叶巴滩水电站拱坝坝肩深部卸荷带影响研究

Study on Effect of Deep Unloading Zone in Abutment of Yebatan Hydropower Station

针对叶巴滩拱坝左右坝肩内存在的深部卸荷带等不良地质缺陷,采用地质力学模型试验超载法,对叶巴滩2 750 m高程拱坝和坝肩的工作性态开展平面地质力学模型试验研究。通过试验获得拱坝、坝肩及深部卸荷带的变形特性和破坏形态,探明了深部卸荷带对拱坝和坝肩的工作性态的影响,揭示了工程的薄弱部位。研究表明深部卸荷带对拱坝和坝肩的工作性态有明显影响,其影响程度与强松弛IVs类岩体所处位置及与拱端附近断层的组合作用有关。位于左坝肩强松弛IVs类岩体对拱坝和坝肩的变位、拱推力的传递影响较大,位于右坝肩的断层f29(f74)对坝肩稳定有明显影响。对左右坝肩内的这些薄弱部位需采取相应的加固措施,以改善拱坝和坝肩的工作性态。

According to the adverse geological defects such as deep unloading zone in both abutments of the Yebatan arch dam,the plane geomechanical model test based on the overloading method was conducted to research the working performance of the arch dam and abutment at EL.2 750 m.The deformation characteristics and failure patterns of the arch dam,abutment and deep unloading zone were obtained by the test.In addition,the effect degree of the deep unloading zone on the working performance of dam and abutment was studied.The weak parts of the project were revealed as well.The deep unloading zone has an evident impact on the working performance of dam and abutment.The effect degree is related to the position of the strongly relaxed rock mass IVsand the combination with faults near the arch abutment.The strongly relaxed rock mass IVsin the left abutment has a great effect on the deformation of the arch dam and abutment and the transmission of arch thrust.The stability of right abutment is affected by the fault f29(f74).Some reinforcement measures should be adopted to treat these weak parts in the left and right abutment to improve the working performance of the arch dam and abutment.