开采与均布载荷条件下无粘结双层叠梁变形-开裂-垮落的数值模拟
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摘要
采用已开发的拉格朗日元方法、变形体离散元方法及虚拟裂纹模型耦合的连续-非连续方法,开展了开采及均布载荷条件下无粘结双层叠梁变形-开裂-垮落的数值模拟研究,研究了开采间隔(可比拟开采速度)、均布载荷(可比拟开采深度)及单梁叠放顺序的影响。叠梁由上软下硬或上硬下软两单梁构成。研究发现:随着开采间隔的增加,叠梁的位移值先增加后基本不变,首次开裂对应的开采距离减小,开裂位置增多,但增速变慢;随着均布载荷的增加,在开采过程中,叠梁先后呈现出弹性变形、开裂及垮落,离层变得不明显,叠梁的位移值增大,但不超过采高,首次开裂对应的开采距离减小,开裂位置有增多的趋势。当均布载荷较小时,上硬下软叠梁的开裂位置多于上软下硬叠梁的;但当均布载荷较大时,二者大小不确定,这反映了叠梁开裂后岩块之间复杂的相互作用。当均布载荷较大时,单梁叠放顺序的影响变小。
Numerical simulation of the deformation-cracking-collapsing of double-layer beams with no cohesions under uniform loading and excavation is conducted by use of a developed continuum-discontinuum method in which the Lagrangian element method, deformational discrete element method and fictitious crack model are coupled. Effects of the number of timesteps between two consequent excavations(in analogy to the mining velocity), the uniform loading(in analogy to the mining depth) and the order of single beams are studied. A double-layer beam is composed of an upper-soft single beam and a lower-hard single beam, or is composed of an upper-hard single beam and a lower-soft single beam. The following results are found. With an increase of the number of timesteps between two consequent excavations, values of displacements of double-layer beams firstly increase and then remain constant, the mining distance corresponding to the first cracking decreases, the number of new nodes due to cracking increases, but there is a slow increasing tendency. With an increase of the uniform loading, the elastic deformation and cracking are firstly found in the double-layer beams under excavation, and thenthe collapsing is found. Bed separation becomes less apparent, values of displacements of double-layer beams increase until the mining height is reached, the mining distance corresponding to the first cracking decreases and the number of new nodes due to cracking has an increasing tendency. At lower uniform loading, the number of new nodes due to cracking is greater for the upper-hard and lower-soft double-layer beam than for the upper-soft and lower-hard double-layer beam, while at higher uniform loading, no specific results is found, which reflects the complex interactions between rock blocks due to cracking of double-layer beams. At larger uniform loading, the influence of the order of single beams is negligible.
Numerical simulation of the deformation-cracking-collapsing of double-layer beams with no cohesions under uniform loading and excavation is conducted by use of a developed continuum-discontinuum method in which the Lagrangian element method, deformational discrete element method and fictitious crack model are coupled. Effects of the number of timesteps between two consequent excavations(in analogy to the mining velocity), the uniform loading(in analogy to the mining depth) and the order of single beams are studied. A double-layer beam is composed of an upper-soft single beam and a lower-hard single beam, or is composed of an upper-hard single beam and a lower-soft single beam. The following results are found. With an increase of the number of timesteps between two consequent excavations, values of displacements of double-layer beams firstly increase and then remain constant, the mining distance corresponding to the first cracking decreases, the number of new nodes due to cracking increases, but there is a slow increasing tendency. With an increase of the uniform loading, the elastic deformation and cracking are firstly found in the double-layer beams under excavation, and thenthe collapsing is found. Bed separation becomes less apparent, values of displacements of double-layer beams increase until the mining height is reached, the mining distance corresponding to the first cracking decreases and the number of new nodes due to cracking has an increasing tendency. At lower uniform loading, the number of new nodes due to cracking is greater for the upper-hard and lower-soft double-layer beam than for the upper-soft and lower-hard double-layer beam, while at higher uniform loading, no specific results is found, which reflects the complex interactions between rock blocks due to cracking of double-layer beams. At larger uniform loading, the influence of the order of single beams is negligible.
引文
[1]张百胜,康立勋,杨双锁.大断面全煤巷道层状顶板离层变形模拟研究[J].采矿与安全工程学报,2006,23(3):264-267.(ZHANGBaisheng,KANG Lixun,YANG Shuangsuo.Numerical simulation on roof separation and deformation of full seam roadway with stratified roof and large section[J].Journal of mining&safety engineering,2006,23(3):264-267(in Chinese)).
