Study on Correction of Surrounding Rock Classification for Single-tube Four-lane Highway Tunnel Based on the Failure Characteristics of Surrounding Rock
(1. China Railway Siyuan Survey and Design Group Co., Ltd., Wuhan 430063; 2. School of Civil Engineering, Southwest Jiaotong University, Chengdu 610036)
Abstract：
In order to investigate the surrounding rock classification method that takes account of the excavation method for single-tube four-lane highway tunnel, the failure process of surrounding rock in the tunnel excavation process is analyzed after a field survey, to identify 3 types of failure characteristics of surrounding rock ranked from good to poor. Then several cases under different surrounding rock classes are calculated by using the numerical simulation method. The failure characteristics of surrounding rock are investigated according to the calculation results.On this basis, the surrounding rock parameters are classified and the tunnel excavation method is determined. At last, the method is demonstrated through field test. As the study results indicate: (1) The 3 failure characteristics including abrupt increase of plastic zone of surrounding rock, formation of tension zone at the arch and overall instability resulting from insufficient bearing capacity are used as the basis for classifying surrounding rock into Classes Ⅲ, Ⅳ and Ⅴ. (2) For single-tube four-lane highway tunnel, according to the results of numerical calculation and analysis of structural failure characteristics, the full face method is suitable under Class Ⅱ surrounding rock condition, the bench-cut method under Class Ⅲ surrounding rock condition, the CD method under Class Ⅳsurrounding rock condition, and CRD method under Class Ⅴ surrounding rock condition. (3) After analysis of the calculation results, the BQ value of the surrounding rock classification is proposed that takes account of the correction of surrounding rock failure characteristics of single-tube four-lane highway tunnel.
QU Jianrong1 JING Yawen2 REN Zhaodan1 XIONG Ying2 CHEN Xuefeng1 FENG Jimeng2
.Study on Correction of Surrounding Rock Classification for Single-tube Four-lane Highway Tunnel Based on the Failure Characteristics of Surrounding Rock[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(1): 48-55
2024, Vol. 61 