistance of the lock anchor. In addition, this pore naturally also has a deaeration and dehydration function,
With this function, the water-cement ratio at the time of solidification of the grout material is reduced. Therefore, at the time of injection from the injection hole 8, the water-cement ratio can be increased to impart appropriate fluidity to facilitate the injection. At the same time, at the time of solidification, the water-cement ratio decreases, and an anchor head with high strength can be promptly obtained. Even when the pores are destroyed after the bag body 3 is expanded, the insertion hole 2 which has already been plastically deformed and expanded constitutes the periphery of the expanded portion of the anchor head, and the wall portion of the insertion hole 2 and the grout material are further formed. The pulling resistance of the lock anchor can be sufficiently secured by adding the adhesive force with the lock anchor.

FIG. 5 shows another embodiment, which is a permanent construction of the embodiment shown in FIG. In the figure, (A) shows a state in which the lock anchor body 1 is inserted into an insertion hole 2 bored in the ground or rock, and (B) shows a grout material through an injection hole 8 vertically penetrated into the lock anchor body 1. 3 shows a state in which the bag body 3 is inflated by press-fitting into the bag body 3. In this embodiment, the lock anchor body 1
The closing means 16 is provided so as to cover the discharge port 15 formed at the base end portion of the, and expands by the inflow pressure of the grout material to close the gap with the insertion hole 2, and the closing means 16 and the bag body. 3 is provided so as to cover the discharge port 17 bored between the grout material 3 and the second discharge portion 18, which is broken by the inflow pressure of the grout material and supplies the grout material between the two. Have. Therefore, in the case of the present embodiment, the bag body 3 is inflated and the bag body 3 is expanded by injecting the grout material as in the case of the above embodiment.
The anchor head is formed by solidifying the grout material in the inside, and the second discharge portion 18 is broken, and a part of the grout material flows out into the space between the bag body 3 and the closing means 16 and solidifies, so that the grout material is pulled out. To further improve resistance. In the figure, numeral 19 is an exhaust pipe for bleeding air when the grout material flows into the space between the bag body 3 and the closing means 16.

FIG. 6 and FIG. 7 show another embodiment, which is different from the above-mentioned embodiment in that a baffle plate 21 for changing the discharge direction is provided for the discharge port 20 in the bag 3. It has features. FIG. 6 shows a construction state for temporary construction, and FIG. 7 shows a construction state for permanent construction. Each (A) shows a lock anchor body 1
(B) shows a state in which the grout material is inserted into the insertion hole 2 formed in the ground or rock, and the grout material is press-fitted into the bag body 3 through the injection hole 8 longitudinally penetrated by the lock anchor body 1. 3 shows an expanded state. Therefore, in this embodiment, the grout material is injected through the injection hole 8,
When the grout material is discharged from the discharge port 20, the baffle plate 2
The direction of the inflow into the bag body 3 is adjusted by 1 and the average supply of grout material is achieved. That is, by adjusting the discharge direction and the opening area between the lock anchor body 1 and the baffle plate 21, a circulating flow of the grout material as shown in the drawing is formed, and the supply is averaged.

FIGS. 8 and 9 show still another embodiment. Compared to the above-described embodiment, the bag 3 is destroyed by the inflow pressure of the grout material so as to further cover the discharge port 22. The second bag body 23 is characterized in that it is arranged. FIG. 8 shows a construction state for temporary construction, and FIG. 9 shows a construction state for permanent construction. Each (A) shows a state in which the lock anchor body 1 is inserted into an insertion hole 2 formed in the ground or rock,
(B) shows a state in which the grout material is pressed into the bag body 3 via the second bag body 23 and the bag body 3 is inflated. Then, in this embodiment, when the grout material is injected through the injection hole 8, the grout material flows into the second bag body 23 through the discharge port 22. As a result, when the second bag body 23 is filled with the grout material and the internal pressure in the second bag body 23 reaches a predetermined pressure, a part of the second bag body 23 begins to be broken, and the second bag body 23 is broken. Outflow into the bag body 3 is started via the portion. As described above, in the case of the present embodiment, first, the second bag body 23 is filled with the grout material, and then the supply of the grout material to the bag body 3 is started. It is extremely effective as a means. In this case, it is preferable that a weak portion is formed in a predetermined portion of the second bag body 23 and the setting is made so that the destruction always starts from the predetermined portion. Furthermore, bag 3
Even if the pores of the rock anchor are destroyed after the expansion, the lock anchor can still secure the required pull-out resistance force.

