溃散性滑坡成因机理、监测预警与定量风险评价

In recent years, a few landslides constructed of saturated loose granular geo-materials (e.g. Shenzhen landslide (2015)) are obviously characterized with sudden large domain collapse (rather than failure on a certain slide surface), static liquefaction, long run-out liquidity flow movement as well as other unique phenomenon. Those characteristics are extremely similar to the diffuse failure phenomena that are being studied as a research hotspot by the international geotechnical scholars. However, this new type of landslide, diffuse failure landslide, has not yet been fully understood and studied heretofore. In this project, a series of soil unit tests, flume tests and large geotechnical centrifuge model tests based on various granular materials with different grain-size distributions (e.g. silt, sand, silt sand, gravel soil) will be firstly designed and implemented to find out the constitutive conditions of formation and failure of this kind of diffuse landslide, and to reveal its mechanisms of abrupt collapse failure and subsequent liquidity flow movement. Accordingly, a novel data acquisition system based on an adaptive frequency adjustment sampling technology will be developed to capture the comprehensive information during the abrupt instability process. Furthermore, a monitoring system fully integrated with multi-parameters (e.g. deformation, pore water pressure, micro-seismic/acoustic emission, infrasonic and electromagnetic signals etc.) will be deployed and applied both in laboratory tests and field landslide observations. Advanced features extraction approaches and precursors will be studied carefully and in detail based on the collected abundant signals with respect to evolution process of the diffuse failure. And then, a scientific and advanced monitoring technique and early-warning indicators will be proposed based on the analysis results. Finally, theoretical model of quantitative risk assessment, including simulation of scope of liquidity flow movement and quantitative evaluation model of vulnerability of building structures and landslide destructiveness, for the diffuse landslide will be built and presented.

近年来发生的多起由饱水松散颗粒材料构成的滑坡（如2015年深圳光明新区滑坡）表现出显著的整体坍塌性突然破坏、静态液化和远程流动性运动等独特现象。相关特征与国际土力学界新发现的diffuse failure极为吻合，是一类新的失稳破坏模式——溃散性滑坡。本项目首先利用不同粒径和级配的颗粒材料，开展系列的单元体试验、水槽试验和大型离心模拟试验，查明溃散性滑坡的形成条件、突发性失稳和流动性运动机理；随后，针对其突发性失稳的特点，研发自适应调整采样频率的现场监测技术，并通过室内试验和现场滑坡的全面综合监测(变形、孔隙水压力、微震、次声、电磁信号等)和监测数据精细分析，研究其前兆信息及获取方法，提出针对性的科学的监测预警指标和监测预警技术方法。最后，为科学防控此类滑坡风险，研究建立溃散性滑坡定量风险评价理论和技术方法，包括流动性运动堆积范围模拟分析、滑坡破坏力和建构筑物易损性定量评价模型等。

由饱水松散颗粒材料构成的溃散性滑坡具有启动的突发性、高速远程流动性与极强的破坏性，往往会引发灾难性地质灾害事故。对于这类特殊的边坡破坏模式，其成因机理、针对性的监测预警方法与基于定量风险评价的科学防控方法成为当前研究的热点和难点。通过本项研究，初步查明了溃散性滑坡的基本特征和形成条件，揭示了溃散性黄土滑坡、溃散性碎石土滑坡的成因机理，研发了溃散性滑坡自动监测仪器及监测预警系统，建立了基于变形和地下水位特征的溃散性滑坡早期识别及危险性判别方法，构建了溃散性滑坡预警模型与短期时间预报方法，并初步建立了溃散性滑坡定量风险评价理论与方法体系。相关成果为溃散性滑坡潜在隐患识别和判定，滑坡运动和危害范围分析预测提供了理论支撑，并在西北黄土地区、西南汶川地震灾区的地质灾害危险性评估与科学防控中发挥了实际应用。相关成果作为重要支撑成果之一获得2019年度国家科技进步二等奖1项。共发表标注本项目资助的学术论文85篇，其中SCI源刊论文34篇，EI检索论文10篇，北大中文核心期刊论文40篇，会议论文1篇。出版学术专著1部，主编行业标准1部，申请和授权专利17项。主办国际学术会议5场，主办国际博士课程培训班4期，承办研讨会2次。在项目执行期间，项目负责人作国际会议特邀（邀请）报告6次，分组报告1次，国内会议特邀（大会）报告26次。