Distribution Law of the Initial Temperature Field in a Railway Tunnel with High Rock Temperature: A Model Test and Numerical Analysis

Abstract

The distribution of the initial temperature field of a high-rock-temperature tunnel is critical for determining the tunnel line and the construction scheme. This study used model testing, numerical analysis, and field measurement to investigate the initial temperature field distribution of a tunnel with high rock temperatures. A model test system was developed, and the experimental results show that the boundary conditions set by the model are reasonable. The results show that the temperature along the tunnel line is high in the middle and low at both ends. Obviously, the periodic boundary conditions have a significant influence on the temperature field distribution. Then, the corresponding two-dimensional unsteady numerical model is established, and the numerical model is verified by the model test. Next, the numerical model is applied to the actual Jiwoxiga tunnel, which is a high-rock-temperature tunnel. The results show that the maximum ground temperature in the direction of the Jiwoxiga tunnel line is 52.5 °C, the tunnel lengths with ground temperatures above 28 °C account for 96.25% of the total tunnel length, and the tunnel length with a ground temperature above 45 °C comes to nearly 1200 m. In addition, this result is also verified by the field drilling data and field-measured data after excavation. The effectiveness and accuracy of the numerical model are fully demonstrated. This study provides theoretical support for the design and construction of high rock temperature tunnels.