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Theoretical and experimental study on seepage failure mechanism of soil in three-dimensions

三维土体渗流破坏机理理论与试验研究

基本信息

批准号：
14360142
负责人：
TANAKA Tsutomu
金额：
$ 5.25万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

In excavation of soil with a high groundwater level, seepage failure such as piping, boiling etc. is a problem at the base of excavation. Seepage failure occurs even in recent days when technology has proceeded. Because an in situ condition is usually three dimensional, the seepage failure problem should be treated three dimensionally. Seepage flow problems should be discussed from a view point of flow conditions such as one-dimensional flow, two-dimensional flow (2Dflow), two-dimensional concentrated flow (2DCflow), axisymmetric concentrated flow (AXSflow), two-dimensional radial flow and axisymmetric radial flow. In this study, the seepage failure of soil was discussed for the AXSflow as a model of three dimensional flow.From a theoretical point of view, the prismatic failure concept was extended for an axisymmetric seepage flow condition. Seepage flow patterns and critical hydraulic head differences H_c were discussed for 2Dflow, 2DCflow and AXSflow conditions. The effects of three- … More dimensional concentration of seepage flow on equi-potential lines, critical hydraulic head differences H_c, modes of failure etc. were clarified.Seepage failure tests were conducted for 25 cases in the AXSflow condition. Changes of Equi-potential lines, changes of modes of soil with increase in a hydraulic head difference H were considered. H- Q_<15> relationships, hydraulic head differences at deformation, hydraulic head differences at failure were also clarified.Case studies are necessary for improvement of the theory of seepage failure. From case studies, it is important to understand the situation of seepage flow through soil, clarify the causes of failure and find out preventive methods against seepage failure. The following three case studies were here discussed : (1) A case study on boiling in excavation of subsoil for Daiichi-Shinkawa bridge pier, (2) Blow-out of soil particles during construction of a caisson type pile (K-line bridge abutments construction), (3) Stability for seepage failure of excavated soil within Misono Shaft.A lot of problems have remained in the present theory of seepage failure. The case studies are important for application of the theory to practice as well as the theoretical and experimental studies. Based on the results obtained here, it is necessary to establish the theory of seepage failure comprehensively. Less

在地下水位较高的土体开挖过程中，管道、沸腾等渗漏故障是开挖基础上存在的问题。即使在技术进步的最近几天，渗漏故障也会发生。由于原位条件通常是三维的，因此渗流破坏问题应该三维地处理。渗流问题应从一维流、二维流（2Dflow）、二维集中流（2DCflow）、轴对称集中流（AXSflow）、二维径向流和轴对称径向流等流动条件的角度来讨论。在本研究中，以 AXSflow 作为三维流模型讨论了土壤的渗流破坏。从理论角度来看，棱柱形破坏概念被扩展到轴对称渗流条件。讨论了 2Dflow、2DCflow 和 AXSflow 条件下的渗流模式和临界水头差 H_c。明确了渗流三维浓度对等势线、临界水头差H_c、破坏模式等的影响。在AXSflow工况下进行了25例渗流破坏试验。考虑了等位线的变化、土壤模态随着水头差H的增加而变化。还阐明了H-Q_<15>关系、变形时的水头差、破坏时的水头差。案例研究对于完善渗流破坏理论是必要的。通过案例研究，了解渗流通过土壤的情况，明确渗流破坏的原因，找出渗流破坏的预防方法具有重要意义。这里讨论了以下三个案例研究：（1）第一新川大桥桥墩底土开挖沸腾案例研究，（2）沉箱式桩（K线桥台施工）施工过程中土壤颗粒的吹出，（3）Misono竖井内开挖土体渗流破坏的稳定性。目前的渗流破坏理论仍然存在许多问题。案例研究对于理论应用到实践以及理论和实验研究都很重要。基于这里获得的结果，有必要全面建立渗流破坏理论。较少的