Research On The Distribution Regularity Of Surrounding Rock Break Zone In Highway Tunnel

The process of numerous highway tunnel construction and monitoring prove the fact that there is break zone due to stress redistribution in the process of tunnel excavation. Break zone’s development and stability is very important for the stability of the tunnel, and the supporting of the surrounding rock loose circle theory is called break zone supporting theory.In order to apply the break zone supporting theory in the designing of highway tunnel, we study the distribution law of the internal rock break zone, and get a determining method of broken zone distribution, which promote the development of the break zone supporting technology. Firstly, through theoretical research, analysis and comparison of the elasticity, plasticity, elastic-plastic theory to determine the method and obtain surrounding rock broken zone, and established the calculation method of broken zone range, which based on the theory of elastic-plastic mechanics. Secondly, through the numerical simulation research, steps which using FLAC3D software to determine surrounding rock broken zone are given. Through the comparison of the plastic zone, shear strain nephogram and volume strain nephogram, so we could determine the distribution of broken zone. Lastly, through the measurement research, summarize the method of testing broken zone with multipoint displacement meter, and determine the distribution of broken zone by analysis displacement curve and measurement data. The results was given according to Cha Zhen tunnel and XiShipo tunnel combined the elastoplastic calculation, numerical simulation, and multipoint displacement measurement. The results showed that broken zone were all within2m according tea town tunnel’different surrounding rock level; broken zone dividing point between2m-3m according tea town tunnel’different surrounding rock level.The theoretical calculation, simulating data and the monitoring data of surrounding rock break zone in the same rank of surrounding rock obtain good consistency. By comparing the advantages and disadvantages of theory calculation, elastic plastic numerical simulation and multi-point displacement measurement technology. Firstly, through theoretical calculation and numerical simulation obtain the support parameters during the design using broken zone support theory. Secondly, Support parameters optimization was necessary according to the measurement result. So as to ensure the information construction in a safety and quickly way.