锚杆施作时机对炭质千枚岩隧道力学响应影响研究

Research on Influences of Construction Time of Anchor Bolts on Mechanical Response of Carbonaceous Phyllite Tunnel

针对炭质千枚岩隧道施作锚杆时容易剥落掉块并导致局部失稳的问题,对先喷后锚法与传统先锚后喷法进行比较研究。为了分析2种施工方法对围岩与支护体系力学响应的影响,借助三维数值分析手段对洞周位移变化、初期支护结构受力、锚杆受力及围岩的塑性发展进行分析。结果表明,先喷后锚法引起的围岩变形与支护体系应力略大,先锚后喷法对控制围岩变形效果显著,二者均可满足一般工程需要;当对围岩变形控制要求严格时应选用先锚后喷法。

In allusion to the problems of easy peeling and chipping as well as loss of stability caused during construction of anchor bolts in grey phyllite tunnels,this paper studies the construction method for tunnels, namely erection of steel frames followed by spraying concrete and then construction of anchor bolts,i.e. the method of spray of concrete before construction of anchor bolts and the traditional method of construction of anchor bolts before spray of concrete.In order to analyze the influences of two construction methods on mechanical responses of wall rocks and supporting systems,the paper analyzes changes of peripheral displacement,initial stress on supporting structures and anchor bolts as well as plastic development of wall rocks by means of 3D numerical analysis means.The results show that the method of spray of concrete before construction of anchor bolts leads to slightly larger deformation of wall rocks and stress on supporting systems,while the method of construction of anchor bolts before spray of concrete exhibits significant effect on control for deformation of wall rocks,and both methods can satisfy the needs of general projects;when control for deformation of wall rocks is strictly required,the method of construction of anchor bolts before spray of concrete should be selected.