大连地区改良路基土力学试验及模型研究

发布时间：2018-06-17 03:45

本文选题：路基 + 石灰土　；参考：《大连海事大学》2015年硕士论文

【摘要】：由于受到大连地区特有的低温,近海气候环境的影响,大连地区的路基存在着冻融,海水侵蚀等不利因素,使得控制路基沉降变得十分困难。石灰作为道路工程中常见的工程材料,由于对路基土具有良好的加固作用,能够有效提高土体强度等,同时成本低廉,经济效果好,在我国得到了广泛的应用。本文主要针对大连金普线路基修筑工程实际存在着的土体强度不足,不满足实际工程需要等问题,采用土中掺加石灰的方法,用室内试验与理论分析相结合的方法研究石灰土的变化规律,确定工程最优石灰掺量。为了解决大连路基的冻融与海水侵蚀问题,通过大连大黑石处路基土的试验,分析对比了大连地区冻融,海水侵蚀的固化剂效应。基于试验对邓肯-张模型进行研究分析,采用数值模拟验证试验结果。具体内容为：1、对大连金普线路基修筑工程路基土进行试验,研究了金普线路基土的基本物理特性和力学性质,获得路基土的颗粒级配曲线、界限含水率、渗透系数,确定此试验用土为低液限粉质粘土。采用SLB-1型应力应变控制式三轴剪切渗透试验仪研究了金普线路基土强度指标与应力应变曲线形式。2、对金普线路基土的石灰改良方法进行试验研究,得到石灰对于试验用土的力学特性的影响,发现掺加石灰后明显提高了土体塑限,降低塑性指数。随着石灰改良土石灰掺量的增加,得到其强度、粘聚力、内摩擦角的变化规律,掺加石灰改变了土体的应力—应变特性。3、针对北方地区特有的季冻区环境进行石灰土在冻融环境下的力学试验,得到其变化规律,试验结果表明,石灰作为改良剂能明显提高土体的抗冻性。通过计算土体的弹性模量分析了金普线路基修筑工程路基土的最优石灰掺量。考虑交通荷载作用,进行了路基土在冻融情况下的动三轴试验,得到相应的变化规律。4、通过金普线路基土浸泡试验模拟大连的近海环境,试验表明,石灰改良土随着石灰掺量的增加,水稳性和抗海水侵蚀性都得到明显提高。选取大连大黑石路基土进行强度、冻融、海水侵蚀试验,确定最优固化剂配方。5、对邓肯-张模型研究与分析,基于前期试验结果获得参数,采用FLAC3D软件对金普线DK27+560路基工程段路基模型进行三维数值模拟,并对邓肯-张模型进行路基土参数的敏感性分析,确定模型参数对路基位移的影响。
[Abstract]:Due to the special low temperature in Dalian area and the influence of offshore climate environment, the roadbed in Dalian area has some unfavorable factors, such as freezing and thawing, sea water erosion and so on, which makes it very difficult to control the subgrade settlement. Lime, as a common engineering material in road engineering, has been widely used in our country because of its good strengthening effect on subgrade soil, effective improvement of soil strength, low cost and good economic effect. In this paper, the method of adding lime into the soil is adopted to solve the problems of insufficient soil strength in the subgrade construction project of Dalian Jinpu Line, which does not meet the needs of the actual project. The change law of lime soil was studied by the method of laboratory test and theoretical analysis, and the optimum lime content was determined. In order to solve the problems of freeze-thaw and seawater erosion in Dalian subgrade, the effects of solidifying agent on freeze-thaw and seawater erosion in Dalian area were analyzed and compared through the test of roadbed soil at Dalian Daheishi. Based on the experiment, the Duncan-Zhang model was studied and the results were verified by numerical simulation. In this paper, the basic physical and mechanical properties of subgrade soil of Jinpu line are studied, and the gradation curve, moisture content and permeability coefficient of subgrade soil are obtained. It is determined that the test soil is silty clay with low liquid limit. The strength index and stress-strain curve of embankment soil of Jinpu Line were studied by SLB-1 stress strain control triaxial shear permeation tester, and the lime improvement method of embankment soil of Jinpu Line was studied. The influence of lime on the mechanical properties of test soil is obtained. It is found that the plastic limit of soil is obviously increased and the plasticity index is reduced after adding lime. With the increase of lime content in lime modified soil, the change of strength, cohesion and internal friction angle is obtained. The stress-strain characteristic of soil is changed by adding lime. The mechanical test of lime soil in freeze-thaw environment is carried out in the special environment of seasonal frozen area in the north of China, and the change law is obtained. The experimental results show that, Lime as a modifier can obviously improve the frost resistance of soil. Through the calculation of elastic modulus of soil, the optimum lime content of subgrade soil in embankment construction project of Jinpu Line is analyzed. Considering the action of traffic load, the dynamic triaxial test of roadbed soil under freeze-thaw condition is carried out, and the corresponding variation law .4 is obtained. Through the soaking test of embankment soil along Jinpu Line, the offshore environment of Dalian is simulated. With the increase of lime content, the water stability and seawater erosion resistance of lime modified soil are improved obviously. The strength, freeze-thaw and seawater erosion test of Dalian Daheishi subgrade soil was selected to determine the optimum curing agent formula .5. the Duncan-Zhang model was studied and analyzed, and the parameters were obtained based on the experimental results. FLAC3D software is used to simulate the subgrade model of DK27560 embankment section of Jinpu Line, and the sensitivity analysis of the soil parameters of the subgrade is carried out to determine the influence of the model parameters on the subgrade displacement.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.1

【参考文献】