JPS5919240B2 - Lock bolt construction method - Google Patents

Description

[Detailed description of the invention] Maintaining the excavated space of railway tunnels and road tunnels,
In order to prevent the cliff from collapsing, a hole is formed in the ground using a drilling machine, a non-foaming synthetic resin chemical capsule is inserted into the hole to solidify the rock bolt, and the bolt is inserted deep into the hole. The rock bolt construction method involves pushing the bolt into the hole until it is pushed in, rotating the bolt for a few seconds with a rock machine, crushing the capsule, mixing and stirring the chemical solution, solidifying it, and then fixing the rock bolt and the hole wall with a hardened synthetic resin. It is publicly known.

In the Kafuru construction method, the ground near the entrance of the hole formed in the ground is often soft, so it is more effective to fix the rock bolt with a hardened synthetic resin in a hard place of the rock near the bottom of the hole. There is.

For example, the holes formed in Shikajijima are facing downward, sideways,
There are upward holes, etc., making it impossible to perform certain operations, and the operations are often performed roughly.

For this reason, the chemical solution of synthetic resin, which normally does not have foaming properties, solidifies, and the strength (pulling force) that fixes the rock bolt within the hole wall is greater than that which causes the rock bolt to break.
However, in actual construction methods, the strength was hardly achieved, and the strength varied widely and was unreliable.

The reason for this is that when the capsule is crushed by the rock bolt, the chemical solution flows and, especially in the case of a sideways or upward hole, the chemical solution does not fully fill the space between the rock bolt and the hole wall and becomes solidified. This seems to be the case.

The present invention was invented in view of these points, and its gist is that only the tip of the rock bolt is inserted into the wall of the hole where the ground is the hardest, near the bottom of the hole formed in the ground. The purpose of this method is to provide a rock bolt construction method that can be firmly and strongly fixed simply by partially solidifying with a synthetic resin solidifying agent. A capsule is first inserted into the bottom of the hole, and then a capsule of a chemical solution made of a synthetic resin with foaming properties, which has a shorter rise time than the gel time of the non-foaming synthetic resin, is inserted to fill the space in the hole. Then, a rock bolt is inserted into the hole, and these capsules are crushed by the rock bolt and solidified and foamed and hardened, respectively.

Non-foaming synthetic resin chemicals used for solidifying rock bolts include liquid synthetic resins that solidify at room temperature that are already known in conventional construction methods, such as liquid polyester resins, liquid epoxy resins, liquid urethane resins, Alternatively, it is made of a combination of these synthetic resins and a hardening agent in the form of a paste, and is used after being separated into double capsules made of glass or synthetic resin films.

In addition, as a chemical solution having a foaming property of synthetic resin for filling the space in the hole, for example, a polyol component containing a foaming agent (A
It is best to use a combination of a hardening agent (liquid B) consisting of an isocyanate component and a curing agent (liquid B) consisting of an isocyanate component, divided into double capsules made of glass or synthetic resin film, and with as high a foaming pressure as possible.

In addition, the gel time (the time from the start of the curing reaction to the loss of fluidity) of a synthetic resin chemical solution that does not have foaming properties is longer than the rise time (the time from the start of foaming to the end of foaming) of a synthetic resin chemical solution that has foaming properties. If the gel time of the former is shorter than the rise time of the latter, the former will solidify before the latter starts foaming, and the effect of the present invention cannot be expected. When the gel time of the former is longer than the rise time of the latter, the latter acts as a plug due to the expansion force caused by the foaming of the latter, preventing the former from flowing toward the hole opening, and pressing the former with the expansion force to close the hole. It is possible to fill the space between the wall and rock bolt or even the cracks in the ground, and in this state, it is possible to consolidate and foam harden the former and the latter, and the former fully exerts its consolidation power and is reliable. This is because it can be fixed to.

In the following, the invention will be explained by field testing according to the following example.

Two types of holes were drilled in the mudstone tunnel wall: a horizontal hole (horizontal hole) and an upward hole (a hole facing upward in a direction almost perpendicular to the horizontal) with a diameter of 38 cm and a depth of 2.7 m. did.