[2]李向阳,李俊平,周创兵,等.采空场覆岩变形数值模拟与相似模拟比较研究[J].岩土力学,2005,26(12):1907-1912.(LIXiangyang,LI Junping,ZHOU Chuangbing,et al.Comparative study on numerical simulation and similarity simulation of overburden deformation in abandoned stope[J].Rock and soil mechanics,2005,26(12):1907-1912(in Chinese)).
[3]严红,张吉雄,王思贵,等.特厚煤层巷道顶板离层关键影响因素模拟研究[J].采矿与安全工程学报,2014,31(5):681-686.(YAN Hong,ZHANG Jixiong,WANG Sigui,et al.Simulation study on key influencing factors to the roof abscission of the roadway with extra-thick coal seam[J].Journal of mining&safety engineering,2014,31(5):681-686(in Chinese)).
[4]刘金辉.双层岩梁组合结构研究[D].西安:西安科技大学,2011.(LIU Jinhui.Study of double-layer rock beams structure[D].Xi’an:Xi’an University of Science and Technology,2011(in Chinese)).
[5]赵团芝,李文平,李小琴,等.叠加开采应力及覆岩离层动态变化数值模拟[J].采矿与安全工程学报,2009,26(1):118-122.(ZHAO Tuanzhi,LI Wenping,LI Xiaoqin,et al.Numerical simulation on dynamic changes of stress and overburden bed separation concerned with superimposed mining[J].Journal of mining&safety engineering,2009,26(1):118-122(in Chinese)).
[6]张鑫,乔伟,雷利剑,等.综放开采覆岩离层形成机理[J].煤炭学报,2016,41(S2):342-349.(ZHANG Xin,QIAO Wei,LEI Lijian,et al.Formation mechanism of overburden bed separation in fully mechanized top-coal caving[J].Journal of China coal society,2016,41(S2):342-349(in Chinese)).
[7]LISJAK A,GRASSELLI G.A review of discrete modeling techniques for fracturing processes in discontinuous rock masses[J].Journal of rock mechanics and geotechnical engineering,2014,6(4):301-314.
[8]MAHABADI O K,KAIFOSH P,MARSCHALL P,et al.Three-dimensional FDEM numerical simulation of failure processes observed in Opalinus clay laboratory samples[J].Journal of rock mechanics and geotechnical engineering,2014,6(6):591-606.
[9]刘海燕,伍法权,李增学,等.兖州煤田主采煤层顶板稳定性特征分析[J].岩石力学与工程学报,2006,25(7):1450-1456.(LIUHaiyan,WU Faquan,LI Zengxue,et al.Study on stability characteristics of main seam roof in Yanzhou coalfield[J].Chinese journal of rock mechanics and engineering,2006,25(7):1450-1456(in Chinese)).
[10]郭翔,王学滨,白雪元,等.加载方式及抗拉强度对巴西圆盘试验影响的连续-非连续方法数值模拟[J].岩土力学,2017,38(1):214-220.(GUO Xiang,WANG Xuebin,BAI Xueyuan,et al.Numerical simulation of effects of loading types and tensile strengths on Brazilian disk test by use of a continuum-discontinuum method[J].Rock and soil mechanics,2017,38(1):214-220(in Chinese)).
[11]王学滨.拉格朗日元方法、变形体离散元方法及虚拟裂纹模型耦合的连续-非连续介质力学分析方法[R].北京:中国矿业大学(北京),2015.(WANG Xuebin.A method for continuum-discontinuum medium based on the coupled Lagrangian element method,deformational discrete element method and fictitious crack model[R].Beijing:China University of Mining and Technology(Beijing),2015(in Chinese)).
[12]侯艳丽,张楚汉.用三维离散元实现混凝土I型断裂模拟[J].工程力学,2007,24(1):37-43.(HOU Yanli,ZHANG Chuhan.Mode Ifracture simulation of concrete based on 3D distinct element method[J].Engineering mechanics,2007,24(1):37-43(in Chinese)).
[13]MUNJIZA A.The combined finite-discrete element method[M].London:John Wiley and Sons,2004.
[14]谢广祥,常聚才,华心祝.开采速度对综放面围岩力学特征影响研究[J].岩土工程学报,2007,29(7):963-967.(XIE Guangxiang,CHANG Jucai,HUA Xinzhu.Influence of mining velocity on mechanical characteristics of surrounding rock in fully mechanized top coal caving face[J].Chinese journal of geotechnical engineering,2007,29(7):963-967(in Chinese)).
