Technical measures for improving pulling force of self drilling rock bolt

rock bolt support

1. Choose reasonable drilling technology

1) Drilling hole is strictly prohibited water, which should use high-pressure wind piercing, slag discharge, cooling operation;
2) For determine the diameter of drill bit, it’s should adopt drilling machine when drilling with self drilling rock bolt, check the verticality of the drill pipe, the anchor hole deflection, with footage with a fine wind pipe blowing air hole cuttings;
3) Choose reasonable drilling technical parameters. The main factor of drilling speed depend on the hole deslagging ability,when the hole drilling speed is quickly, drilling every 450~500 mm stop once, concentration of slag hole, then reduce drilling speed, adjust and optimize the drilling speed of 2~2.5 m/h, to ensure the smoothness and aperture. To the depth of the design, continue to drilling 50~l00 mm, using high-pressure wind centralized slag, punching once,it will put slag which is not cleaned or partial collapse formed as far as possible all out of the hole. When drilling, move the drill rod back and forth so as to make the hole wall as smooth as possible.

2. Select the wind pressure and method to remove cuttings from the hole

1) The use of fine air pipe for cleaning holes, the debris(including water) of all holes will be rushed out in an instant;
2) Master the correct way to enter the hole under the wind pipe;
3) The air pressure is controlled at 0.2~0.3 MPa;
4) move the air duct back and forth, and the number of cleaning holes is not less than 3 times.

3. Strictly control batching process

1) Materials meet the requirements, cement, expansion agents and other materials should have a certificate, access to witness sampling, and sampling by the provisions of qualified acceptance before they can be put into use, approach materials by the quality officer is responsible for acceptance;
2) The team leader will deliver the material to the feeding staff before class, and the measurement should be accurate according to the water cement ratio;
3) Quality inspectors do spot check work, heavy penalties for those who do not weigh.

4. strictly control grouting process

1) Before grouting, the grouting pump, pressure gauge and grouting pipe can be inspect strictly
and the size of the pump head can be ensured. The grouting pipe can not be blocked, the grouting pressure can be accurately displayed and the pipeline can be unblocked;
2) Before grouting, raise the drill pipe by 50~l00 mm, so as to avoid the clogging of the grouting hole at the bottom of the borehole;
3) Before using the grouting pump, it shall be calibrated to determine the relationship between the readings of the pressure gauge and the actual pressure so as to control it;
4) 2 grouting method is adopted to determine grouting pressure controlled at 0.3~0.5 MPa, and the grouting speed is decreased appropriately. The amount of grouting is determined according to the depth. When the grout reaches a certain value, the slurry overflows from the bottom of the grouting pipe until the grouting capacity reaches the required level. When grouting, the pipe can not be pulled too fast. When the slurry reaches a certain value, the grouting process is completed from the bottom of the grouting and then stabilized by 2 min;

5. Formulate strict construction management system

1) Strengthen the education of quality consciousness and improve the quality consciousness of operators;
2) Strengthen technical disclosure and inspection, familiar with the standard of cleaning holes. The technical personnel should master the use of fine wind pipe firstly, then give tests to the operator, the operator can use the machine according to the requirements of Grouting grouting; good team leader class before the technical disclosure requirements of feeding personnel strictly according to the mix design of ingredients;
3) Inspector attendant supervision grouting, found disturbing behavior of the design requirements immediately banned;
4) The project department shall strengthen the inspection and regularly check the implementation of the grouting construction management system;
5) Make clear the post responsibility, carry out the measure of rewards and punishments, and punish severely not to execute the management system.

6. Check the effect

In accordance with the technical measures formulated, do second sets of test bolts (2), timely quality control, the completion of drilling and grouting work the same day. After 7 days, the pullout test of anchor rod was carried out, and the pullout capacity met the design requirements.
When the self drilling bolt is formally constructed, the mature operation of the self drilling bolt is performed according to the second sets of tests. Before the construction, the construction organization strictly, in order to anchor the number, the construction management and convenient detection, the whole process of construction with the supervision units supervision, all procedure of cross operation, the anchor processing by the supervision unit acceptance of qualified prospective use of the rear. During the construction, a total of 2 sets of equipment were put into operation, and special personnel were sent to record the whole construction process.
After the completion of the project, according to the requirements of design and specifications, the anchor rod pullout test has been carried out, and the pullout capacity has reached the design requirements.

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