【作者】 马鑫；

【导师】 胡焕校； 王新民；

【作者基本信息】 中南大学 ， 地质工程， 2007， 硕士

【摘要】 自然界中最常见且破坏性最强的随机振动是地震。我国是多地震国家之一,发生在我国的大地震具有强度大、频率高、震源浅的特点,因而引起的滑坡等灾害也是严重的。目前振动诱发边坡灾害方面的研究大多局限于事后的调查分析,由于岩土介质本身的复杂性、边坡工程的开放性以及影响边坡变形与破坏因素的多样性,导致了随机振动下边坡稳定的研究存在着很多的问题。本文以地震作用下均质土坡的稳定性为研究对象,对随机振动下均质土坡的稳定性展开研究。振动系统是指反映因果关系的装置或运算,分为时不变系统（常参数系统）和时变系统（变参数系统）。随机振动指的是不能用确定性的函数描述的运动规律,土层地震响应就是一种典型的随机振动过程,运动过程不可预测,在相同条件下也不重复,具有明确的随机性。随机过程通常是用n维概率分布函数F（X₁,t₁;…,X_n,t_n）或n维概率密度函数f（X₁,t₁;…,X_n,t_n）来描述,随机振动系统动态特征描述方法有脉冲响应法、频率响应法。多自由度系统随机响应几乎都是连续的、非线性的,通常采用离散化模型和近似方法进行处理和求解。均质土坡变形与破坏的根本原因在于土体内的剪应力大于其抗剪强度。边坡土体在振动荷载作用下发生振动时,动应力～应变关系表现出非线性、滞后性及变形积累等三种特征,土的动剪切模量G随着剪应变的增加而减少,与平均有效应力σ₀的幂函数成线性关系;其阻尼比都随着剪应变的增加而增加。边坡土体的变变形为三个阶段:弹性状态;弹塑性阶段;蠕变阶段,平行于边坡土的粘—塑流是边坡变形的另一种形式。边坡土体对振动的反应分析非常复杂,常用的分析方法有一维振动反应分析法和有限元法。从边坡地震破坏的范围、危害程度及工程意义上看,最小诱发滑坡的地震震级为M_L=4.5～4.7,引发边坡崩滑的最小地震烈度为Ⅵ度;地震诱发滑坡区域面积S（km²）与震级M_W见有如下关系:logS=M_W-3.46（±0.4）;滑坡总体积V（m³）与震级M_W之间有如下关系:logV=1.44（±0.21）M_W-2.34（±1.5）;滑坡剥蚀量随震级的增加而加大。地震诱发滑坡受区域发震构造控制,主要沿地震断层破裂方向分布。滑坡轴向受地形控制,沿山坡临空方向的滑动。通过对簸箕山滑坡场地左侧均质山坡的计算发现:土层的PGA随土层深度增加急剧减小,并趋于一常数,在深度10m的范围变化幅度最大;土体在低强度振动下,可恢复弹性变形成分多;滑坡体愈薄,地面PGA愈大,基本上为线性关系。在振动作用下,该均质山坡正向位移量为0.00～470.86cm,负向位移量为0.00～118.24 cm,未来50年内的破坏概率为3.8%。更多还原

【Abstract】 The most common and destructive natural random vibration is earthquake. China is one of country that earthquakes often take place. The earthquakes happened in China have great intensity, frequency and sallow earthquake focus. So landslides and other geology disasters Caused by them are also serious. At present, the study on vibration-induced slope mostly focuses on the post-survey analysis. Because Rock and soil are complexity, the slope is open and the affect factors of slope deformation and failure are diversity, the slope stability impacted by random vibration has many problems. This paper study the slope stability impacted by earthquake to study the slope stability impacted by random vibration.Vibration systems refer to the installation or operation that reflect the relationship between reasons and results, divided into time-invariant systems （constant parameter systems） and time-varying systems （change parameter systems）. Random vibration is movement that can not used the function to describe. Soil seismic response is a typical random vibration, It’s process of movement is unpredicted, it’s movement will not repeat under the same conditions, has clear randomness. Random process usually uses n-dimensional probability distribution function F（x₁,t₁; ..., x_n,t_n） or n-dimensional probability density function f（x₁,t₁; ... , x_n,t_n）to describe. The method to describe random vibration system is impulse response method and frequency response method. The n-freedom random vibration system almost is continuous and non-linear, which used discrete model and approximate method to handle and solve.The fundamental reason of homogenous, soil-slope deformation and damage is the shear stress greater in slop than the shear strength. When slope soil vibration impact by vibration load, the relationship between siol dynamic stress and soil dynamic strain is nonlinearity, hysteresis and deformation accumulation. Soil dynamic shear modulus G decrease when shear strain increase. The relationship between soil dynamic shear modulus G and the power function of average effective stressσ₀ is linear. Soil damping Ratio increase when shear strain increase.The slop soil deformation has three stages: elastic state, slasto-plastic stage, creep stage. Soil visco-plastic deformation that parallel to the slope is another slope deformation form. Slope analysis of soil response to vibration is very complex, the common analytical method is one-dimensional vibration analysis and and finite element method.The minimum earthquake magnitude to induced landslide is M_L=4.5～4.7 according to the scope of slope damage induced by earthquake, dangerous degree and engineering significance. The smallest degree of seismic intensity induce to landslide isⅥ. The relationship between the earthquake-induced landslide area S （ km²） and magnitude M_W is logS=M_W-3.46（±0.4）. The relationship between total volume of landslide and magnitude M_W is logV=1.44（±0.21）M_W-2.34（±1.5）. Landslide amount of erosion increase when magnitude is increase.Earthquake-induced landslide controled by regional tectonic that lead to earthquake, along the fault rupture direction. The direction of landslide axial controlled by topography, the direction of landslide is sliding attack. The result of the homogenous soil hillside left to Boqishan landslide shows that: soil PGA decrease when slop depth increase, and tends to a constant, the changes is largest in 10m depth. The soil restore elastic deformation is more when soil impacted by low-intensity vibration. Ground PGA is larger when landslide is thin, the relationship is linear.The positive displacement of the homogeneous hillside is 0.00～470.86cm, The minus displacement is 0.00～118.24 cm when the homogeneous hillside impacted by random vibration. The damage probability is 3.8% during next 50 years.更多还原