西南某水电站枢纽区夹泥型张裂隙成因机制探讨

通过对某水电工程坝区岩体结构的表生改造形迹调查，发现坝区除了发育与岸坡平行的正常的卸荷破坏方式外，还发育了一种破坏方式——夹泥型张裂隙。裂面性质的弱化和发育的普遍性，使这类破裂带可能成为控制坝区高边坡岩体稳定性的重要岩体力学边界。在其发育过程中的诸多控制因素中，岩体结构对这种岩体破坏方式的发育起了控制作用。夹泥型张裂隙与岸坡成大角度相交的陡倾角裂隙和缓倾角错动带组合并构成一个整体。缓倾角错动带的改造是前提。夹泥型张裂隙的发育则伴随陡倾角裂隙和缓倾角错动带的改造过程而产生，构成由陡倾角断裂或裂隙、缓倾角错动带组合形成的典型的岩体破坏模式。结合本地区构造特征和岩体结构特征，并通过大量的现场调查，该文主要探讨了坝区岩体结构特征和夹泥型张裂隙发育的关系，以及岩体结构对夹泥型张裂隙发育的控制作用。

Discussion on the formation mechanism of silted tensile cracks in a hydropower station dam area in southwest China

By investigating the fracture trace of epigenetic deformation in dam area of a hydropower station, silted tensile crack, a destructive mode of rock mass, controlled by rock mass structure is found except normal unloading destructive mode which is parallel to river bank slope. The weakness of fracture plane and general development make the fracture zone become the important boundary in mechanics of rock masses which controls the stability of the high slope rock masses. Of the many controlling factors rock mass structure is the key factor to control the development of the rock mass destructive mode. Silted tensile crack, steep fracture intersected with high-angle to the bank and the low-angle faulted zone develop to a whole body. The reconstruction of the low-angle faulted zone is the prerequisite of the development, and the silted tensile crack develops along with the deformation of the steep fracture and the low-angle faulted zone, which forms the typical destructive mode combined with steep fault or fracture and low-angle faulted zone. Based on the geological structure and the rock mass structure characteristics and a great deal of field investigation, this paper discusses on the relation of the rock mass structure characteristics and silted tensile crack development and the determinant effect of rock mass structure to the development of silt tensile crack.