# Study on the Fracture Resistance of Mixed Fiber Concrete Lining in a Reverse Fault Tunnel
## 1 Introduction  
Fiber concrete first appeared in a research report by American scholar [PERSON] at the beginning of the last century, and it is widely positioned as a composite material composed of cementitious materials (cement stone, mortar, or concrete) and various types of fibers. Cemertitious materials have advantages such as good compressive properties and high durability, but their low tensile strength and small elongation make them a brittle material, so the structural applicability of considering only ordinary cementitious materials in engineering and construction is limited, and the safety risks are large. Fiber in the history of human construction has a fairly long history [1], with high tensile strength, elongation, toughness, etc., so adding fiber to the cementitious material helps to improve its flexural and tensile properties while also helping toughen the deformation resistance, cracking, and impact resistance, etc., which greatly broadens the applicability of the cementitious material of breadth and depth and therefore has more and more engineering applications, and there is a study on the fiber concrete. At the same time, the research on fiber concrete is still broadening, and the fiber type is also gradually rich, from the initial commonly used metal steel fiber development to today's synthetic fibers, carbon fibers, and so on, and even a variety of fibers mixed came into being. Currently, several scholars have studied concrete materials with steel fibers as the admixture, and their results show that the admixture of steel fibers can effectively improve the stability and strength of concrete, and the nature of the admixture, such as the shape,size, etc., will also affect the performance of the final concrete material. At the same time, a variety of materials simultaneously as an admixture will affect the performance of the concrete material to varying degrees. In 1975, the first organic fiber and inorganic fiber blending test was conducted by [PERSON] [2] and others to investigate the tensile strength and impact resistance of this cement-based composite material. [PERSON] and other first organic fibers and inorganic fibers for mixing test, the study of the tensile strength and impact resistance of the cementitious composites, which is also the first systematic research on mixed-fiber concrete. In 1987, [PERSON] [3; 4] published a series of research results on mixed fibers, which, for the research of this kind of material fever, swept the world. Since then, many scholars have conducted research on mixed fiber concrete [5; 6; 7]. The results show that mixed fibers have a more significant improvement in the mechanical properties of cement composites. The current research on mixed fiber mainly includes steel fiber mixed with polypropylene fiber, steel fiber mixed with polyvinyl alcohol fiber, steel fiber mixed with basalt fiber, basalt fiber mixed with polypropylene fiber, polyvinyl alcohol fiber mixed, etc., which can improve all kinds of properties of the concrete material in different degrees and therefore has become a widely used construction material. With the increasing complexity of the engineering environment in tunnel construction, some projects are located in unfavorable geological conditions, including areas prone to fault movement and other geological hazards. At present, some scholars have studied the anti-fault measures, which mainly propose two ways of anti-seismic joints and flexible joints, to study the anti-fault measures in tunnels. Current scholars on the application of fiber concrete in tunnel lining have been part of the study, such as [PERSON] [8], etc. Through the reinforced concrete and basalt fiber concrete lining indoor mechanical properties model test, the study of basalt fiber concrete lining bearing characteristics found that basalt fibers help to improve the lining of the initial bearing performance, compared with reinforced concrete, which is more conducive to controlling the deformation of the tunnel of the weak surrounding rock. [PERSON] [9] et al.