锚杆拉拔试验的理论和数值分析

详细分析了现场锚杆拉拔试验的实测数据，说明了传统设计中认为界面抗剪应力平均分布的简化假定与近似服从负指数分布的实测结果存在误差。考虑界面黏结强度中化学胶着力、机械咬合力和界面摩擦力逐渐丧失的过程，建立了一个可以通过现场拉拔试验得到的极限荷载反算出界面抗剪强度和解耦长度的理论模型。引入一种可以模拟锚杆与岩土界面复 杂力学特性的摩擦-接触型界面单元建立数值模型进行仿真分析，再现了现场试验全过程的力学响应。通过与实测数据对比分析，验证了理论模型和数值分析的可靠性和精度。

Theoretical and numerical analysis of bolt pull-out test

Based on the pull-out test on bolts in-situ, the test data are analyzed and the difference of shear stress distribution along the bolt is discovered between the usual simplified assumption and the actual condition. In usual analysis, the shear stress along the bolt is assumed even distribution, but the real result is negative exponential distribution under pull-out condition. Considering the working mechanism and damage process of cohesion strength, a theoretical model for the pull-out bolt is rebuilt. In this model, the interface shear strength and uncoupling length parameter can be easily deduced from the ultimate load measured from pull-out test. Furthermore, a numerical model including a friction-contact interface element which can simulate the complex mechanical properties of the interface is introduced; and the mechanical response of bolt under pull-out load is analyzed. Comparing the calculation result with the field test, the reliability and precision of the theoretical model and numerical analysis are verified.