穿越非均匀土体埋地管道地震离心实验研究

CENTRIFUGAL SEISMIC EXPERIMENTAL STRUDY OF BUIED PIPELINES IN NON-UNIFORM SOIL

穿越非均匀土体经历不同地震作用的埋地管线的变形和残余强度严重影响着管道的安全。该文采用离心振动台分别平行于埋地管道长度方向输入0.6 g和0.3 g峰值地面加速度地震波,研究了埋地管道在一系列地震作用和不均匀土体变形共同作用下的响应,得到了PVC和铝合金两种埋地管道穿越软土/硬土土体的地震响应规律。地震引起不均匀土体的瞬时变形,导致埋地管道最大应变发生在土体分界面和软土中,管道拉伸应变幅值软土要大于硬土,而压缩应变幅值正好相反,硬土中管道拉伸应变幅值小于压缩应变幅值,硬土中管道压缩应变幅值受地震烈度影响比软土大。地震引起的土体永久变形对埋地管道残余变形影响很大,硬土中的管道残余应变为压应变,软土中管道的残余应变为拉压应变交替分布。

The deformation and residual strength of buried pipelines caused by the earthquake in non-uniform sites are crucial for the safety of the pipeline.A centrifugal dynamic experiment is carried out to simulate the seismic response of buried pipelines crossing soft and hard soil and study their residual strength after earthquake.Two simulated seismic waves with 0.6 g and 0.3 g of input peak ground acceleration are exerted in sequence to simulate a series of earthquakes.The deformations of ground and pipelines of polyvinyl chloride(PVC)and aluminum alloy(AL)are obtained during and after the earthquake.Results indicate that the strain amplitude of pipelines caused by transient ground deformation reaches peaks at the interface of two soils as well as in soft soil.The maximum tensile strain of pipelines by seismic excitation in soft soil is larger than that in hard soil,while the maximum compressive strain is on the contrary.The maximum tensile strain of pipelines by seismic excitation in hard soil is larger than the maximum compressive strain in soft soil.The maximum compressive strain of pipelines in hard soil is more affected by seismic intensity than in soft soil.Permanent ground deformation caused by earthquake had great effect on the deformation and residual strength of pipelines.The residual strain of pipelines in hard soil is compressive strain,while in soft soil it is compressive and tensile strain alternatively.