西北冻结立井砼井壁爆破损伤模型

Damage model of frozen vertical shaft concrete under blasting load in Northwest China

为研究我国西北地区冻结立井岩石钻爆法施工时,大药量爆破对附近新浇混凝土井壁的损伤情况,根据相似理论制作了15∶1的圆柱形冻结立井模型,在爆破塔内开展了爆破模型试验研究。沿立井轴线方向,在混凝土井壁内侧面上粘贴环向和轴向共4组应变片,测定井壁在微差爆破作用下的变形情况,并根据广义胡克定律近似计算出各点应力。同时采用超声波测试方法测定井壁损伤。结果表明:井壁内侧面各点的应力应变时程曲线与爆破方案密切相关,应力应变峰值与各微段炸药量相对应。得出应力峰值与爆距、药量和岩体介质之间的拟合关系,以爆破前后的波速变化衡量井壁损伤,据此估计多次爆破对井壁累积损伤情况。

In order to determine the damage of new cast reinforced freezing shaft lining near the work plane subject to large excavation blasting in Northwest China using frozen-blasting method,a freezing vertical shaft model was made based on similarity theory,and the ratio of similitude is 15∶ 1.The model test was carried out in blasting tower.In the axial direction,four pairs hoop and axial strain gages was pasted on inner surface of concrete lining,which can be used to measure the strain of shaft lining under millisecond blasting scheme.The stress of shaft lining was calculated according to generalized Hooke law,and the damage was measured by ultrasonic measure method.The results show that strain and stress time history cures of points on the inner surface of shaft lining are closely related to blasting scheme.The peak strain and stress correspond to micro-step explosive quantity.The fitting relationship between peak stress and blasting distance,explosive quantity and rock media was obtained.The damage of shaft lining was estimated on the basis of the variation of wave velocity before and after blasting.