摘要
本文以长江三峡库区地质灾害的防治和预测预报目的出发,通过在长江三峡库区的实地调查研究和对三峡库区堆积层边坡基本特征和滑坡发展变形的位移动力学特征系统分析与研究的基础上,结合饱和-非饱和渗流基本理论,考虑了降雨入渗条件形成的边坡内部渗流规律,及其与边坡应力场耦合影响的作用,运用有限元数值模拟方法探讨了渗渗场与应力场耦合影响下的堆积层边坡加卸载响应比参数的变化规律和特征。本论文方向的研究工作是结合山东省地质环境与效应工程技术研究中心承担的国家自然科学基金资助项目“水诱发堆积层滑坡的加卸载响应比参数与位移动力学预测研究(40672182)”、“水诱发型堆积层滑坡加卸载响应比特征与位移非线性动力学预测研究(40472141)”和山东省自然科学基金资助项目“滑塌型地质灾害的非线性动力学预测研究(Y2003E01)”进行的。主要研究内容如下:
1.本文通过对长江三峡库区典型堆积层滑坡的实地调查和资料数据研究,分析了堆积层边坡与其它类型边坡的主要区别,对此类滑坡的坡体组成、滑移面特征、地下水作用、岩相构成、滑移剪出口等方面作了系统的介绍和分析,得出了堆积层边坡的基本组成要素特征和变形失稳的位移动力学特征。
2.以饱和—非饱和基本理论为基础,分析了降雨入渗对堆积层边坡的影响,给出了多孔介质的渗流基本微分方程,阐述了降雨入渗影响岩土质边坡稳定性的影响机理和边坡体内渗流场与应力场的动态耦合作用机理,并由此给出了渗流场与应力场相互影响的有限元计算模型。
3.本文介绍了非线性加卸载响应比理论的基本原理及其在滑坡预测中的应用情况;在对降雨型堆积层滑坡受降雨条件影响的研究基础上,得出降雨量与滑坡位移变形量有良好的正相关性,探讨了将降雨量条件作为该类滑坡非线性加卸载动力参数的可行性分析;确定了加卸载响应比理论应用于堆积层滑坡稳定性预测的模型及判别依据。
4.本文运用数值模拟的方法和非饱和渗流理论,对不同降雨量条件下的边坡渗流作用情况进行了数值模型模拟,并将渗流场结果引入边坡自重应力场中进行了耦合计算分析,得出了相应的应力和位移场变化规律,以此计算月降雨增量加卸载响应比模型得出加卸载响应比参数变化规律:边坡稳定阶段时,加卸载响应比值会在1值附近波动,而边坡发生位移激增时,加卸载响应比参数也会随之出现远大于1的增长迹象;模型边坡前、中、后缘的加卸载响应比参数变化规律反映出了堆积层边坡受渗流影响表现出不同部位的变化特征;同时加卸载响应比参数值在相对稳定阶段时的波动情况会受月降雨增量加卸载区间的周期性变化影响。
5.本文还对三峡库区秭归县树坪滑坡近年的实际监测数据进行了分析和整理,得出该典型堆积层滑坡的位移变化规律和月降雨增量加卸载响应比参数变化规律与数值模拟计算所得的相应变化规律基本吻合,而且较长加卸载周期(年、半年)下的加卸载响应比参数变化规律能够基本反映出加卸载量(月降雨量)的周期变化规律,并且通过动态加卸载周期的划分可以得出反映堆积层滑坡短期位移变化的加卸载响应比参数变化规律,比较准确的反映出月降雨量加卸载作用下的滑坡位移动力特征。
This article takes the prevention and forecast of geologic disaster happens in Three Gorges region as a goal, and it bases on the fieldwork for Three Gorges region and the systems analysis on the displacement dynamic features of colluvial landslide, it considers the landslide inner seepage rules induced by rainfall and the couple of seepage and stress with the basic theories of saturated-unsaturated seepage. Finally, the rules and changes of load-unload response ratio parameters of colluvial slope under seepage and stress dynamic coupling are discussed with finite element numerical simulation ways. This paper is supported by the projects of National Natural Science Foundation of China "Load-unload responding ratio parameter and displacement dynamic prediction (code No. 40672182)", "Responding ratio feature to load & unload and displacement dynamic prediction of the colluvial landslides (code No. 40472141) " and Natural Science Foundation of Shandong Province "Non-linear dynamic prediction of slide-collapse geologic disaster (code No. Y2003E01)". The mainly research contents as summarized as follows:
(1) On the basis of systematical analysis geological investigation and basic geology data on the typical colluvial landslide in the Three Gorges reservoir, the main differences between colluvial landslide and other types landslide are studied, the basic features and dynamic features of colluvial landslide are summarized by analyze the composites, slippage, groundwater, lithofacies of colluvial slope.
(2) Based on the basic theories of saturated-unsaturated seepage, the influences of rainfall seep through colluvial landslide are analyzed, and the basic differential equations of porous media are given. The mechanism of rainfall seep through soil slope and the coupling of seepage and stress are expatiated, and the finite model of seepage and stress coupling are given.
(3) The fundamentals and applications of nonlinear systems load-unload response ratio are introduced in this paper. The nicer positive pertinence between rainfall and displacement of landslide has been proved which based on study of colluvial landslide induced by rainfall. The possibility of regarding rainfall as load-unload dynamic parameters has been discussed, and the model and judgement of load-unload response ratio applying to colluvial landslide.
(4)The numerical model simulation of seepage in colluvial landslide under diverse rainfall conditions have been simulated, with which the way of numerical simulation and unsaturated seepage theories. The simulated seepage results had been inducted into stress field of slope deadweight, and the variation rules of stress and displacement field an be drawn as follows: When the landslide on relative stable stage, the load-unload response ratio fluctuated near l; when the slope transformed to unstable, the response ratio is far off bigger than 1 accordingly; the response ratio variation rules of different slope part can mirror the variety features of colluvial landslide different part effected by seepage; meanwhile, the fluctuation of response ratio in relative stable stage effected by lunar rainfall periodic variation influence.
(5) Finally, this article take typical colluvial landslide-Shuping Landslide in Zigui County Hubei Province as the example, Calculating response ratio results in this thesis coincident with load-unload response ratio calculate elevation results using practical monitoring data basically. The response ratio under longer load-unload periods, like year and half year, can reflect the periodic rules of load-unload value. The displacement dynamic features of colluvial landslide under lunar rainfall load-unload and response ratio parameters short-term variation rules can be reflected by plot out the dynamic load-unload period.
引文
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