库岸滑坡破坏模式识别方法研究——以三峡水库青石滑坡为例

Study on Identification Method on Failure Mode of Reservoir Landslide:Taking Qingshi Landslide in Three Gorges Reservoir as an Example

青石滑坡是三峡水库岸坡消落带典型的崩坡积层滑坡,基于现场调查和工程勘察分析了三峡水库蓄水运行期间青石滑坡的变形与破坏特征;将滑动面位于175m水位以上的部分假定为弹性介质,位于145-175m之间的部分假定为应变软化介质,提出了两种介质材料的本构模型;通过对滑坡滑动面弹性应变能、滑坡重力势能和地下水渗透势能的计算,采用突变理论建立了滑坡破坏模式判别指标,据此可将滑坡破坏模式分为缓动型和剧动型两类。计算结果表明,青石滑坡在水库运行期间的破坏模式属于缓动型,与实情相符。研究成果对于探索三峡水库岸坡滑坡灾害的形成机制及其减灾具有积极意义。

Qingshi landslide is an representative landslide composed of colluvial deposits in water level fluctuating zone of Three Gorges reservoir.Based on field investigation and engineering survey,this paper analyzes formation and failure characteristics of Qingshi landslide during the running of the three gorges reservoir.Paying attention to slide surface of landslide in reservoir bank,the paper treats the part above 175 ma.s.l.as elastic medium,while the part between 145 ma.s.l.and 175 ma.s.l.as strain softening medium,then establishes two constitutive models respectively.Further,identification index for failure mode of landslide is built up in mutation theory following calculations such as elastic strain energy of slide surface,gravitational potential energy of landslide and osmotic potential energy in landslide.The index represents two failure modes of landslide,the slow failure type and the mutant failure type.Calculation identifies that Qingshi landslide belongs to the slow failure type in running of Three Gorges reservoir,which is consistent to the true state of affair.The research result is valuable in discovery formation mechanism and disaster mitigation for landslide in bank of Three Gorges reservoir.