A Study of Slope Stabilization Method in Land Reclamation

目前，日本正在进行土地复垦，但在花岗岩土分解区边坡稳定造成了水土保持问题。土地复垦的设计不能千篇一律，因为分解后的花岗岩土在水、风化作用下不稳定，而且其矿物成分也因地区而异。对部分复垦地的花岗岩土进行了分解试验，为各地区合理的复垦方法提供了基础数据。根据不同的风化程度，研究了它们的科学和工程性能。因此，它们的科学和工程性质，如土壤级配、抗剪强度和渗透性，会受到矿物成分和风化程度的影响和改变。抗剪强度随含水率的增加而降低。因此，排水方式是影响花岗岩腐土区复垦的最重要因素。即，由于分解后的花岗岩土易受水的破坏和侵蚀，必须通过防水蚀和农作进行快速、安全的排水。提出了泉水排水施工对策对地基稳定性和排水系统设计的着眼点。在此基础上，提出了利用点表法确定土地复垦涵养方案的新型有益的防灾组合方法。需要解决的重要问题是规划采取相应区域的排水和堤防措施，我们认为本研究的结果具有新的观点，可以为分解花岗岩土地区的土地复垦和保护做出科学和技术上的贡献。

Now land reclamation is carried out in Japan, but slope stabilization on the decomposed granite soils area causes problems during land conservation.The design of land reclamation can't be practiced in the same pattern, for the decomposed granite soils are unstable on action of water, weathering, and also components of its minerals differ from region to region.Tests were carried out on the decomposed granite soils sampled from some lands under reclamation to propose elementary data which can be considered for the suitable method of reclamation for each region. We studied their scientific and engineering properties in accordance to various weathering degrees.Consequently, their scientific and engineering properties such as soil grading, shear strength and permeability are influenced and changed with mineral components and weathering degrees. In addition, shear strength deteriorate with moisture content. Accordingly, the method of drainage is the most important factor on reclamation of the decomposed granite soil area. Namely, as the decomposed granite soils are easily broken and eroded by water action, drainage must be done fast and safely by water erosion protection and farming. We suggested the investigating point of construction countermeasure for drainage of spring water to foundation stability and design of drainage system. Furthermore we proposed new beneficial method of disaster prevention combination which are decided with a use of a point table in order to design land reclamation and conservation.The important problem to be solved, is the planning to take measure of drainage and embankment for respective areas, and we think that results of this study hold new point of view and can contribute to land reclamation and conservation for decomposed granite soil areas scientifically and technically.