摘要
为研究人工冻结对白垩系砂岩物理力学特性的影响,以粗粒、中粒砂岩为研究对象,分别开展了一次冻融前后砂岩饱和吸水率试验、氮气吸附实验;并进行20,-30,20℃等不同冻结过程下的强度测试。试验结果表明:2种岩石经历冻融作用后饱和吸水率均有所增大,粗粒砂岩饱和吸水率增加幅度较大。一次冻融循环后粗粒砂岩比表面积和孔容都增大而平均孔径减小,而中粒砂岩区别于粗粒砂岩的是,其孔容呈现减小趋势。冻融作用下两种岩石单轴抗压强度和弹性模量均有不同程度的降低,粗粒砂岩单轴抗压强度和弹性模量降低幅度大于中粒砂岩。低温冻结提高了试验岩石的单轴抗压强度,粗粒砂岩单轴抗压强度提高幅度大于中粒砂岩。揭示了饱和砂岩物理力学特性劣化内在机理,指出了岩体结构特征及饱和状况是控制不同冻结过程损伤状况的主要指标。
To investigate the influence of artificial freezing on the physical and mechanical properties of Cretaceous sandstone,we measured the water absorption of saturated coarse and medium-grained sandstone samples before and after one freeze-thaw cycle,and conducted the Nitrogen adsorption experiment employing the same samples. Besides,uniaxial compressive experiments were performed in the states of room temperature( 20 ℃),over freezing(-30 ℃) and after thawing( 20 ℃) respectively. The results indicate that: Water absorption at saturation of both types of rock samples increase after one freeze-thaw cycle,and coarse-grained sandstone samples increase more. Specific surface area of both types of rock samples rise,while average pore size drop after one freeze-thaw cycle,pore volume of the coarsegrained sandstone increase but the medium-grained sandstone behavior oppositely. Uniaxial compressive strength and elastic moduli of both types of rock samples reduce after one freeze-thaw cycle,and coarse-grained sandstone samples experience more. Freezing significantly strengthens both types of sandstone. The above change of micro-structure and mechanical properties of sandstone after one freeze-thaw cycle can be attributed to frost damage,under the same subzero temperature,pore structure and water content are two essential factors that controls frost damage.
引文
[1]杨更社,屈永龙,奚家米.白垩系地层煤矿立井冻结壁的力学特性及温度场研究[J].岩石力学与工程学报,2014,33(9):1873-1879.YANG Geng-she,QU Yong-long,XI Jia-mi. Study of mechanical properties and temperature field of frozen wall in Cretaceous strata[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(9):1873-1879.
[2]奚家米,付垒,贾晓峰,等.不同冻融状态下白垩系常见岩层物理力学特性对比分析[J].西安科技大学学报,2018,38(2):253-259.XI Jia-mi,FU Lei,JIA Xiao-feng,et al. Experimental study on physical and mechanical properties of Cretaceous rock under freezing-thawing action[J]. Journal of Xi’an University of Science and Technology,2018,38(2):253-259.
[3]魏尧,杨更社,叶万军,等.冻融黄土无侧限抗压强度的析因实验[J].西安科技大学学报,2019,39(1):103-111.WEI Yao,YANG Geng-she,YE Wan-jun,et al. Factorial experiment on unconfined compression strength of freeze-thawing loess[J]. Journal of Xi’an University of Science and Technology,2019,39(1):103-111.
[4]杨更社,申艳军,贾海梁,等.冻融环境下岩体损伤力学特性多尺度研究及进展[J].岩石力学与工程学报,2018,37(3):545-563.YANG Geng-she,SHEN Yan-jun,JIA Hai-liang,et al.Research progress and tendency in characteristics of multi-scale damage mechanics of rock under freezingthawing[J]. Chinese Journal of Rock Mechanics and Engineering,2018,37(3):545-563.
