强震作用下含不连续面高陡岩质边坡动力响应振动台试验研究

发布时间：2018-01-01 21:53

本文关键词：强震作用下含不连续面高陡岩质边坡动力响应振动台试验研究　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：对于岩质边坡的稳定性问题,区域地质情况,特别是边界区域岩体内主要构造断裂体系,及各类节理组及各类软弱面的分布及其组合情况,具有极为重大的意义。岩质边坡在地震荷载作用下的动力响应和稳定性问题是当前岩土地震工程和地震工程学研究的热点问题之一。强震作用下岩质边坡的动力响应在很大程度上是由不连续面的几何分布和物理力学特性决定的。特别是,对于含有顺向节理或逆向节理的高陡岩质边坡,地震时发生崩塌等严重破坏极大的影响了周边建筑结构的安全性。正是由于地质构造、岩体材料、不连续特性以及地震动的复杂性,导致岩质边坡的动力稳定性问题变得非常复杂。本文针对岩体的不连续特性以及地震力的动力特性,采用有限元数值模拟以及大型振动台试验等手段,开展了地震波在含不连续节理岩体中的传播特性研究,明确了含不连续面的高陡岩质边坡的动力响应规律,以及其地震荷载作用下的破坏过程和特征,揭示了不连续面对边坡稳定性的影响。针对含有顺向及逆向节理的岩质边坡,开展了有限元数值模拟。对不连续节理对地震波的传播特性的影响以及其对边坡地震稳定性的影响进行了分析。有限元分析采用时域动力分析,考虑不连续面与周边岩体界面的多重反射折射。分析了不同时刻的波场分布,由于不连续节理与周边岩体界面的作用,地震波在含不连续面边坡中的波场呈现多重反射折射现象,高频成分卓越,并伴随着位相的产生,位相与节理的布设及数量相关。水平输入时,顺岩分布边坡在节理间产生强反射现象,震动持续时间较长;而逆岩分布边坡会尽快趋于稳定。水平输入及垂直输入时的波场分布有着明显的不同。地震动沿坡面呈放大趋势,最大值出现在坡尖,沿坡顶向坡内减小。设计并开展了含不连续面的岩质边坡大型振动台试验研究。利用振动台对含顺向节理的陡倾岩质边坡的动力响应规律进行了研究,特别是对岩质边坡的动力响应规律、变形破坏过程和机制分析进行了详细的讨论。在试验设计阶段,通过材料试验,采用了水泥、砂、铁粉、粘土与混合剂的配比模拟了岩体材料。采用特氟龙布,利用其表面摩擦系数极低的特性,模拟了岩质高陡边坡的不连续节理。制作了含有不连续面的高陡岩质边坡模型。通过一系列的振动台试验,观察了边坡模型从裂缝产生发展到最终滑动破坏的全过程。高陡边坡模型的破坏可总结为三个阶段:裂缝产生阶段、坡面剥落阶段、沿不连续面的崩塌阶段。滑动面发生在距离顶部为坡高的1/3处。通过在边坡不同高程,不同位置布设传感器,采集了地震动力响应(加速度、压力、应变)数据。进行数据处理、对比和分析,得到了不同输入方向和不同输入强度时地震荷载作用下含不连续面的岩质高陡边坡的加速度、动土压力和应变响应,分析和总结边坡模型的动力响应规律及特征。试验结果表明,边坡对输入动荷载具有放大作用,沿坡面向上,PGA放大系数呈上升趋势,最大值出现在坡尖,沿坡顶向坡内减小。坡体内PGA放大系数在垂直向上稍有放大。PGA放大系数变化规律受不连续节理分布和动荷载震动方向的影响。动荷载水平向输入时的最大PGA放大系数明显大于垂直向输入时的最大PGA放大系数,说明坡体在水平向的动力响应更为强烈。随着地震动输入的变化,动力响应在坡体内呈线性放大,在水平向上表现为节律性变化。试验结果有助于了解含不连续面陡倾岩质边坡在不同动荷载作用下的响应规律,对研究其动力失稳机制和抗震结构设计提供了依据。
[Abstract]:For the problem of slope stability, regional geological conditions, especially the main tectonic boundary region in rock fracture system, and all kinds of joint sets and all kinds of soft surface distribution and their combination, is of great significance. The rock slope under seismic load dynamic response and stability is one of the hot issues in the current rock geotechnical earthquake engineering and earthquake engineering research. The earthquake dynamic response of rock slope in large part by discontinuous surface geometric distribution and physical and mechanical characteristics of the decision. In particular, with consequent high steep rock slope joints or reverse joints, earthquake collapse and other serious damage to great effect the safety of the surrounding buildings structure. It is because of the geological structure, rock mass, complexity and continuous vibration characteristics, resulting in dynamic stability of rock slope Becomes very complicated. This paper aiming at the dynamic characteristics of rock mass discontinuity characteristics and seismic force, using finite element numerical simulation and shaking table tests, carried out the research of propagation characteristics of seismic wave in containing discontinuities in jointed rock mass, the dynamic response laws containing discontinuous surfaces of high steep rock slope, and the failure process of the earthquake loads and characteristics, reveals the discontinuities affect the stability of the slope. The rock slope forward and reverse joint, carry out the finite element numerical simulation. The influence on the propagation characteristics of discontinuous joints on seismic wave and its influence on the seismic stability of slope is analyzed. Finite element analysis of the dynamic analysis in time domain, considering the multiple reflection and refraction of discontinuities and surrounding rock interface. Analysis of the wave field distribution in different