山区古滑坡扰动复活肇灾机制及其基于风险控制的处治设计方法

The ancient landslide resurrection that caused by excavation disturbance have become one of the most important disaster resources in mountain-side road，meanwhile，a large number of theoretical and technical problems have emerged which need to be solved urgently. The purpose of this project is to reveal the ancient landslide resurrection mechanism，and put forward a design method which based on risk control .The method of ancient landslide classification and identification is using sequent stratigraphy and architectonic geology, based on geotechnical investigation data. At the same time, it combines limit theorem and shear strength reduction method to build a stability analysis method without impact the stability ability of ancient landslide, and the quantitative characterization of indexes are also put forward. This project constructs a geological body model of ancient landslide on a large geotechnical experimental platform that accords to similar principles and construction method of semi-filling and semi-excavating subgrade in mountain area. It reveals the mechanism of ancient landslide response，ancient landslide jump，ancient landslide resurrection，under the comprehensive and whole process monitoring. Further more, the program FLAC expands the function of the geological body model after the ancient landslide resurrection mechanism implantation, by this approach, some simulation tools of ancient landslide subgrade construction will be developed. The risk control level of instability of the ancient landslide under the roadbed construction is determined though calibration method，and we can built a design approach based on risk control about ancient landslide of road slope with inverse reliability method .The research results will provide the theoretical guidance and technical support in the field of ancient landslide disaster prevention and control, caused by mountain road and infrastructure construction.

古滑坡开挖扰动复活导致滑坡已经成为山区公路的重大灾害源之一，涌现出大量迫切需要解决的理论和技术难题。本项目以揭示其复活机制并构建基于风险控制的处治设计方法为目标。采用层序地层学及构造地质学原理，结合工程勘探资料，建立古滑坡的工程分类及其辨识方法。将极限定理与强度折减法结合，构建未触动古滑坡自稳能力分析方法并提出其定量表征指标。按照相似原理及山区路基半挖半填建造工艺，在大型岩土工程试验平台上建造古滑坡地质体模型，通过模型试验过程的全方位、全过程监测揭示在挖填扰动下古滑坡响应、起跳及复活滑动肇灾机制。将揭示的古滑坡复活机制植入FLAC软件对其功能扩充，研发古滑坡路基建造模拟工具。通过校准法确定各类古滑坡在路基建造开挖扰动下的失稳风险控制水平。采用逆可靠度分析原理，构建基于风险控制的古滑坡公路边坡处治设计方法。研究成果将为山区公路及各类基础设施建造导致的古滑坡复活灾害防治提供理论指导和技术保障。

山区古滑坡通常呈现为相对疏松的区域古堆积体或者地下较深部位的古滑动面。由于其地质年代久远，目前处于相对稳定状态。但当基础设施构筑挖填扰动强度超过了其抗扰动能力时，则可能被唤醒变形失稳，造成巨大灾害。山区公路、铁路是线状工程，在构筑过程中需要穿越多个经历不同地质历史时期的地层，不可避免地会遭遇到古滑坡。项目围绕古滑坡在挖填荷载扰动下的复活机制及相应的预防失稳风险发生的配套处治技术展开研究，主要获得了如下成果。考虑地质材料强度与刚度的联动性，提出了强度折减与刚度退化耦合作用的古滑坡自稳能力分析方法。利用某软件的自带开发语言，将双强度折减法与其稳定性系数等值云图结合，构建出针对多滑面的滑坡稳定性分析工具。探讨了滑面中锁固段的力学及分布特征，确定了单级锁固及多级锁固等锁固形式在坡体稳定中的效能。通过室内模型试验观测，掌握了古滑坡在雨水冲刷下崩塌、各种挖填扰动荷载下复活变形滑动失稳形成过程中的关键特征。通过模拟分析，获得了古滑坡在各种加、卸载作用下坡体、滑面各部位的力学响应机制。将塑性力学中的上限定理与突变模型结合，导得了古滑坡的极限抗扰能力，借助响应面解析式近似推测技术，建立了古滑体功能函数的建立方法。进一步结合逆可靠度理论，搭建了古滑坡在扰动荷载下的失稳风险评估途径。针对古滑坡滑体相对疏松软弱、滑面深大的特征，相应研发了“拉压型预应力锚索锚固端装置”、“深大滑坡超长锚固的预应力锚索锚固端装置”及“适用于山地隧道施工方法”等三项专门技术，形成了预防古滑坡在地表路基挖填或其滑体附近地下隧道掘进扰动下失稳的处治配套措施。本项目的研究总体上获得了古滑坡在公路路基或隧道施工扰动下的失稳机制，提出了预防失稳风险的处治对策。这为减少山区的各类基础设施、水利水电工程建设而引发的滑坡灾害起到有效的促进作用，同时也可能为“一带一路”相关工程建设提供技术手段。