考虑锚杆预应力作用下隧道围岩力学分析及参数设计  

Mechanical Analysis and Parameter Design of Tunnel Surrounding Rock Considering Prestress of Bolt

作　　者：罗春雨[1] 廖杭 余涛 李梦可 王飞阳 方勇[2] LUO Chunyu;LIAO Hang;YU Tao;LI Mengke;WANG Feiyang;FANG Yong(Branch of Road Tunnel,Sichuan Road and Bridge Construction Co.,Ltd.,Chengdu 610200,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]四川公路桥梁建设集团有限公司公路隧道分公司,成都610200 [2]西南交通大学土木工程学院,成都610031

出　　处：《铁道标准设计》2024年第6期153-160,220,共9页Railway Standard Design

基　　金：国家自然科学基金项目(52078428);四川省杰出青年科学基金项目(2020JDJQ0032)。

摘　　要：隧道工程中锚杆设计多依靠经验法和类比法,为研究预应力锚杆支护体系下围岩的力学效应,建立预应力锚杆与围岩力学耦合模型,考虑围岩开挖损伤效应,通过弹塑性力学理论推导出隧道开挖后围岩应力分布及径向位移解析表达式,采用有限差分软件FLAC3D进行算例验证并分析预应力锚杆参数对围岩状态的影响。研究结果表明:理论解析和数值模拟中最大切向应力和围岩塑性区半径分别为4.77 MPa、15 m和4.49 MPa、15.86 m,理论解析与数值模拟所计算隧道围岩应力分布、位移基本一致,在Ⅳ、Ⅴ级围岩地层中验证了理论解析解的合理性;随着预紧力增大,处于塑性区的围岩径向位移及塑性区半径逐渐减小,弹性区基本不受影响;当锚杆自由段长度位于塑性区时,随着锚杆长度增加,围岩塑性区径向位移及塑性区半径逐渐减小。在实际工程中应尽量增大锚杆预紧力,锚杆长度增加对围岩位移以及塑性区的发展控制效果有限,应控制锚杆自由段长度在塑性区内。The design of anchor bolt in tunnel engineering mostly depends on empirical method and analogy method.In order to study the mechanical effect of surrounding rock in prestressed anchor bolt support system,a mechanical coupling model of prestressed anchor bolt and surrounding rock is established.Considering the damage effect of surrounding rock excavation,the analytical expressions of stress distribution and radial displacement of surrounding rock after tunnel excavation are derived by elastic-plastic mechanics theory.The finite difference software FLAC3D is used to verify and analyze the influence of prestressed anchor parameters on the state of surrounding rock.The results show that the maximum tangential stress and the radius of plastic zone of surrounding rock in theoretical analysis and numerical simulation are 4.77 MPa,15 m and 4.49 MPa,15.86 m respectively.The stress distribution and displacement of tunnel surrounding rock calculated by theoretical analysis and numerical simulation are basically the same.The rationality of theoretical analytical solution is verified inⅣandⅤgrade surrounding rock strata.With the increase of pre-tightening force,the radial displacement of surrounding rock in plastic zone and the radius of plastic zone gradually decrease,while the elastic zone is basically unaffected.When the length of the free section of the bolt is located in the plastic zone,the radial displacement of the plastic zone and the radius of the plastic zone of the surrounding rock gradually decrease with the increase of the length of the bolt.In practical engineering,the pre-tightening force of bolt should be increased as much as possible.The increase of bolt length has limited control effect on the displacement of surrounding rock and the development of plastic zone.The length of free section of bolt should be controlled in plastic zone.

关 键 词：隧道工程 预应力锚杆 力学分析 数值模拟 开挖损伤 参数设计 

分 类 号：U441[建筑科学—桥梁与隧道工程] U451.2[交通运输工程—道路与铁道工程]