Assessment of Ground Improvement with Improved Columns by Surface Wave Testing

• Main Authors: Dai,Yung-Zheng, 戴永政
• Other Authors: Lin, Chih-Ping
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/67038193177438365284

碩士 === 國立交通大學 === 土木工程系所 === 97 === Soft ground can be improved to increase the shear strength and bearing capacity by methods such as jet grouting and stone column which may result in heterogeneous ground with improved columns. Experimental methods (Standard Penetration Test, Sampling, Laboratory testing, etc.) used to assess such ground improvement are subjected to several limitations such as small sampling volume, time-consuming, and cost ineffectiveness. Current homogenization equations based on improvement ratio may not be representative. The objective of this study is to investigate the seismic surface wave method as a non-invasive and direct method for assessing the overall quality of the ground improvement, which is characterized by large sampling volume, efficiency, and cost effectiveness. The surface wave test is can be used to determine the shear-wave velocity depth profile which reflects the stiffness and strength of the geotechnical materials. This study investigated the homogenization of surface wave testing in heterogeneous improved ground with improved columns. The lateral sampling space of the surface wave testing was also investigated by field testings of different survey line locations relative to the improved columns. From case studies with different improvement ratio, the difference in shear wave velocity before and after ground improvement is compared with various site characteristics such as improvement rate, SPT-N, and the complex shear strength. The engineering information that can be extracted from the improvement rate of shear wave velocity obtained by surface wave testing is discussed