| For the exploitation of marine resources is more economy and efficient,tension leg platform,SPAR platform,floating production storage & offloading,compliant tower and floating production system that the new deep-water platform constructions is widely applied in engineering.These platform constructions connect the foundation embedded in the sea-bed by moor.As the new deep-water platform constructions are widely applied,the mooring problem of large floating constructions in deep-sea submarine presents some new challenges. The environment of deep-water is very badly,upper constructions,soil conditions of sea-bed, complex load combination,feasibility and economy of execution and so on must be considered to choose foundations of the deep-water platform constructions.In the past 10 years,suction caisson foundation as a foundation of the new deep-water platform constructions are widely applied and so many petroleum Corporations pay attention to it.In this dissertation,the studies are emphasized on failure mechanism and evaluating the bearing capacity of suction caisson foundation on inclined loading.The main investigations consist of the following parts.(1)Based on observing the failure phenomenon of the small scale indoor model test,the failure mechanism of model test and ABAQUS finite element analysis is unanimous.Failure mode consists of spherical failure mode at bottom of caisson and local shear failure mode on sides of caisson.On the same aspect ratio as inclined angle increasing,on sides of caisson the lateral resistance gradually reduces and skin resistance between caisson and soil gradually increases.The potential crack between the posterior wall of caisson and neighboring soil in the active zone is constructed.At the same time,only an individual wedge near the mudline exists in neighboring soil of the passive zone,and a truncate spherical slip surface exists in the base of caisson obviously.On the same aspect ratio as inclined angle increasing,the rotation center of the caisson gradually deviates from axis,failure mode gradually change from spherical failure mode at bottom of caisson to local shear failure mode on sides of caisson.Whenψ=30°,the two failure mode interaction is obvious.(2)Analyzing the results of ABAQUS finite element simulation and model test data,on different aspect ratio the small dispersion of model test ultimate value and ABAQUS ultimate value is 1.8%,and the large is 55.5%.On different aspect ratio the small dispersion of model test ultimate value and ABAQUS shear value is 1.05%,and the large is 29.6%.The above conclusion proves the correctness of the finite element computational model for suction caisson foundation in soft ground and ABAQUS finite element simulation.(3)Based on the ABAQUS finite element simulation for suction caisson loading capacity, studying suction caisson capability under no suction condition and the effect of inclined angleψ.When inclined angleψ=90°,suction caisson loading capacity is large.When inclined angleψ=0°,suction caisson loading capacity is small.The study shows suction caisson loading capacity is largest under vertical loading,as inclined load gradually deviating from horizontal line,suction caisson loading capacity gradually reduces.Suction caisson loading capacity is least under horizontal loading.The study gains V-H failure envelope of suction caisson foundation on different aspect ratio.V-H interaction curve is approximately ellipse. When L/D=1.0 and inclined angle from 15°to 45°,V-H interaction is effective;when L/D=2.0 and inclined angle from 15°to 60°,V-H interaction is effective;when L/D=3.0 and inclined angle from 15°to 60°,V-H interaction is effective.The author discusses suction caisson loading capacity on different aspect ratio.For Inclined angleψ=15°, horizontal loading parameter N_h and vertical loading N_v are almost equally on different aspect ratio.For Inclined angle from 30°to 75°,vertical loading N_v,is greater than horizontal loading parameter N_h on different aspect ratio.
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