基于离散元的节理岩体水工隧洞地震动力特性分析

基于非连续介质理论,借助离散元软件UDEC,建立了大跨度、高边墙的缓倾角层状节理岩体水工隧洞力学分析模型,研究了地震力作用下,隧洞围岩不同部位的波速特性、位移分布、应力分布、塑性区分布等力学特性及围岩稳定性问题,获得了大型地下隧洞不同部位围岩在地震中的响应规律。在垂直方向正弦剪切地震波的作用下,各监测点竖向动力特性明显比水平方向大;地震波作用初期,边墙产生的位移值大于顶拱,随时间的推移,底板围岩变形受地震作用较大;洞室各监测点应力值相对地震波作用前均有较小程度的增大;震后隧洞边墙及底板岩体是塑性区范围扩大较明显的部位。研究结果可为同类大型地下工程的设计和施工及进一步分析地震作用下围岩的变形破坏过程提供参考。

Seismic Dynamic Characteristic of Hydraulic Tunnel in Jointed Rock Based on UDEC

A model of analyzing the mechanics of hydraulic tunnel with gently dipped layered jointed rock with long span and high sidewall was established using UDEC based on the non-continum theory.The wave velocity charac-ters,displacement distribution,stress distribution and plastic zone distribution,as well as the stability of surround-ing rock at different positions of the tunnel under seismic action were analyzed.The response of surrounding rock during earthquake action was acquired.Results revealed that under sine shear seismic wave in vertical direction, the dynamic characteristic of monitoring points in vertical direction were more apparent than that in horizontal direc-tion;in the initial stage of seismic wave action,the displacement of sidewall was larger than that of the roof,and the displacement of bottom surrounding rock was largely affected by seismic action as time went by;after the seis-mic action,the stress of monitoring points all increased slightly;and plastic zone in the tunnel’s sidewall and the bottom surrounding rock enlarged obviously.The results provide references for further analysis on the deformation and failure mechanism of surrounding rock under seismic load.