滨海相沉积软土地基处理及沉降预测研究

发布时间：2018-05-25 21:37

本文选题：地基沉降 + 地基处理　；参考：《北京交通大学》2017年硕士论文

【摘要】：在我国东南沿海地区广泛分布着滨海相软土。这类软土含水量高、强度低、压缩性大、渗透性差。如果在这类软土上修建道路,包括公路、铁路等,则会造成路基开裂、不均匀沉降等严重工程事故。特别是对于一些大面积深厚软土地区,地基处理结果将影响工程的进度、投资和质量,所以针对此类工程要进行相应的场地试验或修建试验段,制定不同的地基处理方案,并对处理结果进行对比与分析,得到最佳的加固方式,为之后的施工提供指导。福建省某港区地处滨海滩涂地,地质勘察报告表明地表以下为滨海相沉积软土。由于港区场地及道路扩建,需要进行地基加固处理。因此,本文以该工程建设中软土地基处理为背景,结合场地环境,制定了六种地基处理方案,通过现场试验、现场监测、原位测试、室内试验等手段,经分析得到不同处理方案之间的差异和优劣。最后采用FLAC3D数值模拟与神经网络相结合的方法预测了运营期的工后沉降。为此,本文做了如下工作:(1)根据工程质量总体目标,应先修建试验段,本文考虑了防护区和路基区两种情况,分别在各自区域内划分出三个试验段,共对应六种不同的软基处理方案。在试验过程中对其进行现场监测,得到不同处理方案下地基的沉降规律,为后期的方案对比提供依据。(2)为了分析不同处理方案的效果,在该工程各试验段上进行原位测试,包括十字板剪切试验和静力触探试验,得到地基处理前后的强度及承载能力变化规律。通过钻孔取样及室内土工试验,得到了地基处理前后的土体力学参数,为后面的沉降预测提供依据。(3)选取最具代表性的三种地基排水固结处理方案进行分析,分别对应试验段2(排水板堆载预压)、试验段3(真空联合排水板)和试验段6(堆载预压和砂桩堆载预压)。以现场监测数据为依据,结合原位测试及室内试验结果,采用FLAC3D数值模拟与神经网络相结合的方法,估算了地基处理期间的前期沉降,并在此基础上对运营期的工后沉降进行分析预测。该工程在福建沿海滩涂地区中极具典型意义,相应的试验过程及沉降预测方法也有着实际意义,为以后类似条件下的软基工程提供了积极的参考价值。
[Abstract]:Coastal soft soil is widely distributed in the southeast coastal area of China. This kind of soft soil has high water content, low strength, large compressibility and poor permeability. If a road is built on such soft soil, including roads and railways, it will cause serious engineering accidents such as subgrade cracking and uneven settlement. Especially for some large areas of deep soft soil, the result of foundation treatment will affect the progress, investment and quality of the project. The results of treatment are compared and analyzed, and the best reinforcement method is obtained, which provides guidance for later construction. A harbor area in Fujian Province is located in the coastal beach. The geological survey report shows that the surface below the surface is coastal and marine sedimentary soft soil. Due to the expansion of the site and road in the port area, it is necessary to strengthen the foundation. Therefore, based on the soft soil foundation treatment in the construction of the project and combining with the site environment, six kinds of foundation treatment schemes have been developed, such as field test, field monitoring, in-situ test, indoor test and so on. The differences between different treatment schemes and their advantages and disadvantages are obtained by analysis. Finally, the method of combining FLAC3D numerical simulation and neural network is used to predict the post-construction settlement in operation period. Therefore, this paper has done the following work: (1) according to the overall goal of engineering quality, the test section should be built first. There are six different soft foundation treatment schemes. In order to analyze the effect of different treatment schemes, the in-situ test was carried out on each test section of the project. Including cross plate shear test and static penetration test, the change law of strength and bearing capacity before and after foundation treatment is obtained. The mechanical parameters of soil before and after foundation treatment are obtained through borehole sampling and laboratory geotechnical tests. It corresponds to test section 2 (drain plate preloading), test section 3 (vacuum combined drainage board) and test section 6 (surcharge preloading and sand pile loading preloading) respectively. Based on field monitoring data, combined with in-situ test and indoor test results, the pre-settlement during foundation treatment was estimated by combining FLAC3D numerical simulation with neural network. On this basis, the post-construction settlement in operation period is analyzed and forecasted. The project is of typical significance in the coastal shoal area of Fujian Province, and the corresponding test process and settlement prediction method are also of practical significance, which provides a positive reference value for the soft foundation engineering under similar conditions in the future.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU447;TU433

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