Case Study of Deep Excavation of Taipei MRT under Limited Soil Space Condition

• Main Authors: Shih-Lun Huang, 黃世倫
• Other Authors: Horn-Da Lin
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/03296604467988204450

碩士 === 國立臺灣科技大學 === 營建工程系 === 103 === This is a case study of deep excavation of Taipei MRT on the effects of limited soil space condition. First, the engineering information of the studied case and the field measurements are collected and summarized. The reasonability of the measured wall displacements and ground settlements are examined. Then, the effects and affecting factors of the limited soil space on the wall displacement are studied. As a result of the case study, several cross sections are selected for further numerical analyses. The numerical analyses adopt Plaxis-2D and Hardening Soil model (HS-model). First, the monitoring results of retaining wall displacements and ground settlements are used to determine reasonable soil model parameters under unlimited soil space. Then, further analyses are conducted to study the responses of the deep excavation and the adjacent structure of the limited soil space condition. Bases on the case study, the limited soil space effects exist and are affected by the distance from adjacent underground structure to diaphragm wall (L), the depth of adjacent underground structure (Ha), the depth of excavation (He), etc. The limited soil space condition results in an decrease in lateral earth pressure acting on the diaphragm wall and less wall displacement. Numerical analysis results of the greenfield condition show that soil stiffness parameters determined using“field and laboratory test results of the studied case” are more in line with measured retaining wall displacements. Analytical results of the limited soil space condition that consider the adjacent underground structure show that the wall displacement results agree with the field measurements and smaller than the unlimited soil space condition. The results indicate that when the existing underground structure is deep enough it will hinder the development of the potential failure surface up to the ground surface such that the effects of limited soil space warrant consideration.