Abstract The overbreak and underbreak caused by tunnel construction will change the stress state of surrounding rocks and even affect the stability of surrounding rocks. The boundary of surrounding rocks is divided into three categories, namely parallel overlay, bottom overlay and complete overlay according to the section contours of tunnel with overbreak and underbreak and the thickness of shotcrete layer; based on the elastic thick-wall cylinder theory, the stiffness of equivalent thick-wall cylinder and the maximum support pressure are deduced; the calculation formula of stiffness and the maximum support pressure of the composite support structure with shotcrete and anchor bolts are established on the basis of parallel system of anchor bolts and shotcrete; stability of the Lianhuashan No. 2 tunnel is analyzed by convergence-confinement theory, and the results show the stability analysis of surrounding rocks considering the effect of overbreak and underbreak is more in accordance with the actual situation, verifying this analysis method.
Abstract：
The overbreak and underbreak caused by tunnel construction will change the stress state of surrounding rocks and even affect the stability of surrounding rocks. The boundary of surrounding rocks is divided into three categories, namely parallel overlay, bottom overlay and complete overlay according to the section contours of tunnel with overbreak and underbreak and the thickness of shotcrete layer; based on the elastic thick-wall cylinder theory, the stiffness of equivalent thick-wall cylinder and the maximum support pressure are deduced; the calculation formula of stiffness and the maximum support pressure of the composite support structure with shotcrete and anchor bolts are established on the basis of parallel system of anchor bolts and shotcrete; stability of the Lianhuashan No. 2 tunnel is analyzed by convergence-confinement theory, and the results show the stability analysis of surrounding rocks considering the effect of overbreak and underbreak is more in accordance with the actual situation, verifying this analysis method.
LIU Mingcai
.Study on Stability of the Support System with Anchor Bolts and Shotcrete under Overbreak and Underbreak Conditions[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(6): 78-84
2019, Vol. 56 