[2]李向阳,李俊平,周创兵,等.采空场覆岩变形数值模拟与相似模拟比较研究[J].岩土力学,2005,26(12):1907-1912.(LIXiangyang,LI Junping,ZHOU Chuangbing,et al.Comparative study on numerical simulation and similarity simulation of overburden deformation in abandoned stope[J].Rock and soil mechanics,2005,26(12):1907-1912(in Chinese)).
[3]严红,张吉雄,王思贵,等.特厚煤层巷道顶板离层关键影响因素模拟研究[J].采矿与安全工程学报,2014,31(5):681-686.(YAN Hong,ZHANG Jixiong,WANG Sigui,et al.Simulation study on key influencing factors to the roof abscission of the roadway with extra-thick coal seam[J].Journal of mining&safety engineering,2014,31(5):681-686(in Chinese)).
[4]刘金辉.双层岩梁组合结构研究[D].西安:西安科技大学,2011.(LIU Jinhui.Study of double-layer rock beams structure[D].Xi’an:Xi’an University of Science and Technology,2011(in Chinese)).
[5]赵团芝,李文平,李小琴,等.叠加开采应力及覆岩离层动态变化数值模拟[J].采矿与安全工程学报,2009,26(1):118-122.(ZHAO Tuanzhi,LI Wenping,LI Xiaoqin,et al.Numerical simulation on dynamic changes of stress and overburden bed separation concerned with superimposed mining[J].Journal of mining&safety engineering,2009,26(1):118-122(in Chinese)).
[6]张鑫,乔伟,雷利剑,等.综放开采覆岩离层形成机理[J].煤炭学报,2016,41(S2):342-349.(ZHANG Xin,QIAO Wei,LEI Lijian,et al.Formation mechanism of overburden bed separation in fully mechanized top-coal caving[J].Journal of China coal society,2016,41(S2):342-349(in Chinese)).
[7]LISJAK A,GRASSELLI G.A review of discrete modeling techniques for fracturing processes in discontinuous rock masses[J].Journal of rock mechanics and geotechnical engineering,2014,6(4):301-314.
[8]MAHABADI O K,KAIFOSH P,MARSCHALL P,et al.Three-dimensional FDEM numerical simulation of failure processes observed in Opalinus clay laboratory samples[J].Journal of rock mechanics and geotechnical engineering,2014,6(6):591-606.
[9]刘海燕,伍法权,李增学,等.兖州煤田主采煤层顶板稳定性特征分析[J].岩石力学与工程学报,2006,25(7):1450-1456.(LIUHaiyan,WU Faquan,LI Zengxue,et al.Study on stability characteristics of main seam roof in Yanzhou coalfield[J].Chinese journal of rock mechanics and engineering,2006,25(7):1450-1456(in Chinese)).
[10]郭翔,王学滨,白雪元,等.加载方式及抗拉强度对巴西圆盘试验影响的连续-非连续方法数值模拟[J].岩土力学,2017,38(1):214-220.(GUO Xiang,WANG Xuebin,BAI Xueyuan,et al.Numerical simulation of effects of loading types and tensile strengths on Brazilian disk test by use of a continuum-discontinuum method[J].Rock and soil mechanics,2017,38(1):214-220(in Chinese)).
[11]王学滨.拉格朗日元方法、变形体离散元方法及虚拟裂纹模型耦合的连续-非连续介质力学分析方法[R].北京:中国矿业大学(北京),2015.(WANG Xuebin.A method for continuum-discontinuum medium based on the coupled Lagrangian element method,deformational discrete element method and fictitious crack model[R].Beijing:China University of Mining and Technology(Beijing),2015(in Chinese)).
[12]侯艳丽,张楚汉.用三维离散元实现混凝土I型断裂模拟[J].工程力学,2007,24(1):37-43.(HOU Yanli,ZHANG Chuhan.Mode Ifracture simulation of concrete based on 3D distinct element method[J].Engineering mechanics,2007,24(1):37-43(in Chinese)).
[13]MUNJIZA A.The combined finite-discrete element method[M].London:John Wiley and Sons,2004.
[14]谢广祥,常聚才,华心祝.开采速度对综放面围岩力学特征影响研究[J].岩土工程学报,2007,29(7):963-967.(XIE Guangxiang,CHANG Jucai,HUA Xinzhu.Influence of mining velocity on mechanical characteristics of surrounding rock in fully mechanized top coal caving face[J].Chinese journal of geotechnical engineering,2007,29(7):963-967(in Chinese)).