吉林地区季冻土力学特性试验研究

发布时间：2018-03-28 06:51

  本文选题：粉质粘土　切入点：冻融循环　出处：《东北电力大学》2017年硕士论文

【摘要】：在国家进行改革开放的进程中,东北地区的经济建设工作有了飞速的发展,其中公路、铁路、水利水电等基础设施的建设当为重中之重。土作为所有工程的基础,其物理性质及力学性质在东北地区特殊气候特征条件下的稳定性和安全性对构筑物至关重要。季冻土冬季冻结成冰,夏季融化,受到冷生作用的影响,季冻土体在冻结融化过程后的力学性质会与未经冻融的土体有着巨大的改变。所以,在对季节性冻土区域的工程进行安全和稳定性的评价时,一定要考虑经过冻结合融化的土体在内部结构方面所发生的变化。现在人们对我国东北地区季冻土的物理力学性质的理论和试验研究都相对薄弱,本文改良真空预压法制备饱和土,自制低温三轴试验机。随后以吉林地区粉质粘土为研究对象,针对浅土层工况和深土层工况对于季冻土力学效应不同需求,分别进行季冻土预冻融试验和正冻融试验,针对土在经历不同初始条件后的力学效应进行研究,也阐述了再两种不同荷载模式下冻融循环作用对吉林地区粉质粘土工程性质的影响规律,主要的工作内容如下:1、本文详细介绍了国内、外对于季节性冻土经历冻融循环作用后的物理力学性质影响规律的研究现状,并分析了目前国内、外对于能够进行冻融试验的设备现状。2、对吉林地区的季节性冻土进行常规物性指标试验,确定吉林地区土体的基本特性,进而研究土体的冻融特性,并介绍其基本相关参数,了解制约土体物理力学性质的弹性模量理论研究。3、改进了真空预压法,制备出饱和土试样,并且验证了土样的合理性,节约土体饱和时间,兼顾制造费用且土样均匀饱和程度高,适合获取大量试验土样。4、针对浅土层工况进行无侧限压力冻结的预冻融三轴试验;分别对不同冻结温度(-3、-7、-12℃)和不同冻融循环次数(0~9次)的试样进行不同围压(100、200、300、400kPa)的三轴剪切试验,得到了各个土样在不同初始条件下的应力-应变曲线,分别对各试样的粘聚力、内摩擦角等抗剪强度参数进行对比分析,分析在预冻融试验模式下初始条件与试验结果的内在联系。5、针对深土层工况进行“边施加围压边对土样进行冻结融化”的正冻融三轴试验,分别对不同冻结温度(-3、-7、-12℃)和不同冻融循环次数(0~9次)的试样进行三轴剪切试验,通过对各组实验结果进行对比分析,总结不同初始条件与试验结果的影响规律。
[Abstract]:In the process of reform and opening to the outside world, the economic construction in Northeast China has developed rapidly. The construction of infrastructure such as highway, railway, water conservancy and hydropower should be the most important. Soil is the foundation of all projects. The stability and safety of its physical and mechanical properties under the special climatic conditions in Northeast China are very important to the structure. The seasonal frozen soil freezes in winter and melts in summer, which is affected by cold generation. The mechanical properties of the seasonal frozen soil body after freezing and thawing will change greatly with the unfrozen soil mass. Therefore, in the evaluation of the safety and stability of the engineering in the seasonal frozen soil area, We must take into account the changes in the internal structure of the frozen and thawed soils. Nowadays, the theoretical and experimental studies on the physical and mechanical properties of the seasonal frozen soils in northeast China are relatively weak. In this paper, the saturated soil is prepared by the improved vacuum preloading method, and the low temperature triaxial test machine is made. Then, the silty clay in Jilin area is taken as the research object, according to the different demands for the mechanical effect of the seasonal frozen soil under the shallow and deep soil conditions. The pre-freeze-thaw test and the positive freeze-thaw test were carried out respectively, and the mechanical effects of the soil under different initial conditions were studied. The influence of freeze-thaw cycle on the engineering properties of silty clay in Jilin area under two different load modes is also described. The main work is as follows: 1. The current research status of physical and mechanical properties of seasonal frozen soil after freeze-thawing cycle is studied, and the current domestic situation is analyzed. For the equipment that can carry out freeze-thaw test, the conventional physical property index test of seasonal frozen soil in Jilin area is carried out to determine the basic characteristics of soil mass in Jilin area, and then to study the freeze-thaw characteristic of soil mass, and to introduce its basic parameters. The theoretical study of modulus of elasticity, which restricts the physical and mechanical properties of soil, is studied. The vacuum preloading method is improved to prepare the saturated soil sample, and the rationality of the soil sample is verified, and the saturation time of the soil is saved. Considering the cost of manufacturing and the high uniform saturation degree of soil samples, it is suitable to obtain a large number of test soil samples .4, and carry out pre-freezing and thawing triaxial tests without lateral pressure freezing for shallow soil conditions. The triaxial shear tests of samples with different freezing temperatures (-3 ~ 3 ~ 7 ~ 7 ~ 12 鈩，

本文编号：1675212