Zequn Hong ^1* FU Shuoren ¹ Yuanhao Wu ² Yong Zhang ¹ Lu Lu ¹

• ¹ China University of Mining and Technology, Xuzhou, China
• ² China Construction Eighth Engineering Division (China), Pudong, Shanghai Municipality, China

In order to explore the influence of horizontal freezing of a proposed tunnel on existing underground structures, a three-dimensional numerical model of 'thermal-mechanical' coupling was established based on the horizontal freezing reinforcement project applied in a shield receiving end, and the temperature field distribution characteristics of different freezing stages were obtained. After confirming that the frozen wall has reached the design thickness based on the temperature field, the mechanical effects of frost heave on the existing structures are investigated, including the side tunnel, the upper subway tunnel, and the end diaphragm wall. The results show that the frost heave pressure is mainly distributed in the structure near the freezing zone, while the structure far away from the freezing zone is relatively less affected by frost heave. By defining the strong and weak influence section, we introduced the influence coefficient η to quantify the frost heave effect on the side tunnel. Under the condition that the thickness of the frozen wall is constant, the strong influence range of the side tunnel reaches 1.4 times the freezing length of the proposed tunnel at a distance of 3.6 times of the frozen wall thickness. The farther the clearance between the side tunnel and the proposed tunnel is, the smaller the influence coefficient η is, and the shorter the strong influence section is. The frost-heaving effect generated by freezing at the shield tunnel receiving end is more pronounced along the diameter of the freezing pipes, while axial release strength is comparatively weaker. This research can provide a reference for evaluating the influence of freezing construction on adjacent underground structures.