FLAC3D中锚杆剪切断裂的数值实现与应用  

Numerical Implementation and Application of Anchor Bolt Shear Fracture in FLAC3D

作　　者：张志强[1] 刘银[1] 赵梓彤[1] 李化云[1,2] ZHANG Zhiqiang;LIU Yin;ZHAO Zhitong;LI Huayun(Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu Sichuan 610031,China;School of Civil Engineering,Architecture and Environment,Xihua University,Chengdu Sichuan 610039,China)

机构地区：[1]西南交通大学交通隧道工程教育部重点实验室,四川成都610031 [2]西华大学土木建筑与环境学院,四川成都610039

出　　处：《中国铁道科学》2019年第4期59-68,共10页China Railway Science

基　　金：国家自然科学基金资助项目(51678503,51878572);国家自然科学基金青年基金资助项目(51608450)

摘　　要：针对地下工程中锚杆剪切断裂这一常见问题,提出锚杆在剪切荷载作用下的全过程形变力学模型,并基于FLAC^3D软件平台,采用FISH语言将该力学模型嵌入PILE单元,得到修正的PILE结构单元。分别采用原始PILE单元与修正PILE单元,进行锚杆剪切试验与单弱面层状岩体隧道锚杆支护的对比分析。结果表明:修正单元可以实现锚杆在剪切荷载作用下的塑性变形与断裂,即当剪力达到抗剪能力极限值时,锚杆进入塑性残余变形阶段;当剪切应变达到极限剪切应变时,锚杆剪切破断,杆体的轴力和剪力突变至0并保持恒定;在进行围岩稳定性分析时,对于承受较大剪力的锚杆而言,无需考虑锚杆的剪断效应会同时夸大锚杆的抗拉与抗剪支护能力;单弱面层状岩体中,锚杆剪断会弱化支护系统对围岩形变的约束能力,但锚杆的剪断位置以及约束能力减弱的程度与层理面的倾角有关。Aiming at the common problem of anchor bolt shear fracture in underground engineering,a mechanical model for the whole process deformation of anchor bolt under shear load is put forward.Based on the FLAC^3D software platform,the mechanical model is embedded into PILE element by FISH language programming,and a modified PILE structural element is obtained.The original and modified PILE elements are adopted respectively to carry out the comparative analyses of anchor bolt shear tests and anchor bolt support in single weak plane layered rock tunnel.Results show that the modified element can realize the plastic deformation and fracture of anchor bolt under shear load.That is,the anchor bolt enters the stage of plastic residual deformation when its shear force reaches the ultimate value of shear capacity.Furthermore,the shear fracture of anchor bolt occurs,the axial and shear forces of bolt body change abruptly to zero and remain constant when the shear strain reaches the ultimate shear strain.In the stability analysis of surrounding rock,for anchor bolts subjected to relatively large shear forces,the tensile and shear support capacities of anchor bolt will be exaggerated simultaneously without considering the effect of shear fracture.In layered rock mass with single weak plane,the shear fracture of anchor bolt will weaken the restraint ability of the support system to the deformation of surrounding rock.However,the shear fracture position of anchor bolt and the weakening degree of restraint ability are related to the inclination of bedding plane.

关 键 词：隧道支护 锚杆 PILE结构单元 剪切断裂 层状岩体 围岩稳定性 

分 类 号：TU476[建筑科学—结构工程]