5 problems and solutions in self drilling anchor bolt construction process

Self drilling anchor bolts are widely used in many geotechnical anchoring projects because of their advantages of one-time completion of drilling, grouting, and anchoring. However, many construction units did not give full play to the advantages of self drilling anchor bolts in the construction process, that is to say, the construction technology of self drilling anchor bolts is relatively complicated, and various technical problems will occur during the construction process, and then have a greater impact on the support effect. Today, Sinorock will summarize and analyze the various problems existing in the construction process of self drilling anchor bolts and their causes, and provide professional solutions for various problems to help you avoid recurrence same questions in the future construction process.

self drilling anchor bolt construction process

Problem1: Drilling into the hole is not straight

Reason: The lower end of the self drilling rock bolt is unstable

When drilling, the lower end of the drilling rig is supported by the ground. If the ground is soft, and the rig is not fixed firmly, the lower end of the rig will be unstable during drilling, which will cause the entire hole to bend, which will affect the subsequent grouting and anchoring effects.

Solution: Check the stability of the drilling rig before drilling to ensure that the lower end of the drilling rig will not shake up and down or left and right during the drilling process.


Problem2: Drilling too deep or too shallow, drill diameter too large or too small

Reason: The construction was not carried out according to the design requirements, or the self-drilling bolt type required by the design was not selected

The main reason for such problems is that the construction personnel are not clear enough about the design requirements, and they cannot carry out construction in strict accordance with the design and construction requirements, and do not select the self drilling anchor bolts that meet the design requirements. Similar problems are unlikely to be caused by the self-drilling bolt construction process.

Solution: Strictly follow the design requirements and select suitable self drilling anchor bolts


Problem3: Debris in eye hole

Reason: Not enough wind for hole cleaning

In the process of drilling, it is necessary to maintain sufficient pressure at all times to avoid blocking the bolt grouting hole or drilling, both of which will affect the subsequent grouting process and thus affect the support effect.

Solution: Closely monitor the air pressure for hole cleaning to ensure that there is no debris inside the hole and the bolt

self drilling anchor bolt construction process

Problem4: Mortar drips when grouting

Reason: The mortar is too thin or the orifice is blocked

If the mortar is too thin, the mortar in the hole will not be full, which will affect the anchoring effect.

Solution: Before the start of grouting construction, the water-cement ratio must be strictly controlled. According to different geological structures, the appropriate water-cement ratio can not only ensure the effect of grouting and anchoring, but also save raw materials.


Problem5: Insufficient or unstable grouting pressure.

Reason: The working state of the grouting machine is abnormal

Insufficient or unstable grouting pressure will directly affect the anchoring effect of self drilling anchor bolts. The grouting pressure is not enough, the mortar in the drilling hole cannot reach the bottom of the grouting hole, the mortar cannot be effectively pressed into the cracks of the rock formation, and the rod body of the self-drilling bolt may not be completely wrapped by the mortar. Over a long period of time, the rod body will be severely corroded.

Solution: Carefully check the state of the grouting machine and test the machine before grouting to ensure that the grouting pressure is stable


Self drilling anchor bolts can be used in different scenarios such as foundation reinforcement, old building reinforcement, wind power tower foundation pile foundation, coastal protection, and retaining wall foundation. In the construction process, it is necessary to strictly follow the self-drilling bolt construction technology, otherwise it will affect the anchoring effect of the project and leave hidden dangers to the future project safety.

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