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工程科学与技术:2019,51(2):90-97
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基于连续排水边界条件的砂井地基固结解析解
(1.中国地质大学 工程学院, 湖北 武汉 430074;2.广西大学 土木建筑工程学院, 广西 南宁 530004)
Analytical Solution of Sand-drained Ground Consolidation Based on Continuous Drainage Boundary
(1.Faculty of Eng., China Univ. of Geosciences, Wuhan 430074, China;2.College of Civil Eng. and Architecture, Guangxi Univ., Nanning 530004, China)
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投稿时间:2018-06-13    修订日期:2019-01-10
中文摘要: 为弥补瞬时恒定荷载下传统砂井固结理论中边界条件存在的缺陷,首先,通过引入连续排水边界条件,采用特征函数法对砂井地基3维固结方程进行解答,得到考虑涂抹及井阻效应的解析解。然后,通过对解析解的退化,与既有的研究结果对比,验证所得解的正确性。最后,根据所得解析解对砂井地基在连续排水边界条件下的超孔隙水压力及平均固结度进行分析。分析结果表明:连续排水边界条件可以通过改变界面参数b值的大小,实现从完全不排水到完全排水整个过程的表达,从而对传统砂井固结理论进行补充。在超孔隙水压力方面,随着b值的减小,地基表面排水能力降低,在地基顶面处,也逐渐出现一定的超孔隙水压力,且b越小,顶面处的超孔隙水压力越大;在同一水平面处,距离砂井越远,孔压越大。在固结度方面,随着b的减小,地基平均固结度显著降低,故传统固结理论中的顶面完全排水条件,可能会高估地基的实际固结速度。涂抹区以及砂井中渗透系数的降低均会显著降低地基固结速度,所以,施工中应减小对井壁土体的扰动,增加竖井的渗流能力,以减弱涂抹和井阻效应。尽管砂井地基以径向渗流为主,但竖向渗流对地基的固结也有较大影响,忽略其作用可能会导致地基的固结沉降预测速度被低估。
Abstract:For the limitations of the boundary condition under instantaneous constant load in traditional sand-drained consolidation theory, the three-dimensional consolidation equation of sand-drained ground was solved based on the continuous drainage boundary. And the analytical solution considering the effects of smear and well resistance was obtained. Then, the rationality of the solution was verified by degenerating and comparing the analytic solution with the existing research results. Finally, the excess pore water pressure and average consolidation degree of sand-drained ground under continuous drainage boundary conditions were analyzed according to the analytical solution. The results showed that the continuous drainage boundary condition realizes the whole process from impermeable to completely permeable by changing the value of interface parameter b, which compensates for the shortcoming of traditional boundary. In terms of the excess pore water pressure, the drainage capacity of ground surface is reduced with the decrease of the value of b. Therefore, the excess pore water pressure exists at the top surface of the ground, and the smaller the b is, the greater the excess pore water pressure is. Meanwhile, the pore pressure increases with the enhancing distance from the sand-drained at the same plane. As for the consolidation degree, the average consolidation degree of the ground decreases with the decrease of b. So, the consolidation rate of the ground may be overestimated under the complete drainage condition of the traditional consolidation theory. Moreover, the consolidation rate of the foundation would be significantly reduced with the decrease of the permeability coefficient in the smear area and the sand well. Therefore, the disturbance to the soil of the well wall should be reduced and the seepage capacity of the vertical drainage should be increased to weaken the smear effect and the well resistance. In addition, the rates of settlements and consolidation will be underestimated if the vertical seepage is ignored, although the radial seepage is dominant in sand-drain.
文章编号:201800677     中图分类号:TU470    文献标志码:
基金项目:国家自然科学基金资助项目(51578164;51678547)
作者简介:张驿(1990-),男,博士生.研究方向:地基处理;软土加固.E-mail:645812313@qq.com
引用文本:
张驿,吴文兵,梅国雄,段隆臣.基于连续排水边界条件的砂井地基固结解析解[J].工程科学与技术,2019,51(2):90-97.
ZHANG Yi,WU Wenbing,MEI Guoxiong,DUAN Longchen.Analytical Solution of Sand-drained Ground Consolidation Based on Continuous Drainage Boundary[J].Advanced Engineering Sciences,2019,51(2):90-97.