基于变位规律的悬索桥锚碇隧道围岩损伤度安全阈值研究

 结合矮寨悬索桥隧道式锚碇的爆破施工，通过数值模拟方法，建立不同损伤度条件下隧道式锚碇变位特征分析模型群，得到不同损伤度条件下隧道式锚碇位移特征曲线。研究结果表明，在大缆拉力的作用下，模型以竖向和沿桥轴向的位移为主，作用表现为使锚碇沿大缆拉力方向滑移和竖直向上抬升。在损伤度D = 0.1，0.4条件下隧道式锚碇位移特征曲线存在2个拐点；当损伤度D = 0.2时，曲线为单峰值曲线，两锚碇附近围岩位移场分布均匀，锚碇隧道围岩对大缆拉力的分担、传递效率较高；而当损伤度D≥0.3时，以左右锚碇为中心，不同损伤度条件下隧道式锚碇位移特征曲线上出现两个峰值点，两锚碇的位移场开始出现不同程度的独立性、位移等值线逐步分离；D≥0.6时，锚碇位移大幅增加，两锚碇的位移场完全分离。鉴于以上结论，可以考虑将损伤度D = 0.2作为锚碇隧道围岩损伤度安全阈值Dcr，D = 0.6作为锚碇失稳破坏的临界值Dur。

STUDY OF SAFETY THRESHOLD OF SURROUNDING ROCK DAMAGE DEGREE OF ANCHORAGE TUNNEL FOR SUSPENSION BRIDGE BASED ON DISPLACEMENT RULE

Based on the blasting excavation in tunnel-type anchorage of Aizhai suspension bridge，the characteristic curves of displacement and rock damage degree D of tunnel-type anchorage are obtained by numerical analysis according to the finite element models established under different damage degrees. The results show that the anchorage slides along the direction of cable tensile forces and uplifts vertically under cable tensile forces. There are two inflection points in the curve of displacement and rock damage degree when D = 0.1 and 0.4. When D = 0.2，the curve is a typical mono-peak one. Displacement field of surrounding rock nearby the anchorage has uniform distribution；and the efficiency of sharing and transferring cable forces by anchorage tunnel surrounding rock is higher. When D≥0.3，the curve of displacement and rock damage degree transforms into a typical double peak curve. Displacement field of the anchorages exhibits a mutual independence to a certain extent，and the displacement contours of the anchorages are separated with each other when the cable being overloaded. When D≥0.6，anchorage displacement increases greatly and its field separates completely. Based on the above conclusions，D = 0.2 and 0.6 can be considered as the safety threshold of damage degree of surrounding rock Dcr and critical value of anchorage failure Dur，respectively.