A Preliminary Study on Numerical Simulation of Direct Shear Test and Calibration of Micro-Parameters of Soils Through Discrete Element Method.

• Main Authors: Wen-roug Chiou, 邱玟融
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/62939890123056494438

碩士 === 國立雲林科技大學 === 營建工程系碩士班 === 95 === In order to calibrate suitable micro-parameters for use in numerical analysis, the study herein had conducted a series of direct shear tests on the material strength data (i.e., macro-parameters). The micro-parameters included friction coefficient (fric) among soil grains, normal stiffness of contacts (Kn), and tangent stiffness of contacts (Ks), etc. Commercial software, PFC2D, by Itasca based on discrete element method has been adopted for the simulation of direct shear test in this study. Ottawa sand and Tzuo-swei sand were used for the testing. Problems encountered during the simulation process, including sample assembling, density controlling, vertical loading, and shearing, etc., are discussed in this paper. The study found the falling height and the soil grain friction coefficient would affect the density of soils. The lesser the friction coefficient or higher the falling height, the greater the density will be. Under the same normal pressure, the decrease in the tangent stiffness of contacts will result in a flatter stress-strain curve, as well as a smaller friction angle and the shear resistance. In spite of different definitions, the micro-parameters, fric and Ks, would result in similar effects on the material strength characteristics. The calibrated micro-parameters of the test sands would be used in the future for numerical simulations on more complicated engineering problems encountered in the field.