节理岩体中锚杆剪切力学模型研究及试验验证

依据最小余能原理,在考虑节理岩体中锚杆剪切变形的基础上,分析了节理面水平剪切位移与锚杆轴向及切向变形之间的关系。结合锚杆受力特点拟定了锚杆屈服模式的判定流程。建立了考虑"等效剪切面积"的加锚节理面抗剪强度理论计算模型,并通过室内物理试验验证了理论计算模型的准确性。讨论了锚杆倾角、围岩抗压强度、锚杆直径、法向应力等因素对加锚节理面抗剪强度的影响规律。结果表明:所建立的锚杆剪切力学模型能够较好的反映锚杆轴向力及剪切力对节理面抗剪强度的贡献;考虑"等效剪切面积"的加锚节理面抗剪强度计算结果与试验结果较为吻合;锚杆倾角及围岩抗压强度越大,锚杆轴向力越小,剪切力越大;锚杆直径增大,锚杆轴向力及剪切力都会增大;节理面法向应力会显著影响剪胀效应,法向应力越大,节理面抗剪强度越高。

Shearing mechanical model and experimental verification of bolts in jointed rock mass

Based on the principle of the minimum residual energy, the relationship between the horizontal shear displacement of the joint surface and the axial and tangential deformation of the bolt is analyzed considering the shear deformation of the bolts in jointed rock mass. The judgment process of the yield mode of the bolt is determined by analyzing the characteristics of the loading on the bolts. The formula for calculating the shear strength of the anchoring joint surface is established considering the equivalent shearing area, and the accuracy of the theoretical calculation is verified by the indoor physical experiments. The influence of bolt inclination, surrounding rock strength, bolt diameter and normal stress on the shear strength of the anchoring joint surface is discussed. The results show that the shearing mechanical model can better reflect the contribution of the axial force and shearing force of the bolts to the shear strength of the joints. The calculated results of the shear strength of the anchoring joint surfaces considering the equivalent shearing area are in good agreement with the experimental ones. The greater the inclination of the bolts and the strength of the surrounding rock, the smaller the axial force of the bolts but the greater the shear force. The axial force and shear force of the bolts will increase with the increase of the diameter of the bolts. The normal stress of the joint surface will significantly affect the dilatancy effect, and the greater the normal stress, the higher the shear strength of the joint.