海洋平台设计中的风浪参数选取标准

以我国渤海某区1970年至1993年风暴过程的后报资料为基础,提出了泊松二维冈贝尔逻辑分布,并将其用于风暴过程中伴生的风速与波高的联合概率计算,给出了美国石油协会(API)行业标准有关环境条件三种设计标准的具体做法.基于新的统计模式,同时提出了联合概率法设计标准.比较了多种标准所得设计参数的差异,给出了适合工程所在海区的环境荷载参数.计算结果表明,新的统计模式适用于遭受风暴影响的海洋工程结构设计,特别是边际油田的开发建设.

Parameter Selection Criteria of Wind Speed and Wave Height in Offshore Platform Design

The long-term prediction of extreme wave height and wind speed plays an imp ortant role in the offshore platform design. It has been common to estimate the 100-year response by exposing the structure to the simultaneous action of 100- year wind and 100-year wave height. Present design codes, for example API RP 2A -LRFD, recommend three definitions to estimate the combined extreme wind and wa ve load. Definition 1 is 100-year return period wave height with associated win d. Definition 2 is any reasonable combination of wind speed and wave height that result in the 100-year return period combined platform response. Definition 3 is 100-year return period wave height combined with 100-year return period win d speed. The former 2 definitions are less conservative approaches and require a joint probability model for the environmental conditions of interest for the pr oblem under consideration. Based on the hindcasting data of storm process occur red in some area of Bohai Bay from 1970 to 1993, this paper proposes a Poisson B ivariate Gumbel Logistic Distribution (PBGLD) to calculate the joint probability of extreme wind speed (or wave height) and concomitant wave height (or wind spe ed) in each storm. Concrete procedures are given to realize three definitions of environmental condition design criteria declared by API RP 2A-LRFD. A novel jo int probability criterion is put forward by means of the proposed statistical mo del. Different design parameters estimated by different criteria are also compar ed to find the suitable loads for selected sea area. Calculations show that new statistical model is clear in the sense of probability and fits the design of oc ean engineering, which frequently suffered from storm attacks, especially the ex ploitation of the marginal fields. Compared with traditional method, the joint d esign criteria of environmental loads calculated by PBGLD are recommended to off shore structure design in Bohai Bay, China.