|
|
|
| EXPERIMENTAL STUDY OF INFLUENCE OF CONFINING PRESSURE UNLOADING SPEED ON MECHANICAL PROPERTIES AND GAS PERMEABILITY OF CONTAINING-GAS COAL ROCK |
| (1. State and Local Joint Engineering Laboratory of Methane Drainage in Complex Coal Gas Seam，Chongqing University，Chongqing 400030，China；2. Key Laboratory for the Resources Exploitation and the Environmental Disaster Control Engineering in Southwest China，Ministry of Education，Chongqing University，Chongqing 400030，China；3. Camborne School of Mines，University of Exeter，Exeter TR10 9EZ，England) |
|
|
|
|
Abstract Using self-made “triaxial stress thermal-hydro-mechanical coal containing gas permeameter”，an experimental study was carried out to investigate how the unloading speed of confining pressure influences the mechanical properties and gas permeability of containing-gas coal rock，under cooperation of different initial confining pressures and various gas pressures. The research result showed that from an aspect of mechanics，the coal would first undergo a stage of stress flat roof，after the unloading process began，and then a break would happen due to destabilization. When the confining pressure was unloaded at a higher speed，the destabilizing breakage was easier to happen on the coal which also represented shorter time to maintain at the stage of stress flat roof. During the unloading process of confining pressures，the time of coal being in the stage of stress flat roof showed a power function with the unloading speed of confining pressures. From an aspect of gas permeation，the permeability of coal was tightly relevant with its deformation and the changing trend of its volume strain could well reflect the changing trend of its permeability. When the confining stress was being unloaded，the permeability of coal varied in an experience of four stages and it kept increasing. The permeability of coal increased at a faster rate when the unloading speed was larger. During the unloading process of confining pressures，the permeability of coal being in the stage of stress flat roof showed an exponential function with the corresponding time.
|
|
Received: 19 July 2010
|
|
|
|
| [1] BROWN E T， HOEK E. Underground excavation in rock[M]. U K：Routledge，1980.
[2] 苏承东，高保彬，南 华，等. 不同应力路径下煤样变形破坏过程声发射特征的试验研究[J]. 岩石力学与工程学报，2009，28(4)：757–766.(SU Chengdong，GAO Baobin，NAN Hua，et al. Experimental study on acoustic emission characteristics during deformation and failure peocesses of coal samples under different stress paths[J]. Chinese Journal of Rock Mechanics and Engineering，2009，28(4)：757–766.(in Chinese))
[3] 刘保县，李东凯，赵宝云. 煤岩卸荷变形损伤及声发射特性[J]. 土木建筑与环境工程，2009，31(2)：57–61.(LIU Baoxian，LI Dongkai，ZHAO Baoyun. Damage evolution and acoustic emission character of coalrock under unloading condition[J]. Journal of Civil，Architectrual and Environment Engineering，2009，31(2)：57–61.(in Chinese))
[4] TIAN Q H，XU Z W，ZHOU G Q，et al. Coefficients of earth pressure at rest in thick and deep soils[J]. Mining Science and Technology，2009，19(2)：252–255.
[5] ZHOU X P，QIAN Q H，ZHANG Y X. The constitutive relation of crack-weakened rock masses under axial-dimensional unloading[J]. Acta Mechanica Solida Sinica，2008，21(3)：221–231.
[6] SUN J S，ZHU Q H，LU W B. Numerical simulation of rock burst in circular tunnels under unloading conditions[J]. Journal of China University of Mining and Technology，2007，17(4)：552–556.
[7] WANG D Y，MA W，CHANG X X. Analyses of behavior of stress-strain of frozen Lanzhou loess subjected to K0 consolidation[J]. Cold Regions Science and Technology，2004，40(1–2)：19–29.
[8] LAU J S O，CHANDLER N A. Innovative laboratory testing[J]. International Journal of Rock Mechanics and Mining Sciences，2004，14(8)：1 427–1 445
[9] XIE H Q，HE C H. Study of the unloading characteristics of a rock mass using the triaxial test and damage mechanics[J]. International Journal of Rock Mechanics and Mining Sciences，2004，41(Supp.1)：74–80.
[10] HUANG R Q，WANG X N，CHAN L S. Triaxial unloading test of rocks and its implication for rock burst[J]. Bulletin of Engineering Geology and the Environment，2001，60(1)：37–41.
[11] SELLERS E J，KLERCK P. Modelling of the effect of discontinuities on the extent of the fracture zone surrounding deep tunnels[J]. Tunnelling and Underground space Technology，2000，15(4)：463–469.
[12] SANER S，AMABEOKU M，KISSAMI M. Formation resistivity response to loading and unloading confining pressure[J]. Journal of Petroleum Science and Engineering，1996，16(1–3)：169–179.
[13] SHIMAMOTO T. Confining pressure reduction experiments：a new method for measuring frictional strength over a wide range of normal stress[J]. International Journal of Rock Mechanics and Mining Sciences，1985，22(4)：227–236.
[14] 苏承东，翟新献，李永明，等. 煤样三轴压缩下变形和强度分析[J]. 岩石力学与工程学报，2006，25(增1)：2 963–2 968.(SU Chengdong，ZHAI Xinxian，LI Yongming，et al. Study on deformation and strength of coal samples in triaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering，2006，25(Supp.1)：2 963–2 968. (in Chinese))
[15] 尹光志，王登科，张东明，等. 两种含瓦斯煤样变形特性与抗压强度的试验分析[J]. 岩石力学与工程学报，2009，28(2)：410–417.(YIN Guangzhi，WANG Dengke，ZHANG Dongming，et al. Test analysis of deformation characteristics and compressive strengths of two types of coal specimens containing gas[J]. Chinese Journal of Rock Mechanics and Engineering，2009，28(2)：410–417.(in Chinese))
[16] SCHEIDEGGER A E. The physics of flow through porous media[M]. 3rd ed. Toronto：University of Toronto Press，1974：102. |
| [1] |
JIA Chong1, 2, LAI Xingping1, 2*, CUI Feng1, 2, 3, 4, WU Xueming5, JI Songtao1, 2, HE Zhe1, 2, WANG Hao1, ZONG Cheng1, ZHANG Bo1, XUE Yifei1. Dynamic response of coal mining under the influence of hard roof breaking step and optimization of fracturing and scour prevention section length[J]. , 2026, 45(6): 1806-1826. |
|
|
|
|
2011, Vol. 30 
