钙质砂场地爆炸成坑实验与数值模拟研究

Experimental and numerical simulation studies on blast-induced craters in calcareous sand

为了建立钙质砂场地爆炸成坑效应的计算方法,首先在开挖出的钙质砂模型场地开展了不同当量、不同埋深的野外爆炸实验,然后基于有限元与光滑粒子流耦合算法建立了适用于钙质砂爆炸成坑计算的数值模型,并分析了炸药形状和土体参数对爆坑形态的影响,最后建立了适用于钙质砂场地中的爆坑计算公式。结果表明:埋置爆下,钙质砂场地爆坑尺寸大于硅质砂土中的爆坑尺寸;光滑粒子流算法能较好地揭示钙质砂场地中爆坑轮廓的形成机理;炸药形状和土体密实度等参数对于钙质砂爆坑形态具有不同程度的影响,拟合得到的钙质砂场地接触爆和埋置爆抛掷型爆坑尺寸计算公式,可较好地预测不同爆炸当量作用下的爆炸成坑尺寸。

With the further development of ocean engineering,the dynamic response of calcareous sand sites under strong dynamic loading has received broad attention.In order to investigate the crater characteristics of calcareous sand sites under explosion impact,filed experiments and numerical simulations were conducted.Firstly,a series of field explosion experiments were conducted on calcareous sand sites,with different equivalent sizes and burial depths.The longitudinal and transverse diameter,as well as the depth of craters were measured for each case.Secondly,a new numerical algorithm(FEM-SPH)was used to simulate the formation process of explosion craters,combining the finite element model(FEM)and the smoothed particle hydrodynamics(SPH).Furthermore,the simulated crater dimensions were compared with the experimental results to validate the accuracy of the FEM-SPH model.Thanks to the advantage of the FEM-SPH in simulating large deformations,the crater formation process of ground contact explosions and buried explosions agreed well with the experimental results.The experiment research showed the crater size resulting from buried explosions is larger in calcareous sand compared to siliceous sand.The phenomenon was mainly attributed to the higher porosity and lower interparticle bonding strength of calcareous sand.With the validated FEM-SPH model,parametric analyses,including soil parameters and shapes of charges,were detailed discussed.Under the same equivalent,the influence of soil parameters on the size of the crater was about 6%,while the change in the shape of the charge caused a significant influence on the shape and size of the craters.Finally,empirical formulas were derived to determine the carter diameter and depth under cubic charge explosion according to the FEM-SPH numerical results in calcareous sand sites.The formulas can predict the dimensions of ground contact explosions and buried explosions within different equivalent charge weight ranges(0-500 kg).The above research results provided a useful reference for the blast-resistant protection design and emergency reinforcement of calcareous sand foundations.