顺层坡含碎石滑带土变形及渗流特性研究

The bedding slope is a type of slope which is often encountered in engineering practice and is more likely to cause damage. The weak interlayer of the connected layer often evolves into a sliding zone and controls the stability of the landslide. Most of the types of slip zone contain cuttings and gravel，which are closely related to the stability of the slope. In view of the phenomenon that this type of slope is unstable, the project is planned to consider the influence of seepage on the basis of indoor test, on-site monitoring and on-site test, and the gravel slip zone with different grading and different water content. The theoretical analysis and experimental study on soil strength and constitutive properties will been carried out. The prediction model and creep law of shear strength of different types of grading slopes and different water-bearing conditions will been obtained；According to the slip zone and slip surface， based on the results of structural research combined with long-term on-site monitoring data, the evolution law of the sliding zone will been obtained. According to the experimental results of the coupling effect of the seepage field and the stress field of the bedding slope under different seepage conditions, the instability law of the slope will been obtained. The nonlinear mechanical model of instability under the seepage condition of the slope is applied, and the research results will been applied to the actual project for validity verification. The research results have important theoretical and practical significance for the extensive development of this type of landslide development mechanism, stability evaluation and prediction, prevention and control.

顺层坡是工程实践中常遇到也是较易产生破坏的一类边坡，其内连通的软弱夹层常常演化为滑带而对滑坡的稳定性起控制作用，该类型滑带土大都含有碎石、岩屑、砾石等成分，与坡体的稳定性密切相关。针对该类型边坡降雨条件下滑坡失稳的现象，本项目拟在室内测试、现场监测及现场试验的基础上，考虑渗流的影响，对不同级配、不同含水情况下的含碎石滑带土强度和本构特性进行理论分析与试验研究，得出该类型顺层坡不同级配、不同含水情况下滑带土的抗剪强度预测模型及蠕变规律；根据滑带土及滑面的微观结构研究成果结合长期现场监测数据，得出滑带的演化规律；根据不同渗流条件下顺层坡渗流场-应力场耦合作用特性实验结果，得出该类型边坡失稳变形规律，从而建立顺层坡渗流条件下失稳的非线性力学模型，并将研究成果应用于实际工程进行有效性验证。该研究成果对广泛存在的该类型滑坡发生发展机理、稳定性评价及预测、防治等方面的研究都具有重要的理论与现实意义。

对顺层坡含碎石滑带土变形及渗流特性系统研究一直是工程地质学和岩石力学领域内极为瞩目和急待解决的问题之一，其研究成果必将有广阔的应用前景，具有重要的理论意义。. 本研究以广州增城至从化高速公路滑坡为例，在充分考虑渗流对碎石滑带土顺层滑坡诱发作用事实的基础上，以试验研究为主要手段，采用宏观试验和微观试验相结合、试验研究和理论分析相结合、理论分析与数值模拟相结合的方法，系统探讨渗流条件下碎石滑带土顺层基岩滑坡失稳机理，在滑带土的物理性质基础上，通过室内试验，重点研究了滑坡的颗粒成分、不同含水率及干密度条件下抗剪强度的变化。取得的主要成果如下：①在保证含水量相同的情况下随着干密度的增加，土颗粒的排列更加紧密，土粒间的胶结作用加强，抗剪强度增加，由于土粒间的排列发生变化，其咬合摩擦加大，内摩擦角与黏聚力也相对较大；②当干密度相同时，随着含水率增加，土体变软，水在土颗粒间的存在形式发生变化，导致土颗粒间的咬合作用减弱，抗剪强度降低，黏聚力与内摩擦角相对减小；③通过蠕变试验得出在相同的初始载荷和多级载荷下，随着水压力的增加，砂岩岩样蠕变应变减小，而岩石蠕变强度和最大加速蠕变速率增加。在较低水压条件下，岩样表面断裂以穿晶和粒间断裂为主，宏观破坏形式以拉张破坏为主；④通过滑坡物理模型的建立，分析了不同渗流场下顺层岩渗流特性及失稳机理，分析试验结果可知在雨型1条件下持续降雨30分钟后坡脚孔隙水压力开始下降，30-60分钟时水压力有些许波动，60分钟后孔隙水压力趋于稳定；在雨型2条件下持续降雨20分钟后孔隙水压力开始变化；在雨型3条件下土压力变化值和孔隙水压力变化值与人工降雨雨型2相比在特殊的时间段具有一定的滞后性；⑤采用尖点突变非线性科学理论建立顺层边坡突变失稳数学力学模型结合数值模拟分析该边坡的稳定性其研究对滑坡的治理具有重要的理论意义和实用价值。