Pipes inevitably encounter high ambient pressure and bending moment during the deepwater pipe-laying process,which can lead to elliptical buckling and even deterioration failure.For the safety of pipe-laying operation...Pipes inevitably encounter high ambient pressure and bending moment during the deepwater pipe-laying process,which can lead to elliptical buckling and even deterioration failure.For the safety of pipe-laying operation,available formulas for the pipe stability are established on the basis of the assumption of uniform deformation along the tube length and symmetrical buckling.This method can predict the nonlinear response of elliptical collapse of steel circular tubes for different ratios of diameter to thickness（D/t）under pure bending or combined bending and external pressure.In these formulas,the strain-displacement relationship is deduced from the nonlinear ring theory,and the Ramberg-Osgood constitutive model is applied to simulate the inelastic material behavior.Meanwhile,the principle of virtual work is adopted to derive the equilibrium equations.A set of equations is solved by the Newton-Raphson method,and the iterative scheme contains nested iteration for the constitutive relation.In order to check the effectiveness of this theoretical method,illustrative examples are presented in this paper.Besides,the numerical simulation is carried out by use of ANSYS.A comparison of the results shows that the theoretical method can provide reasonable prediction for engineering practice.展开更多
为了探索不同径厚比海底管道的压溃屈曲特性,本文分别采用挪威船级社(Det Norske Veritas,DNV)规范、有限元模拟和深海压力舱模型试验,研究不同径厚比海底管道承载外部水压的能力,并就DNV规范压溃屈曲计算公式对不同径厚比管道的适用性...为了探索不同径厚比海底管道的压溃屈曲特性,本文分别采用挪威船级社(Det Norske Veritas,DNV)规范、有限元模拟和深海压力舱模型试验,研究不同径厚比海底管道承载外部水压的能力,并就DNV规范压溃屈曲计算公式对不同径厚比管道的适用性进行了讨论,优化了小径厚比海底管道压溃屈曲的设计方法。研究表明:小径厚比管道的压溃屈曲临界压力对管道径厚比的变化更敏感;DNV规范计算小径厚比管道的压溃屈曲临界压力偏小,在进行深海管道的压溃屈曲设计时,建议采用模型试验结合有限元模拟的方法,计算管道实际可提供的压溃屈曲承载力。展开更多
基于武汉科技大学与中铁港航局联合研制的10 g TNT当量水介质爆炸容器,在爆炸罐内施加不同压强,模拟不同水深梯度,进行多组素混凝土试块的水下爆炸实验,统计炸药爆炸后的各种块度,发现随着水深增大岩石的大块率增加,且水深是主要影响因...基于武汉科技大学与中铁港航局联合研制的10 g TNT当量水介质爆炸容器,在爆炸罐内施加不同压强,模拟不同水深梯度,进行多组素混凝土试块的水下爆炸实验,统计炸药爆炸后的各种块度,发现随着水深增大岩石的大块率增加,且水深是主要影响因素。由于水介质的压力作用,改变了岩石中的轴向压力作用,受到水的围压作用,炸药爆炸后需分配一部分能量用于克服水压作用,而且水深越大,岩石外部围压越大,因此破碎程度远不如同等条件下的陆地爆破,得到相同破碎程度,需要更大的单耗,水深越大所需单耗越大,研究结果可供实际工程参考。展开更多
基金supported by the National High Technology Research and Development Programof China(863 Program,Grant No.2006AA09A105)
文摘Pipes inevitably encounter high ambient pressure and bending moment during the deepwater pipe-laying process,which can lead to elliptical buckling and even deterioration failure.For the safety of pipe-laying operation,available formulas for the pipe stability are established on the basis of the assumption of uniform deformation along the tube length and symmetrical buckling.This method can predict the nonlinear response of elliptical collapse of steel circular tubes for different ratios of diameter to thickness（D/t）under pure bending or combined bending and external pressure.In these formulas,the strain-displacement relationship is deduced from the nonlinear ring theory,and the Ramberg-Osgood constitutive model is applied to simulate the inelastic material behavior.Meanwhile,the principle of virtual work is adopted to derive the equilibrium equations.A set of equations is solved by the Newton-Raphson method,and the iterative scheme contains nested iteration for the constitutive relation.In order to check the effectiveness of this theoretical method,illustrative examples are presented in this paper.Besides,the numerical simulation is carried out by use of ANSYS.A comparison of the results shows that the theoretical method can provide reasonable prediction for engineering practice.
文摘为了探索不同径厚比海底管道的压溃屈曲特性,本文分别采用挪威船级社(Det Norske Veritas,DNV)规范、有限元模拟和深海压力舱模型试验,研究不同径厚比海底管道承载外部水压的能力,并就DNV规范压溃屈曲计算公式对不同径厚比管道的适用性进行了讨论,优化了小径厚比海底管道压溃屈曲的设计方法。研究表明:小径厚比管道的压溃屈曲临界压力对管道径厚比的变化更敏感;DNV规范计算小径厚比管道的压溃屈曲临界压力偏小,在进行深海管道的压溃屈曲设计时,建议采用模型试验结合有限元模拟的方法,计算管道实际可提供的压溃屈曲承载力。
文摘基于武汉科技大学与中铁港航局联合研制的10 g TNT当量水介质爆炸容器,在爆炸罐内施加不同压强,模拟不同水深梯度,进行多组素混凝土试块的水下爆炸实验,统计炸药爆炸后的各种块度,发现随着水深增大岩石的大块率增加,且水深是主要影响因素。由于水介质的压力作用,改变了岩石中的轴向压力作用,受到水的围压作用,炸药爆炸后需分配一部分能量用于克服水压作用,而且水深越大,岩石外部围压越大,因此破碎程度远不如同等条件下的陆地爆破,得到相同破碎程度,需要更大的单耗,水深越大所需单耗越大,研究结果可供实际工程参考。
