嘉绍线软土路基沉降计算及预测方法研究

发布时间：2018-12-25 16:43

【摘要】：我国分布有大量软土地基,尤其以江浙沿海一带分别更为广泛。随着公路建设的迅速发展,不可避免的出现大量公路路基穿越软土地区的情况。软土地基具有压缩性高、渗透性低、力学性质差等特点,在软土地基上修筑的路基产生较大的沉降变形,严重影响工程安全。因此,改进或提高现有的地基沉降计算及预测方法,使沉降的计算值与实测值更接近,具有重大学术价值和社会效益。本文以嘉兴至绍兴跨江通道南岸接线工程为背景,主要工作和研究成果如下： (1)对路基监测数据进行了对比分析。研究发现：路中沉降大于路两侧的沉降；路堤填土及施工均对路基沉降与侧向位移有较大的影响；前期加载的路基沉降较后期加载的路基沉降更为敏感；打设塑料排水板的预压路基沉降速率收敛明显,比不打设排水板快,预应力管桩处理后的地基累计沉降量明显小于塑料排水板处理后的地基。 (2)改进Fox一维大变形固结模型CS2,并编制FORTRAN计算程序。改进后的模型考虑了路基荷载作用下地基中附加应力的变化,采用改进的模型模拟路基填筑软土地基沉降固结过程,计算结果显示地基沉降量的计算值与实测数据吻合。 (3)采用有限元分析软件MIDAS/GTS对一般路段和桥头路段路基沉降变形进行分析。研究表明：一般路段路基最大沉降量发生在第一层填土顶面中心点,路基侧向位移最大值出现在路堤边缘正下方性质较差的土层中；采用预应力管桩处理的桥头路段软土路基,其沉降量和侧向位移都大大减小,且侧向位移主要发生在预应力管桩未达到的土层中。 (4)分别采用SEP计算程序和双曲线预测模型,根据预压路基沉降检测数据来预测路基后期沉降,并将预测值与实测值进行对比。研究表明：SEP计算程序和双曲线预测模型均能较好的预测后期沉降；相比而言,SEP计算程序比双曲线模型能更准确的预测后期沉降。
[Abstract]:There are a large number of soft soil foundations in China, especially in the coastal areas of Jiangsu and Zhejiang provinces. With the rapid development of highway construction, it is inevitable that a large number of highway subgrade pass through soft soil area. Soft soil foundation has the characteristics of high compressibility, low permeability and poor mechanical properties. The subgrade built on soft soil foundation has great settlement and deformation, which seriously affects the safety of engineering. Therefore, it is of great academic value and social benefit to improve or improve the existing calculation and prediction methods of foundation settlement, so that the calculated value of settlement is closer to the measured value. This paper takes the south bank connection project of Jiaxing to Shaoxing River Channel as the background. The main work and research results are as follows: (1) the monitoring data of roadbed are compared and analyzed. It is found that the settlement in the road is greater than the settlement on both sides of the road, the embankment filling and construction have great influence on the subgrade settlement and lateral displacement, and the subgrade settlement loaded in the early stage is more sensitive than that in the later loading. The settlement rate of preloaded subgrade with plastic drainage board converges obviously, which is faster than that without drainage plate, and the accumulated settlement of prestressing pipe pile is obviously smaller than that after plastic drainage board treatment. (2) improve the Fox one-dimensional large deformation consolidation model CS2, and compile the FORTRAN calculation program. The improved model takes into account the variation of additional stress in the foundation under the action of subgrade load. The improved model is used to simulate the settlement and consolidation process of subgrade filled soft soil foundation. The calculated results show that the calculated value of foundation settlement is in agreement with the measured data. (3) the settlement and deformation of roadbed in general section and bridgehead section are analyzed by finite element analysis software MIDAS/GTS. The results show that the maximum settlement of subgrade in general section occurs at the center of the top surface of the first layer of fill, and the maximum lateral displacement of roadbed appears in the soil layer with poor properties under the edge of embankment. The settlement and lateral displacement of the soft soil subgrade in the bridgehead section treated by prestressed pipe pile are greatly reduced and the lateral displacement mainly occurs in the soil layer which is not reached by the prestressed pipe pile. (4) SEP program and hyperbolic prediction model are used to predict the late settlement of subgrade according to the data of pre-compaction subgrade settlement, and the predicted value is compared with the measured value. The results show that both the SEP program and the hyperbolic prediction model can predict the late settlement better than the hyperbolic model, compared with the hyperbolic model, the SEP program can predict the late settlement more accurately than the hyperbolic model.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1

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