JPS6350356A - Cement composition for lock bolt - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a cement composition for construction of rock bolts, which is constructed for the purpose of preventing collapse and peeling of surrounding ground after tunnel excavation.

<Conventional technology and problems> In general, the rock bolt construction method involves artificially inserting rock bolts with axial tensile strength around the tunnel to form a grand arch, which greatly improves the physical properties of the ground. This is a construction method that prevents the surrounding ground from collapsing and peeling. In order to fulfill this role, the materials used for rock bolt construction are generally self-hardening filling materials in the drilled hole, such as steel bars and deformed steel bars that have high compressive elasticity after being filled with cement mortar. Fiber-reinforced plastic rods or ropes are inserted, but the filling material may separate during the insertion of these rock bolts, resulting in repeated installation. For this reason, in many cases, the rear end of the lock bolt is inserted while being struck with a large mechanical force, but it is not possible to insert the lock bolt sufficiently, and it takes time to insert the lock bolt. In the worst case, excessive wr on the rock bolt
This can cause damage and make construction impossible midway through.

In addition, if the direction of the rock bolt insertion hole is upward, the filling material may flow down the hole, making it impossible to securely secure the rock bolt, resulting in unsatisfactory construction.
Furthermore, when spring water occurs, the filling material flows out, making it impossible to secure the lock bolts, which has various other drawbacks.

<Object of the invention> The non-invention was made in view of the above background,
In order to solve the construction disadvantages seen in the conventional rock bolt construction method, it is extremely difficult to cause component separation, so it can be easily inserted into the drilled hole, and it does not flow down even if the drilled hole is in an upward direction. An object of the present invention is to provide a cement composition for rock bolt construction that does not store up and is not washed away due to the occurrence of spring water.

〈Means for solving problems〉 According to the invention, based on 100 parts by weight of cement.

60-120 parts by weight of sand 1 part by weight of polyethylene oxide with a molecular weight of 100,000-5(') 0,000 and 3 parts by weight of water
The present invention will be described in more detail below, in which a cement composition for constructing rock bolts is provided, characterized in that it contains 5 to 55 parts by weight.

The cements constituting the cement composition for rock bolt construction of the present invention include various portland cements such as W-through boltland cement, early strength portland cement, ultra early strength portland cement, moderate heat portland cement; alumina cement; Alumina cement such as lime alumina cement; blast furnace slag mixed cement, pozzolan mixed cement.

Examples include various mixed cements such as fly ash cement. Of these, portland cement;
In particular, ordinary Portland cement is common and can be preferably used.

The cement composition for rock bolt construction of the present invention contains sand as a fine aggregate in addition to the above-mentioned cement. It is desirable to use sand with a maximum particle size of 3 m or less; if the maximum particle size exceeds 3ffW11, it is not preferable because the injection hose is likely to become clogged during injection, making stable construction difficult.

On the other hand, the lower limit of the maximum particle size of sand is not particularly critical, and the amount of sand mixed is 60 to 1
The amount is 20 parts by weight, preferably 80 to 100 parts by weight. If the amount of sand mixed is less than 60 m, it becomes uneconomical, and if it exceeds 120 m, it cannot be used because it lacks fluidity and the resistance when inserting the rock bolt becomes large.

Polyethylene oxide having a molecular weight of 1,000,000 to 5,000,000 is blended into the cement composition for rock bolt construction of the present invention. By mixing polyethylene oxide, the curing speed and strength of the cement composition are not reduced, the occurrence of component separation is prevented, the resistance when inserting the rock bolt is reduced, and the leakage prevention against spring water is achieved. In addition, the flow down when filling an upwardly directed drilled hole is also minimized. rPOLYOXJ (UC
Company C), “Alcox” (Meisei Chemical), “PE○”
Commercially available products such as (Steel Chemistry ■) can be used.

