滞洪区软土地基高速公路拓宽路基差异沉降性状分析

发布时间：2018-05-14 22:18

本文选题：路基拓宽 + 差异沉降　；参考：《长安大学》2015年硕士论文

【摘要】：高速公路拓宽工程中最大的难题是解决新老路基差异沉降过大的问题,过大的差异沉降会使路面结构产生附加应力而开裂破坏,从而影响安全及使用性能。软土地基高速公路拓宽工程,沉降主要来自于地基,此时必须采取合理有效的处治方案以控制差异沉降,实践证明桩土复合地基可以有效地缓解这个问题。但是由于拓宽路基是一个新老路基和地基相互作用的复杂系统,桩土复合地基在拓宽荷载作用下的控沉效果和沉降计算等还不明确,其设计也无规范可依,主要依靠经验技术。滞洪区由于其历史成因及作用,区内表层土不能满足拓宽工程对土质的要求,为此本文依托滞洪区内软土地基高速公路拓宽实际工程,以沉降计算为目标,以不同复合地基处治方案为主线,使用有限元方法,对滞洪区道路拓宽软基处理方案进行了设计验算、评价和优化,并基于现场观测数据,通过双曲线拟合法预测最终沉降量,主要内容如下:(1)根据工程地质资料,分析老王坡滞洪区土体的物理力学性质,以及新老路基下地基土体性质差异,为数值计算提供依据。(2)分析了针对道路拓宽时的有限元中二维模型与三维的适用条件,讨论了利用传统二维模型在桩土复合地基中建模的不足,利用有限元软件建立拓宽路基三维模型,介绍了针对依托工程现场实际情况的三维建模过程。(3)采用有限元方法对老王坡滞洪区内的地基处理拟采用设计方案进行变形分析,得到设计方案的数值模拟结果,根据差异沉降计算结果对地基处理方案合理性进行评价和优化。(4)针对滞洪内采用处理的方案,分别分析桩长、桩径、桩间距、桩体强度、褥垫层模量等因素的改变对拓宽路基差异沉降的影响。(5)选取滞洪区典型断面,进行路基变形观测,根据观测结果采用沉降预测中常用的曲线拟合法预测观测点的最终沉降,验证水泥粉煤灰碎石桩的控沉效果。
[Abstract]:The biggest problem in expressway widening project is to solve the problem of excessive differential settlement of new and old subgrade. Excessive differential settlement will cause additional stress and crack damage to pavement structure, thus affecting safety and performance. The settlement of soft soil foundation expressway widening project mainly comes from the foundation. At this time, reasonable and effective treatment scheme must be adopted to control the differential settlement. The practice has proved that pile-soil composite foundation can effectively alleviate this problem. However, widening roadbed is a complex system of interaction between new and old subgrade and foundation, so the settlement control effect and settlement calculation of pile-soil composite foundation under widening load are not clear, and its design is not standardized, but mainly depends on experience technology. Because of its historical cause and function, the surface soil in the flood detention area can not meet the requirements of soil quality of the widening project. In this paper, based on the actual project of widening the expressway with soft soil foundation in the flood detention area, the settlement calculation is the goal. Taking different treatment schemes of composite foundation as the main line and using finite element method, the design checking calculation, evaluation and optimization of the treatment scheme for widening soft foundation in flood detention area are carried out. Based on the field observation data, the final settlement is predicted by hyperbolic fitting method. The main contents are as follows: (1) based on the engineering geological data, the physical and mechanical properties of soil in Laowangpo flood detention area and the difference of soil properties under new and old subgrade are analyzed. The application conditions of 2D model and 3D model in road widening are analyzed, and the shortcomings of traditional 2D model in pile-soil composite foundation are discussed. The 3D model of widening roadbed is established by using finite element software. The process of 3D modeling based on the actual situation of engineering is introduced. The finite element method is adopted to analyze the deformation of foundation treatment in Laowangpo flood detention area. The numerical simulation results of the design scheme are obtained. According to the results of differential settlement calculation, the rationality of the foundation treatment scheme is evaluated and optimized. The influence of factors such as cushion modulus on widening differential settlement of roadbed. (5) selecting typical section of flood detention area and observing subgrade deformation. According to the observation results, the curve fitting method commonly used in settlement prediction is used to predict the final settlement of observation point. The sedimentation control effect of cement fly ash gravel pile was verified.
【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】：U416.1

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