Comparative study on pullout behaviour of pressure grouted soil nails from field and laboratory tests

作     者：HONG Cheng-yu YIN Jian-hua PEI Hua-fu 

作者机构：Department of Civil Engineering Shantou University Shantou 515063 China Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong China 

出 版 物：《Journal of Central South University》 (中南大学学报（英文版）)

年 卷 期：2013年第20卷第8期

页      面：2285-2292页

核心收录：

学科分类：081401[工学-岩土工程] 08[工学] 0814[工学-土木工程] 

基　　金：Foundation item: Project(NTF 12015) supported by the Scientific Research Foundation for Talent of Shantou University, China Project(PolyU 5320107E) supported by the Research Grants Committee General Research Fund, China 

主　　题：soil nail apparent coefficient of friction overburden soil pressure grouting pressure 

摘      要：Pullout resistance of a soil nail is a critical parameter in design and analysis for geotechnical engineers. Due to the complexity of field conditions, the pullout behaviour of cement grouted soil nail in field is not well investigated. In this work, a number of field pullout tests of pressure grouted soil nails were conducted to estimate the pullout resistance of soil nails. The effective bond lengths of field soil nails were accurately controlled by a new grouting packer system. Typical field test results and the related comparison with typical laboratory test results reveal that the apparent coefficient of friction （ACF） decreases with the increase of overburden soil pressure when grouting pressure is constant, but increases almost linearly with the increase of grouting pressure when overburden pressure （soil depth） is unchanged. Water contents of soil samples at soil nail surfaces show obvious reductions compared with the results of soil samples from drillholes. After soil nails were completely pulled out of the ground, surface conditions of the soil nails and surrounding soil were examined. It is found that the water content values of the soil at the soil/nail interfaces decrease substantially compared with those of soil samples extracted from drillholes. In addition, all soil nails expand significantly in the diametrical direction after being pulled out of ground, indicating that the pressurized cement grout compacts the soil and penetrates into soil voids, leading to a corresponding shift of failure surface into surrounding soil mass significantly.