锦屏二级水电站引水隧洞围岩卸荷力学特性试验研究与应用
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摘要
岩石工程中石方开挖和地下隧道的开挖为卸载条件,当前在岩体力学的计算分析中,采用的是常规加载试验得到的参数和常规的计算模型和方法。即使是在丌挖中模拟卸荷,但也是按荷载线性减少及常规分析方法进行考虑的,且其参数、本构关系及计算软件均为加载条件。实际上,开挖本身为卸荷过程,不但表现在计算荷载为卸载,更重要是相应的岩体卸荷力学状态的岩体力学参数、本构关系及计算软件均为卸荷条件。
因此,现阶段开挖工程研究分析资料与工程实际观测成果很不一致,其主要原因是数值分析参数及模型与实际受力状态不一致所造成的。本文以锦屏二级水电站引水隧洞围岩为研究对象,得到了以下一些结论:
(1)针对岩石卸荷工程监测结果与常规加载分析结果差别较大的实际情况,对取自锦屏二级电站引水隧道中的大理岩样,在室内进行了系统的岩石卸荷试验,分析了卸荷过程中岩石的力学性质。
采用微观试验的方法对锦屏二级电站引水隧道中的大理岩进行研究。对保持主应力和不变的条件下大理岩卸荷试验破坏试样进行了电镜扫描,用灰度分布图统计微结构参数,从而探讨卸荷过程中的微观结构变化规律。
(2)在假设岩石微元的损伤符合统计规律的情况下,定义了损伤变量,推导了考虑卸荷影响的岩石弹性损伤本构方程,用数据拟合的方法,得到了不同卸荷破坏应力状态下的卸荷损伤模型参数,并且验证了模型可以较好的模拟卸荷的应力应变曲线。
(3)根根据得到的统计损伤本构模型,用有限元程序对锦屏的引水隧洞开挖进行了计算,并与不考虑卸荷的有限元计算进行比较。
In rock engineering ,rock and tunnel excavation is under unloading condition, this is absolutely contrary to the rock mechanics analysis ,which always use loading condition parameters and according calculation methods. Even considering linear unloading during the excavation simulation ,it is also conducted by normal method and its constitutive equation and parameters calculation software is in fact considered as loading condition. In fact, excavation is a process of unloading, not only the load is unloading, but also stress condition parameters and constitutive relation are also under unloading condition.Currently, the excavation analysis results do not fit to in-situ measure .sometimes the difference is ten times ,this is mainly because the analysis parameters and model do not fit to the actual loading condition, this thesis mainly discuss marble surrounding rock of the Jinping hydraulic power plant , and some conclusions are summarized as the following:(1) Aim at the great difference between the in-situ measure and normal loading analysis result, indoor unloading experiment are carried out using marble surrounding rock of the Jinping hydraulic power plant, and the mechanical characters during unloading are analyzed.Microstructure method are used to analyze the marble surrounding rock of the Jinping hydraulic power plant. Under the condition of principle stress kept unchanged, the failure section of specimens are scanned by SEM,stat the microstructure using computer, the changing laws under unloading are discussed.(2) By assuming the damage of rock infinitesimal is fit to statistical law, a damage variable is defined, and a constitutive equation considering the influence of unloding is deduced. By data fitting, the parameters under different unloading failure are obtained, and it has been verified that the model curve can fit to the experimental curve well.(3) A FEM equation is deduce from the statistical damage constitutive model, a calculation is conducted to the Jinping water guiding tunnel excavation using the the program according to the constitutive model, and FEM result which do not considering unloading is compared to the above result.
