地震荷载作用下超大跨扁平地下硐室位移特征的影响因素

Displacement characteristics behind influencing factors of super-span flat underground cavern under seismic load

为分析超大跨扁平地下硐室地震响应的影响因素,以国内某超大跨扁平地下硐室工程为例,采用动力时程方法,分析了地震荷载作用下不同地应力特征、围岩条件、硐室跨度及地震加速度峰值对硐室位移特征的影响。结果表明:侧压力系数λ<1时,硐室顶底相对水平位移随侧压力系数增大而减小,且减小幅度较大,当λ≥1时,相对水平位移趋于稳定;围岩级别越高,围岩整体性越好,硐室顶底相对水平位移越小;硐室矢跨比不变时,硐室顶底相对水平位移随跨度增大而增大;随着地震加速度峰值的增大,硐室顶底相对位移呈线性增长。

The paper is aimed at the analysis of the influencing factors of the seismic response of a super-large-span flat cavern.The study building on a large-span flat cavern project in China involves using the dynamic time-history method to analyze the effects of different in-situ stress characteristics,surrounding rock conditions,cavern span and seismic acceleration peak on cavern displacement characteristics under seismic load.The results show that,given the lateral pressure coefficientλ<1,the relative displacement between the arch crown and middle of bottom plate tends to decrease with an increasing lateral pressure coefficient,and with a greater decrease range,and in the case ofλ≥1,the relative displacement tends to be stable;the higher the grade of surrounding rock,the better the integrity of surrounding rock,and the smaller the relative displacement;given no change in the cavern rise-span ratio,the relative displacement increases with the increased span;and the increase of the peak seismic acceleration is followed by a linear increase in the relative displacement between the arch crown and middle of bottom plates.