The effect of pore pressure change on lateral earth pressure at rest in saturated sand

• Main Authors: Guan-Lin Huang, 黃冠霖
• Other Authors: Tzou-Shin Ueng
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/30572023898793526217

碩士 === 國立臺灣大學 === 土木工程學研究所 === 105 === In this study, changes of pore water pressure were induced by applying upward water flow with a permeameter. Water pressure transducers, soil pressure transducers, flow meter and data acquisition system were used to measure the changes of lateral earth pressure. The coefficient of earth pressure at rest in different seepage conditions can then be calculated. Experimental results showed that lateral effective stress did not change much for pore pressure ratio ru from 0 to 0.4. The particles may be subjected to interlocking during pore pressure changes. However, for the value of ru over 0.4, effective lateral stress declined clearly. It indicated that the particle interlocking might disappear under a higher excess pore pressure. The vertical effective stress decrease with increasing pore water pressure. But the lateral effective stress changes little due to the effect of the particle interlocking on the lateral effective stress. As a result, the Ko value increases when pore pressure increases. In the field, the Ko value can reach over 1.0 due to increasing of pore water pressure. The Ko value predicted by Jaky formula is close to the measured value in this study. The value of Ko changes with changing pore water pressure, so Jaky formula does not suitable in the condition when pore water pressure changes. For over-consolidated soil, the measuring value is close to the predictive value according to the relation proposed by Mayne and Kulhawy for various values of OCR.