Study on Mechanical Properties and Prediction Model of Cement-Based Materials in High Geothermal Tunnel

Abstract

The high-rock temperature tunnels along the Sichuan-Tibet Railway seriously affect the performance of initial shotcrete, which has a great impact on engineering activities. Based on the characteristics of high-temperature tunnels, the mechanical strength of cement-based materials is tested. According to the experimental results, combined with the changes in the hydration process of cement-based materials, the corresponding parameters were provided for the construction of the PFC model, and finally, 40°C, 60°C and 80°C were established PFC prediction model for cement-based materials. The results showed that the strength of the numerical model of cement stone decreased with the increase in temperature, and the compressive strength at 80°C decreased by 29.78%, but the residual strength did not change much. However, the lack of change rate is consistent with the change of internal porosity, and the internal porosity is the main factor affecting the structural change of cement particles under the condition that the hydration of cement particles remains unchanged.