锚固体后置膨胀性对围岩径向增压的影响
Influence of anchorage body post-expansion on radial pressurization of surrounding rock
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摘要: 针对如何充分发挥锚杆对围岩的反向挤压能力，使锚固-围岩界面压应力快速平衡进而实现增强主动支护效果等问题，提出了径向增压的锚固方法；通过在水泥浆液中掺入膨胀剂使其形成自应力浆液，在岩体约束下对孔壁产生径向膨胀应力，改善围岩的应力状态；在薄壁钢管约束下，将掺入不同量膨胀剂的水泥浆液结石体产生的径向膨胀应力作为不同的增压变量，利用静态应变仪测得钢管外壁膨胀应力并分析结石体不同膨胀剂掺量下径向应力的变形规律。利用有限元软件ABAQUS模拟了不同增压变量下围岩变形特征，对围岩受力变形时的应力场和位移场进行了系统研究。结果表明：膨胀剂掺量7%的水泥浆液结石体径向应力和强度均优于其他配比，浆液结石体与孔壁之间的压应力明显增大，形成扩体效应；随着浆液结石体径向应力的增加，围岩所受压应力增幅平均达到65%，变形量增幅平均达到71%，且围岩所受径向应力随距离钻孔的增大而减小。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.
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