JPH0674717B2 - Reinforcement method of bedrock - Google Patents

Description

[Detailed Description of the Invention] <Industrial field of application> The present invention relates to a case where a rock is loosened and a crack is generated in its surface layer in a cavity formed by excavation in a rock or a slope cut out in the rock. The method of reinforcing rock mass.

<< Prior Art >> As is well known, there is a rock bolt method as a method of reinforcing a cavity such as a tunnel formed by excavating rock.

The lock bolt construction method is a construction method in which a rigid member of about 2 to 6 m is generally driven into the ground and the entire surface or the tip portion thereof is fixed with mortar or the like.

In this type of construction method, fixing the loosened part due to blasting etc. to the solid ground and preventing the fall, and by inserting a rigid member in the natural ground, the shear resistance of the natural ground increases. The rock mass is reinforced by the ground improvement effect, which increases the loading capacity of the ground.

However, such a rock bolt construction method for reinforcing rock mass has the following problems.

<< Problems to be Solved by the Invention >> That is, in the above-described rock bolt construction method, since a large number of relatively long rigid members are used, it is uneconomical and the length is close to the face face excavating the cavity. It is difficult to place a large rigid member, and it takes time for the fixing mortar to harden, and the rock mass is displaced while the effect as a lock bolt is exerted, and the displacement increases or loosens. There was a risk of expanding the area.

The present invention has been made in view of the above conventional problems, and an object thereof is to reinforce rock mass that can quickly and economically reinforce rock mass that is loosened due to cracking in the surface layer due to blasting or the like. To provide a method.

<< Means for Solving the Problem >> In order to achieve the above object, the present invention, in a method for reinforcing rock mass having a crack, forms a shallow injection hole on the surface of the rock mass in communication with the crack, and the injection hole It is characterized in that expandable cement milk or expandable chemical is press-fitted therein.

INDUSTRIAL APPLICABILITY The reinforcing method of the present invention is applied to a ground where instability such as flaking or movement of a rock mass on a mechanically discontinuous surface such as a crack becomes a problem, and it is applied to medium to hard rocks with developed joints and bedding. The rocky ground is the main target.

In such a ground, it is not necessary to reinforce to the deep part of the bedrock, and if only the surface area of the surface of the cavity or slope is reinforced, the rock mass can be prevented from peeling and moving, and the ground can be kept stable. Because you can

<< Operation >> According to the rock reinforcement method of the above configuration, a shallow injection hole is formed in the excavation surface of the cavity or a slope formed by cutting, communicating with a crack caused by loose rock, and the inside of this injection hole is formed. When the expansive cement milk or expansive chemical is press-fitted into, the expansive liquid agent penetrates into the cracks formed on the excavated surface or slope, and expands so as to spread the cracks.

When the crack spreads, the bedrock between the cracks
Compressive stress is added.

In addition, small cracks that the expansive cement milk and expansive chemical do not penetrate so much are closed by the compressive force due to the expansion of the cracks that these expansive liquid agents have penetrated.
This also increases the shear force of the bedrock.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 and FIG. 2 show an embodiment of a rock mass reinforcing method according to the present invention.

The reinforcing method shown in the figure exemplifies a case where the present invention is applied to the cavity portion 10 formed by excavation in rock.

The cavity 10 is formed in a horseshoe shape by, for example, a blasting method or a tunnel boring machine.

At this time, in the reinforcing method shown in the embodiment, first, as shown in FIG.
A plurality of injection holes 16 are formed along the cracks 14 so as to communicate with the cracks 14 that have been formed in the cracks and are formed by a drilling machine at intervals.

The injection hole 16 differs depending on the rock properties of the excavated surface 12,
A shallow depth of about 30 to 50 cm is sufficient, and its diameter is set to the same level as a normal lock bolt hole.

Further, as the formation location of the injection hole 16, a relatively large crack 14 located on the upper side of the cavity 10 is selected, and the location located on a straight line along the vertical cross section of the cavity 10 is selected. .

