Influence of anchorage body post-expansion on radial pressurization of surrounding rock

Abstract

Aiming at the problem of how to give full play to the reverse extrusion ability of bolt to the surrounding rock to make the interface stress balance quickly and enhance the active support effect, we propose the anchorage method of radial pressurization. By adding expansion agent into cement grout to form self-stress slurry, radial expansion stress is generated on the pore wall under the constraint of rock mass, and the stress state of surrounding rock is improved. Under the constraint of thin-walled steel pipe, the radial expansion stress generated by the cement slurry stone body mixed with different amounts of expansion agent is used as a different pressurization variable, and the expansion stress of steel tube wall was measured by static strain gauge and the deformation law of radial stress in stone body with different expansion agent content was analyzed. The finite element software ABAQUS is used to simulate the deformation characteristics of the surrounding rock under different pressurization variables, and the stress field and displacement field of the surrounding rock under stress and deformation are systematically studied. The results show that the radial stress and strength of cement slurry stone with 7% expansion agent are better than those of other proportions, and the compressive stress between cement slurry stone and pore wall increases obviously, resulting in expansion effect. With the increase of radial stress of grout stone body, the compressive stress increases by 65% and the deformation increases by 71% on average, and the radial stress of surrounding rock decreases with the increase of distance from drilling hole.

Keywords

• bolt support
• radial pressurization
• self-stress slurry
• expansion agent dosage
• surrounding rock control