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与山岭隧道所不同,采用矿山法修建水底隧道,二次衬砌将承受很大外水压力,特别是穿越饱水破碎地层时,具有很大的施工风险。以厦门翔安海底隧道为工程背景,针对F4风化深槽地层,研究不同水位条件下,衬砌荷载与排放流量及排放方式之间相关关系。研究得出:当控制排放量为全排条件流量1/3左右时,可卸掉80%外水压力;从环境和经济角度考虑,可将出现拐点折减系数0.2作为水底隧道限量排放的设计基准值;从支护结构体系组成考虑,对于F4强风化深槽破碎围岩,必须施作注浆圈,才可以保证在水压、土压共同作用下衬砌结构安全,结果显示施作注浆圈能够减少衬砌作用荷载30%～40%,提高安全系数几乎一倍;从主体结构受力特征看,水底隧道最不利受力位置在墙脚和仰拱,因此,无论是防水型还是排水型隧道,均应对仰拱形式及支护参数加强设计。
Different from the mountain tunnel, the tunnel method is adopted to mine the tunnel, and the secondary lining will bear great external water pressure, especially when crossing the saturated water and crushing formation, which has great construction risk. Taking the Xiang’an Subsea Tunnel in Xiamen as the engineering background, the relationship between lining load, discharge flow rate and emission pattern under different water level conditions was studied in F4 weathered deep trough formation. The results show that 80% of the external water pressure can be removed when the control discharge is about 1/3 of the total discharge flow rate. From the point of view of environment and economy, the reduction coefficient of inflection point of 0.2 can be taken as the design of the limited discharge of underwater tunnel Based on the composition of the supporting structure system, for the F4 strong weathered deep groove crushing surrounding rock, grouting ring must be applied to ensure the safety of the lining structure under the joint action of water pressure and earth pressure. The results show that grouting The circle can reduce the load acting on the lining by 30% ~ 40% and improve the safety factor by almost double. According to the stress characteristics of the main structure, the most unfavorable stress position of the underwater tunnel lies on the wall foot and the inverted arch. Therefore, whether it is waterproof or drainage tunnel , Should be inverted arch form and support parameters to strengthen the design.