【作者】 罗杰；

【导师】 隆威；

【作者基本信息】 中南大学 ， 地质工程， 2011， 硕士

【摘要】 近年来,随着我国城市建设的发展,基坑工程大量涌现,开挖深度不断增加,使基坑朝着超大超深的规模发展,由此也带来了许多基坑稳定性问题。研究表明,地下水是影响基坑稳定性主要的因素,尤其在沿海地区,地下水是导致基坑工程事故发生直接的原因之一。基坑工程在开挖施工时,若基底有承压水含水层则易产生基底突涌、基底隆起、管涌或流砂等工程事故。本文主要研究承压水对深基坑底部及周围的影响,采用有限元软件Plaxis模拟分析基坑突涌和渗流对深基坑的影响。由于实际工程在沿海地区,土体主要为粘性土,则在模拟计算时采用软土蠕变模型模拟土体,并对软土蠕变模型进行试验验证,确保模拟的土体与实际情况相符。因为目前设计方法中采用压力平衡法时未考虑土体的抗剪强度,在模拟深基坑抗突涌时采用均质连续体法。对深基坑的渗流模拟得出土层在含有潜水及承压水的情况下,根据有效应力原理计算出的抗渗系数则更接近于实际情况。对实际工程的模拟分析得出深基坑的开挖降水对基坑及其周围的影响很大,其中降水能够提高土的物理力学性质指标,增加土体的有效应力,但是也会引起基坑底部土体的附加沉降。更多还原

【Abstract】 In recent years, with the development of urban construction, excavation engineering have proliferated and the excavation of the foundation pit is much deeper. It makes the scale of excavation engineering be much larger,and also brings more problems about the stability of foundation pit.According to the research, the important factor of stability is the groundwater. It is one of the direct cause of foundation stability in coastal areas vigorously. The confined aquifer under the basement will be easy to cause inrush, basement uplift, piping or the flow of sand and other engineering accident in the excavation of foundation.This paper studies the influence of confined groundwater on the bottom of deep foundation and the surrounding, simulates and analyzes the inrush of foundation pit and the influence of seepage flow by using Plaxis.Using the soft soil creep model to simulate the soil as the actual works in coastal areas,because the chief soil is clay in that areas. Author tested and verified the soft soil creep model through the full size field test to ensure the simulation consistents with the actual situation. Because the pressure balance method in current design manual does not take the shear strength of soil into account, author used the homogeneous continuum method instead of the pressure balance method in the simulation on the anti-inrushing stability of deep foundation pit. According to the simulation of seepage flow, the permeability coefficient which calculated based on the principle of effective stress is more close to the actual situation when the groundwater exists in soil layer. According to the simulation and analysis of the actual project,the excavation pit and dewatering has great impact on foundation and its surrounding. Dewatering can improve the indicators of physical and mechanical properties of soil and increase the effective stress of soil.While it also lead to additional settlement of the soil at the bottom of the pit更多还原