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利用弹性力学理论分别计算了锚固体因轴向压缩导致径向膨胀而产生的径向应变以及锚孔因锚固体挤压周围岩体产生的径向应变。根据锚固体与周围岩土体变形协调假定,导出了压力型锚杆锚固段径向应力、轴向应力、剪应力分布的理论解,并对压力型锚杆足尺模型进行了试验。结果表明:锚固体轴向应变实测值与理论计算值比较吻合,验证了理论解的可靠性。基于上述理论解确定了有效锚固长度,分析了岩土体弹性模量与注浆换算弹性模量比值E/Ea、锚固力F、抗剪强度指标c、φ等岩土体力学参数对有效锚固长度的影响。结果表明:E/Ea值和c、φ值越小、F值越大,所需有效锚固长度越大。
The radial strain caused by radial expansion of the anchor due to axial compression and the radial strain of the anchor hole due to the surrounding rock mass extruded by the anchor were calculated respectively by using elastic mechanics theory. According to the coordination of deformation between anchors and surrounding rocks and soils, the theoretical solution of radial stress, axial stress and shear stress of anchorage section of pressure anchor is deduced. The full-scale model of pressure anchor is tested. The results show that the measured axial strain of anchor is in good agreement with the theoretical calculation, which verifies the reliability of the theoretical solution. The effective anchoring length was determined based on the above theoretical solution. The ratio of elastic modulus of groud to grouting, E / Ea, anchoring force F and shear strength index c, Effect of length. The results show that the smaller the value of E / Ea and the smaller of c and φ, the larger the value of F, the greater the required effective anchorage length.