【作者】 王军；

【导师】 曹平；

【作者基本信息】 中南大学 ， 岩土工程， 2010， 博士

【摘要】 滑坡是典型的地质灾害之一,也是岩土工程领域重点研究的课题。边坡的稳定性问题受多种因素的影响,在评价过程中且多学科相互交融,形成了边坡研究的复杂性、系统性和重要性。目前,国内外在这方面的理论研究远远落后于工程实践,因此要运用现有的理论知识和技术来开创求解和评价边坡稳定性的新方法和新思维,并不断完善既有的理论具有更大的技术挑战性和学术前瞻性。本文在已有研究工作的基础上,综合利用岩土流变力学、渗流理论、土水化学分析效应、数值分析方法和弹塑性力学等多学科知识,借用功能强大的岩土工程有限差分分析软件FLAC3D,高级语言开发环境Visual Studio2008和FORTRAN90有限元计算程序,并结合四项边坡工程实例,进行程序二次开发来研究流变、渗流、固结、锚固和土水化学效应等多重作用影响下的边坡稳定性问题。主要研究内容和结论如下：应用岩土流变力学理论,基于边坡变形特点和Mohr-Coulomb剪切、拉伸屈服准则,对典型西原模型进行改进,提出了一种新的流变元件-加速剪切元件,建立了适应于土质边坡非线性粘弹塑蠕变特性的流变模型,该模型能反映典型蠕变的三个阶段。同时又根据非线性流变的特点,给出了两种粘滞系数与时间和应力状态非线性关系的解析式。土体的抗剪强度指标对边坡的稳定性分析有重要的影响,根据粘结力c随时间变化的过程,提出了粘土长期强度的幂函数经验公式。并结合蠕变变形特点,对传统的强度折减技术进行了改进,推导出了考虑时间效应的强度折减法,可以为流变作用下的土质边坡稳定性计算提供有益补充。现代数值分析方法是广大科研工作者分析边坡稳定性的常用方法,以基坑边坡工程实例为背景,利用有限差分强度折减技术和特征点的位移突变来作为数值计算边坡失稳的判据,结合FLAC3D计算软件的二次开发技术和VC++高级程序语言,嵌入新建的蠕变模型,得出了基坑边坡的位移等值线图和动态监测点的位移,其计算结果与边坡实际监测较吻合,具有明显地蠕变变形特性,验证了新建模型的可靠性。极限平衡法是工程上边坡稳定性分析的常用方法,以同样实例为研究对象,提出了安全系数与锚杆安设角的微分关系式。又通过该流变模型的变形特点,推导出了考虑流变效应最小锚固力的计算式。对多孔介质土体饱和非饱和渗流基本理论和流固耦合的控制方程进行了简要论述,给出了基于孔隙度变化的多孔介质饱和渗流的基本微分方程和基于毛细压力、毛细水上升高度的多孔介质非饱和渗流的土水特征曲线和非饱和渗透系数的解析式。以铁路路基边坡水害为工程背景,并在此基础上分析土质边坡的降雨渗透特性,进行了降雨渗流时的数值分析。由于边坡的变形状态对边坡的稳定性有一定的影响,根据一维Terzaghi固结理论,并结合改进的西原流变模型得出了土体固结流变的微分控制方程,并延伸到土的抗剪强度理论,得到了固结流变效应的有效应力抗剪强度公式,这为后续的边坡稳定性受流固耦合、固结和流变作用的研究提供了理论依据。新颖地介绍了土水化学作用对土体抗剪强度的影响,在此基础上以武广高速铁路路基工程实例作为研究背景,经过统计分析得出了土体的抗剪强度与阴阳离子的线性相关性分析曲线,并引入粉煤灰的适当掺入量对增加软弱土体强度显著效果的分析,将为提高土体工程的稳定性和土体强度对边坡稳定性的影响提供了另一种途径。基于SEF强度发挥系数、点安全度的概念和强度折减技术,运用有限单元极限平衡法程序得出了坡体土体各点安全系数的分布图,并计算出安全系数和确定边坡潜在破坏区。另外,根据边坡潜在滑体沿滑移线能量耗散的特点,新给出了极限平衡法求解安全系数的另一种定义,经过比较分析表明,基于耗散能改进的极限平衡法所得到的滑移线位置和安全系数与Bishop法和有限差分法较接近,同时又可以根据所需的安全系数和滑移线的位置来反求抗剪强度c,φ值,这对极限平衡法求解边坡稳定性是一种有用的补充和完善。更多还原

