【摘要】 武汉杨泗港长江大桥桥墩坐落在硬质黏土层上,沉井施工中为剔除厚井壁下的黏土,设计用钻孔爆破方法将黏土抛出。为确保桥墩地基和沉井壁的安全,运用有限元数值模拟软件ANSYS/LS-DYNA,研究了水下爆炸荷载对基底持力层黏土性质的影响,分析了不同装药量对临空面部分黏土的抛掷效果及最佳装药量下沉井下方黏土的应力、密度等物理力学性质的变化规律,并将之与室内试验结果对比。研究表明:当装药量达到4 kg时,其产生的爆破荷载可将临空面部分的硬质黏土抛掷开,此时装药量达到最佳;爆炸应力随时间的推移不断衰减,其传播规律与实际相同;在最佳装药量下,炮孔下方硬质黏土在爆后密度随爆心距的增大而不断减小,直到其初始密度值;模拟结果与室内试验结果吻合较好,验证了模拟的可靠性。更多还原

【Abstract】 The piers of Wuhan Yangsigang Bridge of Yangtze River are located on the hard clay layer,in order to remove the clay under the thick caisson wall in the process of the caisson construction,the drilling blasting method has been designed to throw the clay away. To ensure the safety of the pier foundation and the caisson wall,the finite numerical simulation software ANSYS/LS-DYNA was used to research the influence of underwater blasting load on the properties of the basal bearing stratum clay of the bridge. It analyses the throwing effects of the clay with a free face by different amount of explosives and the change rules of the density and the pore pressure of the clay under the open caisson with the best doses. The research shows that,when the amount of the explosives reaches 4 kg,the hard clay with a free face under the open caisson can be thrown away by the blasting load,where the dose reaches the best. The explosion stress decreases with time,the same as the practice. With the distance to the blasting center increaseing,the density of the clay decreases to its initial value in the case of best dose. The simulation results are in good agreement with the indoor test results,which verify the reliability of the simulation.更多还原