No abstract

Land subsidence has been seen to have an effect in many countries, especially countries with areas of very soft soil. Settlement is generally found in high economic and developed locations and often depends on the increasing demand of humans for water. Namely, increased water consumption due to groundwater pumping results in an increase in settlement. All of these causes affect the changes in groundwater level. The government of Thailand has created rules to control groundwater consumption in order to solve subsidence and others problems. Changes in the water level directly affect soil settlement. This paper studies the land subsidence behavior by means of soil profiles obtained from Bangkok and the central area of Thailand, which are very similar, as a prototype soil model. The settlement behavior is examined through centrifuge tests performed after the water level drawdown due to water pumping. The groundwater level increases due to controlled pumping. Finally, the settlement results of the centrifuge tests are compared with the land subsidence characteristics of the Bangkok area. This research focuses on the testing methodology and soil settlement behavior. The land subsidence of Bangkok clay occurs continuously, but the vertical settlement of Kaolin clay is seen to be different at each stage of testing.

Geotechnical utilization of construction wastes has been performed extensively in construction sites, and fluidized soils which is one of the geotechnical utilizations of construction sludges have been widely applied in construction works. In particular, the fluidized soils are used by filling construction works with long-distance and construction works at complicated underground spaces. Therefore, the fluidized soils that higher fluidity is possessed (that is a super fluidized soil) are required in their development. This paper discusses to be developed a super fluidized soils. Specifically, a mechanical characteristic and fluidity performance of developed super fluidized soil are clarified experimentally. The developed super fluidized soil satisfies qualities requested for fluidized soils as a result also it is confirmed that high-fluidity is possessed.

ABSTRACT:The chemical grouting is one type of ground-improvement methods. It injects liquid consolidation material into the gaps of a soft sandy ground. It is mainly used for improving a stable ground, such as by preventing liquefaction and increasing the strength of the ground. Chemical grouting has been successfully applied at many construction sites; however, the behavior of the chemical solution being injected into the ground is unclear. Furthermore, because the ground involves uncertainty, it is difficult to determine the penetration range of the chemicals (grouting materials). In this study, the authors carry out a seepage flow analysis of a chemical solution for a ground requiring improvement due to uncertainty. They then compare the difference in the behavior of the chemical solution between the case in which the ground is assumed to be heterogeneous and that in which it is assumed to be homogeneous.

Impervious coating treatment is an original technology which consists of coating of soil and solid waste by particle units with an impervious coating material (a sealing material) containing water-absorbent polymers. The elution of attached substances, such as heavy metals, from the surface of soil particles is suppressed. This is because each particle is uniformly coated with the sealing material. Furthermore, because the sealing material swells, due to the absorption of pore water, and fills the void spaces of the soil and solid waste, the water interception performance of the treated soil can be expected to improve. Through laboratory experiments, this study evaluated the basic characteristics, such as the elution of heavy metals and hydraulic conductivity, of soil and solid waste that have been treated with an impervious coating in order to investigate their reutilisation.