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在离心模型试验中同时考虑隧道开挖所致地层损失效应和质量损失效应,研究不同开挖顺序及不同布置形式下双隧道开挖对管线的影响规律。同时采用基于地层损失比的位移控制有限单元法对离心模型试验及其他4组拓展工况进行分析,其中土体本构模型采用考虑土体小应变特性的HP(Hypoplasticity model)模型,并将试验结果与已有的解析方法进行对比。研究结果表明,双隧道不同开挖顺序及不同布置形式对地表沉降、管线沉降、管线弯曲应变的影响显著;管线存在所产生的“遮拦”效应对管线正上方地表沉降的影响程度随着自由场最大地表沉降的增加而逐渐加剧;双隧道开挖所致管线沉降的主要影响区域为-1.2DT~1.2DT;实际工程中应加强浅埋后继隧道开挖时管线工作性状的监测工作,且不应简单采用叠加原理对不同施工工序及不同布置形式的双隧道开挖所致地表沉降、管线沉降及管线弯曲应变进行预测,应合理考虑后继隧道开挖所致土体的累计剪切应变及上覆隧道的遮拦效应对管-土相对刚度的影响。
In the centrifugal model test, both the formation loss effect and the mass loss effect caused by tunnel excavation are considered at the same time, and the influence rules of double tunneling on the pipeline under different excavation sequences and layouts are studied. At the same time, the displacement control finite element method based on formation loss ratio was used to analyze the centrifugal model test and the other four expansion conditions. The model of soil constitutive model was HP (Hypoplasticity model) considering the small strain of soil, The results are compared with the existing analytical methods. The results show that different excavation sequences and different layouts of double tunnels have significant influence on surface settlement, pipeline settlement and pipe bending strain. The effect of “obstructing” effect of pipelines on surface settlement just above the pipeline increases with the increase of free field The largest surface subsidence increases and gradually aggravate; double tunnel excavation caused by the main line of settlement of the pipeline is -1.2DT ~ 1.2DT; the actual project should strengthen shallow trench subsequent tunnel excavation work performance monitoring, and not The superposition principle should be used to predict the ground settlement, pipeline settlement and pipeline bending strain due to double tunneling with different construction procedures and layouts. The cumulative shear strain of soil due to subsequent tunnel excavation should be considered reasonably Effect of cover obstruction on the relative stiffness of pipe - soil.