爆破挤淤堤坝工后沉降特性离心模拟试验研究

Centrifugal model tests on settlement characteristics of embankment using blasting compaction technology

爆破挤淤技术在海洋围垦工程建设中发挥着重要作用,但其理论研究落后于工程实践。通过离心机点火装置的研制实现离心场中的起爆控制,进而建立概化模型,模拟堆石堤坝存在时爆破挤淤的作用效果,研究爆炸荷载作用下地基土体的孔压消散特性及形成堆石堤坝的工后沉降特性。通过多次尝试性试验,最终取得两组合理有效的爆破试验测试成果。研究表明:地基土含水率越高、强度越低,爆破后堤坝瞬时沉降越大,爆破挤淤置换效果也更显著;在地基土较软弱的条件下,爆破挤淤堤坝工后沉降明显较大;在堤坝上覆压力存在的条件下,爆破瞬间地基土中产生显著的超孔隙水压力,超孔压的产生使得地基土瞬时有效抗剪强度弱化,甚至会丧失结构强度和承载能力,从而为爆破挤淤"泥–石"置换过程创造了有利条件。

The blasting compaction technology plays an important role in the construction of marine reclamation projects,however, its mechanism studies are behind the engineering practice. An ignition device is developed in the centrifuge to initiate and control blasting effect, and two centrifugal model tests on the blasting compaction technology of silt with different water contents are carried out. Furthermore, the settlement of embankment with blasting compaction and the characteristics of the excess pore water pressure of silt foundation are analyzed. The results show that the immediate settlement of embankment is larger after blasting when the silt has higher water content, and the blasting displacement effect is more pronounced. However,the post-construction settlement of embankment is larger when the silt foundation has lower intensity. In addition, the excess pore water pressure is produced after blasting in the silt foundation with overburden pressure, and it will weaken the effective shear strength of silt foundation or even the structural strength and load-bearing capacity will lose, so that favorable conditions will be created for replacement of 'mud- stone' in the process of blasting compaction.