因此,现阶段开挖工程研究分析资料与工程实际观测成果很不一致,其主要原因是数值分析参数及模型与实际受力状态不一致所造成的。本文以锦屏二级水电站引水隧洞围岩为研究对象,得到了以下一些结论:
(1)针对岩石卸荷工程监测结果与常规加载分析结果差别较大的实际情况,对取自锦屏二级电站引水隧道中的大理岩样,在室内进行了系统的岩石卸荷试验,分析了卸荷过程中岩石的力学性质。
采用微观试验的方法对锦屏二级电站引水隧道中的大理岩进行研究。对保持主应力和不变的条件下大理岩卸荷试验破坏试样进行了电镜扫描,用灰度分布图统计微结构参数,从而探讨卸荷过程中的微观结构变化规律。
(2)在假设岩石微元的损伤符合统计规律的情况下,定义了损伤变量,推导了考虑卸荷影响的岩石弹性损伤本构方程,用数据拟合的方法,得到了不同卸荷破坏应力状态下的卸荷损伤模型参数,并且验证了模型可以较好的模拟卸荷的应力应变曲线。
(3)根根据得到的统计损伤本构模型,用有限元程序对锦屏的引水隧洞开挖进行了计算,并与不考虑卸荷的有限元计算进行比较。
In rock engineering ,rock and tunnel excavation is under unloading condition, this is absolutely contrary to the rock mechanics analysis ,which always use loading condition parameters and according calculation methods. Even considering linear unloading during the excavation simulation ,it is also conducted by normal method and its constitutive equation and parameters calculation software is in fact considered as loading condition. In fact, excavation is a process of unloading, not only the load is unloading, but also stress condition parameters and constitutive relation are also under unloading condition.Currently, the excavation analysis results do not fit to in-situ measure .sometimes the difference is ten times ,this is mainly because the analysis parameters and model do not fit to the actual loading condition, this thesis mainly discuss marble surrounding rock of the Jinping hydraulic power plant , and some conclusions are summarized as the following:(1) Aim at the great difference between the in-situ measure and normal loading analysis result, indoor unloading experiment are carried out using marble surrounding rock of the Jinping hydraulic power plant, and the mechanical characters during unloading are analyzed.Microstructure method are used to analyze the marble surrounding rock of the Jinping hydraulic power plant. Under the condition of principle stress kept unchanged, the failure section of specimens are scanned by SEM,stat the microstructure using computer, the changing laws under unloading are discussed.(2) By assuming the damage of rock infinitesimal is fit to statistical law, a damage variable is defined, and a constitutive equation considering the influence of unloding is deduced. By data fitting, the parameters under different unloading failure are obtained, and it has been verified that the model curve can fit to the experimental curve well.(3) A FEM equation is deduce from the statistical damage constitutive model, a calculation is conducted to the Jinping water guiding tunnel excavation using the the program according to the constitutive model, and FEM result which do not considering unloading is compared to the above result.
引文
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[2] 李建林.卸荷岩体力学理论与应用[M].北京:中国建筑工业出版社,1999
[3] 尤明庆.岩石试样的强度及变形破坏过程[M].北京:地质出版社,2000
[4] First Symposium on Rock Mechanixs.Quartedy of the Corolado School of Mines,1956,51 (3):Foreword
[5] 徐志英.岩石力学(第3版)[M].北京:中国水利水电出版社,1993.6
[6] 叶金汉.岩石力学参数手册(第1版)[M].北京:水利水电出版社,1991.5
[7] Da Vinci L, Testing the strength of iron wires of various lengths(Notebook.ca.1500). In: W. B. Parsons. Engineers and Engineering in Renaissance, Baltimore: Williams and Wilkins, 1939,661
