Study On The Seismic Performance Of Buried Pipeline Crossing Faults And Its Rubber-sand Based Earthquake Mitigation

Focusing on the interaction characteristics of long-distance buried pipeline with the seismic faults and the surrounding soil,the seismic action on the buried pipeline can be considered from two aspects: displacement action of the seismic faults and the acceleration effect of far-field ground motions.Aiming at the seismic action and failure of buried pipelines crossing faults,lots of researchers and engineers have investigated the seismic behavior of buried pipeline as well as its failure mechanism.However,there still exists some disadvantages in this topic.Therefore,the influence of fault type,soil and material parameters on its seismic performance is studied in this thesis,and the response characteristics of buried pipelines under far-field seismic action are also analyzed.The strain distribution law of buried pipeline under various buried depth and different seismic attack angle is studied.Based on the low shear modulus rubber particle-sand(rubber sand)backfilling near the fault plane,the rubber sand mitigation method for buried pipeline is proposed.The main contents in this study are listed as follows:(1)Based on ABAQUS software,a refined finite element model of buried pipeline-soil acrossing earthquake fault is firstly built.The factors which affect the seismic performance of the buried pipeline are considered,including the non-linearity of pipeline material,the geometric non-linearity and the pipeline-soil contact properties.Then,the effect on the response of the pipelines such as types of faults,displacement of faults,width of fault crack,pipeline crossing angle,buried depth,surrounding soil characteristics and pipe-soil contact friction are all studied in this chapter.(2)Shaking table test of buried pipeline model with a scale ratio of 1:7 is carried out to investigate the response under ground acceleration excitation.The acceleration response characteristics and strain distribution characteristics of buried pipeline with different buried depth are compared and studied.The strain distribution law of buried pipeline under different seismic attack angles is also analyzed.The measurement method of slip between pipeline and soil is further discussed,and the relationship of the slip between the pipeline and the surrounding soil under different peak ground accelerations(PGAs)is finally analyzed.(3)Based on the strategy of local rubber sand backfilling,the influence of rubber-sand properties,fault types and size of backfilling region on seismic performance of buried pipeline across the fault is discussed.Finally,some reasonable suggestions to improve the seismic performance of pipelines are put forward based on the characteristics of multi-factors affecting pipelines.