真空井点降水、挤密砂桩联合浅层强夯在软基处理中的应用  

Application of vacuum well point dewatering and sand compaction pile combined with dynamic compaction method in soft foundation treatment

作　　者：姚宝宽 刘聪 李全军 李传勋[2] YAO Bao-kuan;LIU Cong;LI Quan-jun;LI Chuan-xun(The Third Geological Brigade of Jiangsu Geology and Mineral Bureau,Zhenjiang 212111,China;College of Civil Engineering and Mechanics,Jiangsu University,Zhenjiang 212013,China)

机构地区：[1]江苏省地矿局第三地质大队,江苏镇江212111 [2]江苏大学土木工程与力学学院,江苏镇江212013

出　　处：《地基处理》2021年第2期118-125,共8页Journal of Ground Improvement

摘　　要：真空井点降水、挤密砂桩及强夯均是软基处理的经典方法,但这些方法单一应用于软基处理时均存在一定的缺陷。真空井点降水对地基承载力提高幅度有限,挤密砂桩复合地基承载力取决于桩周土体的强度,强夯在土体强度偏低时适用性往往受到限制等。鉴于此,以福建永荣科技二期场地软基处理为工程背景,将真空井点降水、挤密砂桩和浅层强夯三种软基处理工法进行有机结合,形成一种复合式挤密砂桩软基处理方法以克服单一方法中的缺陷。通过结合实际工程详细阐述了该复合工法的方案设计、施工工艺,并通过软土施工前后的静力触探试验、十字板剪切试验、土工试验及载荷试验,深入分析了加固前与加固后土体相关指标变化情况。试验结果表明,加固后的地基土体各项物理参数均达到设计要求,其中含水率降低44%,孔隙比降低38%,软土地基承载力达到200 kPa,最大试验荷载作用下的试点沉降量小于15 cm,锥尖阻力、锥侧阻力与抗剪强度得到大幅度提高。与传统单一加固方法相比,这种复合式挤密砂桩的地基处理方法能充分发挥各方法的加固优势,既达到快速排水固结的目的,同时还较大幅度地提高了地基承载力,软土地基的工后沉降也明显减少。Vacuum well point dewatering,sand compaction pile and dynamic compaction are all classic methods for soft foundation treatment,but these methods have certain defects when they are applied separately.The vacuum well point dewatering has a limited improvement in the bearing capacity of the foundation.The bearing capacity of the compacted sand piles composite foundation depends on the strength of the soil around the pile.While the applicability of dynamic compaction is often limited when the strength of the soil is low.This paper combines the three soft foundation treatment methods together and applied in the soft foundation treatment of Fujian Yongrong Science and Technology Phase II site.This combination can overcome the defects of a single method.Combined with the actual project,the scheme design and construction technology of the composite construction method are elaborated in detail.Through the static penetration test,cross plate shear test,soil test and load test before and after treatment,the change of soil properties related indexes is deeply analyzed.The test results showed that all the physical parameters of the reinforced foundation soil met the design requirements.The water content is reduced by 44%,the void ratio is reduced by 38%,and the bearing capacity of the soft soil foundation reaches 200 kPa.The pilot settlement of the foundation under the maximum test load is less than 15 cm.The cone tip resistance,cone side resistance and shear strength have also been greatly improved.In contrast to the traditional single reinforcement method,this composite method fully uses the reinforcement advantages of each method,which not only achieves the purpose of rapid drainage and consolidation,but also greatly improves the bearing capacity of the foundation.The residual settlement of soft soil foundations is also decreased.

关 键 词：井点降水 挤密砂桩 强夯 软基处理 联合加固 

分 类 号：TU472[建筑科学—结构工程]