软土中大直径顶管管道受力特性测试

采用现场实测方法,对深覆软土、长距离顶进、外径4.64m钢筋混凝土顶管的管壁接触压力和环向钢筋受力进行了测试,并与已有文献研究进行对比分析.结果表明:顶管在良好泥浆套中顶进时,管壁接触压力整体分布较均匀,注浆时呈突然增大变化,停顶后逐渐恢复正常水平;管道环向钢筋以受压为主、应力不大,其变化由管道轴向偏移和注浆控制,测试阶段管道受力状态以偏心受压为主;管壁接触压力实测值与按规程计算的设计值相比,管顶处相近、管侧处实测值略大、管底处实测值较小,规程的土压力分布模式用于管道设计计算偏于保守.

Field Test of Mechanical Properties of Large Diameter Concrete Jacking Pipe in Soft Soil

Abstract： Annular reinforcing steel bar stress and pipe-soil contact pressure during pipe-jacking were monitored on the spot. The differences of the active contact pressure from the related research results were analyzed. The results show that when the pipe is pulled in the stable slurry interface which has been already formed, and since the test pipe was pulled into the tunnel bore, the distribution of contact pressure tends to be uniform and remain stable. But the contact pressure will increase suddenly when grouting, and return to normal gradually after stopping pulling. The lateral force of the pipe is also stable, though not big, mainly showing compressive stress, whose changing is controlled by pipeline axial deviation and grouting. Therefore, the pipe is in a state of eccentric compression in the test. Compared with the results of the field test, the specification is rather conservative. Besides, the active distribution of contact pressure is close to the load model developed by Lei Han, which can be used to optimize pipeline structure design.