高应力软岩非弹性体积增加试验研究
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摘要
从砂质泥岩常规三轴试验出发,通过研究体积应变的变化规律,得到不同围压下砂质泥岩完全扩容应变与完全扩容极限.结果表明,软岩在力学作用下产生非弹性的扩容变形.进一步的试验及理论分析认为,砂质泥岩的体积变形存在一个门槛值即压缩扩容边界cd,完全扩容应变既是岩石试件体积应变的最小值同时也是最大压缩应变值.完全扩容应变及完全扩容极限与围压变化幅度一致,说明围压对扩容具有抑制作用.围压越高,压缩扩容边界cd出现的越迟,扩容之前的压缩变形愈大.
Based on the conventional triaxial compression test of sandy mudstone,the absolute dilatancy strain and threshold of absolute dilatancy under confining pressures were obtained by studying the volumetric strain.The result shows that the inelastic volume increase is generated by mechanical action.Through experimental and theoretical analyses,it is found that there is a compression-dilatancy boundary in the volumetric deformation;and the absolute dilatancy strain was estimated by determining the the minimal in pore volume change in other words maximum compression.Furthermore,the absolute dilatancy strain and threshold of absolute dilatancy change at the same extent with confining pressure,which shows that confining pressure strongly inhibites dilatant behavior.The higher confining pressures,the later occurrence of compression-dilatancy boundary is,which means higher values of the compaction changes.
Based on the conventional triaxial compression test of sandy mudstone,the absolute dilatancy strain and threshold of absolute dilatancy under confining pressures were obtained by studying the volumetric strain.The result shows that the inelastic volume increase is generated by mechanical action.Through experimental and theoretical analyses,it is found that there is a compression-dilatancy boundary in the volumetric deformation;and the absolute dilatancy strain was estimated by determining the the minimal in pore volume change in other words maximum compression.Furthermore,the absolute dilatancy strain and threshold of absolute dilatancy change at the same extent with confining pressure,which shows that confining pressure strongly inhibites dilatant behavior.The higher confining pressures,the later occurrence of compression-dilatancy boundary is,which means higher values of the compaction changes.
引文
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[8]杨永杰,宋扬,陈绍杰.三轴压缩煤岩强度及变形特征的试验研究[J].煤炭学报,2006,31(2):150-153.Yang Yongjie,Song Yang,Chen Shaojie.Test study of coal’s strength and deformation characteristics under triaxial compres-sion[J].Journal of China Coal Society,2006,31(2):150-153.
[9]Bridgman P W.Volume changes in the plastic stages of simple compression[J].J.Appl.Phys.,1949,20:1 241-1 251.
[10]Brace W F,Paulding B W,Scholz C.Dilatancy in the fracture of crystalline rocks[J].J.Geophys Res.,1966,71:3 939-3 953.
[11]Alkan H,Cinar Y,Pusch G.Rock salt dilatancy boundary from combined acoustic emission and triaxial compression tests[J].International Journal of Rock Mechanics&Mining Sciences,2007,44:108-119.
[2]陈宗基,康文法.在岩石破坏和地震之前与时间有关的扩容[J].岩石力学与工程学报,1983,2(1):11-21.Chen Zongji,Kang Wenfa.Time dependent dilatancy prior to rock failure and eathqakes[J].Chinese Journal of Rock Me-chanics and Engineering,1983,2(1):11-21.
[3]康红普.岩石扩容与巷道底臌[J].阜新矿业学院学报,1992,11(3):41-45.Kang Hongpu.Rock dilatancy and opening floor heave[J].Journal of Fuxin Mining Institute,1992,11(3):41-45.
[4]Brace W F,Paulding B W,Scholz C.Dilatancy in the fracture of crystalline rocks[J].J.Geophys Res.,1966,71:3 939-3 953.
[5]Kwaniewski M,Takahashi M,Li X.Volume changes in sandstone under true triaxial compression conditions[J].ISRM2003-Technology Roadmap for Rock Mechanics,2003(1):683-688.
[6]廖红建,宁春明,俞茂宏,等.软岩的强度变形时间之间的关系试验研究[J].岩土力学,1998,19(2):8-13.Miao Hongjian,Ning Chunming,Yu Maohong,et al.Experimental study on strength-deformation-time relationship of soft rock[J].Rock and Soil Mechanics,1998,19(2):8-13.
[7]孟召平,彭苏萍,凌标灿.不同侧压下沉积岩石变形与强度特征[J].煤炭学报,2000,25(1):15-18.Meng Zhaoping,Peng Suping,Ling Biaocan.Characters of the deformation and strength under different confining pressures onsedimentary rock[J].Journal of China Coal Society,2000,25(1):15-18.
[8]杨永杰,宋扬,陈绍杰.三轴压缩煤岩强度及变形特征的试验研究[J].煤炭学报,2006,31(2):150-153.Yang Yongjie,Song Yang,Chen Shaojie.Test study of coal’s strength and deformation characteristics under triaxial compres-sion[J].Journal of China Coal Society,2006,31(2):150-153.
[9]Bridgman P W.Volume changes in the plastic stages of simple compression[J].J.Appl.Phys.,1949,20:1 241-1 251.
[10]Brace W F,Paulding B W,Scholz C.Dilatancy in the fracture of crystalline rocks[J].J.Geophys Res.,1966,71:3 939-3 953.
[11]Alkan H,Cinar Y,Pusch G.Rock salt dilatancy boundary from combined acoustic emission and triaxial compression tests[J].International Journal of Rock Mechanics&Mining Sciences,2007,44:108-119.
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