The Study of Direct Shear Test Method on Unsaturated Soil

• Main Authors: Hsieh Pi-Chih, 謝碧枝
• Other Authors: Kai-Ming Lei
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/06429798274174156312

碩士 === 明新科技大學 === 土木工程與環境資源管理系碩士班 === 101 === The ground water exists in nature environment. The soil below ground water table, immerged in water long period of time, is called saturated soil. Due to capillary effect, rainwater infiltration and evaporation, the soil underground water table exhibits native pore water pressure, it is called unsaturated soil. The research of traditional soil mechanics on saturated soil had well developed and results were vigorous. Because of expensive equipment, difficulty of test technics and sensitive of test precision, the study in the field of unsaturated soil is still limited. Minghsin University of Science and Technology locate at Hukou terrace, the ground water table is at -5 meters below ground surface. The soil above the ground water table, dried and wetted altered frequently, is in unsaturated condition. This study tries to apply traditional direct shear test method and contact filter paper method to remodel lateritic soil sample. The relationship between unsaturated soil shear strength and matric suction is studied. The results show that the direct shear behavior of unsaturated soil reveal shear dilation properties, the lower of soil water content, the larger of dilatancy angle. The relative shear strength shows the same effect. Soil matric suction is inverse proportion to soil moisture content. The relationship between soil matric suction and unsaturated soil shear strength is increased nonlinearly. The suggest test method successes apply in unsaturated soil.