砂土中隧道施工对相邻垂直连续管线位移影响的模型试验研究

Model test study of vertical buried continuous pipelines displacements affected by tunnelling in sand

隧道施工会对邻近管线造成危害,但目前对土体位移与管线位移两者之间的关系还没有清晰的认识。针对这一问题,设计砂土中考虑不同管线管径、埋深及抗弯刚度的3组隧道施工模型试验,分析垂直下穿隧道施工过程中砂土和管线位移规律。研究结果表明,Vorster修正高斯公式能较好地拟合砂土沉降分布,其控制参数值在0.2~1.0之间变化,且与地层埋深成正比;土体沉降槽宽度系数i对管线变形有较大影响,埋深相同的条件下管线抗弯刚度与沉降值成反比;深埋管线的变形主要受上拱效应支配,且管径越大上拱效应越明显,而下拉效应主要支配着浅埋管线的位移;Smax/i为影响管土相对位移一个关键参数,在此基础上提出了修正的管土相对刚度计算公式。

The vertical buried pipelines will be damaged by soil movements around pipe induced by tunnelling, but the relationship between soil movement and pipeline displacement has not been understood deeply. Three sets of model tests are established to simulate the effects of tunnel excavation on buried pipeline, in which different embodiments, caliber and bending rigidity are considered, the research is carried out about the displacement of soil and vertical pipelines during tunnelling. The results show that the modified Gaussian curves can describe accurately the Greenfield settlement trough due to tunnelling in sand, and the parameteravaries between 0.2 and 1.0, which is proportional to the depth of soil in sand; The width coefficient of Greenfield soil has great influence on pipeline displacement, and the displacement of pipeline varies inversely to its bending rigidity for the same buried depth;The bigger the caliber is, the more obvious positive downdrag which dominates the behaviour of deep pipelines, however, negative downdrag greatly affect the displacement of pipelines for shallow case;Smax/i is one of the key influence factors for relative pipe-soil settlement, on this basis, a modified formula to calculate the relative pipe-soil rigidity is presented in this paper.