Experimental Study on Evolution Characteristics of the Heat Storage of Surrounding Soil in Subway Tunnels

The evolution characteristics of the heat reservoir of surrounding rock in subway tunnels have been analyzed by a scaled model experimental test for 17 years from new to long-term operation with periodic and dynamic air temperature conditions. According to its variation characteristics with time, soil temperature distribution with time is divided into the dynamic expanding period and the dynamic stable period. The evolution characteristics of soil temperature is varied with depth and the heat storage and release are pointed out. It has been found that the soil heat reservoir thickness is 20m with the peak temperature of the soil heat reservoir 22.7 degrees C and the soil heat reservoir characteristic thickness 2m. All of these works provides references to solve the tunnel. temperature problems in long-term subway operation. (c) 2017 The Authors. Published by Elsevier Ltd.