工程荷载对地埋管线纵向响应影响的模型试验

Model Tests on the Longitudinal Responses of Buried Pipeline due to Construction Load

隧道开挖和地面堆载以土体不均匀沉降的形式作用于管线,使管线产生纵向应力和变形。以物理模型试验手段研究了两种荷载形式下管土相互作用的差别、接头刚度对纵向响应的影响以及隧道开挖下的管土脱开现象。通过修正Gaussian曲线拟合自由土体位移场,对实测弯矩进行归一化处理发现,隧道开挖会引起管线周围相对土体模量下降,而地面堆载则会引起土体模量相对增大。非连续接头管线通过增大转角及变形来降低最大弯矩值,改善了管线的受力状态。当土层损失比增大到一定程度以后,管线下方将出现空洞,并随着损失比的增加而逐渐扩大,最终达到稳定。

The non-uniform soil settlement induced by tunnel excavation and embankment causes extra deformation and bending moment on the nearby buried pipelines. A model test is carried out to investigate the differences under two load forms,the differences including soil-pipe interaction,the effect of the joint stiffness on longitudinal response of the pipeline and the phenomenon of pipe-soil separation under tunneling. The measured bending moment of a pipeline is normalized based on the green field settlement profile,which is fitted by the modified Gaussian curve and it is found that the pipeline-soil interaction reduces in the process of tunneling and increases under embankment. Compared to the continuous pipeline,the jointed pipeline generally experiences a smaller bending moment. When the ground loss ratio is large enough,cavity below the pipeline appears which grows with the increased ground loss ratio and eventually remains in a stable condition.