摘要
为研究单轴循环冲击下冻结砂岩宏观动力学特性和损伤机理,采用分离式霍普金森压杆对不同冻结温度饱水砂岩开展单轴循环冲击试验,以动力学参数构建损伤变量分析冻结砂岩损伤演化规律,提出循环冲击作用下疲劳寿命预测公式。结果表明饱水砂岩最大累计循环冲击次数随入射波应力幅值增大而减少,随温度的降低而增加。在入射波应力幅值区间(22~28 MPa)存在动态参数和损伤变化拐点,冲击荷载小于拐点值时试样动弹性模量先增大后减小,呈现负损伤;大于拐点值时动弹性模量则逐渐减小,损伤累积引起总体损伤度逐渐增大。相同冲击荷载下,不同温度砂岩的损伤演化规律不同,由损伤度曲线斜率可知温度越低,损伤演化越缓慢。结合微观机理分析,0~-5℃时冰晶体的胶结力显著提高冻结砂岩强度,-5~-10℃时水冰相变产生的微裂纹导致损伤特征开始显现。总结建立了冻结砂岩在循环冲击作用下疲劳寿命预测公式,对冻结凿井爆破施工设计中围岩损伤范围和冻结壁稳定性分析具有指导意义。
In order to study the macroscopic dynamic mechanical characteristics and damage mechanism of frozen sandstone under uniaxial cyclic impact,uniaxial cyclic impact tests were carried out on water-saturated sandstone at different freezing temperatures by using split Hopkinson pressure bar.The damage variable was constructed with dynamic mechanical parameters to analyze the damage evolution law of frozen sandstone,and the fatigue life prediction formula under cyclic impact was proposed.The results show that the maximum cumulative cyclic impact times of water-saturated sandstone decrease with the increase of incident wave stress amplitude but increase with the decrease of temperature.There exist inflection points of dynamic parameters and damage changes in the range of incident wave stress amplitude(22~28 MPa).When the impact load is less than the inflection point,the dynamic elastic modulus of the sample first increases and then decreases,showing negative damage.When the value is greater than the inflection point,the dynamic elastic modulus decreases gradually,and the overall damage degree increases gradually due to damage accumulation.Under the same impact load,the damage evolution law of sandstone at different temperatures is different.According to the change of curve slope,the lower the sample temperature is,the slower the damage evolution is.Form the micro mechanism analysis,the cementation force of ice crystals significantly improves the strength of frozen sandstone(0~-5℃),and the damage characteristics begin to appear due to the micro cracks caused by water ice phase transition(-5~-10℃).The fatigue life prediction formula of frozen sandstone under cyclic impact is established,which has a guiding significance for the damage range of surrounding rock and the stability analysis of frozen wall in the blasting construction design of frozen shaft sinking.
作者
王磊
秦越
赵涛
苏宏明
陈世官
WANG Lei;QIN Yue;ZHAO Tao;SU Hongming;CHEN Shiguan(College of Civil and Architectural Engineering,Xi’an University of Science and Technology,Xi’an 710054,China)
出处
《西安科技大学学报》
CAS
北大核心
2021年第5期886-894,共9页
Journal of Xi’an University of Science and Technology
基金
国家自然科学基金项目(51404193)
中国博士后基金项目(2015M572581)
陕西省自然科学基金项目(S2015YFJQ1194)。
关键词
冻结砂岩
单轴循环冲击
损伤演化
疲劳寿命
frozen sandstone
uniaxial cyclic impact
damage evolution
fatigue life
