MECHANISM OF STRAIN ENERGY CONVERSION PROCESS FOR MARBLE DAMAGE AND FRACTURE UNDER HIGH STRESS AND
RAPID UNLOADING
HUANG Da1，2，3，TAN Qing1，HUANG Runqiu2
(1. College of Civil Engineering，Chongqing University，Chongqing 400045，China；2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection，Chengdu University of Technology，Chengdu，Sichuan 610059，China；3. Key Laboratory of New Technology for Construction of Cities in Mountain Area of Ministry of Education，Chongqing University，Chongqing 400045，China)
Abstract：Based on energy theory and marble test of unloading confining pressure before peak strength under high stress，the whole process of strain energy conversion is researched，including absorbing strain energy for axial compression，dissipating strain energy for plastic deformation and cracks propagation，expending strain energy for circumferential deformation，storing and releasing elastic strain energy. The mechanism of strain energy conversion for marble specimens? damage evolution is revealed. The elastic strain energy stored is more than strain energy dissipated before the peak；and the quantity of strain energy dissipation can be significantly increased only near the peak. The stress quickly drops companying with elastic strain energy being rapidly released and strain energy fast dissipated for plastic deformation and fracture expansion after the peak. The rate of strain energy conversion obviously increases with the increasing unloading rate whenever before and after the peak，especially more intensely after the peak. The influence of initial confining pressure on the rate of strain energy conversion is closely related to unloading rate；and the rate of strain energy conversion clearly increases with the increasing initial confining pressure when the rate of unloading is faster；but the change is not obvious relatively when the rate of unloading is slower. The increasing initial confining pressure significantly enhances elastic strain energy storage before the peak. The rate of elastic strain energy release is far larger than that of strain energy expenditure for circumferential deformation；and the strain energy absorbed for axial compression is almost equal to that dissipated for plastic deformation and cracks propagation. So，the hard rock often presents the characteristics of tensional fracture or rip with the orient proximately perpendicular to unloading orientation，even rock burst appears. The mechanism of strain energy dissipation and release for marble damage and fracture under rapid unloading and high stress is that the elastic strain energy stored is more than the strain energy dissipated before the peak；and the elastic strain energy is quickly and largely released and dissipated after the peak；and companies with expending the strain energy for relatively fast confining tensile deformation towards unloading orientation.
黄 达1，2，3，谭 清1，黄润秋2. 高应力强卸荷条件下大理岩损伤破裂的应变能转化过程机制研究[J]. 岩石力学与工程学报, 2012, 31(12): 2483-2493.
HUANG Da1，2，3，TAN Qing1，HUANG Runqiu2. MECHANISM OF STRAIN ENERGY CONVERSION PROCESS FOR MARBLE DAMAGE AND FRACTURE UNDER HIGH STRESS AND
RAPID UNLOADING. , 2012, 31(12): 2483-2493.
[1] MOLNAR P，TAPPONNIER P. Active tectonics of Tibet[J]. Journal of Geophysical Research，1978，83(B11)：5 361–5 375.
[2] ALIK I Z，LE MOUËL J L，SOLOVIEV A，et al. Numerical modeling of crustal block-and-fault dynamics，earthquakes and slip rates in the Tibet—Himalayan region[J]. Earth and Planetary Science Letters，2007，258(3/4)：465–485.
[3] 黄润秋. 岩石高边坡发育的动力过程及其稳定性控制[J]. 岩石力学与工程学报，2008，27(8)：1 525–1 544.(HUANG Runqiu. Geodynamical process and stability control of high rock slope development[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(8)：1 525–1 544.(in Chinese))
[4] 黄润秋，黄 达. 卸荷条件下花岗岩力学特性试验研究[J]. 岩石力学与工程学报，2008，27(11)：2 205–2 213.(HUANG Runqiu，HUANG Da. Experimental research on mechanical properties of granites under unloading condition[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(11)：2 205–2 213.(in Chinese))
[5] 黄润秋，黄 达. 高地应力条件下卸荷速率对锦屏大理岩力学特性影响规律试验研究[J]. 岩石力学与工程学报，2010，29(1)：21–33.(HUANG Runqiu，HUANG Da. Experimental research on affection laws of unloading rates on mechanical properties of Jinping marble under high geostress[J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(1)：21–33.(in Chinese))
[6] HE M C，FENG J L. Rock burst process of limestone and its acoustic emission characteristics under ture-triaxial unloading conditions[J]. International Journal of Rock Mechanics and Mining Sciences，2010，47(2)：286–298.
[7] ZHOU X P，QIAN Q H，ZHANG B H. Zonal disintegration mechanism of deep crack-weakened rock masses under dynamic unloading[J]. Acta Mechanica Solida Sinica，2009，22(3)：240–250.
