三峡库区周期性库水位变化对抗滑桩加固效果非饱和流固耦合分析

Unsaturated Fluid-Structure Interaction Analysis on Reinforcement Effect of Antislide Pile Resistance to Periodical Variation of Water Level in Three Gorges Reservoir Area

三峡库区内广泛发育的滑坡等地质灾害在水库运行水位周期性波动条件下会发生复活乃至失稳。抗滑桩是其中应用广泛、效果良好的防治措施之一。抗滑桩在库水位周期性波动条件下对滑坡的治理加固效果及其自身的变形受力特征是较为重要但研究尚少的问题。采用非饱和岩土本构关系,考虑在库水位周期性波动条件下滑坡体处于饱和-非饱和周期性变化时的流固耦合效应,采用有限元法对设置抗滑桩前后库区某滑坡的位移和稳定状态进行模拟,并分析了抗滑桩内力及其桩顶位移随库水位变化的特征。研究结果表明,抗滑桩对滑坡的水平位移控制效果较为显著,安全系数最少能提高到2以上。在库水位运行的一个周期内,抗滑桩加固滑坡的安全系数变化幅度不超过5.4%,而抗滑桩内力及桩顶位移不超过10.4%。滑坡最小安全系数和抗滑桩最大受力出现在最高水位时,其变化趋势与水位变化趋势较为一致。

The landslide and other geological hazards developed extensively in Three Gorges Reservoir Area will revive even fail on the condition of periodical fluctuation of water level in the reservoir. The Antislide Pile is one of the prevention measures with wide application and good effect. The control and reinforcement effect of Antislide Pile on landslide under periodical fluctuation of water level in the reservoir and the own deformation characteristics under force is the important problem with little research. Using constitutive relationship of unsaturated rock and considering fluid-structure interaction effect of landslide mass in saturated-unsaturated periodical variation under the condition of periodical fluctuation of water level in the reservoir, the displacement and stability of certain landslide in the reservoir area before and after setting of Antislide Pile are simulated by finite element method; the characteristics of internal force of Antislide Pile and the displacement of pile head changed with water level in the reservoir are analyzed. The study results show that Antislide Pile has outstanding effect to control horizontal displacement of landslide with the safety factor increased to 2 at least. During one cycle of water level in the reservoir, the safety factor of Antislide Pile reinforcing landslide is changed by the rate not more than 5.4 % ; and the internal force of Antislide Pile and the displacement of pile head by the rate not more than 10.4 %. The minimum safety factor of landslide and the maximum force of Antislide Pile will take place in case of highest water level with the variation tendency the same as that of water level.