时间累积效应对黄土斜坡稳定性的影响

发布时间：2019-07-08 09:16

【摘要】：我国西北广大地区被黄土所覆盖,典型地区地表千沟万壑。在我国经济建设的大潮中,大量基础设施不断建设,开山修路架桥,修建高楼大厦数量越来越多,接踵而来的是边坡问题的突出,地灾隐患点数目的不断增加,规模持续上升。与此同时我们不断采取工程地质措施来防止治理边坡问题的发生和发展。通过工程经验发现,一般斜坡不会在应力不平衡后立即失稳,而是产生蠕滑变形。斜坡中部分剪切应力随着斜坡变形消散,渐渐趋于稳定,另一部分斜坡蠕变之后进入加速滑动阶段产生滑坡。笔者对时间积累效应因素对斜坡稳定性影响进行了仔细总结,这些因素包括黄土本身所具有的特点,也包括降雨、地表径流、地下水、地震、植被、冻融作用、农业灌溉、修房筑路、矿藏开采等外在因素。时间累积效应主要在这两方面影响斜坡的稳定性。第一、当黄土斜坡强度在峰值强度和长期强度之间,或者由于斜坡所处应力场、黄土自身物理力学性质的改变,使黄土强度进入到上述强度范围以内时,黄土斜坡产生蠕变。斜坡蠕变可能是衰减蠕变,逐步进入稳定阶段,或者是非衰减蠕变,导致黄土斜坡的失稳。第二、随着时间的推移,斜坡受到各种因素影响的机率会不断增大。例如斜坡遭遇突发因素大地震、大洪水的概率增加,使外力高于黄土的峰值强度,使黄土斜坡发生突发性破坏。黄土斜坡可能短期内处于稳定状态,但是随着时间推移,遭遇各种不利因素的影响,会使斜坡不断向失稳的方向发展。选定FLAC3D岩土分析软件进行数值模拟,比较其中各模型的优缺点,最终选定伯格斯组合模型和摩尔库伦模型,来讨论不同坡型、不同力学性质黄土等的时间积累效应稳定性,以及蠕变状态下,斜坡的变形状况。
文内图片：

图片说明：降水渗流讨程图
[Abstract]:The vast areas of northwest China are covered by loess, and the surface of typical areas is thousands of gullies. In the tide of economic construction in our country, a large number of infrastructure facilities continue to be built, open mountains to build roads and bridges, build more and more high-rise buildings, followed by the prominent slope problems, the purpose of hidden dangers of land disasters continues to increase, and the scale continues to rise. At the same time, we continue to take engineering geological measures to prevent the occurrence and development of slope control problems. Through engineering experience, it is found that the general slope does not lose stability immediately after stress imbalance, but produces creep deformation. Part of the shear stress in the slope dissipates with the deformation of the slope and tends to be stable gradually, and the other part of the slope enters the accelerated sliding stage after creep to produce landslides. In this paper, the effects of time accumulation on slope stability are carefully summarized, including the characteristics of loess itself, including rainfall, surface runoff, groundwater, earthquake, vegetation, freeze-thaw, agricultural irrigation, building roads, mining and other external factors such as rainfall, surface runoff, groundwater, earthquake, vegetation, freeze-thaw, agricultural irrigation, building roads, mining and so on. The time accumulation effect mainly affects the stability of slope in these two aspects. First, when the strength of loess slope is between the peak strength and long-term strength, or because of the stress field where the slope is located, the physical and mechanical properties of loess itself change, so that the strength of loess enters the above strength range, the loess slope produces creep. The creep of slope may be attenuated creep, gradually enter the stable stage, or non-attenuated creep, resulting in the instability of loess slope. Second, with the passage of time, the slope will be affected by a variety of factors will continue to increase the probability. For example, when the slope encounters a sudden earthquake, the probability of the flood increases, which makes the external force higher than the peak strength of the loess, and makes the loess slope cause sudden damage. Loess slope may be in a stable state in a short period of time, but with the passage of time, the slope will continue to develop in the direction of instability due to the influence of various adverse factors. FLAC3D geotechnical analysis software is selected for numerical simulation, and the advantages and disadvantages of each model are compared. finally, Boggs combination model and Moor Coulomb model are selected to discuss the stability of time accumulation effect of different slope types and loess with different mechanical properties, as well as the deformation of slope under creep state.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.22

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