[5] JIA Hai-liang,WEI Xiang,Michael Krautblatter. Quantifying rock fatigue and decreasing compressive and tensile strength after repeated freeze-thaw cycles[J]. Permafrost and Periglacial Processes,2015,26(4):368-377.
[6]李云鹏,王芝银.岩石低温单轴压缩力学特性[J].北京科技大学学报,2011,33(6):671-675.LI Yun-peng,WANG Zhi-yin. Uniaxial compressive mechanical properties of rock at low temperature[J]. Journal of University of Science and Technology Beijing,2011,33(6):671-675.
[7]徐光苗,刘泉声,彭万巍,等.低温作用下岩石基本力学性质试验研究[J].岩石力学与工程学报,2006,25(12):2502-2508.XU Guang-miao,LIU Quan-sheng,PENG Wan-wei,et al. Experimental study on basic mechanical behaviors of rocks under low temperatures[J]. Chinese Journal of Rock Mechanics and Engineering,2006,25(12):2502-2508.
[8]张慧梅,彭川,杨更社,等.冻融损伤岩石的强度准则研究[J].西安科技大学学报,2017,37(2):154-158.ZHANG Hui-mei,PENG Chuan,YANG Geng-she,et al.Study on strength criterion of freezing-thawing damage rock[J]. Journal of Xi’an University of Science and Technology,2017,37(2):154-158.
[9]张慧梅,孟祥振,彭川,等.岩石变形全过程冻融损伤模型及其参数[J].西安科技大学学报,2018,38(2):260-265.ZHANG Hui-mei,MENG Xiang-zhen,PENG Chuan,et al. Freeze-thaw damage model and parameters of rock deformation in whole process[J]. Journal of Xi’an University of Science and Technology,2018,38(2):260-265.
[10]李栋伟,汪仁和,范菊红.白垩系冻结软岩非线性流变模型试验研究[J].岩土工程学报,2011,33(3):398-403.LI Dong-wei,WANG Ren-he,FAN Ju-hong. Nonlinear rheological model for frozen soft rock during Cretaceous period[J]. Chinese Journal of Geotechnical Engineering,2011,33(3):398-403.
[11] Petrov V A,Poluektov V V,Zharikov A V,et al. Microstructure,filtration,elastic and thermal properties of granite rock samples:implications for HLW disposal[J]. Geological Society,London,Special Publications,2005,240(1):237-253.
[12] Vaferi B,Gitifar V,Darvishi P,Mowla D. Modeling and analysis of effective thermal conductivity of sandstone at high pressure and temperature using optimal artificial neural networks[J]. Journal of Petroleum Science and Engineering,2014,119:69-78.
[13]刘莹,汪仁和,陈军浩.负温下白垩系岩石的物理力学性能试验研究[J].煤炭工程,2011(1):82-84.LIU Ying,WANG Ren-he,CHEN Jun-hao. Experiment study on physical mechanics performances of Cretaceous System rock under minus temperature[J]. Coal Mine Engineering,2011(1):82-84.
[14]周科平,许玉娟,李杰林,等.冻融循环对风化花岗岩物理特性影响的实验研究[J].煤炭学报,2012,37(s1):70-74.ZHOU Ke-ping,XU Yu-juan,LI Jie-lin,et al. Experimental study of freezing and thawing cycle influence on physical characteristics of weathered granite[J]. Journal of China Coal Society,2012,37(s1):70-74(5).
[15]李杰林,刘汉文,周科平,等.冻融作用下岩石细观结构损伤的低场核磁共振研究[J].西安科技大学学报,2018,38(2):266-272.LI Jie-lin,LIU Han-wen,ZHOU Ke-ping,et al. An LFNMR study of the micro-structural deterioration of rocks under the effect of freeze-thaw cycles[J]. Journal of Xi’an University of Science and Technology,2018,38(2):266-272.
