砂岩冻融劣化机理的多尺度试验研究
Multi-scale Experimental Study on the Deterioration Mechanism of Sandstone under Freeze-thaw Cycles
王生祖 1武康森 1达哇 2王冲3
作者信息
- 1. 青海省交通规划设计研究院有限公司,西宁 810001
- 2. 玉树藏族自治州交通运输局,玉树 815000
- 3. 中国科学院,西北生态环境资源研究院,冻土工程国家重点实验室,兰州 730000
- 折叠
摘要
在寒区的工程建设中,冷暖交替所产生的冻融循环是寒区岩石材料劣化的主要原因之一.为了得到寒区环境下岩石的冻融劣化机理,选用砂岩作为研究对象,对其开展不同循环次数的冻融循环试验,并进行了一系列宏、细、微观多尺度试验研究.研究结果表明:随着冻融循环次数的增多,砂岩的纵波波速、横波波速与抗压强度均随之降低.冻融循环会粗化砂岩的孔隙结构,循环次数越多,砂岩孔隙粗化的现象越严重,孔隙率也越大.砂岩的孔隙率与孔径分布区间会从 0 次时的2.17%与0.000 28～13.339 84 μm变为90 次时的5.11%与0.004 55～43.422 36 μm.此外,由于孔隙体积的增大,孔隙之间相互连通会致使砂岩中的孔隙数量随着冻融循环次数的增多而减小.正是因为冻融循环劣化了砂岩的孔隙结构,砂岩试样在宏观尺度上会表现出波速与力学性能的劣化,并使得应力应变曲线中的孔隙压密段应变与峰值应变均随着循环次数的增多而增大.综合多尺度试验结果发现,冻融循环对砂岩的劣化速率随着循环次数的增多而不断加剧.研究成果可为寒区的工程建设提供参考.
Abstract
The freeze-thaw cycle caused by the alternations of cold and warm is one of the main reasons for the deterioration of rock materials in cold regions.In order to get the freeze-thaw deterioration mechanism of rock in cold regions,sandstone was selected as the research object to carry out freeze-thaw cycle tests with different cycles,and a series of macro,meso,and micro multi-scale tests were carried out.The results show that the P-wave velocity,the S-wave velocity,and the compressive strength of sandstone decrease with the freeze-thaw cycle number.The freeze-thaw cycle will coarsene the pore structure of sandstone.The more cycles,the more serious the pore coarsening phenomenon and the larger the porosity.The porosity and the pore size of sandstone will change from 2.17%and 0.000 28～13.339 84 μm at0 cycle to5.11%and0.004 55～43.422 36 μm after90 cycles.In addition,due to the increase in pore volume,the interconnectivity between pores leads to the decrease in the pore number as the freeze-thaw cycle number increases.It is precisely because of the deterioration of the pore structure by freeze-thaw cycles that sandstone samples show deterioration of wave ve-locity and mechanical properties on the macro scale,and the pore compaction stage strain and the peak strain increase with the cycle number.Based on the multi-scale test results,it is found that the deterioration rate of sandstone caused by freeze-thaw cycle increases with the cycle number.The research results can provide reference for engineering construction in cold regions.
关键词
冻融循环/砂岩/多尺度/孔隙结构Key words
freeze-thaw cycles/sandstone/multiscale/pore structure引用本文复制引用
基金项目
青海省科技计划项目(2022-SF-172)
出版年
2023
NETL
NSTL
维普
万方数据