三峡工程永久船闸高边坡岩体卸荷松弛特征研究

Study on unloading and relaxation characteristics of the rockmass of permanent shiplock high rock slope of three gorges project

三峡工程永久船闸高边坡岩体卸荷松弛特征明显,采用地质调查、钻孔声波测试、内外部变形监测、现场变形试验、钻孔芯样力学试验、压水试验、孔壁录像、钻孔弹模测试等手段进行综合研究,结果表明,边坡岩体可划分为强、弱、微三个卸荷带,强、弱卸荷带岩体力学性质有明显弱化,微卸荷岩体力学性质无明显变化。在卸荷带内未产生新的结构面,但卸荷引起了结构面的进一步扩展和张开。岩体变形是结构面张开和岩块变形的综合反映,主要受开挖卸荷影响,锚索对于限制结构面张开作用明显。

The rock mass of permanent shiplock high rock slope of the Three Gorges Project（TGP） has marked characteristics of unloading and relaxation. Kinds of methods such as geological investigation, sonic velocity test, monitor of deformation, in-situ test of elasticity modulus of rock mass, test of rock permeability, kinescope in hole, test of elasticity modulus of rock mass in hole, etc., have been applied to studying the characteristics. The study shows that the rock mass of the slope can be divided into three zones, strong-unloading zone, middling-unloading zone and slight-unloading zone. The degeneration of properties of rock mass in strong-unloading zone and middling-unloading zone is notable, while degeneration of properties of slight-unloading rock mass is not obvious. The structure and properties of the rock in unloading zone do not alert obviously; but the unloading causes the growth of the joints＇ length and width. The deformation of rock mass of the slope mainly depends on the deformation of joints and elastic deformation of rock block, which is affected by excavation. The reinforcement cables have obvious effect on confining deformation of joints.