【作者】 文畅平；

【导师】 杨果林；

【作者基本信息】 中南大学 ， 土木工程， 2013， 博士

【摘要】 依托铁道部科技研究开发计划课题“高陡边坡特殊支挡工程抗震技术研究”(编号：2008G028-D),以建设中的大瑞铁路为背景,对其沿线厚覆盖层与基岩边坡(简称基覆边坡)和厚覆盖层与顺层岩石边坡(简称顺层边坡)的多级支挡结构与边坡系统,在地震作用下的动力特性及抗震设计方法开展研究。基于大型振动台模型试验,对支挡结构的地震动力响应特性进行系统分析,并开展数值模拟验证工作。基于模型试验所采集到的动位移数据,开展支挡结构动位移模式的分析研究。基于塑性极限分析上限定理和强度折减技术,建立多级支挡结构地震动土压力的上限解,并开展多级支挡结构与边坡的地震动力稳定性分析,以及多级支挡结构抗震设计方法的研究。研究工作主要包括以下几个方面：(1)大型振动台模型试验方案设计分别设计并完成相似比为1：8的3个基覆边坡和3个顺层边坡模型。根据相似关系理论,对大型振动台模型试验的相似关系进行设计,确定模型试验相似常数,确定模型试验的相似材料及其主要物理力学参数。以汶川波、大瑞波和Kobe波作为设计输入地震波,确定试验加载方案。(2)支挡结构一边坡系统动力响应特性分析分别对上述3个基覆边坡模型和3个顺层边坡模型,在不同地震波、激振加速度峰值及其激振方向下的加速度动力响应、动土压力响应、动位移响应和锚杆动应变响应等动力特性,进行了详细和系统的分析研究。在基覆边坡模型动力特性分析中,根据试验数据对支挡结构的动力响应特性进行对比分析,并分析其抗震性能。在顺层边坡模型动力特性分析中,根据试验数据对比分析了支挡结构在不同岩层倾角下的动力响应特性。(3)支挡结构一边坡系统动力响应特性数值模拟按平面应变问题,以汶川波XZ双向加载工况为例,采用有限差分软件FLAC3D进行数值分析。在基覆边坡数值模拟中,主要针对重力式挡墙—基覆边坡的振动台试验模型,将数值模拟结果与振动台模型试验进行对比分析。在顺层边坡数值模拟中,模拟不同岩层倾角下的重力式挡墙的动力响应特性,并将数值模拟结果与振动台模型试验进行对比分析。(4)支挡结构地震动位移模式研究基于3个基覆边坡模型的大型振动台模型试验,根据各加载工况所采集到的地震永久位移响应数据,研究重力式挡墙、桩板式挡墙、格构式框架结构等支挡结构的地震动位移模式及其变化规律,得到支挡结构在地震波作用下,其动位移模式有：滑动(平动)、转动或滑动与转动的耦合等。研究认为,挡墙动位移量、动位移模式及其变化方式,不仅受激振波、激振方式和激振加速度峰值的影响,还受到挡墙结构型式、不同支挡结构组合方式的影响。此外,通过动位移模式的研究,分析不同类型支挡结构的抗震性能。(5)多级支挡结构动土压力及抗震设计方法研究结合塑性极限分析上限法和强度折减技术,对多级支挡结构地震动土压力进行分析和研究,建立基于强度折减技术的多级支挡结构地震主动、被动土压力上限解。上限解考虑水平和竖向地震系数、墙背倾角、坡面形式及多级支护方式、上挡墙对下挡墙的影响、土体粘聚力、土体与墙背的粘附力等诸多因素,可适用于无粘性土和粘性土、复杂坡面等的地震土压力计算。(6)多级、组合支挡结构与边坡系统的静动稳定性分析及抗震设计方法研究将边坡安全稳定系数直接作为岩土体抗剪强度参数的折减系数,基于强度折减技术和极限分析上限法,对锚杆挡墙支护高边坡的三种方式,进行地震条件下的动力稳定性分析,根据正交试验设计法进行参数敏感性分析,并进行抗震设计方法的研究。通过实例分析,提出抗震设计方法与建议。更多还原