[16]杨更社,奚家米,邵学敏,等.冻结条件下岩石强度特性的试验[J].西安科技大学学报,2010,30(1):14-18.YANG Geng-she,XI Jia-mi,SHAO Xue-min,et al. Experimental study on rock strength properties under freezing conditions[J]. Journal of Xi’an University of Science and Technology,2010,30(1):14-18.
[17]杨更社,奚家米,王宗金,等.胡家河煤矿主井井筒冻结壁岩石力学特性研究[J].煤炭学报,2010,35(4):565-570.YANG Geng-she,XI Jia-mi,WANG Zong-jin,et al.Study on rock mechanical properties of frozen wall of main shaft in Hujiahe Coal Mine[J]. Journal of China Coal Society,2010,35(4):565-570.
[18]杨更社,奚家米,李慧军,等.煤矿立井井筒冻结壁软岩力学特性试验研究[J].地下空间与工程学报,2012,8(4):690-697.YANG Geng-she,XI Jia-mi,LI Hui-jun,et al. Experimental study on the mechanical properties of soft rock of coal mine shaft sidewalls under the frozen conditions[J]. Chinese Journal of Underground Space and Engineering,2012,8(4):690-697.
[19]杨更社,奚家米,李慧军,等.三向受力条件下冻结岩石力学特性试验研究[J].岩石力学与工程学报,2010,29(3):459-464.YANG Geng-she,XI Jia-mi,LI Hui-jun,et al. Experimental study of rock mechanical properties under triaxial compressive and frozen conditions[J]. Chinese Journal of Rock Mechanics and Engineering,2010,29(3):459-464.
[20] Jia H,Leith K,Krautblatter M. Path-dependent frostwedging experiments in fractured,low-permeability granite[J]. Permafrost and Periglacial Processes,2017,28(4):698-709.
[21]中华人民共和国国家质量监督检验检疫总局. GB/T23561. 5-2009.煤和岩石物理力学性质测定方法.第5部分:煤和岩石吸水性测试方法[S].北京:中国标准出版社,2009.General Administration of Quality Supervision,Inspection and Quarantine of the People’s Republic of China.GB/T23561. 5-2009. Methods for determining the physical and mechanical properties of coal and rock-part5:methods for determining the water absorbability of coal and rock[S]. Beijing:China Standard Publishing House,2009.
[22]中华人民共和国国家质量监督检验检疫总局. GB/T19587-2004.气体吸附BET法测定固态物质比表面积[S].北京:中国标准出版社,2004.General Administration of Quality Supervision,Inspection and Quarantine of the People’s Republic of China.GB/T19587-2004. Determination of the specific surface area of solids by gas adsorption using the BET method[S]. Beijing:China Standard Publishing House,2004.
[23]贾海梁,项伟,申艳军,等.冻融循环作用下岩石疲劳损伤计算中关键问题的讨论[J].岩石力学与工程学报,2017,36(2):335-346.JIA Hai-liang,XIANG Wei,SHEN Yan-jun,et al. Discussion of the key issues within calculation of the fatigue damage of rocks subjected to freeze-thaw cycles[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(2):335-346.
[24] Odler I. The BET-specific surface area of hydrated portland cement and related materials[J]. Cement&Concrete Research,2003,33(12):2049-2056.
[25] Kaufhold S,Dohrmann R,Klinkenberg M,et al. N2-BET specific surface area of bentonites[J]. Journal of Colloid&Interface Science,2010,349(1):275-282.
[26] Tóth J. Calculation of the BET-compatible surface area from any type I isotherms measured above the critical temperature[J]. Journal of Colloid&Interface Science,1999,212(2):402-410.
[27] Barrett E P,Joyner L G,Halenda P P. The determination of pore volume and area distributions in porous substances:I. computations from nitrogen isotherms[J].Journal of the American Chemical Society,1951,73(1):373-380.
[28] Murton J B,Peterson R,Ozouf J C. Bedrock fracture by ice segregation in cold regions[J]. Science,2006,314(5802):1127-1129.