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工程科学与技术:2018,50(2):32-41
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半透水边界砂井地基的真空预压固结解
(浙江大学 滨海和城市岩土工程研究中心, 浙江 杭州 310058)
Consolidation Solution for Sand-drained Ground with Impeded Boundaries Under Vacuum Preloading
(Research Center of Coastal and Urban Geotechnical Eng.,Zhejiang Univ.,Hangzhou 310058,China)
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投稿时间:2017-08-01    修订日期:2017-12-31
中文摘要: 针对砂井地基顶部存在垫层和底部存在下卧层的现状,采用半透水边界反映其对砂井地基固结的影响。假定地基变形符合等应变条件,考虑水平向渗透系数沿半径发生变化,建立上下边界为半透水边界时真空预压砂井地基的固结理论,通过分离变量法获得固结度和沉降的级数解析解答,分析底部透水系数、顶部透水系数、井阻、渗透系数沿半径分布特性对砂井地基固结度和沉降的影响规律。研究表明:当底部半透水时,最终负孔压和有效应力呈沿地基深度衰减的变化规律。当其他条件相同时,底部透水系数越大的地基固结度越大,但最终沉降和径向固结时间因子相同时的固结沉降却越小。当底部边界不透水时,最终沉降不会随着顶部透水系数改变而改变,但当底部边界半透水或完全透水时,最终沉降随着顶部透水系数增大而增大;顶部透水系数越大的地基固结度越大,径向固结时间因子相同时的固结沉降也越大。均匀井阻的大小不会影响负压最终竖向分布特性,也不会改变最终沉降,但会明显降低砂井地基固结度,延长固结完成时间。渗透系数径向分布模式会对砂井地基的固结度产生影响;其中不考虑涂抹作用的工况1计算的固结度最大,假定涂抹区渗透系数恒定的工况2计算的固结度最小,假定涂抹区内渗透系数向原状土渗透系数线性过渡的工况3计算的固结度介于两者之间。半透水边界对真空预压砂井地基固结过程的影响规律与堆载预压砂井地基相比存在明显不同。
Abstract:Since the cushion generally exists on the top and a substratum below the bottom of sand-drained ground,impeded boundaries were used to describe its effect on consolidation process of sand-drained ground.Assuming that ground deformation satisfies the condition of equal vertical strain and considering the radial variation of horizontal permeability coefficient,consolidation theory was established for sand-drained ground with top and bottom impeded boundaries under vacuum preloading.The series analytical solutions of consolidation degree and settlement were achieved by the separated variable method.The effect of the pervious coefficient of top boundary,the pervious coefficient of bottom boundary,the well resistance and the radial distribution feature of permeability coefficient on the consolidation degree and settlement of sand-drained ground were analyzed.The researches show that the final negative pore pressure and the effective stress exhibit a decrease with increasing depth of ground.When the other conditions are same,the ground with big bottom pervious coefficient has big consolidation degree,while it has small final settlement and the consolidation settlement at same radial consolidation time factor.When the bottom boundary of ground is impervious,the final settlement of ground hardlychange with the top pervious coefficient,but when the bottom boundary of ground is impeded or completely permeable,the final settlement increases with top pervious coefficient.The ground with big top pervious coefficient has big consolidation degree and consolidation settlement at the same radial consolidation time factor.Resistance of sand drain neither affect the final vertical distribution features of negative pressure,nor change the magnitude of the final settlement,while the resistance of sand drain can significantly decreases the consolidation degree of sand-drained ground and extends the finish time of consolidation.The radial distribution mode of permeability coefficient affects the consolidation degree of sand-drained ground.The consolidation degree of mode 1 is the biggest,mode 2 is the smallest,and mode 3 falls between mode 1 and mode 2.The effect laws of impeded boundary on the consolidation process of sand-drained ground under vacuum preloading are obviously different from those under surcharged preloading.
文章编号:201700610     中图分类号:TU472.33    文献标志码:
基金项目:国家自然科学基金资助项目(51178419)
作者简介:胡亚元(1968-),男,副教授,博士.研究方向:地基处理;土的本构关系和多场耦合作用.E-mail:huyayuan@zju.edu.cn
引用文本:
胡亚元.半透水边界砂井地基的真空预压固结解[J].工程科学与技术,2018,50(2):32-41.
HU Yayuan.Consolidation Solution for Sand-drained Ground with Impeded Boundaries Under Vacuum Preloading[J].Advanced Engineering Sciences,2018,50(2):32-41.