ANALYSIS OF CONSTRUCTION MONITORING AND TEMPERATURE FIELD OF CROSS-PASSAGE OF SUBWAY IN SEASHORE AREA IN XIAMEN USING GROUND FREEZING METHOD

Currently, cross-passages in the section of twin-tunnels have become an indispensable part, which has the functions, such as drainage, fire prevention, connecting the two tunnels, and acting as "escape passages" in tunnel accidents. To accurately grasp the development law of the temperature field during construction of tunnel cross-passages in seashore area in Xiamen using the ground freezing method, the full process monitoring and analysis of the ground freezing construction of No.2 cross-passage in Ma-ji section of Xiamen Metro Line 6 were conducted. Correspondingly, the three-dimensional finite element model was established to analyze the variation law of the temperature field in the process of freezing construction. The numerical results were compared with the measurements of some typical points. The results show that the tendency of the temperature change of each measuring point is basically the same, and the deeper the position of the point, the better the effect of freezing. In the early stage, the discrepancies of the pressures between various pressure relief holes are mainly caused by the inherent earth pressure of points at different positions. The closer to the freezing pipes the soil is, the faster the temperature drops, the higher the strength of the frozen soil. Accordingly, the freezing efficiency is enhanced after the formation of a frozen wall. The temperature field by the numerical analysis is unsymmetrical. This numerical modeling method is of convenience, good feasibility, and high reliability. It can be an approach to predict the temperature field in the process of freezing construction of similar projects.