【作者】 周中；

【导师】 刘宝琛； 傅鹤林；

【作者基本信息】 中南大学 ， 岩土工程， 2006， 博士

【摘要】 本文结合交通部科技项目：“西部地区公路地质灾害监测预报技术研究(2003-318-802-01)”，采用室内试验、现场试验、理论分析和数值模拟相结合的研究方法，对土石混合体滑坡的流-固耦合特性及其预测预报进行了系统深入的探讨。主要工作有：1．采用自制的大型常水头渗透仪，测定了不同含砾量时土石混合体渗透系数值，研究发现含砾量与土石混合体渗透系数之间存在指数关系；基于幂平均法，提出了土石混合体复合渗透系数的计算公式，并通过试验结果验证了该式的正确性，为土石混合体渗透系数的理论计算提供了一个简明实用的计算工具。2．土石混合体属于典型的多孔介质，其渗透特性与颗粒的大小、孔隙比及颗粒形状关系密切。利用自制的常水头渗透仪，采用正交实验方法，研究了砾石含量、孔隙比和颗粒形状三个因素在不同水平下对土石混合体渗透系数的影响。通过正交试验确定了三种因素对土石混合体渗透系数的影响顺序及各因素的显著性水平。3．土石混合体边坡人工降雨致滑的原位监测试验表明：在降雨入渗影响下滑动变形区为坡面以下0-4m之内，变形量以坡面最大，从坡面到坡体深部逐渐减小；在实施降雨的前2小时，平均入渗百分率为86％，之后，入渗率由于地表径流的增加而随时间逐渐减少，一段时间(6小时)之后，入渗率降到一个相对稳定值(50％)；降雨入渗造成土体中孔隙水压力增加，致使边坡土体的抗剪强度由于有效应力的减少及土体吸水软化而降低，降雨入渗的这一双重效应是降雨诱发土石混合体边坡失稳的主要原因之一。4．土石混合体边坡开挖致滑的原位监测试验表明：土石混合体在切坡开挖影响下多发浅层牵引式破坏，滑动变形区为坡面以下0-4m之内，变形量以坡面最大，从坡面向下逐渐减小；此类边坡切坡开挖的警界临空高度为3m，临空高度超过3m的边坡应采取适当的防范措施；切坡开挖后裸露的土石混合体边坡，在强降雨的影响下易发生滑塌事故。5．考虑流体的可压缩性和土石混合体变形特性，建立了孔隙率n和渗透系数K的动态计算模型；针对应力场对土体孔隙率和渗透系数的影响、渗透体积力对应力场的影响进行了量化的分析，建立了土石混合体流-固耦合的数学模型，并根据有限元变分原理，对耦合微分方程组进行空间离散和时间离散，建立了两场的耦合有限元方程组。6．运用FLAC(Version 5.0)对土石混合体边坡在降雨入渗条件下不同水位时的渗流场与应力场进行分析，研究了流-固耦合作用下滑坡体的变形趋势与破坏特征，探讨了不同水位时滑坡的稳定性变化规律。7．在Verhulst反函数预报模型的基础上，与BP神经网络相结合，建立了Verhulst反函数残差修正模型。对该模型的建立及预报方法进行了系统的讨论，并通过国内外滑坡监测实例对比分析，预报结果接近实际观测数据，验证了模型的正确性，为滑坡的预测预报提供了一个新途径。更多还原

【Abstract】 Associated with the scientific research projects of ministry ofcommunications "The study of monitoring-prediction technology in westhighway geology disaster (2003-318-802-01)", the fluid-solid couplingcharacteristic of soil and rock blending landslide and its prediction andforecast were studied comprehensively, with the combined researchmethod of laboratory tests, field tests, theory analysis, numericalsimulation. The main contents include followings:1. The permeability coefficient of soil and rock blending at differentgravel content were measured by artificial constant head permeameter,which show there exists index relationship between them. A empiricalformula for calculating the composite permeability coefficient of soil androck blending is put forward based on power averaging method and theformula is proved by the experimental results, have offered a concise anduseful computational tool for the theory calculation of coarse-grained soilpermeability coefficient.2. Soil and rock blending is a typical porous medium, and itsseepage is closely related to the particle-size, porosity ratio and particleshape. With self-made constant head permeameter, the influence of gravelcontent, porosity ratio and particle shape on the permeability coefficientof soil and rock blending was studied by lab orthogonal test. Orthogonaltest confirmed the influence orders of three factors to permeabilitycoefficient of soil and rock blending and the significance levels ofdifferent factors.3. Through artificial rainfall simulation tests and field syntheticmonitored on a soil and rock blending slope, some results were obtained:the deformed zone of soil and rock blending landslides caused by rainfallinfiltration lies within the top 4m soil layer, where the deformation valueof slope surface is the biggest, which gradually reducing from dome to the deep part of slope. The average percentage of infiltration during thefirst 2 hours is 86%, it reduce gradually with time later because of theincrease of the surface runoff. The average percentage of infiltration dropto a relatively stable value (50%) 6 hours later. Rainfall infiltration leadspore-water pressure to increase, which may result in a reduction of shearstrength due to a decrease in effective stress and wetting-inducedsoftening, the double effects of rainfall infiltration are the main reason ofrainfall infiltration induced landslides in soil and rock blending slope.4. By the situ-monitoring of excavation tests on a well-instrumentedsoil and rock blending slope, these results show: Most of soil and rockblending landslides caused by excavation are shallow draught slopefailures, and deformed zone lies within the top 4m soil layer, anddeformation value of slope surface is the biggest, which reduce fromdome to the deep part of slope gradually; The alert height of the free faceis 3m in such soil and rock blending slope, when the free face exceed 3mheight proper defend measures are necessary; Under the influence ofstrong rainfall, the uncovered soil and rock blending slope afterexcavation easily lead to collapse accident.5. In consideration of the deformation of the soil and rock blendingand the compressibility of the fluid, the dynamic models of porosity andpermeability are acquired; Quantitative analysis the effect of stress fieldon the porosity and permeability and the effect of seepage force on thestress field, fluid-solid coupling mathematical model in soil and rockblending are acquired; By Galerkin theory, differential coefficientequations are dispersed on space and time domains, then the couplingfinite element equations of the seepage field and stress field areestablished.6. Under the fluctuation of different water levels caused by rainfallinfiltration, the seepage-stress fields, the deformation trends and thefailure process of soil and rock blending landslide are analyzed withFLAC(Version 5.0). In addition, the change of landslide stability is discussed after water levels fluctuation in this dissertation.7. On the basis of Verhulst inverse-function mechanism predictionand forecast model, and in combination with Back Propagation NeuralNetwork, a new error fitting of Verhulst inverse-function mechanismprediction and forecast model is built. The establishment of the predictionand forecast model and the process of application are discussed in detail.In engineering practice, the application research is compared with actuallandslides case nationally and internationally. The results are similar toactual data and proved the correction of model, which provides a newway for landslide prediction and forecast.更多还原