动载下饱冰平行裂隙砂岩细观开裂机理研究  

The Meso-cracking Mechanism of Ice-Saturated Sandstone with Parallel Fractures under Dynamic Loading

作　　者：王林鑫 杜祎玮 任富强 常远 WANG Linxin;DU Yiwei;REN Fuqiang;CHANG Yuan(School of Civil Engineering,University of Science and Technology Liaoning,Anshan 114051,Liaoning,China)

机构地区：[1]辽宁科技大学土木工程学院,辽宁鞍山114051

出　　处：《昆明理工大学学报(自然科学版)》2025年第2期34-44,共11页Journal of Kunming University of Science and Technology(Natural Science)

基　　金：国家自然科学基金项目(52074292);辽宁省博士科研启动基金项目(2022BS280)。

摘　　要：为探究动荷载下饱冰平行裂隙砂岩的动力响应机制,开展了4组不同裂隙倾角(0°、30°、60°和90°)下4种不同饱冰平行裂隙砂岩(双长型、双短型、上长下短型和上短下长型)的落锤冲击试验,对应变时程曲线及破坏模式进行了分析,并结合PFC^(2D)数值模拟探讨了其细观开裂机理.结果表明:饱冰平行裂隙岩样下方裂隙长度相同时应变响应相似,其中双长型和上短下长型岩样峰值应变的大小和出现时间受裂隙倾角影响较大.裂隙尖端的裂纹平均起裂角随裂隙倾角增加而递减.随着冲击次数的增加,岩样的应力应变曲线的斜率减小、包络面积增大,即多次冲击时试样的动态弹性模量减小,但积累的应变能增加.除上长下短型岩样外,其他岩样的裂隙倾角增加时峰值应力、损伤应力、起裂应力呈先减后增的变化规律.以双短型岩样为参照,分别增加上下裂隙长度时岩样的峰值应力、损伤应力、起裂应力基本呈减小的趋势.裂隙冰对裂隙起到填充、支撑以及黏结抗拉作用使得平行裂隙砂岩的强度提升.This study performed drop hammer impact tests on four types of ice-saturated parallel fractured sandstones(double-long,double-short,upper-long-lower-short,upper-short-lower-long)at four different fracture dip angles(0°,30°,60°,90°)to comprehend the dynamic response mechanism under dynamic loads.By analyzing the strain time history curve and failure mode,and incorporating PFC^(2D) numerical simulation,the study explored the underlying meso-cracking mechanism.The findings demonstrated a consistent strain response among the ice-saturated parallel fractured rock samples.The crack dip angle significantly influenced both the peak strain and occurrence time of the double-long and upper-short-lower-long samples.Additionally,the average crack initiation angle at the crack tip decreased as the crack inclination angle increased.Increasing the number of impacts resulted in a decrease in the slope of the stress-strain curve and an increase in its envelope area,suggesting a reduction in the rock sample s dynamic elastic modulus during multiple impacts and an increase in accumulated strain energy.Except the upper-long-lower-short samples,the remaining samples exhibited a trend of initially decreasing and then increasing for peak stress,damage stress,and initiation stress as the fracture dip angle increased.When the double-short rock sample was used as a reference and increasing the length of the upper and lower cracks individually,a general decline was observed in the peak stress,damage stress,and crack initiation count.The study revealed that fissure ice contributes to the filling,supporting,and bonding of cracks,thereby enhancing the strength of parallel fractured sandstone.

关 键 词：落锤冲击 饱冰平行裂隙 裂纹扩展 细观机制 数值模拟 

分 类 号：TU45[建筑科学—岩土工程]