止水帷幕在深基坑支护及降水中的作用效果研究

发布时间：2018-05-17 16:06

本文选题：深基坑 + 止水帷幕　；参考：《山东大学》2015年硕士论文

【摘要】：我国目前正处于经济建设高速发展的时期,城市化水平的稳步提高使得城市中建筑用地日趋紧张。越来越多的基坑工程应运而生,其中不乏大型深基坑。在深基坑设计及施工中,设置好止水帷幕是不可或缺的-环。止水帷幕在基坑降水中的作用是延缓或者阻止地下水流向基坑内,以此避免因地下水位下降而造成的基坑外围地面沉降；同时保证基坑内部基本干燥,便于施工。绝大多数的止水帷幕设计都是为了获得最好的止水效果,而很少从力学角度考虑其合理性。本文从力学理论出发,利用FLAC3D软件对基坑开挖支护全过程进行模拟,并在开挖后对基坑顶部加载。通过对比多种工况,用一系列数据分析止水帷幕的力学作用,探讨止水帷幕在不同位置、弹性模量、厚度等工况下对基坑位移和土钉轴力的影响。目前在有止水帷幕时的基坑降水设计中,还没有能准确计算出与工程实际相符合的水位降深与抽水量的理论公式,本文利用ABAQUS软件对基坑降水进行模拟,通过对比多种工况在降水60天后的结果,探讨止水帷幕在不同插入深度下对孔隙水压力场、基坑内外水位降深、降水影响半径及基坑涌水量的影响。最后通过分析目前降水设计中常用的井点(管井)降水理论,结合数值模拟的结果,讨论现有公式在基坑降水设计中的实用性并提出存在止水帷幕时基坑涌水量的计算方法。
[Abstract]:At present, China is in the period of rapid development of economic construction. The steady improvement of urbanization level makes the construction land in cities increasingly tense. More and more foundation pit projects emerge as the times require, including large deep foundation pit. In the design and construction of deep foundation pit, it is indispensable to set up water-proof curtain. The function of the waterproof curtain in the dewatering of foundation pit is to delay or prevent the groundwater flowing into the foundation pit, so as to avoid the ground subsidence around the foundation pit caused by the decrease of groundwater level, and at the same time, to ensure the basic dryness of the foundation pit interior and facilitate the construction. Most of the watertight curtain are designed to obtain the best sealing effect, but rarely consider its rationality from the mechanical point of view. Based on the theory of mechanics, this paper simulates the whole process of excavation support by using FLAC3D software, and loads the top of foundation pit after excavation. By comparing various working conditions and analyzing the mechanical function of the waterproof curtain with a series of data, the influence of the curtain on the displacement of foundation pit and the axial force of soil nailing under different working conditions, such as elastic modulus and thickness, is discussed. At present, in the dewatering design of foundation pit with watertight curtain, there is no theoretical formula for calculating the water level drop and pumping volume which is in accordance with the engineering practice. In this paper, the foundation pit dewatering is simulated by ABAQUS software. By comparing the results of various working conditions after 60 days of precipitation, this paper discusses the influence of water stop curtain on the pore water pressure field, the depth of water level inside and outside the foundation pit, the influence radius of dewatering and the water discharge of foundation pit at different insertion depths. Finally, through the analysis of well point (pipe well) dewatering theory commonly used in dewatering design at present, combining with the results of numerical simulation, the practicability of existing formulas in foundation pit dewatering design is discussed, and the calculation method of foundation pit water discharge in the presence of waterproof curtain is put forward.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU753

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