海相软土地基沉降模式的研究分析

发布时间：2018-08-02 10:26

【摘要】：随着我国国民经济的快速发展,对高速公路建设质量要求也越来越高,而在公路建设中,对软土路基工后沉降控制成为质量控制的一项重要指标。如何设计地基处理方案、合理的规划施工进度成为软土路基迫切解决的重大课题,进行区域性软土路基沉降观测并通过对观测数据的分析对设计年限内的沉降进行预测,成为解决这一课题的必然途径。本文通过对天津滨海新区某在建道路穿越坑塘段为依托,通过对海相软土路基K13+840~K14+000段现场实际观测资料和相关地质资料进行分析,得到荷载—沉降—时间关系曲线。同时,建立灰色理论系统模型对沉降观测数据进行最终沉降量的预测分析,采用三次样条B.Spnlie插值函数对原始数据进行等时距处理。并应用大型有限元ANSYS软件对软土路基进行数值模拟。对数值模拟的结果与实测数据、灰色理论预测数据进行对比分析,通过分析整理以期能够建立天津地区坑塘回填沉降模式,对以后坑塘回填起到一定指导作用。本文主要研究内容及结论有如下几点:(1)通过对现场实测数据的分析,可实现对路堤填土速率控制、地基固结情况的预测和确定构筑物的施工工期。(2)通过对现场实测沉降数据绘制累积沉降量曲线与用ANSYS有限元软件模拟路基沉降观测点的竖向位移随时间的变化曲线相比较可知:有限元模拟分析出的软基累积沉降曲线与现场实际观测数据绘制的累积沉降曲线其沉降变化趋势都随着时间的增长逐渐收敛于某一稳定值。说明采用该模型对该段路基的沉降情况进行模拟是切实可行的。有限元模拟分析结果偏小于实测数据,造成这一结果的主要原因是,在软土路基模拟过程中没有考虑渗流因素的影响,且在堆载过程中,没有考虑地下水位的变化和对孔隙水压力的影响。(3)通过对路基沉降观测值和GM(1,1)模型的预测值进行对比分析可知,GM(1,1)模型沉降预测序列在路基施工开始阶段产生误差相对较大,当观测的实际沉降观测数列越来越多时,其相对误差有减小的趋势,在观测过程中受施工条件、环境条件的变化、观测人员主管条件等因素影响,局部也有波动情况。在实际沉降观测中的观测数据越多,GM(1,1)模型预测精度就越高。(4)海相软土路基沉降变形总的规律是:在路堤加载施工期间,沉降发展明显加快,停止加载一定时间后,沉降速率的波动随之变缓,沉降曲线趋于平缓。在路堤土预压期间,沉降速率趋向收敛某一较小值。
[Abstract]:With the rapid development of the national economy in China, the quality requirements for highway construction are becoming more and more high. In the highway construction, the settlement control of soft soil subgrade has become an important index for quality control. How to design the foundation treatment scheme and plan the construction schedule reasonably is an important issue for the soft soil subgrade to be solved urgently. The settlement of the soft soil subgrade is observed and the settlement in the design life is predicted by the analysis of the observation data. It is an inevitable way to solve this problem. Through the actual observation data and related ground of the K13+840~ K14+000 section of the marine soft soil subgrade through the excavation of a tunnel in the Tianjin Binhai New Area. The qualitative data is analyzed and the load settlement time relation curve is obtained. At the same time, the grey theory system model is established to predict the final settlement of the settlement observation data, and the three spline B.Spnlie interpolation function is used to carry out the equal time distance processing for the original data. And the large finite element ANSYS software is applied to the soft soil subgrade. The results of the numerical simulation and the measured data, the grey theory forecast data are compared and analyzed. Through the analysis and arrangement, we can establish the backfilling settlement model in Tianjin area, and play a guiding role in the backfilling of the pit. The main contents and conclusions of this paper are as follows: (1) through the analysis of the field measured data, The rate control of embankment filling can be realized, the consolidation of the foundation is predicted and the construction period of the structure is determined. (2) the cumulative settlement curve is drawn by the measured settlement data in the field and the vertical displacement curve of the subgrade settlement observation point is compared with the time change curve with the ANSYS finite element software. The cumulative settlement curve of the base cumulative settlement curve and the actual observed data in the field have been gradually converged to a certain stable value with the increase of the accumulated settlement curve. It shows that it is feasible to simulate the settlement of the subgrade by using this model. The result of finite element simulation analysis is less than the measured data, which causes this knot. The main reason is that the influence of seepage factors is not considered during the simulation of soft soil subgrade, and the change of groundwater level and the effect on pore water pressure are not considered during the loading process. (3) by comparing the prediction values of the subgrade settlement observation and the GM (1,1) model, the GM (1,1) model settlement prediction sequence is in the subgrade In the beginning of construction, the error is relatively large. When the observed number of actual settlement observation series is more and more, the relative error has a tendency to decrease. In the process of observation, the conditions of construction, the environment conditions, the conditions of the observation personnel are affected, and the local also fluctuates. The more observed data in the actual settlement observation, the GM ( 1,1) the higher the prediction accuracy of the model. (4) the general law of settlement deformation of the subgrade of the marine soft soil is that the settlement development of the embankment is obviously accelerated during the construction of embankment, and the settling rate fluctuates slowly and the settlement curve tends to be gentle after the loading of the embankment, and the settlement rate tends to converge to a small value during the embankment preloading.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU447;TU433

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