摘要
冻结岩石热融过程中强度会出现软化,是最易发生破坏的阶段。研究冻结岩石的热融软化规律对冻结地层解冻过程中的稳定性和安全性评价至关重要。本文开展了不同融化温度下冻结岩石的单轴压缩试验,在还原岩石孔隙结构及对细观参数进行精确标定的基础上,利用颗粒流软件(PFC^(2D))模拟了冻结岩石的压缩破坏过程。基于微裂纹起裂规律和微裂纹扩展规律分析,探讨了孔隙冰对冻结砂岩热融软化规律的控制作用。研究结果表明:(1)冻结岩石的强度、弹性模量等参数均随着温度的升高呈两阶段变化趋势,在-4℃至-2℃之间存在某一温度,使得试样的强度及变形参数发生骤降。(2)当温度低于-15℃时,微裂纹的起裂扩展主要由矿物颗粒之间的接触强度控制;当温度在-2℃和-15℃之间时,主要由冰颗粒之间和冰-矿物之间的接触强度控制;而当温度大于-2℃时,则主要由冰颗粒之间的接触强度控制。(3)通过分析孔隙冰在冻结岩石受荷破坏过程中所起的“支撑作用”和“黏结作用”,发现在-6℃至-4℃之间,冰颗粒之间黏结强度和冰-矿物黏结强度均迅速衰减,导致冰的支撑和黏结作用弱化,是该温度区间力学性质快速弱化的本质原因。
In high-altitude and high-altitude areas,the stability of steep mining slopes containing years of frozen layers is controlled by the mechanical properties of frozen rock layers.Excavation of the strata exposes the frozen rock layers to the air,and coupled with blasting vibrations or mechanical disturbances during excavation,the frozen rock layers gradually soften and heat melt,leading to a decrease in slope stability.With the continued global climate warming,the thermal thawing softening of frozen rock layers accelerates,further exacerbating the risk of instability in mining slopes.The strength of frozen rocks will soften during the hot melt process,which is the most susceptible stage to failure.Studying the thermal thawing softening law of frozen rocks is crucial for evaluating the stability and safety of frozen strata during the thawing process.This article conducted uniaxial compression tests on frozen rocks at different melting temperatures.Based on the restoration of rock pore structure and precise calibration of microscopic parameters,the particle flow software(PFC^(2D))was used to simulate the compression failure process of frozen rocks.Based on the analysis of the initiation law and propagation law of microcracks,this paper explores the control effect of pore ice on the thermal thawing softening law of frozen sandstone.The research results indicate that:(1)the strength,elastic modulus and other parameters of frozen rock show a two-stage trend with the increase of temperature.There is a certain temperature between -4℃ and -2℃,which causes a sudden decrease in the strength and deformation parameters of the sample.(2)As the temperature increases,the failure of frozen rocks at peak stress gradually shifts from being dominated by mineral particle frameworks to being dominated by ice.When the temperature is less than -2℃,the degree of damage to the frozen rock skeleton is higher;When the temperature is greater than -2℃,the damage to porous ice is more significant.When the temperature is below-15℃,the initiation and propagation of microcracks are mainly controlled by the contact strength between mineral particles;When the temperature is between -2℃ and -15℃,it is mainly controlled by the contact strength between ice particles and ice minerals;When the temperature is greater than-2℃,it is mainly controlled by the contact strength between ice particles.(3)By analyzing the supporting and bonding effects of pore ice during the load failure process of frozen rocks,it was found that between -6℃ and -4℃,the bonding strength between ice particles and between ice minerals rapidly decayed,leading to a weakening of the supporting and bonding effects of ice,which is the essential reason for the rapid weakening of mechanical properties in this temperature range.For high-altitude and high-altitude areas,the thermal thawing softening of frozen rock layers is a core process related to their stability and safety.Therefore,studying the thermal thawing softening law and load failure process of frozen rocks is of great engineering significance.
作者
贾海梁
王振阳
赵涛
孙强
唐丽云
JIA Hailiang;WANG Zhenyang;ZHAO Tao;SUN Qiang;TANG Liyun(School of Architecture and Civil Engineering,Xi'an University of Science and Technology,Xi’an 710054,China;CCCC First Highway Survey and Design Institute Co.,Ltd.,Xi’an 710054,China)
出处
《冰川冻土》
CSCD
2024年第2期578-591,共14页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(42271148)资助。
关键词
冻结岩石
热融软化
细观结构
微裂纹扩展
PFC2D
frozen rock
thawing and softening
microscopic structure
microcrack propagation
PFC2D