【Abstract】 Based on the Project of Study on Seismic Design Method of Special Retaining Structures in High and Steep Slopes (No.2008G028-D) supported by the Ministry of Railway, seismic dynamic response characteristics and seismic design methods of multistage retaining structures and slopes in Dali-Ruili Railway were studied. Based on series of large-scale shaking table tests, seismic dynamic response characteristics of multistage retaining structures of bedrock and overburden layer slopes and consequent rock slopes were studied systematically, numerical models were established and the model tests of Wenchuan earthquake XZ-excitation conditions were simulated. The seismic displacement modes and its characteristics under earthquake loadings were discussed according to the displacement response data of model tests. The upper bound theorem of limit analysis and strength reduction technique based on pseudo-static method, seismic earth pressures of retaining walls in multistage slopes were analysed, and the study on seismic dynamic stability of the multistage retaining structures for high slopes and its seismic design method were conducted. The key studies are as follows:(1) Slope models design for large-scale shaking table testsThree models for bedrock and overburden layer slopes and three models for consequent rock slopes, which the geometric scale is1:8, were designed respectively. According to similarity theory, the similarity relations of the main physical quantities were studied, the main similarity coefficients and the simulation materials and its main properties of physical and mechanics for large-scale shaking table model tests were determined. Three seismic waves including Wenchuan earthquake wave, Darui synthetic seiswave and Kobe seismic wave were used in the model tests, and the excitation rules of six model tests were determined.(2) Seismic dynamic response behaviors analysisThe dynamic response behaviors of acceleration, seismic earth pressure, seismic displacement, and bolt seismic strain response under different seismic waves, its peak excitation acceleration and excitation directions were studied systematically according to three models for bedrock and overburden layer slopes and three models for consequent rock slopes respectively. According to different earth retaining structures, the comparison analysis of dynamic response characteristics of the models for bedrock and overburden layer slopes were conducted. In the study of dynamic response characteristics of earth retaining structures for consequent rock slopes, the same works but according to the rock layer angles were finished.(3) Numerical simulation about the seismic response behaviors based on the large-scale shaking table model testsNumerical models according to the plane strain problem were performed, and FLAC3D was employed based on the XZ-excitation conditions of Wenchuan seismic wave of shaking table tests. In the simulation of dynamic response characteristics of the bedrock and overburden layer slopes models, the comparison analyses were conducted between gravity retaining walls, and the results can be used as a supplement or verification for shaking table model tests. In the numerical simulation of dynamic response behaviors of models for consequent rock slopes, the comparison analyses according to the different rock layer angles were finished, and the simulation results can be used as a supplement or verification for shaking table model tests samely.(4) Study on seismic displacement modes of retaining structuresThe study of the seismic displacement modes and its characteristics of the retaining structures including gravity retaining wall, sheet-pile retaining wall, and anchor lattice frame structures were conducted according to the permanent displacement response based on three large-scale shaking table model tests of bedrock and overburden layer slopes respectively. The study indicates that the seismic displacement modes of retaining structures can be as follows:sliding or translaction mode, rotation inward or outward about base, and the coupling of the sliding to or from the filling soil mass and the rotation inward or outward about base. Moreover, the displacement magnitude, seismic displacement mode, and its behavior can be influenced not only by the exciting seiswave, excitation direction and type, peak excitation acceleration, but by the retaining structures itself and its combination. In addition, the seismic behaviors of the retaining structures were discussed on the basis of the study on seismic displacement modes.(5) Study on seismic earth pressure and seismic design method of multistage retaining structuresAccording to the upper bound theorem of limit analysis and strength reduction technique based on pseudo-static method, seismic earth pressures of multistage retaining walls were studied, and the upper bound solutions for determining seismic active and passive earth pressures were deduced. The following factors are taken into account including horizontal and vertical seismic coefficients, the angle of the retaining wall back, slope surface shape and its retaining structures, the influence of upper retaining wall on the lower, soil cohesion, adhesive strenghth between soil and retaining wall back. The propsed methods can be applied to the determination of seismic active and passive earth pressures of cohesionless and cohesive soils, and complicated slope shapes.(6) Static-dynamic stability analysis and seismic design method of multistage and combination retaining structuresThe safety factor of slope stability was directly used as the strength reduction coefficient, the seismic stability analyses of three kind of supporting types of anchored retaining walls on the high slopes were studied according to the upper bound theorem of limit analysis and strength reduction technique based on pseudo-static method. In addition, the sensitivity of the parameters was analyzed using the orthogonal analysis method, and the seismic design methods of retaining structures were studied. The seismic design methods and the suggestions for the practice were put forward through case studies.更多还原