三峡库区土石堆积层滑坡水-力相互作用的滞回效应

The deformation and failure of reservoir wading soil-rock accumulated landslides may happen in both of the water level increasing and decreasing stages, and also in both of the preliminary operation stage of the reservoir and a certain number of years later after several water level fluctuation periods. The stability is directly correlated with the hydro-mechanical properties and hysteresis of the sliding rock and soil mass, especially the locked patches in sliding zones during the water level variation process. In order to more deeply understand the hydro-mechanical mechanism and hysteresis of reservoir induced landslides, We will take a typical soil-rock sliding debris in the Three Gorges Reservoir Area as study objects, test the hydro-mechanical properties of sliding rock and soil mass by laboratory and in-situ tests in both drying and wetting paths. Emphatically analyze the effect of hydro-mechanical hysteresis on the seepage, strength and deformation properties of sliding rock and soil mass. Establish a three dimensional geologic models of the landslide according to the investigation data, and then quantitatively calculate the variation of total stress, effective stress, pore water pressure, suction stress, hydrostatic pressure and self-weight of landslide body induced by the fluctuation of water level. Compare and verify the theoretical calculation results by the multi-physics and tridimensional field monitoring data of actual landslides, propose a hysteresis mechanical model for reservoir wading landslide. Finally, verify and correct the hysteresis mechanical model by the wading landslide physical model tests, provide the theoretical foundation for the long term stability evaluation and evolutionary trend prediction of reservoir wading landslides.

库区涉水土石堆积层滑坡的变形与破坏既可能发生在水位上升阶段，也可能发生在水位下降阶段；既可能发生在水库运行初期，也可能发生在多次水位升降周期之后。其稳定性与库水位变化过程中滑坡岩土体，特别是滑带锁固段的水-力相互作用性质与滞回效应直接相关。为更加深入地认识水位变化诱发该类滑坡问题的水-力相互作用机制与滞回效应，以三峡库区典型涉水滑坡为研究对象，通过室内和原位试验测试滑坡岩土体干湿路径的水-力相互作用性质，重点分析在吸水和脱水不同路径中滞回效应对滑坡岩土体渗流、强度与变形性质的影响。通过水-力耦合方法定量化计算水位变化引起滑坡体总应力、有效应力、孔隙水压力、吸应力、静水压力以及自重的变化过程。将理论计算结果与实际滑坡多场立体监测数据进行对比验证，提出库区涉水滑坡滞回力学模型。通过涉水滑坡物理模型试验对滞回力学模型进行验证与修正，为库区涉水滑坡的长期稳定性评价与演化趋势预测提供理论依据。

三峡工程是目前人类历史上最大规模的水利工程，三峡库区滑坡地质灾害的变形与破坏问题仍然是威胁工程长期安全的重大威胁。库区涉水滑坡的稳定性与库水位变化过程中滑坡岩土体的水-力相互作用性质与滞回效应直接相关。本项目以三峡库区典型涉水滑坡为研究对象，通过室内和原位试验测试了滑坡岩土体干湿路径的水-力相互作用性质，重点分析了在吸水和脱水不同路径中滞回效应对滑坡岩土体渗流、强度与变形性质的影响。通过水-力耦合方法定量化计算了水位变化引起滑坡体总应力、有效应力、孔隙水压力、吸应力、静水压力以及自重的变化过程。得出如下主要成果：1.将降雨与水位变化对滑坡体地表和深部变形速度的综合影响加以区分。结合水-力耦合相关理论，探讨了降雨与水位变化对库区涉水滑坡浅层与深层稳定性的不同影响机制。对黄土坡滑坡群各部分不同区域的稳定性与变形趋势进行了评价，提出了滑坡处理建议。2. 基于前期勘察剖面与新的钻探、硐探与监测数据，建立了临江1号滑坡体滑带空间分布模型。提出该滑坡体存在东西两个深浅不同的滑动面，从而临江1号滑坡体可分为1-1和1-2东西两个部分重叠的的次级滑坡体。上述成果可为三峡库区重大滑坡灾害防治提供农数据支撑与决策依据。3. 发明研制了一种相对湿度控制式非饱和土干湿路径抗拉强度测试仪。通过温湿度控制系统对相对湿度和温度进行全自动控制。通过拉伸系统与应力-应变测控系统开展等吸力拉伸试验，获取土样在干湿路径，不同吸力状态下的抗拉强度与应力-应变曲线。可广泛用于各类涉及土力学基础理论的实际工程建设与科学研究领域。4. 发明了一种坠落撞击式模型试验装置与试验方法。利用坠落物体与地面碰撞瞬间产生超重现象的原理，提高物理模型实际所处的竖向加速度状态。试验装置结构简单，成本较低，该试验方法不仅具备离心模型试验的优势，可直接使用原型岩土材料建立模型，而且可开展大尺寸的三维物理模型试验，试验过程操作简易。