JPH0658039B2 - Reinforcement method of bedrock - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to a method for reinforcing rock mass having a crack in the surface layer.

≪Conventional technology≫ For example, cracks occur on the inner wall surface of a tunnel cavity formed by excavation in rock mass, or on the surface of rock mass such as slopes cut out in rock mass due to loosening of rock mass due to blasting or excavation. There are cases.

On the other hand, as is well known, the rock bolt method is known as one of the methods for reinforcing a cavity or the like such as a tunnel excavated and formed in rock.

This rock 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 rock bolt construction method for reinforcing the looseness of the rock as described above, since a large number of relatively long rigid members are used, it is uneconomical and the cavity is excavated. It is difficult to place a long rigid member close to the cutting face,
In addition, it takes a long time for the fixing mortar to harden, and the rock mass may be displaced while the hardening as the lock bolt is exerted, resulting in an increase in displacement and an increase in a loosened region.

The present invention has been made in view of such conventional problems, and an object thereof is to provide an economical method for reinforcing rock mass that can quickly reinforce looseness of the rock mass. .

<< Means for Solving the Problem >> In order to achieve the above object, the present invention is a method for reinforcing rock mass in which a crack is generated in the surface layer, in which a wedge member is inserted and placed in the crack, and in the rock mass, It is characterized in that a compressive stress acting in a direction along the surface of the bedrock is applied.

The reinforcement method of the present invention is applied to the ground so that instability such as flaking and movement of rock mass on a mechanically discontinuous surface such as a crack becomes a problem, and the medium hard rock with joints and bedding is hardened. 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 it is reinforced only in the vicinity of the surface of the cavity or slope, the rock mass can be prevented from peeling or moving, and the ground can be kept stable. Is.

<Operation> According to the rock mass reinforcing method having the above structure, since the wedge member is inserted and placed along the cracks of the rock mass, a compressive stress acting in a direction along the surface is added to the rock mass surface. .

In addition, when reinforcing the inner wall surface of the tunnel cavity, if a wedge member is placed substantially on the line along the cross-sectional direction of the cavity or within a predetermined width, the arch area where a compressive force is applied to the cavity periphery is applied. Is formed, which also effectively reinforces the cavity.

The minute cracks located between the wedge members that have been placed close due to the compressive stress acting in the direction along the surface due to the insertion and placement of the wedge members, which also increases the shear force of the rock mass. To be done.

<< Examples >> Hereinafter, preferred examples of the present invention will be described in detail 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 hollow 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, and immediately after excavation, a wedge bolt 16 as a wedge member is inserted into the crack 14 generated in the excavation surface 12 due to loosening of the rock mass. Set up.

At this time, in the reinforcing method shown in the embodiment, the wedge bolt 16
Are placed on the upper side of the excavation surface 12 at substantially equal intervals on a straight line along the vertical cross section of the cavity 10.

An example of the shape of the wedge bolt 16 is shown in FIG.

The wedge bolt 16 has a so-called wedge shape with a sharp tip, and for example, a metal such as iron or iron alloy or FRP having rigidity equivalent to metal is used, and its length 1 and tip angle θ are The optimum one is appropriately selected depending on the properties of the bedrock and the width of the crack 14.

As described above, when a plurality of wedge bolts 16 are driven into the crack 14 located on a substantially straight line along the vertical cross section of the excavated surface 12 of the cavity 10 at intervals in the circumferential direction and the axial direction, the cracks are formed. When the rock 14 is expanded, a compressive stress is applied to the rock mass sandwiched between the bolts 16 in the direction along the surface layer of the rock mass, that is, in the direction indicated by the arrow in FIG.

In the present embodiment, the wedge bolt 16 is inserted and driven almost on the line along the vertical cross-sectional direction of the excavation surface 12 of the cavity portion 10. Therefore, on the upper side of the excavation surface 12 is the surface of the rock mass. An arch region is formed in which a compressive stress is applied in a direction along the direction, which positively reinforces the cavity 10 immediately after excavation and prevents unnecessary rock loosening, and at the same time, the excavation surface 12
It is possible to control the expansion of the displacement.

Further, as shown in FIG. 3 in detail, the minute cracks 14a located between the wedge bolts 16 that have been inserted and driven are formed by the compressive stress due to the insertion and driving of the wedge bolts 16 and the cracks 14a.
Since a is closed, this also increases the shear force of the rock mass.

In the above embodiment, the wedge bolt 16 is laid on a straight line along the vertical cross section of the cavity portion 10. However, the wedge bolt 16 may be inserted and laid at random in the cracks 14 that have occurred. .

In addition, the reinforcing method of the present invention uses the hollow portion 10 formed by excavation.
Not only can it be applied to the reinforcement of slopes cut out in rock.

<< Effects of the Invention >> As described in the above embodiments, according to the rock mass reinforcing method of the present invention, the wedge member is inserted and driven along the cracks of the rock mass, so that the rock mass is sandwiched between the wedge members. , The loose rock can be easily reinforced by applying compressive stress acting in the direction along the rock, and the rock can be reinforced quickly and economically by the simple work of inserting and placing wedge members. can do.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of a method for reinforcing rock mass according to the present invention, FIG. 2 is a plan view of a bolt used in the reinforcing method, and FIG. 3 is an enlarged view of a main part of FIG. 10 ... Cavity 12 ... Excavation surface 14 ... Crack 16 ... Wedge bolt

Claims (1)

[Claims] 1. A method of reinforcing a rock bed having a crack in the surface layer, wherein a wedge member is inserted into the crack and placed, and
A method for reinforcing rock mass, which comprises applying a compressive stress acting in a direction along the surface of the rock mass.