论文部分内容阅读
对宁波洋沙山近岸海域进行了浅部地层探测和浅部地层特征描述、分析,并结合前人的研究成果对该区地层中不良工程地质现象进行了分析和解释,结果表明:(1)在海底面以下约20m的剖面记录中,有3个反射界面比较清晰,地层自上而下可分为4个层组,前三层为全新世的海相沉积地层,第四层为晚更新世时期的沉积地层。(2)海底面以下地层中存在着埋藏基岩和浅层气等不良工程地质现象。埋藏基岩分布区共有4处,其中3处集中分布在洋沙山沿岸,基岩顶面埋藏深度一般为8～12m,最小埋深为3～4m;另一处埋藏基岩位于平石礁以南约1900m处,其顶面埋藏深度大多超过14m,最小埋深为9m。相当一部分海域地层中含有浅层气,分布面积约占调查海区面积的25%,其东部浅层气顶面埋深一般为6～8m,而西部埋深一般达11～15m,显示出该区浅层气分布较分散,强度不大,气顶面埋得较深等特点。
In this paper, the shallow strata and shallow stratum characteristics of the offshore area of the Yingsha Mountain in Ningbo are described and analyzed, and the unproper engineering geological phenomena in the strata of the area are analyzed and explained according to the previous research results. The results show that: (1 ) In the profile record of about 20m below the seafloor, there are three reflection interfaces that are relatively clear. The strata can be divided into four strata from the top to the bottom. The first three are Holocene marine sedimentary strata and the fourth one is late Pleistocene sedimentary strata. (2) Undesirable engineering geological phenomena such as bedrock and shallow gas exist in the strata below the sea floor. Buried bedrock distribution area has a total of 4, of which 3 are concentrated in the coast of the Yousha Shan, bedrock top buried depth is generally 8 ~ 12m, the minimum depth of 3 ~ 4m; another buried bedrock located in Pingshijiao At about 1900m south, the top burial depth is mostly over 14m and the minimum burial depth is 9m. A considerable part of the sea area contains shallow gas, with an area of about 25% of the surveyed sea area. The top of the shallow shallow gas in the east is generally 6 ~ 8m in depth and 11 ~ 15m in the west, indicating that the area Shallow gas distribution is more dispersed, the intensity is not big, gas buried deep and so on.