Fem Model Analysis Of Triple Clustered Suction Piles Under Lateral And Pulling Loads

With the increasing popularity of offshore Petroleum &Gas exploration and offshore wind power generation, marine engineering begins to take off rapidly. The site of exploration crawls from shallow offshore to deep sea, which challenges the current construction of deep marine foundation. All kinds of new floating structures which lead to uplift load to the foundation contrary to downwards load generated by offshore platform come to use and make the traditional compression based pile no longer applicable. The suction pile with the merit of feasibility for deep sea soft clay and sand, economical steel consumption and low expense, short construction period and reusability bas been widely concerned and possesses great application potential. The clustered suction pile consists of a plurality of suction piles and has higher regulation accuracy and more stability except for the advantages of single suction pile. At present, research about the stability and theoretical analysis for the mechanical characteristic of triple suction pile is still at a groping stage. Therefore, the numerical calculation for the deformation mechanism and bearing capacity of the triple clustered suction pile foundation under varies of loads has important scientific significance and practical value. In this paper, the three-dimensional nonlinear finite method and displacement control method is adopted in the ABQUS to simulate the failure mechanism and bearing capacity of the triple clustered suction pile. Results show that:(1) Under vertical load, the triple clustered suction pile with bigger length-diameter ratio will has greater displacement of soil plug when pulled out; thedisplacements of soil plug will stay the same for different pile space.(2) Under horizontal load, variation of the position of the anchor will lead the triple clustered suction piles to three different failure modes, namely forward tilted rotation failure, sliding failure and tilted rotation failure.(3) The larger the length-diameter ratio is, the greater the uplift ultimate bearing capacity and the horizontal bearing capacity of the triple clustered suction piles will be. The bigger the pile spacing is, the greater the horizontal bearing capacity of the triple clustered suction piles will be while uplift ultimate bearing capacity is constant.(4) With the increase of the ratio of the length to diameter, the failure envelope of the triple clustered suction pilesshows a trend of outward expansion under both horizontal and uplift force and this proves the ultimate bearing capacity improvement of the triple clustered suction piles. Comparison of the failure envelopes of triple clustered suction piles with different pile spacing shows that only when the angle of envelope is less than 45 degrees, the envelope will expand outward, so will the bearing capacity. When the angle of envelope is more than 45 degrees, the promotion of bearing capacity is limited.(5) Under the same load condition, the horizontal bearing capacity of the triple clustered suction piles with 3 kinds of long diameter ratio and 3 kinds of pile spacing is always the biggest. When the load angle is 0 degrees, it is the best load angle of the triple clustered suction piles.(6) With the increase of the length-diameter ratio, the position of the optimal load of the triple clustered suction piles will move up. With the increase of the pile space, the position of the optimal load of the triple clustered suction piles will stay the same. When the ultimate bearing capacity of the triple clustered suction piles reaches the maximum, the displacement of the triple clustered suction piles will be horizontal approximately.