【作者】 孙凯；

【导师】 王建华；

【作者基本信息】 天津大学 ， 工程硕士（专业学位）， 2021， 硕士

【摘要】 当海洋导管架平台无自备钻机时,往往需要自升式钻井船在其附近进行辅助作业。作业时,需要将大直径桩靴贯入海床以提供承载力。桩靴贯入会对桩靴周围一定范围的土体造成极大扰动,使邻近的海洋平台桩承受附加荷载作用,进而影响桩基的稳定性和承载力。应变软化粘土具有应变超过峰值强度对应的应变后强度弱化的特性,桩靴贯入应变软化粘土与无应变软化粘土时,邻近桩桩身响应及桩靴贯入影响范围可能存在明显差异。故本文采用耦合欧拉-拉格朗日(CEL)数值仿真方法,分析了桩靴贯入应变软化粘土时邻近受荷单桩的桩身弯矩增量、桩头水平与竖向位移增量以及桩身轴力增量随桩靴与邻近桩之间距离、应变软化粘土的残余强度比以及桩头荷载的变化,得出如下结论:(1)桩靴贯入影响范围随应变软化粘土的残余强度比增大而减小。(2)桩径对桩靴贯入影响范围有影响。对于2 m直径的钢管桩,当应变软化粘土的残余强度比从1增大至4时,桩靴贯入影响范围从1.0D(D是桩靴最大直径)减小至0.47D。对于1m直径的钢管桩,当残余强度比从1增大至4时,桩靴贯入影响范围从1.0D减小至0.79D。(3)对于本文分析工况,桩头水平荷载对桩靴贯入影响范围的影响较小。(4)桩靴贯入对邻近桩水平响应的影响范围大于对竖向响应的影响范围,因此桩靴贯入对邻近桩的影响范围取决于对桩水平响应的影响范围。更多还原

【Abstract】 Offshore jacket platforms often require the assistance of drilling vessels.When a jack-up rig works near a jacket platform,it is necessary to insert large-diameter spudcan into the seabed to provide bearing capacity.The penetration of spudcan will cause great disturbance to the soil around the spudcan,so that the adjacent piles will bear additional loads,affecting the stability and bearing capacity of the pile foundation.The strength of strain-softened clay decreases when strain exceeds the strain corresponding to the peak strength.In the strain-softened clay,the response of the adjacent pile and the influence range of spudcan penetration may be great different from those in the non strain-softened clay.Therefore,the CEL numerical simulation method is used to analyze the pile bending moment increment,the pile head horizontal and vertical displacement increment,and the pile axial force increment with the spudcan-pile clearance,residual strength ratio and pile head load when the spudcan penetrates into the strain-softened clay.The following conclusions are drawn:(1)The influence range of spudcan penetration decreases with the increase of residual strength ratio.(2)The pile diameter has an influence on the range of spudcan penetration.For the steel pipe pile with a diameter of 2 m,when the residual strength ratio of the strain-softened clay increases from 1 to 4,the influence range of spudcan penetration decreases from 1.0D(D is the maximum diameter of the spudcan)to 0.47D.For the steel pipe pile with a diameter of 1 m,when the residual strength ratio increases from 1 to 4,the influence range of spudcan penetration decreases from 1.0D to 0.86D.(3)For the working conditions analyzed in this paper,the horizontal load of the pile head has less influence on the influence range of the spudcan penetration.(4)The influence range of spudcan penetration determined by the horizontal response of adjacent piles is greater than that determined by the vertical response.Therefore,the influence range of spudcan penetration should be determined by the horizontal response of adjacent piles.更多还原