摘要
胀裂破岩是常见的破碎岩石手段,为研究单孔岩样的胀裂效果,制作了4种不同边距的贯通、半贯通圆孔红砂岩试样。借助自制的胀裂装置,在刚性伺服机上进行单轴加载,分析不同加载速率、钻孔边距和钻孔深度下圆孔周边的裂纹扩展形式,研究不同边距下试样的破坏特征。研究发现:当边距为40 mm时,半贯通试样破坏所需的时间超过贯通试样。达到峰值荷载时,大部分半贯通试样的胀裂只在一侧产生裂纹,小部分出现2条不规则的裂纹,大部分裂纹只延伸一定长度而未贯穿至试样底部。随着边距增加,贯通试样在2种加载速率下破坏时间的差值逐步扩大,0.4 mm/min速率下试样的胀裂时长快速增加,破岩速率大幅降低,而0.8 mm/min速率下试样破坏时发生的位移更小。分析试样的局部应变发现,2种加载速率下试样的局部应变变化规律差异并不明显。研究结果表明:相比半贯通试样,贯通试样更容易发生变形,胀裂产生的裂纹水平对称;在边距和孔深一定的情况下,2种加载速率对试样的胀裂破坏差异较小。研究结果可为钻孔胀裂法破碎岩石提供参考。
Dilatation is a common means of rock breaking,to study the dilatation effect of single-hole rock specimens,four different types of perforated and semi-perforated red sandstone specimens with different edge distances were prepared.The crack propagation patterns around the round hole under different loading rates,edge distances and borehole depths were analyzed and the failure characteristics of specimens under different edge distances were studied after the specimens were loaded axially on a rigid servo machine with the help of a selfmade bulging and cracking device.It was found that the failure time of semi-perforated specimens exceeds that of perforated specimens when the edge distance is 40 mm.When the peak load is reached,most of the semiperforated specimens only have cracks on one side,and only a small part of them shows two irregular cracks;most of the cracks only extend to a certain length without penetrating to the bottom of the specimens.With the increase of edge distance,the difference in the failure time between the two loading rates gradually expands.Meanwhile,the dilatation duration of the specimens increases rapidly at the rate of 0.4 mm/min,leading the rockbreaking rate to decrease significantly,while the failure displacements of the specimens at the rate of 0.8 mm/min become smaller.The local strain analysis showed that the difference in the strain variation laws between the two loading rates was not obvious.The results show that compared with the semi-perforated specimens,the perforated specimens are more likely to deform and the generated cracks are symmetrical horizontally.When the edge distance and borehole depth are constant,the loading rate has little effect on the characteristics of crack expansion of the specimens.The research results can provide a reference for rock breaking by the borehole dilatation method.
作者
吴睿
范祥
曹校勇
邓志颖
WU Rui;FAN Xiang;CAO Xiaoyong;DENG Zhiying(School of Highway,Chang’an University,Xi’an 710064,China;CCCC First Highway Consultants Co.,Ltd.,Xi’an 710075,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2022年第6期1616-1625,共10页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(41807241)
中国博士后科学基金资助项目(2021M693544)
长安大学中央高校专项资金资助项目(300102211205)。
关键词
胀裂破岩
裂纹扩展
破岩效率
钻孔深度
边距
dilatation and fracture
fracture propagation
rock breaking efficiency
borehole depth
edge distance
