断层对孟底沟高拱坝坝肩变位及稳定性的影响研究

孟底沟水电站高拱坝由于左岸坝肩岩体受到 f1、f2、f6断层的切割，使得左坝肩形成了四个大块体。由于 f6与库水连通，若不做处理，蓄水后作用在 f6上的全水头渗压势必将使左岸坝肩岩体向河谷变形。因此左坝肩岩体变形连续性，拱坝坝体变位对称性及坝肩控制性滑块稳定性成为该工程的突出问题。充分考虑左岸坝肩断层交汇和切割关系，采用刚体弹簧元法对上述问题进行了计算分析和研究。结果表明：f6断层水压推力作用将使得断层交汇处出现不连续变形，断层产生错动现象，断层交汇点最大错动位移达到2．03 cm ，同时削弱了拱坝坝体变位对称性，左右半拱顺河向和横河向最大位移差分别为1．42 cm 和0．86 cm ；坝肩控制性滑移块体稳定安全系数下降，最大降幅可达18．19％。建议对 f6进行封堵或者置换处理，防止库水侵入山体。

The Effect of Faults to Displacement and Stability of the Mengdigou High Arch Dam Abutment

The left bank rock mass of Mengdigou high arch dam abutment is cut by f6 、f1 、f2 faults ,resulting in four big blocks in left abutment .Since the f6 fault is opening to the reservoir ,if not treated ,the rock mass of dam abutment in left bank is bound to deform towards valley due to the full head of seepage pressure acting on f6 fault after reservoir im-pounding .Therefore ,the deformation continuity of the rock mass in left bank abutment ,the displacement symmetry of the arch dam and the governing slip blocks’ stability of the dam abutment are prominent issues in this project .Rigid body-spring element method was used to analyze and study above issues in full consideration of faults intersecting and cut -ting in left bank abutment .Because of the hydraulic thrust acting on f6 fault ,the results show that discontinuous defor-mations appear at the fault intersections ,and the maximum displacement of dislocation at the fault intersections is 2 .03 cm .The displacement symmetry of the arch dam is weakened for the maximum displacement differences of the left and right arch abutment at vertical and horizontal direction are respectively 1 .42 cm and 0 .86 cm .The stability safety factors of the governing slip blocks in dam abutment are decreased and the maximum decrease is 18 .19% .The closure and re-placement measures of opening f6 are suggested to prevent water intruding into the mountain .