Then, insert the outer capsule into each hole and
2mm, wall thickness 0.8mm, length 640mm, outer diameter ioam as inner capsule, wall thickness 0.5mm, length 580m
Two double capsules A containing a liquid polyester main material and a hardening agent (benzoyl peroxide) as rock bolt solidifying agents are inserted into a glass tube made of M. Push the double capsule A to the bottom of the hole with a rock bolt, rotate the rock bolt at 350 to 400 per minute with a band auger, crush the double capsule A, and stir for 15 seconds to mix.
After 4 hours, a pullout test of the rock bolt was conducted using the conventionally known rock bolt construction method.

Pulling out is a result of force. Horizontal hole 3.6 tons to 15.5 tons Upward hole
1.8 tons to 15.2) The above-mentioned double capsule A was a room temperature curing type and had a gel time of 3 minutes.

On the other hand, in the same construction method as the conventional construction method, one of the two double capsules is replaced with capsule B for filling the space by the construction method of the present invention, double capsule A is inserted first, and then the second capsule is inserted. The force results of the pull-out after inserting Heavy Capsule B were as shown below and were very stable.

The shape of the double capsule B and the composition of the foam filling drug contained in the double capsule are as follows.

Capsule-shaped outer capsule Outer diameter: 32 mm Wall thickness: 0.8 mvt Length: 640 mm Inner capsule Outer diameter: 25.5 mm Wall thickness: 0.8 mm Length: 580 mm Polyether polyol for capsules not formulated with foam-filling chemical solutions 50 parts by weight polyol (
(Contains amine group) 10 Auxiliary agent (contains organometallic catalyst as curing agent) 1O Reinforcing agent 30 Total 100// MDI prepolymer for inner capsule 100 parts by weight Note that the foaming pressure of the above mixture in a closed room was determined in a laboratory. 10 when measured with
．． 6 K91cr! It was a room temperature foam curing type and had a rise time of 3 seconds.

Adhesion force: Horizontal hole: 13.2 tons ~ 16.8 tons; Upward hole: 12.4 tons ~ 16. (In addition, using the above formulation and setting the rise time only to 10 minutes, gel time 3 of capsule A)
The results of the pull-out force performed 7 minutes later than the previous method are as follows, and as with the conventional method, the pull-out force had large variations and lacked stability.

According to the present invention, in horizontal holes, upward holes, etc., the pulling force is 4.5 tons to 15.4 tons or more.
Even if the caking agent temporarily flows toward the entrance of the hole when the capsule of the caking agent is crushed with a rock bolt, it will not be inserted into the entrance of the hole and crushed with the rock bolt first. The foam of the filling capsule that starts foaming and hardening acts as a stopper and prevents the flow of the solidifying agent, so there is no need to worry about the solidifying agent flowing toward the inlet, making it possible to lower the viscosity.
It becomes possible to perform the stirring and mixing work efficiently and more uniformly.

In addition, as the foam expands, the fluid solidifying agent is pushed up near the bottom of the hole, not only filling the space between the hole wall and the rock bolt, but also actively pushing the solidifying agent into the cracks in the ground. This makes it possible to make the solidifying agent flow, and the solidifying power of the solidifying agent can be fully demonstrated at the bottom of the hole, which is the hardest part of the rock.The rock bolt can be securely and stably fixed in the borehole with a small amount of solidifying agent, and it is possible to It also has the effect of reducing costs.

Claims (1)

[Claims] 1 First insert a chemical liquid capsule made of non-foamable synthetic resin into the hole formed in the ground for solidifying the rock bolt,
Next, a capsule of a chemical solution made of a synthetic resin having foaming properties whose rise time is shorter than the gel time of the non-foaming synthetic resin is inserted to fill the space in the hole, and then a lock bolt is inserted into the hole. The rock bolt construction method is characterized by crushing these capsules with rock bolts and starting consolidation and foam hardening, respectively.