长期循环荷载作用下饱和软黏土静动力特性试验研究

发布时间：2018-01-08 01:08

本文关键词：长期循环荷载作用下饱和软黏土静动力特性试验研究　出处：《江西理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：我国东部沿海分布着大量的软弱土,随着经济的飞速发展,有很多的大型交通设施兴建在软弱土地基上。而兴建在软弱土地基上的交通设施除承受了静荷载外还承受着反复的循环动荷载,由于其对软土的动力特性影响研究还不够深入具体。因此有必要对软黏土进行不同周数循环荷载下的静动力特性进行研究。本文所采用GDS动三轴仪对土的静动力特性进行试验。目的在于研究原状土和重塑土在不同围压下静力剪切时的应变、孔压以及应力路径等因素的发展规律;循环荷载土体的动力特性的发展规律以及分别在排水和不排水条件下以及连续循环荷载下和分阶段循环荷载下土体的动力特性的发展规律。1通过对原状土和重塑土在不同围压下的静力剪切实验研究得到:(1)原状土和重塑土的应变和孔压在剪切过程中都经历过土体的弹性阶段,急剧剪切阶段,和破坏阶段这3个类似的发展阶段;在实验过程中,重塑土的应力-应变曲线和有效路径比原状土的应力-应变曲线和有效路径表现的更明显。(2)同围压下,原状土的应力-应变曲线滞后于重塑土的应力-应变曲线;在1%ε时,原状土和重塑土的应力-应变曲线近似呈直线增长;在1%ε时,原状土也能给-应变曲线滞后于重塑土应力-应变曲线。2开展原状土在不同循环荷载和不同排水条件的土的动力特性试验,研究发现:(1)土体在排水条件下的残余应变比不排水条件下土体的残余应变更大,而土体在不同排水条件下土体的累积应变在振动前期近似呈直线增长,在振动后期排水条件下的累积应变比不排水条件下的累积应变增长较快;(2)在排水条件下,土体振动产生的应力-应变滞回曲线更密集,土体在排水条件下振动之后更容易首先达到稳定状态。3针对交通温州软土的动力特性设施在不同阶段下土体的受荷不同,研究发现:(1)不管是在排水和不排水条件下,土体在振动的第一阶段的应变和孔压,累积应变都增长较大,在随后的振动阶段内,都会有不同程度的变化;(2)在振动过程中,不排水条件下产生的回弹应变一直比排水条件下振动产生的回弹应变大,在第一阶段内,排水条件下回弹应变有略微减小,不排水条件下回弹应变有略微增长;
[Abstract]:There are a lot of soft soil in the east coast of China, with the rapid development of economy. There are many large transportation facilities built on the soft soil foundation, and the traffic facilities built on the soft soil foundation bear not only static load but also repeated cyclic dynamic load. It is necessary to study the static and dynamic characteristics of soft clay under cyclic loads of different cycles. The GDS dynamic triaxial instrument used in this paper is used to study the static behavior of soft clay. The purpose of this study is to study the strain of undisturbed soil and remolded soil under different confining pressures under static shear. The development law of pore pressure and stress path; The development law of the dynamic characteristics of the soil under cyclic loading and the development of the dynamic characteristics of the soil under drainage and undrained conditions, as well as under the continuous cyclic load and the staged cyclic load. The static shear experiments of plastic soil under different confining pressures show that:. (. 1) the strain and pore pressure of undisturbed soil and remolded soil have experienced elastic stage in shear process. The rapid shear stage and the failure stage are three similar stages of development; During the experiment, the stress-strain curve and effective path of the remolded soil are more obvious than the stress-strain curve and the effective path of the undisturbed soil under the same confining pressure. The stress-strain curve of undisturbed soil lags behind that of remolded soil. At 1% 蔚, the stress-strain curves of the undisturbed soil and the remolded soil are approximately linear. At 1% 蔚, the stress-strain curve of the undisturbed soil can also lag behind the stress-strain curve of the remolded soil. 2. The dynamic characteristics of the undisturbed soil under different cyclic loads and different drainage conditions can be tested. It is found that the residual strain of the soil under the drainage condition is larger than that of the soil under the undrained condition, and the cumulative strain of the soil under the different drainage conditions increases approximately in a straight line in the early stage of vibration. The cumulative strain increases faster in the later stage of vibration than in the undrained condition. 2) under the condition of drainage, the stress-strain hysteretic curve produced by soil vibration is denser. It is easier for the soil to reach stable state at first after vibration under the drainage condition. 3. According to the dynamic characteristic facilities of Wenzhou soft soil in different stages, the soil is subjected to different loads. It is found that the strain, pore pressure and cumulative strain of soil in the first stage of vibration increase greatly, and there will be some changes in the later stage of vibration, regardless of whether the strain and pore pressure of soil in the first stage of vibration increase greatly under the condition of drainage or undrainage. 2) in the process of vibration, the springback strain under undrained condition is always larger than that produced by vibration under drainage condition, and in the first stage, the springback strain under drainage condition decreases slightly. The springback strain increases slightly under undrained condition.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU41

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