Study on Mechanism of Piping and Its Preventive Methods

管道损坏机理及预防方法研究

基本信息

批准号：
07556053
负责人：
TANAKA Tsutomu
金额：
$ 4.48万
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：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07556053/
关键词：
Seepage flow Piping Seepage failure Two-dimensional seepage failure test Anisotropy Prismatic failure Cofferdam Excavation

项目摘要

Seepage failure is a problem in hydraulic structures, cofferdams at the location of high ground water level. Once the seepage failure occurs, it causes serious damage to the work itself and/or neibouring places from the economical point of view. There are still many problems unknown, in the seepage failure phenomena, which have to be made clear.In this study, the seepage failure problem of soil within a cofferdam was mainly considered. First the existant theries of seepage failure given by Harza and Terzaghi are investigated precisely, and Prismatic failure -A new method of calculating stability against boiling of sand within a cofferdam is presented. Typical three examples (isotropic and antisotropic one-layred soils, and two-layred soil) were analyzed using these theories, and the characteristics of these theories of seepage failure were then clarified precisely.Second eight examples of case histories on seepage failure were reported and analytical considerations of these problems we … More re given. The possible causes of seepage failures for these examples were discussed and classified as follows : (1) Desige was mistaken or wrong countermeasures were taken. (2) Unexpected situation occurred. (3) Creep length was too short. (4) Inhomogeneous subsoil (including multi-layred soil) was encountered. (5) Seepage flow concentrated three dimensionally into the soil surrounded by a cofferdam. (6) Permeability of soil was highly anisotropic. (7) Rock foundation was weathering in deep excavation. (8) Seepage flow concentrated into the end of a structure constructed within a cofferdam during dewatering. (9) Filter was clogging with the passage of time.Finally, 47 cases of experiments were made on seepage failure of soil within a cofferdam. Analysing the state of soil (homogeneity, anisotropy of soil), changes in formation of soil surface and distribution of equipotentials, the relationship between hydrautic head difference and discharge, hydraulic head differences at which soil starts being deformed and failure occurrs, and angle of repose of soil in water. The hydraulic head difference at which the soil starts being deformed is estimated from Prismatic failure (Friction). Relative density of soil makes effects on modes of failure, hydraulic head differences at being deformed and at failure. Less

渗透失败是氢化结构，高地下水位位置的Cofferdams的问题。一旦发生渗漏故障，它就会从经济角度对工作本身和/或新型位置造成严重破坏。在渗漏失败现象中，仍然有许多未知的问题，必须明确。在这项研究中，主要考虑了Cofferdam内部土壤的渗漏衰竭问题。首先，精确研究了Harza和Terzaghi给出的现有的渗漏故障理论，并进行了棱柱状故障 - 一种新的计算稳定性的方法，以抗Cofferdam内的沙子沸腾。使用这些理论分析了典型的三个例子（各向同性和抗智性一层土壤以及两层土壤），然后精确地阐明了这些渗透衰竭理论的特征。报道了第二八个案例历史史的例子，并报告了这些问题的分析考虑。我们……更多。讨论了这些示例的渗漏失败的可能原因，并分类如下：（1）索引被误认为是错误或错误的对策。（2）发生意外情况。（3）蠕变长度太短。（4）遇到了不均匀的地下土（包括多层土壤）。（5）渗流将三维集中在Cofferdam周围的土壤中。（6）土壤的渗透性高度各向异性。（7）岩石基金会在深入的发掘中处于风化状态。（8）渗流集中在脱水过程中Cofferdam内构建的结构的末端。（9）过滤器随着时间的流逝而堵塞。在最后，在Cofferdam内部土壤的渗漏失败时进行了47例实验。分析土壤状态（均匀性，土壤各向异性），土壤表面的形成和等效分布的变化，液压头差与排放之间的关系，液压头差异，土壤开始变形和破坏的液压头差异以及水中静止的角度。从棱镜衰竭（摩擦）估计土壤开始变形的水力头差。土壤的相对密度对故障模式，液压头部差异和失败时产生影响。较少的