公路软基侧限堆载预压技术研究及变形分析

发布时间：2018-09-19 20:18

【摘要】：随着我国高铁与公路建设的实施和普及,工程实际中常遇到各种不良地质,如软土、膨胀土、湿陷性黄土等。公路软基的沉降变形分为垂直沉降产生的变形和侧向挤出引起的沉降变形。侧向挤出不仅对路基总沉降产生影响,甚至会影响周边建筑物的安全稳定性。为了限制软土在预压荷载作用下的侧向挤出,减少堆载预压排水固结对周边环境的不利影响,提出侧限堆载预压控制技术。本文以导师的科研项目为依托,结合相关文献的实际工程,通过有限差分分析软件,对这一技术展开了研究。并在合理假设的基础上,构造出了有无侧限条件下地基土沉降的近似解析算式。主要有以下几方面结论:1.为限制软土堆载预压及堆载预压区以外的地下水位降低对周边环境的不利影响,提出侧限堆载预压控制新技术。基于土力学理论提出了侧限水泥土墙的计算内容及计算方法。2.基于FLAC~(3D)有限差分分析软件并结合实际工程,建立了无侧限条件下的堆载预压排水固结模型。将无侧限堆载预压模型的模拟结果与相关文献实测结果进行了对比,验证了堆载预压排水固结数值模拟模型的合理性及可行性。3.基于FLAC~(3D)有限差分分析软件,考虑分级堆载的影响,建立了侧限条件下堆载预压排水固结模型。讨论了侧限位置、侧限水泥土墙的埋置深度及宽度对堆载预压排水固结效果的影响。研究结果表明:堆载预压侧限控制技术能有效降低软土地基沉降,提高前期固结速率,固结度达80%堆载预压时间比无侧限堆载预压时间最大可缩短10 d。侧限设置位置对堆载预压沉降量影响显著。当侧限位置位于堆载预压区边缘时,与无侧限相比,堆载预压区最大沉降可降低58.93%。最佳的侧限位置位于堆载预压区边缘。4.在合理假设的基础上,构造了满足位移边界条件的位移函数。基于弹性力学中变分法,建立了有无侧限堆载预压地基变形的变分方程,推出了有无侧限堆载预压地基变形计算的近似解析算式,并利用MATLAB软件编制程序。将理论结果与模拟结果进行对比,验证了计算方法的合理性和可行性。
[Abstract]:With the implementation and popularization of high-speed railway and highway construction in China, various kinds of bad geology are often encountered in engineering practice, such as soft soil, expansive soil, collapsible loess and so on. The settlement deformation of soft foundation is divided into vertical settlement and lateral extrusion. Lateral extrusion not only affects the total settlement of roadbed, but also affects the safety and stability of surrounding buildings. In order to limit the lateral extrusion of soft soil under preloading and to reduce the adverse effect on surrounding environment caused by surcharge preloading and drainage consolidation, a lateral limit preloading control technique is proposed. In this paper, based on the scientific research project of the tutor, combining with the actual engineering of the related literature, the research on this technology is carried out by using the finite difference analysis software. On the basis of reasonable assumptions, an approximate analytical formula for the settlement of foundation soil with or without lateral limit is constructed. The main conclusions are as follows: 1. In order to limit the adverse effects on the surrounding environment caused by the decrease of groundwater level outside the soft soil load preloading and the surcharge preloading area, a new technology of side limit surcharge preloading control is put forward. Based on the theory of soil mechanics, the calculation content and calculation method of side limit cement earth wall are put forward. Based on FLAC~ (3D) finite difference analysis software and practical engineering, the consolidation model of surcharge preloading drainage with no side limit is established. The simulation results of the unconfined surcharge preloading model are compared with the measured results of relevant literatures, and the rationality and feasibility of the numerical simulation model of surcharge preloading drainage consolidation are verified. Based on FLAC~ (3D) finite difference analysis software and considering the influence of graded heaped load, the consolidation model of preloading drainage is established under the condition of side limit. The influence of the side limit position, the depth and width of the side limit cement soil wall on the consolidation effect of the surcharge preloading drainage is discussed. The results show that the lateral limit control technique of surcharge preloading can effectively reduce the settlement of soft soil foundation and increase the consolidation rate in the early stage. The maximum consolidation time of 80% surcharge preloading can be shortened by 10 days compared with the maximum time of unconfined surcharge preloading. The position of side limit has a significant effect on the settlement of surcharge preloading. When the side limit is located at the edge of the surcharge preloading zone, the maximum settlement of the surcharge preloading zone can be reduced by 58.93% compared with the non-side limit. The best side limit is located at the edge of the surcharge preloading zone. A displacement function satisfying the displacement boundary condition is constructed on the basis of reasonable assumptions. Based on the variational method in elastic mechanics, the variational equation of foundation deformation with or without lateral limit surcharge preloading is established, and the approximate analytical formula for calculation of foundation deformation with or without lateral limit surcharge preloading is derived, and the program is compiled by using MATLAB software. The theoretical results are compared with the simulation results to verify the rationality and feasibility of the calculation method.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.1

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