隧道围岩全长黏结式锚杆界面力学模型研究  

Study of mechanical model of fully grouted rock bolt’s anchorage interface in tunnel surrounding rock

作　　者：文竞舟[1,2] 张永兴[1,2] 王成[3] 

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]重庆大学山地城镇建设与新技术教育部重点实验室,重庆400045 [3]重庆交通大学隧道及岩土工程系,重庆400074

出　　处：《岩土力学》2013年第6期1645-1651,1686,共8页Rock and Soil Mechanics

基　　金：长江学者和创新团队发展计划资助(No.IRT1045);国家自然科学基金科学仪器基础研究专款(No.51027004)

摘　　要：分析围岩弹塑性介质中全长黏结式锚杆的锚固界面层应力分布和变化特征,对研究隧道工程初期支护系统的力学效应具有重要意义。根据全长锚杆微段的受力平衡以及锚固界面层剪应力的传递机制建立了关于锚杆轴向位移的微分方程,通过求解锚杆轴向位移的微分方程可得到锚杆与围岩相互作用下的轴向载荷和锚固界面剪应力的分布函数。然后将锚杆界面剪应力对围岩的支护反力转化为圆形隧道轴对称径向体积力,进而求解有锚喷支护作用下圆形隧道围岩塑性区半径。在此解析模型基础上,可对隧道围岩-支护系统进行详细的分析和评判。算例分析表明,初期支护时机的选择对锚固效应和围岩稳定性有较大影响;适当增加全长黏结式锚杆的锚固层厚度能明显降低锚杆端部剪应力的应力集中度,能有效改善锚杆的锚固效果。It is of great importance for studying mechanical effect of initial support system in tunnel engineering when analyzing distribution and variation of fully grouted rock bolt＇s stress in elastoplastic surrounding rock. A bolt＇s axial displacement differential equation is established according to the stress equilibrium in a small section of a rock bolt and the shear stress transfer mechanism of anchorage body interracial layer between rock bolt and surrounding rock. Then the axial load distribution function and the shear stress distribution function on the interface of the fully grouted bolt are obtained by solving the differential equation under the interaction between rock bolt and surrounding rock mass. The reaction of the shear stress on interface of the fully grouted bolt on the surrounding rock is assumed to be symmetric radial action. The plastic zone radius of circular tunnel for bolt-shotcrete support can be solved by means of Mohr-Coulomb yield condition. On the basis of the model and function above, the mechanical effect of system for surrounding rock and initial support is analyzed. According to the analysis of example, it is shown that selection of supporting time has great influence on anchoring effect and surrounding rock stability. It is suggested that increasing the thickness of the grouted layer properly can decrease efficiently shear stress concentration at bolt end and also can improve the reinforcement effect of fully grouted rock bolt.

关 键 词：全长黏结式锚杆 界面剪应力 隧道围岩 锚固层厚度 解析法 指数积分函数 

分 类 号：TU32[建筑科学—结构工程]