Study On Basic Mechanical Properties Of Fiber Reinforced Shotcrete And Its Application In Underground Engineering

With the continuous development of highway, a lot of long highway tunnels have sprung up in recent years. At the same time, the analysis of cross structure stability of underground ventilator rooms has become one of the key technologies in the construction of auxiliary channel of long tunnel. Thus, it is of great theoretical significance and practical value to study the stability of cross structure of underground ventilator rooms. Based on different cross structure types of Baotashan 2# underground ventilator rooms, this paper studied the basic mechanical properties of PPFC. Then the changing law of deformation and crack and contact stresses under construction when applying PPFC to the tunnel support structure are systematically analyzed, which provides technical insurance for safe construction of underground cross structure. The main research contents and results are as follows:(1) With theoretical analysis and laboratory simulation test, the relation between matrix concrete strength and PPF parameters is studied. And that the optimal PPF parameters corresponding strength index are obtained.(2) Aiming at the complexity of cross structure of underground ventilator rooms and according to the support parameters of different cross structure types, the three-dimensional numerical model is established. By studying the deformation of surrounding rock and the internal forces and crack distribution patterns and destruction forms of structure, the stability of surrounding rock and support structure are evaluated. Thus, the conclusion can provide theoretical and technical support to the future construction of similar engineering.(3) Based on contact algorithm, this article established different contact units according to different types of typical cross structure units. And that the normal contact stresses and tangential contact forces is analyzed in order to determine the overall distribution patterns and the degree of concentration and the changing law of normal and tangential contact stresses under different types of cross structure. At the same time, the normal contact stresses changing regularity and tangential contact stresses changing regularity with different excavation area are compared.(4) Through the analysis of longitudinal deformation law of tunnel’s different cross section, the extent of deformation of different cross structure types can be ascertained:The influence range of double T cross structure is 1.9 times the maximum span cross section; the influence range of decussation structure is 2.1 times the maximum span cross section; the influence range of T cross structure is 1.4 times the maximum span cross section.