地震荷载作用下风积沙高路堤稳定性模型试验研究

发布时间：2019-04-08 12:45

【摘要】：本文以陕西省榆林地区的风积沙为主要研究材料,通过室内土工试验及动三轴试验,获取风积沙的物理力学性能参数及动力特性参数,根据相似理论,通过振动台相似模型试验,分析研究风积沙填筑的高路堤在地震荷载下的稳定性,并得出了一些规律性的认识。本文主要开展的研究工作有:1.通过筛分、直剪、击实试验测得风积沙试样的基本力学参数,通过动三轴试验获得试样动力特性参数,基于等效动黏弹性本构模型,确定模型材料并验证了其合理性;2.根据振动台特性参数和试验目的,设计并制作了符合试验要求的模型箱,验证了模型箱模拟边界条件的合理性,对比分析模型箱与模型土体自振频率的差异,排除了模型箱对试验结果造成的影响;3.设计并制作模型,选择传感器种类、型号及布设方式,选择EL-Centre波、兰州波和正弦波为试验用波,制定加载制度,明确试验流程;4.根据试验结果完成路堤结构在地震荷载下的稳定性分析,主要包括分析加速度、位移的动态响应,分析地震波类型、加速度峰值、模型坡率等因素对路堤稳定性影响。以加速度为例,分析结果表明:模型路堤上各点加速度峰值随着输入地震加速度峰值的增大而增大,加速度放大系数随着竖直高度的增大而增大,加速度放大效应在高程上明显大于水平方向,其中路肩处的放大效应最为明显;5.根据试验现象结合试验数据,对模型路堤破坏过程及破坏形态进行总结和分析。分析结果表明:模型路堤在EL-Centre波和兰州波作用下主要表现为浅层土体松动,内部土体滑移,边坡坡面和路基顶部产生裂缝,裂缝逐渐向路基内部发育,形成潜在的圆弧型滑动面;在正弦波作用下,模型二和模型三均在边坡坡脚位置开始发生破坏,并逐渐向上延伸,最终原始路堤结构形态完全被破坏。
[Abstract]:Taking the aeolian sand in Yulin area of Shaanxi Province as the main research material, the physical and mechanical properties and dynamic characteristic parameters of the aeolian sand were obtained through indoor geotechnical test and dynamic triaxial test, and according to the similarity theory, Based on the similar model test of shaking table, the stability of high embankment filled by aeolian sand under earthquake load is analyzed and studied, and some regular knowledge is obtained. The main research work carried out in this paper is as follows: 1. The basic mechanical parameters of aeolian sand samples were measured by screening, direct shear and compaction tests, and the dynamic characteristic parameters of the samples were obtained by dynamic triaxial test. Based on the equivalent dynamic viscoelastic constitutive model, the model material was determined and its rationality was verified. According to the characteristic parameters of the shaking table and the purpose of the test, the model box which accords with the test requirements is designed and made. The rationality of the simulation boundary conditions of the model box is verified, and the difference of the natural vibration frequency between the model box and the model soil is compared and analyzed. The influence of the model box on the test results is excluded. 3. Design and make the model, select the type, type and arrangement of the sensor, select EL-Centre wave, Lanzhou wave and sine wave as the test wave, make the loading system, clear the test procedure; 4. According to the test results, the stability analysis of embankment structure under earthquake load is completed, mainly including analyzing the dynamic response of acceleration and displacement, analyzing the influence of seismic wave type, acceleration peak value and model slope ratio on the stability of embankment. Taking the acceleration as an example, the results show that the acceleration peak value of each point on the model embankment increases with the increase of the input seismic acceleration peak value, and the acceleration magnification factor increases with the increase of vertical height. The acceleration magnification effect in elevation is obviously greater than that in horizontal direction, in which the magnification effect at the shoulder is the most obvious. 5. Based on the experimental data, the failure process and failure pattern of the model embankment are summarized and analyzed. The results show that under the action of EL-Centre wave and Lanzhou wave, the model embankment mainly displays shallow soil loosening, internal soil slip, cracks on slope and top of roadbed, and cracks gradually develop into the interior of roadbed. Forming a potential circular sliding surface; Under the action of sine wave, both model two and model three begin to destroy at the base of slope, and extend up gradually. Finally, the structure of original embankment is destroyed completely.
【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】：U416.12

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