A research of failure mechanism of tropical expansion soil in Africa and its countermeasure of symbiosis with nature

广泛分布于非洲赤道地区的一种热带膨胀土：泥灰土，在岩土工程领域具有体积变化的特点。雨季由于水分高，泥炭体积增大，旱季泥炭体积减小。由于下部建筑物的重量不能承受膨胀压力，收缩和膨胀引起的变形会引起差异沉降和膨胀。通过对达喀尔周边地区的实地调查，根据建筑物类型、建筑物损坏类型和地质条件对影响因素进行了调查。此外，还从达喀尔主要受灾地区收集了样本。为了了解Marl的物理机械性能和微观结构，将样品运往日本，并在日本进行了实验室测试。根据这些测试的结果，详细研究了Marl的主要特征。由于泥灰岩的力学特性随着含水率的变化而变化，L…在不同含水率下进行了更多的流产试验。本文研究了高含水率条件下土体的强度折减和膨胀性，以及排水条件下强度和膨胀性的恢复。本研究的实际目的是建立达喀尔地区土袋加固地基的施工方法。为了验证土袋作为地基处理方法(SOLPACK法)的有效性，进行了土袋的各种试验。在实验结果的基础上，研究了Solpack方法的适用性，并进行了数值模拟。通过一系列的研究，提出并制定了索尔帕克法的设计标准和手册。为了将索尔帕克法应用于达喀尔地区，达喀尔市与达喀尔地区的管理工程师、建设者、达喀尔地区的研究人员和达喀尔大学的法尔教授举行了技术会议。索尔帕克方法是为达喀尔地区的研究人员和工程技术人员提出的，它是为适应不同地区的具体情况而建立的。预计未来将由这些地区的研究人员为当地制定详细的设计手册。较少

A kind of tropical expansion soil : Marl that widely spread in equatorial area of Africa has a feature of volumetric change in geotechnical field. The volume of Marl increase due to high moisture in rainy season, on the other hand the volume is reduced in dry season. As the weights of lower building do not have bearing resistance against swelling pressure, the deformation caused by shrinkage and expansion invoke differential settling and swelling. From the field investigations around Dakar, factors are investigated based on the type of building, type of damage for building and geological condition. In addition, samples are collected from the major-damaged area in Dakar. In order to understand the physical and mechanical properties and microstructure of Marl, the samples were shipped to Japan and laboratory tests were carried out in Japan. From the results of those tests, the main features of Marl is investigated in detail. As the mechanical feature of Marl changed with water content, l … More aboratory tests were conducted under various water contents. The reduction of strength and the swelling character in high water content condition andtherecovery of strength and swelling character under drainage condition are studied in the research.The practical goal of this research is to establish the construction method to improve the ground stiffness using soil bag in Dakar area. In order to confirm the effectiveness of soil bag as the ground improving method (Solpack-method), various tests using soil bag were conducted. Based on the experimental results, the applicability of Solpack-method is investigated and numerical simulations are carried out in addition. From a series of research, a standard and a manual for design of Solpack-method is proposed and established.In order to apply the Solpack-method in Dakar area, technical meetings are held in Dakar city with engineers of administration, builders, researchers in Dakar area and Professor Fall of Dakar University. Solpack-method, which is established to apply for various local regions in detail, is proposed for researchers and engineers in Dakar area. It is expected to develop the detail manual of design for local area by the researchers in those areas for the future. Less