埕岛海域波浪引起不同区域土体的液化程度

THE DEGREE OF LIQUEFACTION OF SEABED INDUCED BY STORM WAVE IN CHENGDAO SEA AREA

收集埕岛海域地区近十余年的地质勘察资料,汇总该区地质灾害的类型及其分布情况,发现该区存在着凹坑、冲沟、滑塌、泥流舌、海底穿刺、粗糙海底和埋藏古河道等地质灾害,在海域西北、中部和东南部均有分布,简要探讨形成机理,计算波浪循环荷载在海床中产生的循环应力比,以及根据标贯击数和黏粒含量建立土体的循环阻抗比,然后,计算不同风浪等级下每个钻孔1m深度处土体抗液化安全系数,采用surfer8.0软件绘制安全系数等值线图。发现抗液化性能较好的区域主要分布在海域中部三块地区,随着风浪等级增大,整个区域内液化面积也逐渐扩大,海域东南地区有少量油井和管线分布,区地质灾害发生频率较高,土体抗液化性能较差,工程设施应重视较大风浪期间土体液化对其安全性能的影响。

The types and locations of geological disasters in Chengdao sea area were collected and summarized by analyzing the geotechnical surveying information in this area. It revealed that some geological disasters such as pits, gullies, slump, mud flow, diapiric structures, rough seabed and buried ancient river channels, were distributed in the northwest, middle and southeast of the sea area, and the formation mechanism was simply introduced. Then the cyclic stress ratio （CSR） induced by wave in the seabed and cyclic resistance ratio （CRR） which is related with SPT-N and clay content were calculated, and safety factors of liquefaction contour map in the depth of 1 m was drawn under different degrees of wind wave. Some conclusions were got. （1） With increased level of wind wave, the whole region liquefaction of the sea area was gradually expanding. （2） Three good anti-liquefaction areas are mainly distributed in the middle of the oilfield. （3） In the southeast, the influence of soil liquefaction on oil wells and pipeline safety should be paid much attention during high wind waves, as the bad anti-liquefaction seabed exists here.