deep-draft

Owing to the lack of such materials as sands and stones, and on the basis of economical and applicable principles, the improvement project of the deep-draft channel of the Yangtze Estuary, a state key project, adopts various kinds of geotextile on different structural positions.

国家重点工程&长江口深水航道治理在施工过程中，因工程所在地区砂石材料的短缺，所以本着经济适用原则，拟采用各类土工织物布置在导堤的不同结构部位。

The depth of many ports' channel for ship to enter/ leave harbor can not meet the need of deep-draft ships all day, so some ships need to use the sub-period tide to enter/ leave the port.

许多港口的进出港航道水深不能全天候满足大型深吃水船的航行要求，船舶需要利用潮汐分时段乘潮进出港。

Secondly, analyze the natural environments, navigation conditions, and characteristics of project construction both above and under water in Yang Shan Deep-draft Port, find out the difficulties in maritime management.

第二，通过对洋山深水港水域自然环境、通航状况、水上水下工程建设时期特点的分析，找出海事管理的难点。