【作者】 王振；

【导师】 周子龙；

【作者基本信息】 中南大学 ， 岩土工程， 2025， 博士

【摘要】 寒区露天矿山爆破破岩效率受低温影响显著,低温导致矿岩物理力学性质发生显著变化,极大地增加了爆破破岩的复杂性。当前的爆破破岩理论和技术未能充分满足寒区露天矿山安全高效开采的需求。本文以冻结砂岩为研究对象,首先探讨了低温条件下冻结砂岩及冰材料的动力响应规律,理论分析了爆破诱发炮孔内冰介质不耦合装药和含冰-岩结构面的冻结岩体裂纹扩展规律。通过实验模型分析了低温对冻结砂岩爆破损伤和及其碎片尺寸分布的影响。基于经过室内爆破试验验证的数值模型参数,进一步研究了冰充填炮孔及含冰充填节理冻结岩体在爆破荷载下的损伤与破碎特征。最后,在多梯度低温冻结岩体深孔台阶爆破损伤模式分析的基础上,提出适用于寒区多梯度含冰充填层理冻结岩体深孔台阶爆破的优化方案,并通过数值模拟与现场台阶爆破试验进行了验证。主要研究内容和成果如下:低温下冰材料和冻结砂岩的动态力学强度和能量耗散密度呈现出显著的率效应。在相同的条件下,冻结砂岩的动态强度、弹性模量和能量耗散密度随着温度由室温(20℃)降低至-40℃的过程中先增加后降低,冻结砂岩动态参数的转折温度发生在-30℃。在-10℃至-40℃的温度范围内,冰试样的动态参数随温度的降低而增加。爆破诱发冻结砂岩应变波的衰减规律呈现指数函数的特征,随着冻结砂岩的温度由20℃降低至-40℃,爆破诱发冻结砂岩裂纹扩展的总长度先减小后增加,冻结砂岩的温度为-30℃时,裂纹扩展的总长度最短。爆破诱发冻结砂岩的破碎程度在温度由20℃降至-30℃的过程中逐渐降低,随着温度进一步降低至-40℃时,冻结砂岩的破碎程度增加。爆破诱发不同温度下冻结砂岩损伤和破碎难易程度的变化是由于冻结砂岩孔隙中水和冰相对含量的改变以及不同基质矿物在低温下的不一致收缩共同导致的。冰充填炮孔爆破的孔壁压力峰值随着冰介质温度的降低而增加,爆破诱发冰介质不耦合装药爆破冻结岩体粉碎区损伤范围随温度的降低逐渐增加,裂隙区损伤范围随温度的降低先减小后增加,针对由于冻冰占据炮孔体积导致炸药量低影响破岩效果的问题,可以通过提高炸药性能与调整起爆位置的方式进行优化。爆破应力波在冰-岩结构面传播的透射系数随结构面内冰温度的降低逐渐减小,随着冰充填节理厚度的增加,应力波的透射系数逐渐降低。此外,应力波的透射系数随着冰充填节理倾角由45°增加至90°的过程中逐渐增加。随着冰充填节理厚度由30毫米增加至70毫米,爆破诱发冰充填节理岩体整体的破碎程度先增加后降低。爆破诱发岩体的破碎程度随充冰节理长度的增加而降低。此外,随着冰充填节理长度的增加或节理内冰温度的降低,爆破诱发岩体损伤程度降低。岩体爆破的破碎程度随着冰充填节理角度的增大而增加。爆破诱发多梯度低温冻结岩体的损伤分布不同于室温岩体爆破的均匀分布,而是沿炮孔轴向由下至上先减小后增加,随着多梯度冻结岩体低温层数由10层增加至20层时,爆破诱发岩体的损伤和破碎程度增加。此外,多梯度冻结岩体的低温范围和低温渗透深度增加均不利于岩体的爆破破碎。在寒区多梯度低温冻结岩体深孔台阶爆破中,台阶内含冰充填层理的存在相较于空层理更有利于台阶的爆破破碎,针对寒区多梯度含冰充填层理冻结岩体深孔台阶爆破冻结层部分岩体破碎大块率高的问题,可以通过优化装药结构和布孔方式来改善由于冻结层岩体导致的岩体爆破大块率高的问题。图113幅,表8个,参考文献216篇更多还原

