混凝土含水裂隙中爆炸压力传播的模型试验研究

Model experimental study of explosion pressure propagation in concrete water-bearing crack

爆炸作用下含水裂隙中水压力的分布及传播特征对分析含水裂隙岩体初始裂纹扩展机制具有重要意义。通过含水裂隙的混凝土室内爆炸试验,测量了爆炸时含水裂隙中的水压力,分析了含水裂隙中水压力的荷载特性及传播特征,并研究了裂隙张开宽度及爆炸药量对水压力荷载的影响。试验研究结果表明:爆炸作用下含水裂隙中水压力时程分布呈多峰波动分布,水压力来源包括爆源通过水介质直接传递的荷载及通过混凝土间接传递的荷载,且在不同裂隙长度,荷载峰值主要来源不同;相同装药条件下,含水裂隙中水压力随距爆源距离增大而迅速衰减,裂隙中同一位置水压力大小与裂隙张开宽度呈负相关;混凝土室内爆炸试验含水裂隙中水击波所带能量频谱主要集中在7.8~62.5 kHz,是一种高频信号。随距爆源距离的增加,能量分布向低频集中;水击波频带能量分布特征受爆炸药量及裂隙张开宽度的影响。当量为4.5 g TNT(三硝基苯)乳化炸药装药相比8.1 g TNT乳化炸药装药爆炸时水击波高频信息更丰富;相同爆炸药量时,随混凝土中含水裂隙张开宽度的增加,水击波频带能量分布峰值呈现向中间频带移动的趋势。

The distribution and propagation characteristics of water pressure in water-bearing crack under blasting load are of great significance to the study of the initial crack propagation mechanism in water-bearing fractured rock mass. Through the laboratory blasting experimental in concrete with water-bearing crack, the water pressure in water-bearing crack was measured during blasting,and its loading characteristics and propagation law were analyzed, while the effects of crack aperture and blasting charge quantity on water pressure were studied. The experimental results show that the time-history distribution of water pressure in water-bearing crack presents multi-peak fluctuation distribution. And the sources of water pressure include the blasting load directly transmitted through the water and indirectly transmitted through the concrete;the main source of load is different for different crack lengths. Under the same charging condition, the water pressure in water-bearing crack attenuates rapidly with increase of distance from the detonation source, and the water pressure at the same position in crack is approximately inversely proportional to the crack aperture. The energy spectrum of water hammer wave in water-bearing cracks is mainly concentrated in 7.8-62.5 kHz during laboratory explosion test of concrete with water-bearing crack, which is a high frequency signal. Meanwhile, the energy distribution trends to concentrate in the low frequency range with increase of distance from the detonation source. The energy distribution characteristics of water hammer wave are affected by charge and crack aperture, and the explosion induced by emulsion explosive of the equivalent 4.5 gTNT charge can generate water hammer wave with more abundant high frequency information in comparison with the equivalent 8.1 g TNT emulsion explosive charge. For the same blasting charge quantity, the peak energy distribution of the water hammer wave frequency band tends to move to the middle band with the increase of crack aperture.