雅砻江两河口水电站泄洪建筑物进口布置于庆大河左岸边坡,继在边坡中下部圈定3个变形体后,在边坡上部发现变形体Ⅳ区,严重威胁泄洪建筑物的安全.通过探硐、赤平投影等手段,结合研究区地质环境,确定了边坡变形破坏机理,该边坡为中薄层岩体反倾边坡,青藏高原隆升伴随河流下切,边坡卸荷,在上部岩体自重作用下,坡脚薄层岩体发生倾倒弯折,河流侵蚀作用下变形加剧导致局部弯折贯通形成底滑面,在外力作用下崩滑破坏,上部变形体失去支撑后倾倒弯折破坏加剧,由于岩层薄,变形体多为碎裂散体结构.采用Geo-slope软件对变形体进行稳定性分析,结果表明自然状态下Ⅳ区变形体处于极限平衡状态,下部变形体清除后,Ⅳ区变形体失稳.最后,根据结果制定了合理的变形体处理措施.%The flood discharge inlet of Lianghekou hydropower station could decorate at the left bank slope of Qingdahe River.A new deformation rock mass (Ⅳ) is found after three were identified in the previous stages.The construction safety is largely dependent on the stability of the deformation rock mass.On the basis of engineering geological methods such as exploratory tunneling and stereographic projection,the deformation mechanism is analyzed.The rock slope is toppling with thin and medium-thickness rock stratum.As the uplift of Qinghai-Tibet Plateau and incision of Qingdahe River,the slope is unloaded at the free face.The thin rock stratum is toppling and buckling at the slope toe and then the upper location.The deformation is aggravated with river erosion and a slip plane could be formed gradually.Landslide tends to occur with external disturbances e.g.rainstorm or earthquake.The deformation mass at the upper slope could get further damaged after slope toe failure.Because the thickness of rock stratum is small,the joint group nearly vertical to the bedding plane is developed well and the rock mass is strongly toppling,buckling and fragmentized.The stability is studied quantitatively with Geo-slope software.The results show that the deformation mass Ⅳ is in the limit equilibrium state and could get unstable after the deformation masses located at the lower part of the slope is clear off.Some proper treatment measures are then suggested.
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