time, due to the discontinuity of joints and weeks The role of edge rock interface, seismic wave containing discontinuities in slope of wave field shows multiple reflection refraction, the high-frequency components of excellence, and accompanied by a phase of production, layout and number of phase and joints. The level of input, along the slope rock distribution strong reflection phenomenon in the joint, shaking lasted for a long time the inverse slope; rock distribution as soon as possible will tend to be stable. The output of the input level and vertical wave field distribution are obviously different. The earthquake along the slope was enlarged trend, the maximum value appears in slope decreases along the slope to the tip top. Design and carry out the discontinuity of rock slope with large-scale shaking table test study. Using the vibration table with consequent bedding rock slope dynamic response were studied to joint steep, especially the rules of dynamic response of rock slope and deformation are discussed in detail in the failure analysis process and mechanism. Test the design stage, through the experiment, using the cement, sand, clay and iron powder, mixture ratio of simulated rock material. By using Teflon cloth, utilizing the characteristics of the surface of a very low coefficient of friction, simulation of discontinuous joints of high steep rock slope. Made with discontinuous surface of high steep rock slope model through a series of shaking table tests of the model slope observation from the cracks to the development of the whole process of sliding failure. The model of high steep slope failure can be summarized into three stages: the stage of crack, slope spalling stage along the discontinuity of the collapse stage. The sliding surface in the distance from the top of 1/3 slope high. The elevation at different slope, different position sensor, the acquisition of seismic response (acceleration, pressure, strain) data. For data processing, comparison and analysis, obtained the different input direction and different input When the intensity of earthquake loads with discontinuity with high and steep rock slope acceleration, earth pressure and strain response analysis and dynamic response of slope model summarize the rules and characteristics. The experimental results show that the slope has amplification effect on the input load, upward along the slope, PGA amplification coefficient increased, the maximum value appeared the slope decreases along the slope to the tip top of the slope. The slope PGA amplification coefficient in vertical upward slightly enlarged.PGA amplification coefficient variation law affected by discontinuous joint distribution and dynamic load vibration direction. The dynamic load level to the PGA input amplification coefficient was significantly greater than the vertical maximum input PGA amplification coefficient that, the slope in the horizontal direction of the dynamic response is more intense. With the change of seismic input, the slope in the linear amplification of dynamic response in the horizontal direction is shown as the rhythm changes. The results will help In order to understand the response rule of steep slope with discontinuous face under different dynamic loads, it provides a basis for studying its dynamic instability mechanism and the design of aseismic structure.

【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

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