1. Introduction

Self-boring type centre-holed grouting rock bolt is a new supportive tool that is installed on tunnel crowned arch、sidewall 、upward arch、 side slope and the side wall of deep foundational hole . Because the rock bolts co-function with the shot-Crete, the bearing annulus、soil nailed wall、 mini pegs、rock anchor thus come into being. So does the bearing power. It can be used in complex stratum for drilling bore, such as fracture zone, weathered rock formation, backfill layer, sit etc. The effect is good for the construction of side slope、deep foundational ，pre-support system for tunnel and upland stress，distorting control of laneway projects etc. It is the first preferred anchoring material for rushing to repairs and fast speed projects by convenient construction.

2. Component of products

Self-boring type centre-holed grouting rock bolt is composed of alloyed rod body、alloy aiguille、 splint、screw cap、vent-pipe、grouting-stop stopper and rubber hammer. （See Fig.）

The alloyed rod body is the full screw thread rod body which is made of raw and proceeds material.

Self-boring type anchor head is made of alloy steel，the type is cross and ball-tooth etc.

Splint and screw cap ：They are prestressed、exterior and locked fastening pieces . Guide Pin connected with air-bleed hole.

vent-pipe：It is fixated on trailing bar by the air-bleed hole of the splint，and one end inserted into bore，another end putted outside of bore .It can be corporately used ，according to the method of installing and centre-holed grouting rock bolt.

Grouting-stop stopper ：They are the assistant materials，and the effect or grouting can be improved when using them .

3. The specification and technical parameters

4. Technical code for construction

  (1) Installing bolt is done by different stratums and different functions，it should adopt Self-boring type centre-holed grouting rock bolt for crash stratum of the easy collapsing bore. The body is the drill pipe，which is fitted on the alloy aiguilles. The bolt is anchored in the stratum. The grouting is done piecewise.

 (2) when using the grout ，the ratio is between 0.40 and 0.55.If using grouting mortar，the ratio is between 0.35 and 0.45. The denseness is proper, so that the grout is towards up poured into the vertical bore，prevent the grout from drooping flow.

 （3）The depth and diameter of drilling should meet the requirement of design，when drilling the hole. Clean away the dirt and loose fragments by waterpower and air pressure of drill. The grout should be poured into from the bottom of the rock bolt. alumina cement mortar is rapidly used for obturating orifice，then pull the splint and locked the screw cap after 5 to 10 minutes.

The pressure should be controlled within 15-45BAR when secondary grouting is needed. The grouting-stop stopper should be putted on the end of bolt in order to prevent the grout from exosmosis. In principle ，the installing of bolt should be at 24 hours later，and fasten the splint and screw cape . The splint should be on the shot-Crete，or on the abnormal shape of rock  ，the bolt won’t bring blend stress by transferring the bear strength to the bolt equably.

5.The advantages of products：

 1. It can be finished one time for drilling, grouting and anchoring.

 2. The rock bolt bears international standard wave whorl. The strength of anchoring is strong; the pull is between 100kn and 1800kn.

3. Using grout to reinforce the bore wall for subaqueous slump, the thimble is not needed.

4. Self-boring type centre-holed grouting rock bolt has the character of lengthening the border of drilling ，and suits for the construction of right section .

5. It can be compounded with all kinds of drills，such as 7655 、hand hammer drill、 YT27 、 YT28 、Ingersoll-Rand boring rig，stockless anchor，drills of Luoyang factory etc.