基于有限元法的闸室抗震安全评价

Finite element method-based seismic safety assessment on sluice chamber

由于我国建设初期的水闸工程设计经验有限,未充分考虑到闸室抗震的实际需要,设计标准偏低,需要进行抗震安全复核。以某水闸为例,由于其初设时未考虑抗震因素,但水闸位于地震基本烈度Ⅷ度区,运用有限元软件ANSYS建立模拟水闸基础及上部结构的三维模型,采用模态分析反应谱法进行了地震动力计算分析。结果表明:地震荷载作用下闸室最大沉降为31.43 mm,闸底板平均沉降26.18 mm,处于安全范围之内;地基土层最大沉降变形集中发生于闸室地板边缘向下、土层Ⅰ、土层Ⅱ、土层Ⅲ上部,土层Ⅱ部分沉降变形30 mm左右,在8级地震下有可能发生液化。闸室最大压应力为0.465 MPa,最大拉应力为-76.76 k Pa,满足规范要求。闸室抗滑稳定性不满足要求,地震条件下闸室带阻滑板抗滑稳定安全系数为0.944,不带阻滑板抗滑稳定安全系数为0.708,均小于允许抗滑稳定安全系数1.05的要求,建议闸室拆除重建。

Because of the limited experience for the engineering design of sluice during the initial construction period in China,the actual seismic demand from sluice was not fully considered at that time,thus the design standard is a little bit lower,for which the seismic safety is necessary to be made. By taking a sluice as the study case,a 3-D model for simulating the foundation and the upper structure of the sluice is established through the finite element software-ANSYS,as the sluice is located at a region with the seismic basic intensity of VIII without any considerations on the seismic factors in its initial design,and then a seismic dynamic analysis is made for it with the modal analysis and response-spectrum method. The result shows that under the effect of seismic load,the maximum settlement of the sluice chamber is 31. 43 mm and the average settlement of the sluice bottom slab is 26. 18 mm,which are in the margin of safety,while the maximum settlement deformation of the foundation soil concentrates downward at the edge of the sluice bottom slab,soil layer I,soil layer II,the upper part of soil layer III and the settlement deformation of a part of soil layer II is about 30 mm,which are possibly to be liquefied under the 8-magnitude earthquake.The compressive stress of the sluice chamber is 0. 465 MPa and the maximum tensile stress is-76. 76 k Pa,and then both of them can meet the requirement of the relevant specification. However,the sliding stability of the sluice chamber cannot meet the relevant requirement,i. e. under the seismic condition,the sliding stability safety factor of the sluice chamber with anti-sliding slab is 0. 944 and the sliding stability safety factor of the sluice chamber without anti-sliding slab is 0. 708,thus both of them are lower than the requirement of the allowable sliding stability safety factor of 1. 05. Therefore,it is suggested that the sluice chamber must be demolished and reconstructed.