Then, the injection hole formed in parallel with the drilling of the injection hole 16
16 is the expansive cement milk or expansive chemical, for example, expansive liquid agent such as phenol urethane resin.
18 is press-fitted.

In press-fitting the expansive liquid agent 18 into the injection hole 16, the press-fitting tool 22 connected to the material supply hose 20 shown in FIG. 1 (B) is used.
Is used.

The press-fitting tool 22 has a flange portion 24 formed at the tip thereof, and a packer for preventing the expansive liquid agent 18 from leaking to the flange portion 24.
26 is attached, and the expansive liquid agent 18 is supplied so as to press the packer 26 against the outer peripheral edge of the injection hole 16.

Further, as shown in FIG. 1 (C), the press-fitting tool 22 may be inserted into the injection hole 16 and the packer 26 may prevent leakage, and then the expansive liquid agent 18 may be supplied.

The expansive liquid agent 18 press-fitted into the injection hole 16 penetrates deeply into the crack 14 due to the injection pressure.

Then, the expansive liquid material 14 that has penetrated into the cracks 14 expands in a relatively short time, and when the expansive liquid agent 18 expands, the spaces between the cracks 14 are expanded, whereby the cracks 14 are sandwiched between the cracks 14. A compressive force is generated on the excavated surface 12 as shown by an arrow in FIG.

When the compressive force is applied in this way, an arch region to which the compressive force is applied is formed on the upper side of the excavation surface 12, whereby the hollow portion 10 immediately after excavation is positively reinforced and unnecessary. It is possible to prevent loosening of the rock mass and at the same time suppress expansion of displacement of the excavation surface 12.

In this case, in particular, if the one that expands and then hardens like an expandable cement milk is selected as the expandable liquid agent 18,
The expanded crack 14 is maintained in that state for a long time, and the reinforcing effect by the arch region is sufficiently exerted.

Further, the small crack 14a in which the expansive liquid agent 14 is not press-fitted,
As shown in detail in FIG. 2, the expansive liquid agent 14 penetrates and the compressive force due to expansion closes the crack 14a, which also enhances the shear force of the rock mass.

Then, after the press-fitting of the expansive liquid agent 14 is completed, the expelled expansive liquid agent 14 can be prevented from flowing out by applying the sprayed concrete 18 to the excavation surface 12 as needed, and the reinforcing effect by expansion can be enhanced.

The reinforcement method of the present invention can be applied not only to the hollow portion 10 formed by excavation but also to the reinforcement of rock that has other cracks such as slopes cut out of the rock.

<< Effects of the Invention >> As described in the above embodiments, according to the rock mass reinforcing method of the present invention, an injection hole is formed on the surface of the rock mass in communication with the crack of the rock mass having a crack, and the injection hole is formed. By injecting expansive cement milk or expansive chemical into the cracks, these expansive liquid agents permeate and expand into the cracks, and the rock sandwiched between the cracks is reinforced by applying compressive force, so The work can be performed easily even in the vicinity, and the reinforcing effect is exhibited in a relatively short time by press-fitting these expansive liquid agents.

Further, since the reinforcing effect can be obtained only by press-fitting the expansive cement milk or the expansive chemical into the shallow injection hole formed in communication with the crack, it is far more economical than the conventional rock bolt.

[Brief description of drawings]

FIG. 1 is an explanatory view of an implementation state of a method for reinforcing rock mass according to the present invention, and FIG. 2 is an enlarged view of a main part of FIG. 10 …… Hollow part, 12 …… Excavation surface 14 …… Crack, 16 …… Injection hole 18 …… Expandable liquid agent (expandable cement milk or expandable chemical)

Claims (1)

[Claims] 1. A method for reinforcing a rock mass having a crack, characterized in that a shallow injection hole is formed on the surface of the rock mass in communication with the crack and an expansive cement milk or an expansive chemical is press-fitted into the injection hole. How to reinforce the bedrock.