矮寨悬索桥隧道锚碇稳定性数值分析

通过三维显式有限差分计算,对矮寨大桥C线方案吉首岸隧道锚碇系统进行了数值模拟,分析了由于施工开挖引起的锚碇、塔基和公路隧洞围岩位移和应力变化,计算了在设计荷载P作用下锚碇结构体系围岩的变形和应力响应;在此基础上,对C线方案锚碇体系的围岩稳定性作出评价.计算分析表明:锚碇、塔基和公路隧道处于浅地表且布置较集中,相互影响显著;虽然开挖引起的围岩变形大部分小于1 mm,但是由于锚碇后部与下部公路隧道间岩柱较薄导致出现拉应力集中和较大面积的塑性区;在设计荷载作用下,该处的塑性区进一步扩大;在3P超载情况下,锚碇后部至公路隧道顶拱的塑性区贯通,对锚碇的长期承载有较大威胁,且引起下方公路隧道顶拱岩体的稳定性严重恶化而难以自稳.

Numerical Analysis of Rockmass Stability in Tunnel Anchoring of Aizhai Bridge

Under the action of excavation and design load,the rockmass stability of tunnel anchorage system of Aizhai Bridge was calculated by using FLAC-3D.The variations of displacement and stress of sarrounding rock mass of this system due to the influences of excavation,anchoring,main tower base and highway tunnel were analyzed and calculated.It was found that,for the anchoring,the tower-base and the highway tunnel are centrally located,so the influence with each other is distinct.On the basis of the result,the stability of the tunnel anchoring was estimated. According to the analysis,although the most of the displacements of rockmass are less than(1.0) millimeter,there exist many yielding zones in the rock masses under the condition of excavation and design load.Furthermore,the tunnel anchorage system isn't stable under the action of treble design load.