强震区水电站引水隧洞衬砌结构动力稳定性分析

摘要

为了获得100年超越概率1％的地震作用下水电站引水隧洞衬砌结构的动力稳定性，采用动力时程法对某大型水电站的引水隧洞进行了三维动力分析，得到了引水隧洞各个关键位置在地震作用下的应力、位移、加速度的响应及塑性区分布特征。计算结果表明：引水隧洞的衬砌结构均按照激励地震动做相似的受迫振动，地震动峰值越大，衬砌结构的动位移和拉、压应力就越大。在引水隧洞进口处的上平段的拉、压应力最大，最大拉应力为1．3 MPa。隧洞衬砌拉应力在水平向上并不对称，每条隧洞靠近另一条隧洞的一侧，应力值较大，而远离另一条隧洞的一侧，应力值较小。引水洞塑性区离隧洞进、出口距离愈远，塑性区范围愈小，8条引水洞之间围岩的塑性区均未发生贯通。地震作用结束后，8条引水隧洞的围岩只有在出口位置发生塑性区贯通。引水隧洞在100年超越概率1％的地震工况下，局部会发生破坏，但整体上是安全稳定的。%To obtain dynamic stability of lining structure of water diversion tunnel under the 100 years beyond 1% proba-bility earthquake condition,the three-dimensional dynamic analysis for water diversion tunnel of large hydropower station is conducted by the dynamic time history method.The distribution of plastic zone and response characteristics of the stress and the displacement and acceleration of each key position of water diversion tunnel under earthquake is obtained.It is shown that the lining structure of the diversion tunnel makes similar forced vibration in accordance with the excitation earthquake. The peak value of earthquake is larger,the dynamic displacement,tensile stress and compressive stress of lining structure is greater.The compressive stress and tensile stress of the diversion tunnel inlet on the horizontal section is the biggest.The maximum tensile stress is 1.3 MPa.The stress of tunnel lining is asymmetry in the horizontal direction and the stress of the side of every tunnel near another tunnel is larger,and the stress value is smaller away from another side of the tunnel.The plastic zone of diversion tunnel is smaller far away from the tunnel inlet and outlet distance.The plastic area of the sur-rounding rock between the eight water diversion tunnels does not occur through.After the earthquake,the plastic zone is through only in the export position of eight diversion tunnels.The local position in the diversion tunnel is damaged under the 100 years beyond 1% probability earthquake condition,but the whole tunnels are safe and stable.