Large Soft Schist Tunnel Deformation Control Technology Research

With the continuous development of the national infrastructure, more and more highwayand railway extended to the mountainous areas, in order to shorten the mileage and protect thenatural environment along the tunnel, the tunnel will become one of the major forms of design.Due to the complexity of geological conditions, the existing tunnel engineering technologycan not completely solve the problem encountered in engineering, such as high stress, invertuplift and deformation of soft rock big problem. Currently, the soft rock large deformationlaw has become a hot issue in the study of soft rock tunnel construction, and the control ofsurrounding rock in soft rock tunnel construction process is often the key to the success of thesoft rock tunnel construction. Because of the complexity of the deformation characteristics ofsurrounding rock in soft rock tunnel, the tunnel in soft rock large deformation controltechnology is still in dispute and exploration stage. In this paper, a soft schist tunnel projectrelying on soft law schist tunnel rock deformation and large deformation analysis ofcontrolling technology systems. The main research contents and conclusions are:(1) Based on the analysis of lithology, engineering and mechanical properties of softschist force and deformation characteristics, I study the influence of soft rock tunnel schistfactors and the deformation characteristics of large deformation.(2) According to the findings of previous studies, the rheological properties of soft rockis obvious, and rheology mainly soft rock creep; based on the analysis of creep deformation ofsoft rock foundation and constitutive model, combined with the deformation of the soft schistrock tunnel,I found the Burgers creep constitutive model is more in line with the deformationcharacteristics.(3) In view of the application of FLAC3Dnumerical simulation software in geotechnicalengineering and its advantage in large deformation analysis, this paper uses the software ofFLAC3Dto simulate soft schist tunnel; due to the soft schist structural surface tunnels andfractured joints, and the construction disturbance and water softening, the selected analogsection of surrounding rock simplified isotropic material.(4) After the excavation of the five selected to simulate conditions, we found:(5.0m) twostep length and three step excavation on deformation and stress of surrounding rock affected;ultrashort (2.5m) step excavation, can effectively reduce the stress and deformation ofsurrounding rock; reserved nuclear subsoil can effectively control the deformation of tunnelface and the vault, enhance tunnel face stability, but the crown of the plastic zone influence.(5) for advanced a small catheter simulation, we found: forepoling parts can form a dome bearing arch which can vault effective control of deformation; Although changing the angle ofa small catheter in advance, the construction of a small catheter to the stability of surroundingrock its resistance to a certain effect, the effect is not obvious. Bolt on system simulation that:length bolt for its role in soft rock is very obvious, selecting the appropriate length of the boltcan play a cost-effective results.(6) the creep effect is the important theory of soft rock tunnel surrounding rock andsupport structure interaction, the paper from the creep theory, and through the tunnelsurrounding rock and support of different components of the long-term deformationmonitoring, analysis of the supporting structure of the force and deformation characteristics ofthe early and long-term stable rock mass under the action of self weight.