【Abstract】 The efficiency of blasting rock fragmentation in cold regions open-pit mines is significantly affected by low temperatures,which induce substantial changes in the physical and mechanical properties of ore-rock,greatly increasing the complexity of blasting rock fragmentation.Current theories and technologies for blasting rock fragmentation are insufficient to meet the requirements of safe and efficient mining in cold regions open-pit mines.This study focuses on frozen sandstone as the research object.First,the dynamic response characteristics of frozen sandstone and ice materials under low temperature conditions were investigated.Theoretical analysis was conducted on the blasting-induced crack propagation mechanisms in frozen rock masses with ice-filled boreholes and frozen rock masses containing ice-filled joints.Experimental models were used to analyze the effects of low temperatures on blasting-induced damage and fragment size distribution in frozen sandstone.Based on numerical simulations validated by laboratory blasting test parameters,further research was conducted on the damage and fragmentation characteristics of frozen rock masses subjected to ice-filled borehole blasting and ice-filled jointed rock mass blasting.Finally,based on an analysis of the damage patterns in multi-gradient low temperature frozen rock masses during deep-hole bench blasting,an optimized scheme for deep-hole bench blasting in multi-gradient ice-filled bedding plane frozen rock masses in cold region open-pit mines was proposed and validated through numerical simulations and field bench blasting tests.The main innovative achievements of this thesis are as follows:The dynamic strength,elastic modulus,and energy dissipation density of frozen sandstone and ice materials exhibit significant rate effects under low temperatures.At the same condition,the dynamic strength,elastic modulus,and energy dissipation density of frozen sandstone initially increase and then decrease as the temperature decreases from room temperature(20℃)to-40℃,with a turning point occurring at-30℃.In the temperature range of-10℃ to-40℃,the dynamic parameters of ice samples increase as the temperature decreases.The attenuation of blasting-induced strain waves in frozen sandstone follows an exponential function.As the temperature of frozen sandstone decreases from 20℃ to-40℃,the total length of cracks induced by blasting initially decreases and then increases,reaching a minimum at-30℃.The degree of fragmentation of frozen sandstone gradually weakens as the temperature decreases from 20℃ to-30℃,but increases again when the temperature drops further to-40℃.These variations in blasting-induced damage and fragmentation difficulty at different temperatures are attributed to changes in the relative content of water and ice in the pore spaces of frozen sandstone,as well as differential thermal contraction of various mineral matrices under low temperatures.The peak borehole wall pressure during ice-filled boreholes blasting increases with decreasing ice medium temperature.Blasting-induced ice medium uncoupled charge blasting frozen rock mass damage range in the crushed zone gradually increases with decreasing temperature,and the damage range in the fracture zone first decreases and then increases as temperature drops.The issue of reduced rock fragmentation efficiency caused by insufficient explosive charge due to ice occupying blast hole volume can be optimized by enhancing explosive performance and adjusting initiation points.The transmission coefficient of blasting stress waves at ice-rock interfaces decreases with decreasing ice temperature within the interface.As the thickness of ice-filled joints increases,the transmission coefficient of stress waves gradually decreases.Furthermore,the transmission coefficient increases as the inclination angle of ice-filled joints increases from 45°to 90°.When the thickness of ice-filled joints increases from 30mm to 70 mm,the degree of blasting-induced ice-filled joints rock mass fragmentation first increases and then decreases.The degree of blasting-induced rock fragmentation decreases with increasing ice-filled joint length or decreasing ice temperature within the joint.Moreover,the degree of blasting-induced rock fragmentation increases with increasing ice-filled joint inclination angle.The damage distribution in multi-gradient low temperature frozen rock masses induced by blasting differs from the uniform distribution observed in room temperature rock masses.Specifically,the damage distribution along the borehole axis initially decreases and then increases from bottom to top.As the number of low temperature layers in multi-gradient frozen rock masses increases from 10 to 20,the degree of blasting-induced damage and fragmentation increases.Additionally,an extended range of low temperatures and increased depth of low-temperature penetration in multi-gradient frozen rock masses are detrimental to blasting-induced damage and fragmentation.In deep-hole bench blasting of multi-gradient frozen rock masses in cold regions open-pit mines,the presence of ice-filled bedding planes is more favorable for bench blasting fragmentation compared to empty bedding planes.To address the problem of high oversize ratio in the frozen layer during deep-hole bench blasting of multi-gradient ice-filled bedding plane frozen rock masses,optimizing the explosive charge configuration and borehole arrangement can enhance fragmentation efficiency.更多还原