饱和砂土中浅埋单药包爆炸效应研究

Study of blast response induced by single shallow-buried detonations in saturated sand

为探究饱和砂土场地中药包最佳埋设深度,基于室外大型爆炸试验场地,开展一系列饱和砂土中的浅埋单药包爆炸试验,分析超孔隙水压力变化规律及爆炸成坑效应。研究结果表明:实测孔隙水压力峰值和累积值均随爆距的增大而快速下降;药包埋深的增加有利于超孔隙水压力的累积及维持,相同比例距离处的超孔隙水压力比随着比例埋深的增加而有增大的趋势;超孔隙水压力比在比例距离半对数坐标中近似呈线性规律,其变化趋势与完全封闭爆炸时的基本一致,然而,较小的药包埋深使得部分爆炸能量直接通过自由面耗散,导致超孔隙水压力的上升比深埋爆炸时的明显减弱;相比湿砂环境,饱和砂土中爆坑周围的局部砂土有液化流动的趋势,使得爆坑的横向扩展更为剧烈,因此,在相同药量及埋深条件下,饱和砂土中的爆坑直径比湿砂中的更大。

To study the optimal burial depth for explosive charges in saturated sand, series of single shallow-burieddetonation tests were conducted at a large-scale field site and crater formations and excess porewater pressure generationswere investigated. The results show that both the peak and accumulative values of porewater pressure decrease with theincrease of the blast distance. The accumulation and duration for the maximum constant level of porewater pressure arepromoted with the increase of the charge’s burial depth. For a given scaled distance, a deeper burial explosion cangenerate a higher porewater pressure. Approximate linear fitting between the recorded excess porewater pressure ratioand the scaled distance is observed in a semi-logarithmic scale. The liquefaction tendencies showed by the fitting linesare basically in accordance with the results produced by a fully contained detonation. However, smaller growing of porewater pressure is recorded during the tests with shallow-buried charge, since a portion of explosion energy dissipatesthrough the ground surface. Saturated soil particles near a crater have liquefied tendencies under blast loading, whichleads to a more intense horizontal expansion of a crater compared with that in wet sand. Therefore, crater diameter insaturated sand is much larger than that in wet sand under the same blast loading and buried depth.