库水作用下堆积层滑坡滑面应力状态识别与渐进破坏机理研究

The colluvial landslide caused by reservoir water is a serious threat to people's lives and property. The stress state of the potential sliding surface plays an important role in the process of progressive failure. The colluvial reservoir bank slope is studied in this project considering its characteristics of progressive damage along the sliding surface. A novel set of test methods is proposed to obtain local stress state of the sliding surface using some new monitoring technologies, such as Fiber Bragg Grating sensors, six-axle force sensors, Particle Image Velocimetry method. It is used to grasp the distribution characteristics and variation of stress state along the sliding surface. The deformation response characteristics of sliding surface at different locations under different stress state is studied based on the measurement and numerical result of indoor slope model test. The effect of reservoir water action on stress state of the surface is clarified, and a method that using the deformation response of the sliding surface to distinguish its stress state is established. After that, the monitoring work of the Majiagou colluvial slope in the Three Gorges Reservoir is carried out to study its deformation response characteristics under the action of reservoir water. The stress state of sliding surface at different locations is distinguished and evaluated based on the study result from laboratory tests. The progressive failure process of the slope is simulated based on the numerical slope model of seepage as well as deformation. The progressive failure mechanism of the slope deformation and evolution is revealed.

库岸堆积层滑坡灾害严重威胁库区人民的生命财产安全，库水作用下潜在滑面的应力状态对滑坡渐进破坏起决定作用。本课题以库岸堆积层滑坡为研究对象，针对滑坡沿滑面变形渐进式破坏的特点，采用新型的光纤光栅和多维力感测器、高精度数字图像测量等技术，提出了一套滑面局部应力状态量测的试验方法，掌握边坡滑动过程中滑面应力状态的分布特征及其变化规律；基于室内边坡模型试验，结合数值模拟分析，得到滑面不同位置、不同应力状态下的变形响应特征规律；分析库水作用对滑面应力状态的影响，建立基于滑面变形响应特征的滑面应力状态识别方法；在此基础上，以三峡库区马家沟堆积层边坡为例，进行边坡潜在滑动面的识别与监测，研究其在库水作用下的变形响应特征；基于室内试验研究成果，确定滑面不同测点位置的应力状态，结合数值分析模型，模拟该边坡变形发展过程，揭示其渐进破坏的演化机理。

库岸堆积层滑坡灾害严重威胁库区人民的生命财产安全，其在库水升降下变形规律和渐进破坏机理一直是研究热点。本课题以库岸堆积层滑坡作为研究对象，采用自主研发的滑面剪切应力传感器，结合先进的光纤传感等监测技术，提出了一套边坡滑面应力及变形的新型试验量测方法，与以往研究关注变形相比，聚焦于滑面应力状态的识别和监测，具有一定的创新性，为研究堆积层滑坡渐进破坏机理提供新的参考思路，有助于深入掌握边坡渐进破坏过程中的滑面应力状态演化规律。.主要研究内容和成果如下：.（1）研发了一套边坡滑动面应力应变监测系统来获取滑动面剪应力、土压力和变形，通过传感器标定和堆积层边坡模型后缘加载破坏试验，验证研制的剪力传感器能够良好地监测滑动面剪应力的变化情况。开展水位波动下堆积层滑坡模型试验，利用剪力传感、土压力传感器和FBG土体应变传感器。滑面测点的剪力和土体压缩变形整体呈现随水位上升而增大，水位下降而降低的规律。.（2）建立边坡后缘逐级加载下渐进破坏的数值模型，深入研究滑面应力和变形的演化过程。结果显示滑坡推力从后缘逐渐向前缘传递，距离加载面越近，滑面剪应力和剪切位移的增长幅度越快，呈加速增长趋势。边坡安全系数近似以幂函数降低，当局部剪力达到抗剪强度后，安全系数出现阶梯式降低的现象。.（3）开展水位波动下堆积层滑坡数值模拟。在滑动面上存在某个可以区分滑面不同应力状态变化的分界点，在此位置前的边坡前缘部分滑面剪应力和滑面土体位移均随着库水位的增加而增加，随着库水位的降低而降低，而该位置后的情况正好相反。距离分界点位置越近的测点，滑面应力状态和位移随水位波动的影响越小。各测点滑面土体应变变化量则同库水位变化的响应规律一致，均随着库水位的增加而降低，随着库水位的降低而增加。同样地，滑带土的应变距离分界点越近，对水位波动的响应越低。此外，该分界点的位置受滑面初始应力状态影响较小。