[8] Von Karman. Festigkeitsversuche unter allseitigem, Druck. Zeitscht. Ver. Dentsch. Ing. 1911,55:1749—1757
[9] Mogi K. Effect of the intermediate principal stress on rock failure. J. Geophys. Res. 1967, 72(20): 5117—5131
[10] Cook. N. G. W, Hojem. J. P. M. A rigid 50-ton compression and tension testing machine. South Africa Mech. Eng. 1966,16:89—92
[11] 葛修润,任建喜,蒲毅彬等.煤岩三轴细观损伤演化规律的CT动态试验[J].岩石力学与工程学报,1999,18(5):497—502
[12] 王恩元,何学秋.煤岩变形破裂电磁辐射的试验研究[J].地球物理学报,2000,43(1):131—137
[13] 华安增,孔圆波,李世平等.岩块降压破碎的能量分析[J].煤炭学报,1995,20(4):389～392
[14] 陈顒,姚孝新,耿乃光.应力途径对岩石脆性和延性的影响[J].地球物理学报,1980,23(3):312-319
[15] 尤明庆,华安增.卸围压法测量岩石材料的泊松比[J].试验力学,1997,12(2):274～278
[16] 李天斌,王兰生.卸荷应力状态下玄武岩变形破坏特征的试验研究[J].岩石力学与工程学报,1993,12(4):321～327
[17] 吴玉山.应力途径对凝灰岩力学特性的影响[J] 岩土工程学报,1983,2(1),112
[18] 葛修润、任建喜、蒲毅彬等.岩土损伤力学宏细观试验研究[M].北京:科学出版社,2004.6
[19] 吴义祥.工程粘性土微观结构的定量评价[J].中国地质科学院院报,1991,23:143-151
[20] 胡瑞林,李向全,官国琳等.粘性土微观结构定量模型及其工程地质特征研究[M].地质出版社,1995:151-155
[21] 夏蒙棼,韩闻生,柯孚久等.统计细观损伤力学和损伤演化诱致突变(Ⅰ)[J].力学进展,1995,25(1):1-3
[22] NO.8, (1958):26-31
[23] 1959
[24] Robotnov Y N. Creep rupture, Proc 12, Inter. Congress, Appl. Mech. Stanford, Springer Berlin, 1969
[25] 谢和平.岩石混凝土损伤力学[M].徐州:中国矿业大学出版社,1990:2-7
[26] 黄克智,徐秉业.固体力学发展趋势[M].北京:北京理工大学出版社,1993:1-8
[27] Dougill J. W., Lau J.C. and Burt N. J.. Toward a theoretical model for progressive failure and softening in rock, concrete and similar materials. Mech in Engng., ASCE-END, 335-355,1976
[28] Dragon A. and Mroz Z.A.. Continuum model for plastic-brittle behaviour of rock and concrete. Int. J.Engng. Sci,1979,17:121-137
[29] Mazars J. A description of micro-and macroscale damage of concrete structure, Engineering Fracture Mechanics, 1986, 25(5/6): 729-737
[30] Krajcinovc D. and Fonseka G. U.. The continuous damage theory of brittle materials, part Ⅰ and part Ⅱ. ASMEJ. Appl. Mech., Vol.48,PP.809-824,1
[31] Krajcinovc D. and Silva M.A.G.. Statistical aspects of the continuous damage theory. Int. J. Solids Structure, Vol. 18, NO.7, 1982
[32] Kachanov M. A microcrack model of rock inelasticity, part Ⅰ: frictional sliding on microcrack, part Ⅱ: propagation of microcracks. Mech Mat, 1982a(1):3-28
[33] Lemaitre J. A continuous damage mechanics model for ductile fracture Art. Trans. ASME, J. of Engng. Mat. and Techn, 1985,107:83-89
[34] 谢和平.大理岩微观断裂的分形模型研究[J].科学通报,1989,34(5)
[35] 谢和平,高峰.岩石类材料损伤演化的分形特征[J].岩石力学与工程学报,1991,10(1)
[36] 谢和平,Sanderson D.J.,Peacock D.C.P..雁形断裂分形模型与能量耗散[J].岩土工程学报,1994,16(1)
[37] 凌建明,孙均.脆性岩石的细观裂纹损伤及其时效特征[J].岩石力学与工程学报,1993,12(4)
[38] 凌建明,孙均.应变空间表述的岩体损伤本构关系[J].同济大学学报,1994,22(2)
[39] 周维垣,剡公瑞,杨若琼.岩体弹脆性损伤本构模型及工程应用[J].岩土工程学报,20(5)
[40] 赵永红.岩石弹脆性分维损伤本构模型[J].地质科学,1997,32(4)
[41] 李广平.类岩石材料微裂纹损伤模型分析[J].岩石力学与工程学报,1995,14(2)
[42] 杨更社.岩体损伤力学特性及细观损伤的CT识别[D].西安理工大学,1995
[43] 吕运水,陈幸福.关于损伤张量的价次[J].应用数学与力学,1989,10(3)
[44] Gurson A. L.. Theory of ductile rupture by void nucleation and growth: Part Ⅰ-yield criteria and flow rules for porous ductile media. J. of Eng. Materials and Tech., 1977, 99:2-15
[45] [45]Horii H and Nemat-Nasser S. Overall moduli of solids with microcracks: load-induced anisotropy. J. Mech. Phys. Solids, 1983, 31:315-330
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