[8] 黄润秋. 现代系统科学理论与工程地质系统观[J]. 水文地质工程地质，1997，24(1)：1–6.(HUANG Runqiu. Modern system science theory and engineering geological system view[J]. Hydrogeology and Engineering Geology，1997，24(1)：1–6.(in Chinese))
[9] 谢和平，鞠 杨，黎立云. 基于能量耗散与释放原理的岩石强度与整体破坏准则[J]. 岩石力学与工程学报，2005，24(17)：3 003– 3 010.(XIE Heping，JU Yang，LI Liyun. Criteria for strength and structural failure of rocks based on energy dissipation and release principles[J]. Chinese Journal of Rock Mechanics and Engineering，2005，24(17)：3 003–3 010.(in Chinese))
[10] 苏承东，张振华. 大理岩三轴压缩的塑性变形与能量特征分析[J]. 岩石力学与工程学报，2008，27(2)：273–280.(SU Chengdong，ZHANG Zhenhua. Analysis of plastic deformation and energy property of marble under pseudo-triaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(2)：273–280.(in Chinese))
[11] 黄润秋，许 强. 开挖过程的非线性理论分析[J]. 工程地质学报，1999，7(1)：9–14.(HUANG Runqiu，XU Qiang. Nonlinear theory analysis of rock mass movement in excavation[J]. Journal of Engineering Geology，1999，7(1)：9–14.(in Chinese))
[12] 黄润秋，黄 达，段绍辉，等. 锦屏I级水电站地下厂房施工期围岩变形开裂特征及地质力学机制研究[J]. 岩石力学与工程学报，2011，30(1)：23–35.(HUNAG Runqiu，HUANG Da，DUAN Shaohui，et al. Geomechanics mechanism and characteristics of surrounding rock mass deformation failure in construction phase for underground powerhouse of Jinping I hydropower station[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(1)：23–35.(in Chinese))
[13] ZHANG Z X，KOU S Q，JIANG L G，et al. Effects of loading rate on rock fracture：fracture characteristics and energy partitioning[J]. International Journal of Rock Mechanics and Mining Sciences，2000，37(5)：745–762.
[14] LINDQVIST M. Energy considerations in compressive and impact crushing of rock[J]. Minerals Engineering，2008，21(9)：631–641.
[15] TSOUTHRELIS C E，EXADAKTYLOS G E. Effect of Rock discontinuities on certain rock strength and fracture energy parameters under uniaxial compression[J]. Geotechnical and Geological Engineering，1993，11(2)：81–105.
[16] NARA Y，KANEKO K. Sub-critical crack growth in anisotropic rock[J]. International Journal of Rock Mechanics and Mining Sciences，2006，43(3)：437–453.
[17] ZHOU X P. Triaxial compressive behavior of rock with mesoscopic heterogeneous behavior：strain energy density factor approach[J]. Theoretical and Applied Fracture Mechanics，2006，45(1)：46–63.
[18] BAGDE M N，PETROŠ V. Fatigue and dynamic energy behaviour of rock subjected to cyclical loading[J]. International Journal of Rock Mechanics and Mining Sciences，2009，46(1)：200–209.
[19] 张 嫒，许 江，杨红伟，等. 循环荷载作用下围压对砂岩滞回环演化规律的影响[J]. 岩石力学与工程学报，2011，30(2)：320–326. (ZHANG Yuan，XU Jiang，YANG Hongwei，et al. Effect of confining pressure on evolution law of hysteresis loop of sandstone under cyclic loading[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(2)：320–326.(in Chinese))
[20] HUA A Z，YOU M Q. Rock failure due to energy release during unloading and application to underground rock burst control[J]. Tunnelling and Underground Space Technology，2001，16(3)：241–246.
[21] 陈卫忠，吕森鹏，郭小红，等. 基于能量原理的卸围压试验与岩爆判据研究[J]. 岩石力学与工程学报，2009，28(8)：1 530–1 540. (CHEN Weizhong，LU Senpeng，GUO Xiaohong，et al. Research on unloading confining pressure tests and rock burst criterion based on energy theory[J]. Chinese Journal of Rock mechanics and Engineering，2009，28(8)：1 530–1 540.(in Chinese))
[22] 张 凯，周 辉，冯夏庭，等. 大理岩弹塑性耦合特性试验研究[J]. 岩土力学，2010，31(8)：2 425–2 434.(ZHANG Kai，ZHOU Hui，FENG Xiating，et al. Experimental research on elastoplastic coupling character of marble[J]. Rock and Soil Mechanics，2010，31(8)：2 425–2 434.(in Chinese))
2012, Vol. 31 
