【作者】 许建聪；

【导师】 尚岳全；

【作者基本信息】 浙江大学 ， 防灾减灾工程及防护工程， 2005， 博士

【摘要】 为了总结碎石土滑坡的一般发育规律,分析碎石土滑坡的稳定性,揭示碎石土滑坡变形解体破坏的机理、碎石土古滑坡复活破坏的主要机理和它们的主要诱发因素,通过资料搜集整理和分析、现场工程地质调查与勘探、现场测试与监测和室内外的物理力学试验,采用数理统计分析法、不平衡推力法、大变形弹塑性有限元算法、弹塑性有限元接触算法,运用非线性科学的尖点突变理论和碎石土边坡地下水管网状排泄系统的理论,系统研究了碎石土滑坡的发育规律,分析了滑坡体位移与降雨量以及滑坡稳定性系数与滑体饱水面积比、滑面岩土体抗剪强度参数之间的相关关系,建立了碎石土滑坡位移与降雨量的通用统计模型和强降雨作用下浅层滑坡的尖点突变模型,分析了降雨对碎石土滑坡稳定性的影响,揭示了碎石土滑坡变形解体破坏的机理以及碎石土古滑坡复活破坏的主要机理和主要诱发因素,并提出了碎石土滑坡稳定性分析的新方法。研究取得以下一些主要成果和认识。 碎石土自然边坡地下水排泄的管网系统发育,地下水的渗流具有很大的不均匀性和集中渗流的特性;碎石土滑坡的变形破坏是一个缓慢的发展过程;降雨,特别是强降雨,是碎石土滑坡的主要触发因素。 分别对典型浅层和中层松散土质滑坡坡体位移、降雨量进行指数模型和幂函数模型的非线性回归分析和比较,得出浅层和中层松散土质滑坡坡体位移与降雨量相关关系一般服从幂函数分布的规律,为降雨条件下浅中层碎石土滑坡的变形解体破坏机理及稳定性研究和预测预报提供科学的依据。滑坡稳定性系数与滑体饱水面积比的关系服从线性分布,滑坡稳定性系数随滑体的饱水面积比增大而减小。影响碎石土滑坡稳定性主要因素的敏感性分析结果表明,按因素敏感度从大到小排列,依次为滑面岩土体内摩擦角、地形坡度、滑体饱水面积比和滑面岩土体的内聚力。 提出采用不分离接触弹塑性有限元强度折减法分析顺层滑坡的稳定性和计算滑坡稳定性系数的新方法,结合工程实例表明采用该方法分析顺层滑坡的稳定性可以更加逼真地反映滑坡变形、解体和破坏的实际情况。 采用大变形弹塑性有限元极限塑性应变分析法确定碎石土滑坡的滑动面,并根据极限状态下塑性应变值的大小确定滑面不同抗剪强度取值段,提出全面考虑滑面上岩土体抗剪强度不同发挥程度的不平衡推力法,并通过实例分析表明该方法能更加精确地计算碎石土滑坡的稳定性系数和分析滑坡的稳定性,更加真实地更多还原

