Study on mechanical properties of new supporting materials for soft rock underground engineering

Foam concrete contains many holes inside, which has the properties of light weight, shock absorption, energy absorption. It is a good energy absorption buffer material. However, it also has the disadvantages of large shrinkage and poor ductility. In this paper, based on the requirements of foam-fiber concrete for buffering and energy absorption in soft rock support, fiber materials were added to foam concrete, and six-factor three-level orthogonal test was carried out. Combined with the analytic hierarchy process, the optimal mix ratio of each component was determined, and a new type of foam-fiber concrete was prepared. The mechanical properties and deformation law of foam-fiber concrete were studied by indoor axial compression test, DIC digital speckle test, triaxial compression test and Brazilian splitting test. The test results show that the new foam-fiber concrete has good strength, tensile and energy absorption capacity. At the same time, in order to evaluate its energy absorption effect as a buffer layer, through comparative tests, the energy absorption and buffering effect of the new foam-fiber concrete in underground engineering is analyzed. The research results provide a good reference for the study of soft rock flexible support.