侏罗系砂泥岩缓倾斜坡异性接触带泥化致灾机理研究

Shear strength soften caused by argillation of soft rocks is the key factor for slow-inclination slope evolved to landslide. Many studies have been done on the strength variation after argillation of soft rock blocks and their meso-microscopic mechanism. However, few previous literatures on strength variations of contact zone between heterogeneous rocks after argillation, and quantitative changes of meso-microscopic parameters. Replying to it, contact zone between heterogeneous rocks in slow-inclination slopes composed of Jurassic sandstone and mudstone taken as study subject, series of argillation tests and meso-microscopic tests will be conducted under combined condition of loading and dry-wet cycles firstly to learn the variation of meso-microscopic parameters after argillation by identification of particle sizes, mineral composition, microstructure, etc. And the rate of argillation will be determined by comprehensive analysis of hardness and microstructure variation of argillation zones. Then, series of direct shear tests and numerical simulation shear tests, which the parameters of argillation elements in the numerical model will be changed according to rate of argillation, will be carried out to research the shear strength variation of contact zones, and a mathematical responded model will be proposed between macroscopic mechanics, shear strength, and meso-microscopic parameters. Lastly, based on the argillation progress of contact zone, a numerical simulation will be conducted to research the evolution of slow-inclination slope from stable one to landslide, which is the progress of ‘deformation-cracking-sliding’. That will reveal the landslide genetic mechanism by argillation of contact zone between heterogeneous rocks in slow-inclination slope composed of Jurassic sandstone and mudstone. This research will provide theoretical basis for genetic mechanism of slow-inclination slope composed of sandstone and mudstone, and early identification for landslide disasters.

软弱岩体遇水泥化导致的抗剪强度弱化是砂泥岩缓倾斜坡演化为滑坡的关键因素。目前国内外对软岩块体泥化的强度变化及细微观机制已有较多研究，但针对异性接触带（即不同岩性接触带）泥化强度演变及细微观参数定量变化的研究相对较少。本申请以侏罗系砂泥岩缓倾斜坡的异性接触带为对象，开展载荷和“干—湿”循环共同作用下的泥化试验和细、微观试验，识别接触带泥化的细微观参数（颗粒粒度、矿物成分、微观组构等）变化特征；综合泥化带硬度和微观结构变化，确定泥化速率；开展室内直剪、基于泥化速率动态调整泥化单元参数的数值剪切试验，研究异性接触带泥化抗剪强度演变规律，建立宏观力学（抗剪强度）演变与细微观参数间的响应数学模型；根据异性接触带泥化过程，模拟研究侏罗系砂泥岩缓倾斜坡的“变形—开裂—启滑”灾变演化过程，揭示异性接触带泥化导致砂泥岩缓倾斜坡灾变的机理。研究成果为砂泥岩缓倾斜坡灾变机理研究、滑坡早期识别提供理论基础。

侏罗系砂泥岩缓倾斜坡演化为滑坡是内、外因协同作用的结果，软弱层泥化导致的强度弱化是关键因素之一。由于砂岩和泥岩渗透性的差异，地下水主要在砂泥岩接触带富集，进而导致砂泥岩异性接触带的泥化，诱发大规模、群发性滑坡。.项目采用工程地质调查、无人机航测、力学试验、微观测试、理论分析和数值模拟等手段，研究了侏罗系砂泥岩缓倾斜坡异性接触带泥化致灾机理，主要取得以下成果：.（1）以三峡库首侏罗系砂泥岩斜坡为重点研究区，采用信息量模型与人工神经网络、随机森林、XGBoost、支持向量机等多模型耦合的机器学习方法，进行了区域滑坡灾害易发性评价，识别了侏罗系砂泥岩斜坡灾变的关键研究区为水系及路网两侧的斜坡地带。.（2）自主研发动水循环与荷载条件的泥化过程模拟装置，进行砂泥岩异性接触带泥化试验，通过大量的泥化过程微观结构SEM测试，揭示了砂泥岩异性接触带泥化过程的细微观结构变化。对SEM图像的二维和三维可视化分析，采用孔隙个数、直径、面积、孔隙率、分形维数、孔隙方向、孔隙形状、孔隙类型分布等表征指标，揭示了砂泥岩异性接触带泥化过程的细微观结构定量变化规律。.（3）统计分析三峡库区侏罗系200余组砂岩、泥岩强度试验数据，获得了砂岩、泥岩的物理力学性质的变化规律。进行不同泥化过程的砂泥岩异性接触带的室内试验和数值模拟试验，研究了砂泥岩异性接触带强度随泥化过程的指数衰减变化规律。.（4）通过工程地质精细调查和无人机多期次测绘结合的方法，进行了典型砂泥岩缓倾斜坡灾变过程的实例研究。在对灾变过程动力学参数反分析的基础上，模拟再现了砂泥岩缓倾斜坡的变形、灾变过程，揭示了砂泥岩异性接触带泥化诱发缓倾角斜坡灾变的机理及运动、堆积过程。.相关成果在landslides等期刊公开发表论文7篇，申请专利2项，学术报告5人次，培养硕士研究生5人，协助联合培养博士研究生1人。相关成果初步在三峡库区湖北省秭归县的滑坡灾害的监测预警与预测预报中应用。