【作者】 邓龙胜；

【导师】 范文；

【作者基本信息】 长安大学 ， 岩土工程， 2010， 博士

【摘要】 我国的黄土地区具有非常特殊的地质构造背景,其覆盖了我国的南北地震带、华北大地震带和祁连地震带,是我国地震灾害最频发的地区之一,发育了大量的历史强震。由于黄土具有强烈的地震易损性、震陷性和液化性,因此,这些地震诱发了大量的地质灾害,特别是1920年爆发的海原大地震,诱发了不计其数的黄土地震滑坡。本文以宁夏西吉—海原—固原地区作为研究区,研究了该区地震滑坡的分布、特征、破坏类型及发育机理,通过收集该区域范围的地震资料,得到了该区的地震动衰减关系,并人工合成典型滑坡点的地震动时程。在此基础上,对黄土的动应力—应变关系、震陷、液化特性,以及边坡的动力响应和动力稳定性进行了研究。通过本文的研究,主要取得以下几点创新性的成果：(1)对研究区地震滑坡的特征进行总结,提出了研究区地震滑坡具有集中发育、扎堆群发的分布特点,主要发育在高度较矮、坡度较缓、以及地貌破碎、单薄的山梁上,并且,研究区地震滑坡具有方向性、运动液化的特点,以及流线形和波浪形的微地貌特征。(2)首次从破坏机理上对黄土地震滑坡进行破坏模式分析,将该区黄土地震滑坡分为振动软化—剪切破坏、振动液化—流动破坏、振动崩塌破坏以及震后蠕变破坏四种破坏类型,并从地壳破裂几何投影中心、岩土分布特征、地貌特征、地震波频谱效应几个方面分析研究区地震滑坡密集发育的原因及机理。(3)收集了该区域范围的地震资料,通过统计回归分析和转换的方法,首次得到了适合于研究区的地震动衰减关系,并通过地震危险性分析,人工合成典型滑坡点不同超越概率的地震动时程,并据此作为该滑坡黄土动力特性试验、边坡动力响应,以及边坡动力稳定性分析的输入激振波。(4)对随机波作用下的黄土进行动力特性试验,得到了随机地震波作用下黄土的应力—应变关系；对黄土的震陷表达式进行修正,提出了随机波作用下的残余应变公式,并研究了地震波频谱特征和方向、固结比、含水量等变化的影响效应；首次提出了随机地震波作用下黄土的孔压增长模型,以及地震作用对黄土抗剪强度的影响效应。(5)根据所得到的地震动时程和应力应变关系编制子程序,对黄土边坡进行动力响应分析,得到了地震动时程幅值的大小、频谱特征、入射方向以及活断层的影响效应。(6)在对黄土边坡进行动力稳定性计算时,提出了要采用能体现边坡的地震地质构造背景、震源特征及传播介质特性的地震动时程进行动力响应分析和动力试验,在计算中要考虑振动引起的孔压增长、骨架抗剪强度损伤以及残余变形的影响的计算方法。更多还原

【Abstract】 Science its special geological structure background, the regions covered by loess in china which include the south-north Seismic belt, north of china seismic belt and QI-Lian Seismic belt, is one of the regions with the maximum frequency of earthquake occurred in our country, and has the massive history strong earthquake records. For the reason of earthquake vulnerability, subsidence and liquation of loess, the history earthquake induced numerous of seismic geological disaster, especially the 1920 Hai Yuan earthquake, trigger a lot of loess landslides.In this paper, the XiJi-HaiYuan-GuYuan region in south of Ning Xia Province has been chosen as a investigation target area, and the distribution, characters and failure model, development mechanism of the landslide induced by earthquake has been studied, and then, the seismic data of this regions has been collected to build the attenuation relation of ground acceleration, and gained the seismic wave. Based on these, the dynamic constitutive equations, seismic subsidence and liquation of loess, the dynamic response and dynamic stability of loess slope has been studied.Some main innovative ideas are got as follows in this paper:(1) in the summary, with the centralized appearance and huddled together distribution characters, the earthquake landslides in the target area are mainly happened in the low, gentle slope and incised strongly, thin and weak loess side slope, and these landslides has specifically movement aspect, liquefaction phenomenon, and has streamline and undee physiognomy characters.(2) Based on its failure mechanism, the failure modeles are defined as the softened-sheared model, the liquefaction-flow model, and the falling model, hysteretic landslide model, and then, the reason and mechanism of landslide happened serriedly in the target regison are owed to its location, material and physiognomy, and predominant frequency of seismic wave.(3) the earthquake history data are collected, and the attenuation relation of ground acceleration induced by earthquake are gained by the methodes of statistic, regression and transform analysis, in succession, the artifical earthquake wave are produced after the earthquake fatalness analysis, which are used to research the loess dynamic triaxial test, dynamic response and dynamic stability loess slope.(4) after the dynamic triaxial test, the dynamic constitutive equations are gained, and the seismic subsidence mechanism of loess are disclosed, and its expression are revised, and gained the formula of subsidence in condition of seismic wave, as well as the effection of superexcellent frequency, maximum value and aspect of seismic wave, and the consolidation ratio, moisture content etc, and more farther, the por water pressure increase model of loess in seismic condition are gained, and the effect of shear strength by reason of earthquake wave acted on the sample.(5) based on the attenuation relation of ground acceleration and dynamic constitutive equations, the dynamic response of loess slope are studied as well as the effect of maximum value, superexcellent frequency and aspect of seismic wave, active fault.(6) when forecast the stability of loess slope in earthquake condition, a seismic wave which exhibit the geological and seismic structure background, epicenter and spread medium character should be chosen to obtain the dynamic response and test parameters, and the increase value of pore water pressure, the soften of loess framework shear strength and the seismic subsidence should be take into account.更多还原