【Abstract】 Slope sliding is an important branch on geologic disaster and can become a key basilic discussed problem in geotechnical engineering.There are many factors to effect the slope stability related to mining engineering,expressway and bridge engineering, water conservancy and structure engineering，et al.Slope engineering is studied by various subjects and theory,so it is inevitable to be difficult and complicated field. At present,such is the fact that slope engineering practice is forward to theory research, including calcuted methods and mechanical knowledge. It is an flinty challenge that new solution and innovated theory can be obtained and applied in slope engineering construction.This paper attempts to study slope engineering with rheological mechanics, seepage mechanics,chemical action of soil-water, numerial analysis and engineering mechanics,and so on. Thereinto,finite difficult method software(FLAC3D) is applied to analyze practice instance.The main research contents are as follows:Based on character on slope deformation procession and Mohr-Coulomb yield rule for extension and shear yield,a new rheological model is established,named accelerated shear component,which is operated to modify classical and linear Xiyuan rheological model.It is ascendant to the creep model that can show non-linear and three typical phase on rheological deformation to geotechnical engineering destroy. Simultaneously, the two non-linear formula on viscosity coefficient for soil is established,which can be ascertained by integral calculation and it is very complicated formula for non-linear relation on many variable factors including stress,cohesion intensity,inner friction angle, creep time and modulus.Slope stability is further affected on anti-shear strength.In this paper,the experience formula for longe term strength on clay is provided for analyzed slope numerical calculation, which can mainly show power function relation of cohesion intensity between time and experience constant.Numerical calculation is often used to research geotechnical engineering,and slope stability can be accurately judged including stress,strain,deformation,safety factor, various plastic region, structure element variable et al and it can also predict many case.Taking for foundation pit with anchor support instance, slope stabitity analysis can be operated by shear strength reduction technique on cohesion intensity and inner friction angle and calculated termination criterion on deformation break of characteristic points in slope soil including vertical displacement and horizontal displacement.Based on secondary exploitation technique for FLAC3D,which is founded in Americal to mainly calculate tunnel,slope,foundation pit,soft groundwork disposed and dam and so on.Lastly,the creep deformation can be obtained by FLAC3D to validate the reliability feasibility and applicability accoring to measurement data comparison on spot.It is well known that limit equilibrium method is typical calculation on slope stability.In this paper, according to homogeneous,continuous and isotropy character on soil strcture,the safety factor formula can be achieved to solute foundation pit support with limited equilibrium method.The function on differential coefficient function between safety factor and installed anchor angle is obtained. According to the new rheological model, the minimum anchored load can be also obtained.The theory of saturated,unsaturated seepage and fluid-solid coupling of porous media and its differential equation are introduced.The soil-water characteristic curve resolution of porous degree and capillary stress and height of capillary water and penetrability coefficient are obtained.The numerical seepage analysis on soil slope is performed under the condition of rain infiltration to analyze slope deformation which can direct soil slope stability.Based on consolidation theory on Terzaghi under vertical orientation,the differential coefficient equation is built on soil consolidation and rheology according to modified xiyuan model,which many parameters is calculated including penetration coefficient,fluid weight,time, hole water compressive stress and viscosity time gene newly founded.And anti-shear strength equation is modified with the domino offect on conslidation and rheology for effective stress,which is one of rules for soil field destroy under Terzaghi theory.The academic evidence can serve as slope stability on consolidation,fulid-solid coupling,consolidation and rheology.The water-soil chemical interaction is a very important effect on soil shear strength. Based on ion effect and the porpose of improved soft roadbed soil, samplings of soil,ground water and clays are abtained to observe and analyze the effect. The analysis on mechanics of water-soil interaction is carried out in order to find factors of shear strength, including mechanics effect of water chemical, analysis test on water chemical,linear correlation regress and effect of loadbed soil improvment. The results show the weakened effect occurs on soil cohesion and inner friction angle with Ca2+、HCO3-、K+ and Na+ ion consistency. But dispersed inner friction angle character is marked with ion consistency. Simultaneously, the correlation is found among cohesion and testing index including total salinity,hardness, K+, Na+, Ca2+ and HCO3-.Lastly, it is also found that the effect is remarkable with clays when the consistency was close to 10 percent.Generally, the failure of tension and shear is presented in slope soil. Based on index of resisted shear:c andφ, elasto-plastic theory and finite element method are applied in calculation and numerical model of slope stability is established and characteristic of strength exertion factor can be combined, which verdict the programe convergence that the calculation procedure executed on the dissimilar SEF. It is presented that steady safety factor of holistic soil slope and latent failure region and extent of strength exertion on soil failure and so on.According to slope stability analysis with limit equilibrium method theory and character of energy dissipation on slope sliding mass along latent sliding curve,the stability analysis on homogeneous and mulitilayer soil slope was calculated in order to take on energy dissipation advantage based on limit equilibrium method than other calculated methods,including limit analysis,numerical modeling method, intelligence method and engineering analogy method.Taking the action of new formula transform on coordinate curve integral,the safety factor function equation was built based on modified limited equilibrium method with energy dissipation on friction resistance to solute extremum along sliding curve,and the curve function differential equation was also abtained by limited safety factor value on differential coefficient of the slope safety factor equation.The slope examples on 2D strain were cited to validate the above differential coefficient equation for engineering application and theory study.The WJED program with VC++on calculated safety factor and researched sliding curve function equation was firstly applied to evaluate stability for homogeneous and mulitilayer soil slopes.The results show the parse formula for latent sliding curve accords with exponential equation for energy dissipation and accords with circle equation for Bishop method one of limit methods. Simultaneously,both the safety factor amount and sliding location are between Bishop method and finite difference method,The directed application on slope reinforcement engineering is obvious and after comparement analysis limited equilibrium analysis on slope stability is subjoined by energy dissipation method.更多还原