摘要:
西部矿井建设中,穿越含水裂隙岩体会采用冻结立井法施工进而会形成冰-岩组合体,然而,施工期间的爆破冲击波会对冻结状态下的围岩造成影响,进而对工程安全构成威胁。因此,利用霍普金森压杆试验装置,系统分析了爆破后应力波在冻结岩石裂隙结构面内的传播与衰减规律,主要结论如下:(1)当冲击气压达到试件破坏阈值时,0°与15°试件的反射系数(R)值随冲击气压的的增大先减小后增大,而透射系数(T)值先上升后下降;30°与45°试件的R与T值均随冲击气压的增加而递减。(2)当入射应力波强度小于岩石的动态压缩强度但大于冰的动态抗压强度时,冰岩组合体的破坏模式随结构面角度与加载应变率的变化呈现压缩破坏、剪切破坏和压剪复合破坏三种形式。(3)结构面产生的整体弱化效应显著强于应变率带来的强化作用,其中,当结构面倾角为45°时,R值的下降趋势逐渐减缓,T值的降幅依然显著,即大倾角结构面对应力波反射能力的敏感性较低,而对透射作用的敏感性则较高。研究可为寒区工程在冻结立井施工下裂隙岩体抗扰动作用提供理论参考。
Abstract:
In western mining construction, the freezing shaft method is employed to penetrate water-bearing fractured rock masses, forming ice-rock composite structures. However, the blast shock waves during construction can affect frozen surrounding rock, posing safety risks. Using the Hopkinson bar test apparatus, we systematically analyzed the propagation and attenuation patterns of post-blast stress waves in frozen rock fracture surfaces. Key findings include: (1) When impact pressure reaches the specimen failure threshold, specimens 0 and 15 exhibit decreasing reflection coefficients (R) followed by increasing transmission coefficients (T) as pressure rises, while specimens 30 and 45 show decreasing R and T values. (2) When incident stress wave intensity is below rock's dynamic compressive strength but above ice's dynamic compressive strength, the ice-rock composite demonstrates three failure modes: compressive, shear, and combined compressive-shear failure, depending on structural surface angle and loading strain rate. (3) The overall weakening effect at structural surfaces significantly outweighs strain rate-induced reinforcement. Notably, specimens with 45° inclination show gradually reduced R value decline but maintain substantial T value decrease, indicating lower sensitivity to stress wave reflection at steep angles compared to transmission effects. This study provides theoretical insights for mitigating disturbance effects in fractured rock masses during freezing shaft construction in cold regions.