真空预压法在吹填陆域软基工程中的加固效果研究

发布时间：2018-06-19 12:37

本文选题：真空预压法 + 吹填土　；参考：《武汉理工大学》2014年硕士论文

【摘要】：近些年来，随着沿海城市的高速发展以及对外开放步伐的不断加快，沿海城市对于土地需求日益迫切。而我国海岸线绵长，海域资源非常丰富。因此吹填陆域、围海造陆成为城市发展的必经之路。所谓吹填土，是在整治和疏通江河航道时，用挖泥船和泥浆泵把江河和港口底部淤积的泥砂通过水力吹填而形成的沉积土，其工程性质呈现三高一低，即天然含水量高、孔隙比大、压缩性高、抗剪强度低、渗透系数小的特性。为了改善其工程性质，提高吹填土的承载力，工程实践中，常采用真空预压法处理吹填土软土地基。真空预压法是利用大气压力为预压荷载的一种排水固结法，它由抽气系统、排水（气）系统和密封系统，三部分组成。其具有加固周期短、加固效果良好、经济效益明显、适用于大面积软土地基加过等特点，在处理吹填土软土地基工程中得到了广泛的运用。因此，对于真空预压法在吹填土软基工程中的加固效果、施工工艺的优化设计的研究，具有重要的实践指导意义。本文首先对于真空预压的加固机理进行了详尽的阐述，对于基于ABAQUS有限元计算的本构模型做了详细介绍，，其次结合连云港地区某吹填陆域软基处理工程的实际情况，通过现场测量获取孔隙压力、沉降位移等相关加固效果的实测数据；再通过有限元软件ABAQUS对真空预压过程进行模拟，对比分析研究不同施工条件下的加固效果，得出如下结论：（1）在连云港某吹填陆域软基处理工程中，真空预压法的工程设计及工程施工方法、工艺取得了比较理想的加固效果，满足规范和设计的要求。（2）塑料排水板的打设间距和加固区的地基形状系数对真空预压法的加固效果都有较大的影响。随着塑料排水板的打设间距减小和加固区地基形状系数增大，真空预压加固效果有了明显的提高。这时就要根据具体情况，考虑经济效益选取合理的组合。（3）施工中加固区密封的、真空度的稳定性、垂直排水通道对于真空预压法的加固效果都会产生影响。加固区密封到位，抽真空工作稳定、正常，垂直排水通道顺畅，这些将会大大提高膜下真空度的传递效率，减少真空度的损失，提升加固效果。
[Abstract]:In recent years, with the rapid development of coastal cities and the accelerated pace of opening to the outside world, the demand for land in coastal cities is becoming increasingly urgent. But our country coastline is long, the sea area resources is very rich. Therefore, fill the land, land reclamation become the only way to urban development. When dredging and dredging the channel of rivers and rivers, dredgers and mud pumps are used to fill the silt sand deposited at the bottom of rivers and ports through hydraulic filling. Its engineering properties are three high and one low, that is, the natural water content is high. High porosity, high compressibility, low shear strength and low permeability. In order to improve the engineering properties and increase the bearing capacity of the filled soil, the vacuum preloading method is often used in engineering practice. Vacuum preloading is a kind of drainage consolidation method which uses atmospheric pressure as preloading load. It consists of three parts: air extraction system, drainage system and sealing system. It has the characteristics of short reinforcement period, good reinforcement effect, obvious economic benefit, suitable for large area soft soil foundation and so on. It has been widely used in the treatment of soft soil foundation engineering of blow fill. Therefore, it is of great practical significance to study the reinforcement effect of vacuum preloading method and the optimum design of construction technology in the soft foundation engineering of blow fill. In this paper, the reinforcement mechanism of vacuum preloading is described in detail, and the constitutive model based on Abaqus finite element calculation is introduced in detail. The measured data of pore pressure, settlement displacement and other related reinforcement effects are obtained by field measurement, and the vacuum preloading process is simulated by finite element software Abaqus, and the reinforcement effect under different construction conditions is compared and analyzed. The conclusions are as follows: (1) in the engineering design and construction method of vacuum preloading method, ideal reinforcement effect has been obtained in a soft foundation treatment project in Lianyungang. It meets the requirements of specification and design. 2) the spacing of plastic drainage plate and the foundation shape coefficient of the strengthened area have great influence on the reinforcement effect of vacuum preloading method. With the decrease of the spacing between the plastic drains and the increase of the foundation shape coefficient, the effect of vacuum preloading is improved obviously. According to the concrete situation, the reasonable combination of economic benefit should be considered. The stability of vacuum degree and the stability of vacuum degree in the strengthened area during construction, and the vertical drainage channel will affect the reinforcement effect of vacuum preloading method. The strengthened area is sealed in place, the vacuum pumping is stable, normal, and the vertical drainage channel is smooth, which will greatly improve the transfer efficiency of vacuum under the film, reduce the loss of vacuum, and enhance the reinforcement effect.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U655.544.4

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