The amount of polyethylene oxide is Cement 810.
0.1 to 2.0 parts by weight, preferably 0 parts by weight
．． 71-1.0 Jushabu is used. If it is less than 0.1 parts by weight, component separation will occur and resistance will increase when inserting the rock bolt, while if it is less than 2.0 parts by weight, the viscosity of the cement composition will increase. Insertion resistance increases.

In the invention, 28,100 parts by weight of cement and 35 to 5 parts by weight of iJL water were added.
Add 5 parts by weight, preferably 38 to 12 parts by weight. In the present invention, in addition to the two components, a water reducing agent is added to the cement.
0.1 to 2.0 parts by weight, preferably 0.00 parts by weight
．． By blending a water reducing agent, which may be blended in an amount of 3 to 1.2 parts by weight, the amount of water added can be reduced within the above-mentioned range, and high strength can be developed. As the water reducing agent, naphthalene sulfonic acid formalin condensate, lignin sulfonate, oxycarboxylate, etc. can be used. As a commercially available product, "Mighty 100" (Kao Soap ■) can be preferably used.

5112 of the cement composition for rock bolt construction of the present invention.
To do this, first add water using a commonly used paddle mixer, then add polyethylene oxide and stir.1 Next, add cement, sand, and water reducing agent as necessary while stirring. is added to make FA.

When installing rock bolts, the cement composition of the present invention is filled into the drilled holes, and then the rock bolts are inserted by hand or using an insertion device such as a roller6.
If the cement composition of the present invention is used, rockpole construction with a construction length of about 4 m can be performed with a small insertion force of about 30 kg at maximum, and manual pushing work by one worker is usually sufficient for construction. .

<Effects of the Invention> If the cement composition for rock bolt construction of the present invention is used, rock bolts can be inserted with a small resistance force, and since the adhesiveness is strong, even when constructing rock bolts in an upward direction, it is possible to insert rock bolts immediately after filling. It is possible to perform high-quality construction without the filling composition flowing down. Furthermore, even in construction at locations where spring water occurs, high-quality construction is possible without the filling composition being washed away by spring water.

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

eclipse For 100 parts by weight of ordinary Portland cement.

Sand (maximum particle size 3nn+) 107 parts by weight, molecule;! 1tl
o.

0.6 parts by weight of polyethylene oxide, 0.6 parts by weight of water reducing agent (product name "Mighty 100" manufactured by Kao Soap Garden),
A cement composition for rock bolt construction was prepared using 40 parts by weight of water.

After kneading the cement composition 2 of this formulation and injecting it into a drilled hole 1 with a hole diameter of 36 um and a hole length of 4 m using a pump, a rock bolt 3 was inserted using a feeding roller 4, and its insertion resistance value was measured. . As a result, complete construction was possible with a small insertion resistance of about 30 kg at most.

It should be noted that the filling material 411 taken out of the hole by inserting the rock bolt remained in a normal state as formulated.

In comparison to the Example, a rock bolt 3 was inserted into the drilled hole 1 in the same manner as in Example 1, except that a cement mortar of the following composition, which is conventionally used in construction, was used.

Ordinary Portland cement 100 parts by weight Sand (maximum particle size 3 nm) 107 parts by weight Water reducing agent (``Mighty 100'' Kao Soap ■) 0.6 parts by weight Water
When the 40 weight part lock bolt 3 was press-fitted by the feed roller 4, the insertion depth was 3 m.
As a result, insertion resistance increased rapidly, reaching a maximum of over 250 kg, and construction was no longer possible.

It was also found that the filling mortar that was expelled from the hole by inserting the rock bolt contained excessive moisture, and the filling material left inside the hole was in a state of detached water.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of a construction state of a rock bolt using the cement composition of the present invention. 1. Hole drilling, 2. Filling material, 3. Rock bolt, 4
...Feeding roller.

Claims (1)

[Claims] 60 to 120 parts by weight of sand per 100 parts by weight of cement;
Polyethylene oxide with a molecular weight of 100,000 to 5,000,000.
A cement composition for constructing rock bolts, comprising 1 to 2.0 parts by weight and 35 to 55 parts by weight of water.