【Abstract】 In order to summarize the general regular development pattern of debris landslide, analyze its stability, and reveal its mechanism of deformation, disintegration and failure, and the main reviving and failure mechanism of ancient debris landslide and their main induced factors, through the collection, arrangement and analysis of related datum, the site investigation and exploration of engineering geology, site test and monitoring, indoor and outdoor physical mechanics test, adopting the analytic means of mathematic statistics, unbalanced-thrust method, large deformation elastic-plastic FEM algorithm, elastic-plastic FEM contact algorithm, nonlinear science cusp-catastrophe theory, and the theory of groundwater pipe network drainage system, some studies were completed as follows: First, the general regular development pattern of debris landslide was researched systematically. Second, the relationship between slop-mass slide displacement and precipitation and the one among the landslide stability coefficient, the saturation-area ratio of slip-mass, and the shear-strength parameters of rock and soil of sliding surface were analyzed. Third, the general statistical model of slope-mass displacement and precipitation for debris landslide and the cusp-catastrophic model of shallow landslide under intensive rainfall were established. Fourth, the influence of rainfall on the stability of debris landslide was analyzed. Fifth, the mechanism of deformation, disintegration and failure of debris landslide, the main reviving and failure mechanism of ancient debris landslide, and their main induced factors were revealed. Furthermore, the new methods of the stability analysis of debris landslide were raised. Through these studies, some main results below are obtained.In the first place, the pipe network system of groundwater discharge in natural debris landslide is often developed. Furthermore, groundwater seepage has great inhomogeneity and characteristic of concentrating seepage. The deformation and failure of debris landslide is a slow-developing process. Rainfall, especially, intensive rainfall is the main induced factor of debris landslide.Secondly, by the nonlinear regression analysis and comparison of exponent model and power function one to the slope-mass slide displacement and precipitation of typical shallow and medium layer loose soil landslide separately, the distribution law of power function generally followed by the relationship between slope-mass slide displacement and precipitation is derived, which may provide the scientific basis for the study on themechanism of deformation, disintegration and failure, the stability, and the forecast and prediction of this kind of loose soil landslide under rainfall. The linear distribution law followed by the relationship between the saturation-area ratio of debris landslide slip-mass and its stability coefficient is derived also. Furthermore, its stability coefficient decreases as the saturation-area ratio of slip-mass increases.Through the sensitivity analysis of main factors to influence on the stability of debris landslide, its order is internal friction angle of sliding surface, topographic grade, saturation-area ratio of slip-mass and cohesion of sliding surface by descending order of their sensitivity coefficients.Thirdly, the new method that is used to analyze the stability and compute the stability coefficient of bedding landslide by the non-separation contact elastic-plastic FEM strength reduction method is provided, furthermore, connected with the concrete engineering example, it is shown that to analyze the stability of bedding landslide may more clearly reflect actual state of landslide deformation, disintegration and failure.Fourthly, the sliding surface of debris landslide is determined by the method of limit plastic strain analysis of large deformation elastic-plastic FEM. The sections of different utilization degrees of shear strength are determined on the basis of plastic strain value under the limiting state of landslide. The unbalanced-thrust method comprehensively thinking over different utilization degrees of shear strength of rock and soil on sliding plane is provided, and it is shown by the analysis of concrete engineering example that it may be very well used to analyze the stability of debris landslide and calculate its stability coefficient by this new method, which can more really reflect actual locating state of debris landslide.Fifthly, three dimensional contact elastic-plastic FEM strength reduction method is used to compute the integral stability coefficient of debris landslide and analyze its stability and process of the deformation, disintegration and failure, which the mechanism of deformation, disintegration and failure is revealed. Furthermore, the research result shows that adopting the new method may think over the spatial effect of landslide mass and better reflect the actual locating state and sliding process of debris landslide. In addition, the new method to compute the stability coefficient by the contact elastic-plastic FEM algorithm is led on the basis of physical meaning of landslide stability coefficient, that is, the method to compute the two dimensional section stability coefficient of debris landslide by extracting the friction stress on sliding surface on the basis of the compute result by the three dimensional contact elastic-plastic FEM algorithm. Furthermore, that this new method is fitter to analyze the stability of debris landslide is derived from the comparison among it, the unbalanced-thrust method and the strength reduction method of two dimensional contact elastic-plastic FEM used to compute the stability coefficient of debris landslide.Sixthly, connected with concrete engineering practice, through site exploration and test and indoor physical-mechanics experiment of rock and soil, the process ofdeformation, disintegration and failure of debris landslide under rainfall is analyzed by the analytic means of mathematic statistics, the unbalanced-thrust method, two dimensional non-separation contact elastic-plastic FEM algorithm and three dimensional one, and the theory of debris slope groundwater pipe network drainage system, based on the characteristic analysis of debris general physical-mechanics and seepage. Furthermore, the main mechanism and general mechanics mechanism of deformation, disintegration and failure of debris landslide under rainfall are revealed. Meanwhile, the research result is shown that intensive rainfall and long time proper strength steady rain or intensive rainfall are separately the main induced factors of shallow debris landslide and medium and deep one taking place instability. Additionally, the rainfall influence on the stability of debris landslide is modeled and analyzed by coupling the unbalanced-thrust method adopting equivalent shear strength with the saturation-area ratio of slip-mass with two dimensional non-separation contact elastic-plastic FEM algorithm and three dimensional one.Seventhly, through site exploration and test, and indoor physical-mechanics experiment of rock and soil, adopting the analytic means of mathematic statistics, unbalanced-thrust method, three dimensional large deformation elastic-plastic FEM contact algorithm, and the theory of groundwater pipe network drainage system, the reviving and failure process of ancient debris landslide and its stability are analyzed. Furthermore, not only the main reviving and failure mechanism of ancient debris landslide under rainfall is revealed, but it is revealed also that long time proper strength steady rain or intensive rainfall is the main induced factor of its reviving instability and failure. Meanwhile, the research result is shown that adopting the three dimensional large deformation elastic-plastic FEM contact algorithm to analyze the stability of ancient debris landslide may think over the spatial effect of landslide mass, which makes compute result still more accurate.Eighthly, based on the correlation data of slope-mass sliding displacement and precipitation reported by documents and connected by engineering concrete example, one cusp-catastrophic model of shallow landslide is established by the analytic means of mathematic statistics, the unbalanced-thrust method and the means of nonlinear science cusp-catastrophe theory. Meanwhile, according to this model, the failure mechanism of sudden instability of shallow landslide under intensive rainfall is revealed. Furthermore, it is revealed also that intensive rainfall is the most decisive triggering factor of shallow landslide and the external main reason that influences the stability coefficient value of shallow landslide and its stability. In addition, the reason that few of shallow landslides sometimes come down after intensive rainfall taking place is revealed through the established cusp-catastrophic model of shallow landslide.更多还原