【作者】 常伟涛；

【导师】 苏永华；

【作者基本信息】 湖南大学 ， 岩土工程， 2008， 硕士

【摘要】 近些年来,在高等级公路的建设过程中,频繁遇到半填半挖路基的修筑问题。由于半填半挖路基一侧为原状路基,一侧为新填路基,所以交界面两侧土的物理力学性质有很大的差别,再加上沉降时间不同,成为很难解决的工程问题。要解决上述问题,最可行、最经济的办法就是采取合理的路基结构,减小差异沉降,加强新填路基和原状路基间的整体性。对于山区半填半挖路基,可以采用土工合成材料(如土工格栅、土工格室等),一方面靠土工合成材料的抗拉强度增加新填部分和原状路基之间结构联系,使两者具有足够的整体性,另一方面可明显减少半填半挖路基的不均匀沉降。本文根据绍怀高速公路溆浦连接线半填半挖路基的实际情况,在室内进行了三组半填半挖路基的模型试验。模型试验原状路基用加石灰土,以模拟原状路基的先期固结沉降和强度差别,新填路基采用不加石灰土,模拟施工顺序分层填筑。加载装置采用砝码进行重力加载,模型试验的沉降和应力采用沉降标和压力盒进行测量。试验数据表明,土工材料的效果明显,并根据试验数据系统分析了土工材料的在半填半挖路基中的作用效果和力学机理。另外,本文还以工程实例为背景,拟定比较合理的半填半挖路基结构,并运用大型有限元分析软件ANSYS进行有限元分析。为了更好的模拟现场情况,采用ANSYS软件的生死单元的功能,先计算地基和原状路基在自重下的沉降和应力,再读取初始应力场,然后分层填筑新路基。就不同半填半挖路基结构在不同的情况(主要指不同的路基高度、路基宽度、不同地基模量、不同的加筋材料和不同加筋层数等)下,对土工合成材料减少半填半挖不均匀沉降的效果进行分析计算,结果表明,土工格栅,特别是土工格室对减小路基的差异沉降和使路基内部的应力均匀化效果显著。讨论了半填半挖路基在不同情况下的变形特征和沉降规律。最后,本文根据实际情况建立了车辆的简化加载模型,模拟了车辆在路面上的瞬时动载情况。结果表明,加土工材料不管是对车辆动载的瞬时最大沉降和循环荷载下的最终沉降都效果显著。更多还原

【Abstract】 In recent years, in the process of high-grade highway construction, we often encounter the construction of the cut and fill sub-grade.Because on one-side of the cut and fill sub-grade roadbed is original state but the another is new, so they are qutie different from the the physical mechanics properties of soil, And the time is different, so that the cut and fill sub-grade roadbed is a difficult problem of the project. The most economic and feasible approach to solve the question is to select a correct ambankment structure, to improve the whole and lateral stability between the cut and fill sub-grade roadbed.In the mountain area, geosynthetics (such as geotextile, geogrid and so on) can be used as a treamment in the process of widening the original state on ground. On the one hand, the tensile strength of geosynthetics can reinforce the structural association between the the cut and fill sub-grade roadbed, and make them have enough entirety. On the other hand, geosynthetics can greatly reduce non-uniform settlement of the the cut and fill sub-grade roadbed.In this paper, according to the Xvpu connecting line of Shao-Huai highway, three model experiments of the cut and fill sub-grade roadbed are maked. For simulation concretion settlement and different intension, calcareousness soil is used to simulate original state roadbed. The new roadbed is primed layered by soil. The load device is weight. The settlement and stress of the model experiment are measured by settlement sign and pressure box. The results of experiment show that the result of the geosynthetics is obvious. At last, the action mechanism of geosynthetics in the soil is analyzed systematically.What’s more, the paper based on a project example, suggested a rational Bankment structure by using finite element software-ANSYS. For simulation the fact, the life and death element of the software-ANSYS is used to simulate the original stress,then the new roadbed is primed layered. according to diferent environment of the cut and fill sub-grade roadbed on ground (including different height of embankment, different width, and diferent subgrade modulus, diferent Geosynthetics different lays and so on), the paper also analyzed the efects of the geosynthetics which reducing the non-uniform settlement of the cut and fill sub-grade roadbed, the results show that the result of the geosynthetics is obvious to reduce different settlement and stress concentration. The deformation characteristics and setlement rule of the widening embankment structure is analyzed.Then a simple model in load of vehicles is built to simulate the transient state and analyze the difference between reinforced and unreinforced. The results show that the geosynthetics have obvious effect on transient settlement and finally settlement.更多还原