Safety Level and Reliability Index for Bank Slope Stability

Based on statistics and analysis of the safety factor of unstable bank slopes,the relation be-tween safety level and reliability index of stability is studied and discussed,and then the elementary cali-brating calculation is carried out to the levels of safety and reliability for bank slope stability in the rangeof safety factors stipulated in existing China Technical Specifications for Port Engineering—FoundationPart(1987)and to those reached by some stable bank slopes already built.The results show that the relia-bility index β in the effective stress method is able to reach a high value of 2.4～4.1(mid-value 3.25),while the value of β in other three kinds of total stress method can just reach a lower value of 0.5～2.8(mid-value 1.65),which are in conformity with the engineering experience in China,and thus acceptable.Some suggestions are also given in this paper to the adoption of the value of β_0—objective reliability indexfor bank slope stability.     

Reliability Index of Caisson Breakwaters for Load Variables Correlated

In order to suit the condition that the wave uplift is correlated with the horizontal wave load acting on a vertical breakwater, a generally used method for determining the reliability index β of the breakwater, i.e. the Hasofer-Lind method, is extended in a generalized stochastic space for correlative variables. The computational results for a caisson breakwater indicate that the value of β for the case of correlated variables is obviously smaller than that for the case of independent variables.     

Numerical Study on the Probability of Fatigue Failure of a Semi-Submerged Platform Structure

On the basis of Miner's linear cumulative damage theorem, random variables are introduced to evaluate objectively the fatigue damage of a semi-submerged platform structure and a method is presented to analyze the fatigue reliability of the structure in its design life. The reliability of the method is verified through numerical examples and some conclusions are drawn, which have certain guiding and reference value for design and inspection.     

Coupled BEM-FEM Analysis of the Large-Diameter Cylinder Structure System

A method of coupled BEM-FEM analysis for the elastic spatial structure system is presented. It can be applied to the calculation of the stress and deformation of the large-diamater cylinder structure system and it is suitable for symmetric or non-symmetric structures under the distributed or concentrated load. Numerical examples show that the proposed method and computer program BEFEM are quite efficient in the analysis of the large-diameter cylinder structure problems in ocean engineering.     

Three-Dimensional Model Test for Port Engineering with Multi-Directional Waves

-The necessity of using irregular waves, especially multi- directional waves to conduct three-dimensional model tests for port engineering and the test method are described in this paper through an example of model test for a port. The test results show that a deep navigation channel has a large effect on the waves in front of the breakwater near the port entrance and on the wave condition in the port.     

Structural Design and Protective Methods for the 100 kW Shoreline Wave Power Station

1 .IntroductionThe 1 0 0kWshorelinewavepowerstationofChinaisanOscillatingWaterColumn (OWC)wavepowerdeviceintegratedtoanelectricgrid .ItislocatedattheZhelangTown ( 2 2°39’Nand 1 1 5°34’E) ,ShanweiCityofGuangdongProvince .Theresearchanddevelopmentofthe 1 0 0kWOWCshore linewavepowerstationissupportedbyChina′sNationalKeyTechnologiesR&DPrograminthe 9thfive yearplan .TheconstructionofthestationstartedinJune 1 998andwascompletedinFebruary2 0 0 1 .Uptonow ,ithasbeenoperatingfor2years …     

Maximum Entropy Estimation of n-Year Extreme Waveheights

A new method for estimating the n (50 or 100) -year return-period waveheight, namely, the extreme waveheight expected to occur in n years, is presented on the basis of the maximum entropy principle. The main points of the method are as follows: (1) based on the Hamihonian principle, a maximum entropy probability density function for the extreme waveheight H, f(H)= aH^γe-^βH4 is derived from a Lagrangian function subject to some necessary and rational constraints; (2) the parameters α,β, and γ in the function me expressed in terms of the mean H, variance V=(H-H^-)^2—— and bias B = (H - H^-)^3——; and (3) with H^-, V and B estimated from observed data, the n-year return-period wave height Hn is computed in accordance with the formula 1/1-F(Hn)=n, where F( Hn ) is defined as F( Hn ) = ∫0^Hnf(H)dH .Examples of estimating the 50 and 100-year return period waveheighls by the present method and by some currently used method from observed data acquired from two hydrographic stations are given. A comparison of the estimated results shows that the present method is superior to the others.     

Stochastic Analysis Method of Sea Environment Simulated by Numerical Models

1 .IntroductionNumericalmodelsmostwidelyusedforseaenvironmentandsedimenttransportfocusonsolvingseriesofdifferentialequations .Theinputandoutputofanumericalmodelareconsideredasdecisivefactors .Butinrealitythecausesofnaturaleventssuchasmeteorological,astronomical,oceanograph ic ,geomorphologicandgeophysicalfactorsarerandom .Therearemanyuncertaintiesinvolvedininputfactorsinnumericalmodels .Correspondinglytheoutputsofnumericalmodelsarealsorandom .There fore ,theoutputparametersofnumericalmodelsca…     

Dynamic Response of Fluid-Single Leg Gravity Platform-Soil Interaction System

- An approximate method is presented to investigate the earthquake response of the fluid-single leg (shortened for S. L.) gravity platform-soil interaction system. By assuming a suitable form of the velocity potential of the radiation waves and by using the motion equation and the boundary conditions, the unknown coefficients can be obtained. Thereafter the function of frequency for the interaction system may also be obtained. In this paper, the difference of the system dynamic response between rigid foundation is analyzed and the influences of the various foundation geometric dimension and the various water-depth on the hydrodynamic loading and dynamic response of the system is illustrated.