拱北隧道工程中曲线顶管顶进力实测分析

港珠澳大桥珠海连接线拱北隧道工程口岸暗挖段采用曲线顶管管幕支护的施工方法，在复杂地层条件下计算曲线顶管顶进力是顶管施工的重点与难点。工程共计使用了37根外径为1 620 mm、平均长度约为255 m的钢顶管。结合现场施工记录，采用2种不同的计算方式对顶进力进行了估算并与实际顶进力进行对比验证。结果表明： 经验公式中的摩阻力计算在埋深较大时比较符合实际情况，在浅层的淤泥质地层中则偏大；直接采用被动土压力计算迎面阻力是偏保守的；顶进力的大小与泥浆润滑关系密切，初始阶段泥浆的润滑作用并不显著，在形成稳定的泥浆套过程当中摩阻力会逐渐下降，甚至小于1 kN/m2。

Analysis of Jacking Force of Curved Pipe Jacking in Gongbei Tunnel

The pipe curtain retaining method of curved pipe jacking is applied to the construction of mined section of Gongbei Tunnel, which is a significant part of Hong Kong Zhuhai Macao Bridge Connecting Project. The estimation of total jacking force in curved alignment still remains its necessity and difficulty especially when driving in complex ground. A total of 37 steel pipelines with diameter of 1 620 mm and average length of 255 m are installed around the tunnel section as an advance support. Two different calculation methods, including an empirical formula and a theoretical formula are used to estimate the jacking force and compare with the in site driving force. The results indicate that: 1) The friction force calculated by empirical formula coincides with actual friction force in deep buried condition; however, it is larger than actual friction force in shallow silty ground. 2) Compared with the measured penetration load, the calculated passive earth pressure is more conservative. 3) The slurry shows a significant influence on the jacking force, but not so obvious in the initial stage of jacking; however, when a continuous and complete slurry jacket is formed, the friction force reduces (lower than 1 kN/m2).