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Surrounding rock plays a key role in the bearing structures of roadway according to the interaction system between surrounding rock and support. Stability control in the bearing structures of surrounding rock thus significantly influence the stability of roadway. Based on the engineering and geological properties of soft and broken surrounding rock，some theoretical models were established considering the strength characteristic，stress distribution and deformation behavior of rock mass after excavation. The stress，displacement and plastic zone were then studied in the elastic zone，plastic soften zone and broken zone，respectively. Considering the influence of several key factors，such as the strength soften and dilation at post-peak state and the support resistance，based on the bearing characteristics of surrounding rock，two main bearing structures around the excavation which are the shallow and deep bearing structures were defined. A key bearing structure was found in the deep bearing structure，which was subjected to most part of the external load. Theoretical studies and numerical simulation using Flac3D code were performed to investigate the characteristics of the bearing structures and the deformation of roadway. The results show that the bearing structures will develop obviously with a big residual strength. The dilation effect occurs in the deep bearing structure，while it leads to the deformation of shallow bearing structure. The thicknesses of the two bearing structures increase with the increase of in-situ stress. [ABSTRACT FROM AUTHOR]

In order to obtain accurate ground stress, deformation and failure law, and instability mechanism in deep soft rock tunnel, the two caverns at the same level in 1 km deep mine were selected for testing acoustic emission technology to gain the value and direction of respective ground stress. The test found that the distribution of vertical stress has a slight difference, and the distribution of horizontal stress had great difference. Based on the theory of in-situ stress calculation formula, the corresponding program was written with VB6.0, for calculating the value and direction of main stress field in corresponding part. Combining with the field drilling histogram, a model was established using ANSYS, and then imported into FLAC3D to make numerical analysis. Therefore, the cavern surrounding rock deformation law and instability mechanism under corresponding main stress field were obtained. It shows that there was larger concentration degree and wider distribution of shear stress in weak region, and the destruction of surrounding rock was very serious. Finally, the study found that the field measurement data is in consistent with numerical simulation results. It found that the seriously damaged surrounding rock also has a big convergence rate, which reveals the law of deformation and destruction in deep soft rock roadway and explains that the surrounding rock lithology, the concentration degree and the range of shear stress play an important role in the roadway stability. [ABSTRACT FROM AUTHOR]