JPH0674716B2 - Reinforcement method of bedrock - Google Patents

Description

[Detailed Description of the Invention] <Industrial application field> 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, for example, there is a rock bolt method as a method of reinforcing a cavity such as a tunnel formed by excavation in 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 such conventional problems, and an object thereof is to quickly exert a reinforcing effect on rock mass that is loose due to cracks in the surface layer due to blasting, etc. The purpose of this is to provide a method of reinforcing a rock mass.

<< Means for Solving the Problem >> In order to achieve the above object, the present invention, in a method of reinforcing a rock mass having a crack, the surface of the rock mass having the crack is sprayed with an expansive cement milk or an expansive chemical, It is characterized in that these are permeated into the cracks and expanded.

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 method for reinforcing rock mass having the above-mentioned configuration, in the excavated surface of the cavity immediately after excavation, the slope immediately after cutting, and the like,
When expansive cement milk or expansive chemical is sprayed on the cracked rock surface so that they penetrate the cracks, the expansive liquid agent that has penetrated expands so as to expand the cracks.

When the crack is expanded, compressive stress is applied to the rock mass sandwiched between the cracks.

In addition, the minute cracks that the expansive cement milk or expansive chemical does not penetrate so much close the cracks due to the compressive force by the expansion of the cracks penetrated by these expansive liquid agents, which also increases the shear force of the rock mass. It

<< Embodiment >> A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

1 to 3 show an embodiment of a method for reinforcing rock mass 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, the expansive cement milk or expansive chemical, for example, an expansive liquid agent 14 such as a phenol urethane resin is sprayed on the excavated surface 12 of the cavity 10 immediately after excavation through the spray nozzle 16. Is jetted.

The sprayed expansive liquid agent 14 adheres to the excavation surface 12 and penetrates into the relatively large crack 16 generated in the excavation surface 12.

Then, the expansive liquid material 14 that has penetrated into the cracks 16 expands in a relatively short time, and when the expansive liquid agent 14 expands, the gaps between the cracks 16 are expanded, whereby the cracks 16 are sandwiched between the cracks 16. A compressive force is generated on the excavated surface 12 as shown by the 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 an expansive liquid agent 14 is selected that expands and hardens like an expansive cement milk,
The expanded crack 16 is maintained in that state for a long time, and the reinforcing effect by the arch region is sufficiently exerted.

In addition, the minute cracks 16a with little penetration of the expansive liquid agent 14
As shown in detail in FIG. 2, the expansive liquid agent 14 permeates and cracks 16a due to the compressive force due to expansion.
This also increases the shear force of the bedrock as it closes.

Then, when the spraying of the expansive liquid agent 14 is completed, as shown in FIG. 3, spraying concrete 18 is applied to the excavation surface 12 as necessary to prevent the expansive liquid agent 14 from flowing out,
The reinforcing effect due to expansion can also 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 with other cracks such as slopes cut out in the rock.

<< Effects of the Invention >> As described above, according to the method of reinforcing rock according to the present invention, the expansive cement or the expansion is applied to the crack by spraying the expansive cement milk or the expansive chemical on the surface of the rock having the crack. Infiltrate and expand the volatile chemicals to add compressive force to the bedrock sandwiched between the cracks to reinforce it, so the expansion of these expansive liquid agents provides the bedrock reinforcement effect in a relatively short time. Since such a reinforcing effect can be obtained only by the operation of spraying the expandable cement milk or the expandable chemical, it is possible to reinforce the rock mass much more economically than the conventional rock bolt method.

[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, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is an explanatory view showing another embodiment. 10 …… Cavity 12 …… Drilling surface 14 …… Expandable liquid agent (expandable cement milk or expandable chemical) 16 …… Crack

Claims (1)

[Claims] 1. A method of reinforcing a rock mass having a crack, comprising:
A method for reinforcing rock mass, characterized by spraying expansive cement milk or expansive chemical on the surface of the rock mass having the cracks, and infiltrating them into the cracks to expand.