大直径钢筋混凝土顶管穿越河道顶进力研究

Jacking Force and Safety of Large-diameter Steel Concrete Pipe Jacking Crossing River

顶管施工过程中顶进力不仅影响顶进效率,而且关系到管节结构、周边建(构)筑物和环境的安全。为分析大直径钢筋混凝土顶管穿越河道施工的力学性能,依托佛山市某电力隧道钢筋混凝土穿河顶管工程,通过对顶进力、管周压力和管节轴向应变进行监测,依据管节轴向应变和管周压力反算管土摩擦系数,将其用于顶管施工过程的数值模拟,并通过将模拟结果与现场实测数据进行验证对比,揭示管土摩擦系数在时空上的变化规律以及不同因素对顶进力预测的影响。结果表明:空间上,管土摩擦系数主要受地层性质的影响,在由淤泥质黏土层进入夹强风化岩块的粉质黏土层时其变化最为明显,前者仅为后者的55.65%;时间上,因为泥浆从注入到发挥作用需要时间,期间的管土摩擦系数较大,当泥浆套形成时,管土摩擦系数保持在较小状态;综合考虑地层性质、地形以及注浆作用时间效应等因素的顶进力预测模型与仅考虑单一因素的顶进力预测模型的模拟结果相比,其与实测值更为吻合,验证了本文提出方法的正确性。

In the process of pipe jacking construction,the jacking force not only affects the jacking efficiency,but also relates to the safety of pipe joint structure,surrounding buildings and environment.Based on the steel concrete pipe jacking project of a power tunnel crossing the river in Foshan,this paper uses the monitored jacking force,pipe circumferential pressure and pipe joint axial strain to analyze the mechanical properties of large-diameter steel concrete pipe jacking construction,and then,according to the axial strain and pipe circumferential pressure,inversely calculates the pipe-soil friction coefficient used in the numerical simulation of pipe jacking construction.The simulation results are compared with the field measured data to reveal the variation law of pipe-soil friction coefficient in time and space and the influence of different factors on the prediction of jacking force.The results show that in space,the pipe-soil friction coefficient is mainly affected by the stratum properties,and the change is most obvious when entering the silty clay with strongly weathered rock blocks from the muddy soil layer,and the former is only 55.65%of the latter;in terms of time,because it takes time for mud to play its role from injection,the pipe-soil friction coefficient is large.When the mud sleeve is formed,the pipe-soil friction coefficient remains small.Compared with the results of the single factor setting model,the model which comprehensively considers the factors such as stratum properties,topography and grouting time effect,is more consistent with the measured values,which verifies the correctness of the method proposed in the paper.