As described above, in any of the embodiments, when the strength of the ground is less than a predetermined value, the expansion of the bag causes the ground to be plastically deformed and the anchor head having a diameter larger than the diameter of the front insertion hole. Is formed, and a predetermined pull-out resistance force is secured mainly by the difference in these diameters. On the other hand,
When the strength is above a certain level, such as bedrock, the bag body adheres to the hole wall of the insertion hole and the grout material flows out, and the specified pullout resistance is mainly due to the adhesive force between the grout material and the hole wall. Is secured. From these facts, the degree of anchor head formation is controlled by selecting the injection pressure of grout material according to the ground conditions, and the pullout resistance of the lock anchor is controlled by measuring the injection pressure of grout material. Will be possible. In the above description of each embodiment, an example in which the bag body 3 is attached only to the tip portion of the lock anchor body 1 has been described, but the bag body 3 is not necessarily attached to the tip portion of the lock anchor body 1. There is no need, and more than one can be installed if necessary. The recess 1 formed on the outer peripheral surface of the lock anchor 1
1 can also be changed to an appropriate concavo-convex shape such as a screw shape instead, and can be applied not only to the inside of the bag body 3 but also to the entire outer peripheral surface of the lock anchor 1. It is also possible to change the screw portion 5 to a hook or the like.

[0014]

According to the present invention, the following effects can be obtained based on the above configuration. (1) The expansion of the bag attached to the lock anchor body causes plastic deformation of the surroundings when the ground is soft, or the inner surface shape of the insertion hole when the ground has a strength of a predetermined level or more like rock. Since the anchor head is formed by the enlarged diameter grout nodule in a state of being closely adhered along the edge, the pullout resistance of the lock anchor is significantly increased. (2) Furthermore, since the grout material flows out to the periphery of the bag body through the pores of the bag body, the grout material fills voids around the bag body, or the surrounding ground or rock Since it also enters into cracks and gaps and solidifies, the periphery is further strengthened, and at the same time, the adhesion to the periphery of the anchor head is also improved, so that the pullout resistance of the lock anchor is further increased. (3) In addition, since the water-cement ratio at the time of solidification of the grout material becomes small due to the degassing and dehydrating functions of the pores of the bag body, the water-cement ratio is increased at the time of the injection from the injection hole to increase the appropriate fluidity. Even if added, the water-cement ratio is reduced at the time of solidification, and an anchor head with high strength can be quickly obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing a construction state in an example of the present invention.

FIG. 2 is a schematic view showing a construction state in an example of the present invention.

FIG. 3 is a cross-sectional view showing a construction process of an example of the present invention.

FIG. 4 is a perspective view showing a bag body according to the embodiment.

FIG. 5 is a sectional view showing a construction process of another embodiment of the present invention.

FIG. 6 is a sectional view showing a construction process of another embodiment of the present invention.

FIG. 7 is a sectional view showing a construction process of another embodiment of the present invention.

FIG. 8 is a sectional view showing a construction process of another embodiment of the present invention.

FIG. 9 is a sectional view showing a construction process of another embodiment of the present invention.

[Explanation of symbols]

 1 ... Lock anchor body 2 ... Insertion hole 3 ... Bag body 4 ... Insertion reinforcement cone 5 ... Screw part 6 ... Tightening nut 7 ... Washer 8 ... Injection hole 9 ... Discharge port 10 ... Discharge Exit 11 Recess 12 Fold Fold 13 Fastening band 14 Fastening band 15 Discharge port 16 Closing means 17 Discharge port 18 Second discharge part 19 Exhaust pipe 20 Discharge port 21 ... Baffle plate 22 ... Discharge port 23 ... Second bag

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hidetaka Mizukami 955-9 Ohadomari, Koshigaya City, Saitama Prefecture (72) Fumio Sato 1-6-8 Usanan, Gifu City, Gifu Prefecture Dainippon Engineering & Construction Co., Ltd.

Claims (2)

[Claims] 1. A lock anchor body having a bag body for anchor head formation, which penetrates an injection hole of grout material vertically and is connected to the injection hole, is inserted into an insertion hole formed in the ground or rock. By expanding the bag body by press-fitting the grout material through the injection hole and letting the grout material flow out to the surroundings through the pores of the bag body, the lock anchor body has an expanded diameter grout nodule for an anchor head. And a strengthening the periphery of the expanded diameter grout nodule. 2. A lock anchor main body which penetrates the injection hole of the grout material, communicates with the injection hole, expands and deforms by press-fitting of the grout material from the injection hole, and allows the grout material to flow out. A lock anchor characterized in that a bag body for forming an anchor head is attached.