The brittle fracture probability and reliability are obtained in terms of dislocation mechanism of microcrack evolution. The statistical distribution functions and statistical deviations of elongation, strength, plast...The brittle fracture probability and reliability are obtained in terms of dislocation mechanism of microcrack evolution. The statistical distribution functions and statistical deviations of elongation, strength, plastic work, crack extension force, fracture foughness, critical and crack length, can be derived in a unified fashion.展开更多
In this paper the thickness of a broken zone, a state parameter of roadway surrounding rock, is used as the index to evaluate the stabi1ity of surrounding rock of a deep roadway. The paper gives a theoretic formula fo...In this paper the thickness of a broken zone, a state parameter of roadway surrounding rock, is used as the index to evaluate the stabi1ity of surrounding rock of a deep roadway. The paper gives a theoretic formula for calculating the thickness of the broken zone. The author points out that not only the ultimate strength of rockmass but its residual strength and strain-softening level all have a great influence on the stability of surrounding rock of a deep roadway. The paper’s results show that to reinforce surrounding rock, raise its residual strength and lower its strain-softening level should be taken as a basic requirement for supports of a deep roadway. In addition, the research also indicates that it is impossible for roadway supports to change surrounding rock states of a deep roadway, so it is certain for them to work in a broken state. For this reason, a sufficient yieldable quantity is necessary for roadway supports used in deep mining.展开更多
Based on the heterogeneity of fault plane strength,the macro rupture process of a fault plane can be treated as the rupture accumulation process of local micro-elements in the fault surface.Assuming that the strength ...Based on the heterogeneity of fault plane strength,the macro rupture process of a fault plane can be treated as the rupture accumulation process of local micro-elements in the fault surface.Assuming that the strength of the local micro-elements follows the Weibull probability distribution,the macro-fault constitutive relationship of the complete load-deformation process is derived from a statistical mechanics viewpoint.Applying a one-dimensional earthquake mechanics model and using far-field displacement a as the control variable,the problem of earthquake instability is investigated by employing the stability theory.The results show that the system stiffness ratio(stiffness ratio of fault to surroun-ding rock) β is the important parameter that affects the occurrence of earthquakes.Earthquake instability occurs only when β < 1,and the sudden stress jump appears at the displacement turning point of the equilibrium path curve.The expression of three important parameters for earthquakes(fault half-dislocation distance after earthquake,earthquake stress drop and elastic energy release) is also given.When β≥1,the earthquake does not occur and the fault only slips slowly without an earthquake.展开更多
Impurity scattering in a superconductor may serve as an important probe for the nature of superconducting pairing state. Here we re- port the impurity effect on superconducting transition temperature Te in the newly d...Impurity scattering in a superconductor may serve as an important probe for the nature of superconducting pairing state. Here we re- port the impurity effect on superconducting transition temperature Te in the newly discovered Cr-based superconductor K2Cr3As3. The resistivity measurements show that the crystals prepared using high-purity Cr metal （≥99.99%） have an electron mean free path much larger than the superconducting coherence length. For the crystals prepared using impure Cr that contains various non- magnetic impurities, however, the Tc decreases significantly, in accordance with the generalized Abrikosov-Gor＇kov pair-breaking theory. This finding supports a non-s-wave superconductivity in K2Cr3As3.展开更多
Lenin＇s theory of imperialism, which was based on a combination of Marxist theory with active reference to and dialectical critique of the theories of classical imperialism current at the time, provides an empirical ...Lenin＇s theory of imperialism, which was based on a combination of Marxist theory with active reference to and dialectical critique of the theories of classical imperialism current at the time, provides an empirical analysis of the historical logic and laws of motion of capitalism. It realizes the sublation of theory and ideology by means of critical, explanatory and constructive logic, displaying a unique theoretical originality. Lenin＇s theory of imperialism offers a theoretical reflection on the development of capitalism and its historical trends; it is a practical response to the world structural contradictions arising from imperialism, an epochal reflection that vigorously explores and constructs the value claims of a new civilization and provides in-depth Marxist view of world history. The methodology and general principles of Lenin＇s study of imperialism are based on the materialist view of history. They are not out of date, nor are the propositions in his theory of imperialism, based as they are on research into monopoly. At the same time as it declared war on the values, systems and practices of the old world, Lenin＇s theory provided a completely new cognitive method, philosophical attitude and ideal values for the future society. This has become the precious wealth of mankind, wealth that transcends historical time and space.展开更多
文摘The brittle fracture probability and reliability are obtained in terms of dislocation mechanism of microcrack evolution. The statistical distribution functions and statistical deviations of elongation, strength, plastic work, crack extension force, fracture foughness, critical and crack length, can be derived in a unified fashion.
文摘In this paper the thickness of a broken zone, a state parameter of roadway surrounding rock, is used as the index to evaluate the stabi1ity of surrounding rock of a deep roadway. The paper gives a theoretic formula for calculating the thickness of the broken zone. The author points out that not only the ultimate strength of rockmass but its residual strength and strain-softening level all have a great influence on the stability of surrounding rock of a deep roadway. The paper’s results show that to reinforce surrounding rock, raise its residual strength and lower its strain-softening level should be taken as a basic requirement for supports of a deep roadway. In addition, the research also indicates that it is impossible for roadway supports to change surrounding rock states of a deep roadway, so it is certain for them to work in a broken state. For this reason, a sufficient yieldable quantity is necessary for roadway supports used in deep mining.
基金supported by the Central Public-interest Scientific Institution Basal Research Fund of Institute of Geophysics,China Earthquake Administration(DQJB08B21)
文摘Based on the heterogeneity of fault plane strength,the macro rupture process of a fault plane can be treated as the rupture accumulation process of local micro-elements in the fault surface.Assuming that the strength of the local micro-elements follows the Weibull probability distribution,the macro-fault constitutive relationship of the complete load-deformation process is derived from a statistical mechanics viewpoint.Applying a one-dimensional earthquake mechanics model and using far-field displacement a as the control variable,the problem of earthquake instability is investigated by employing the stability theory.The results show that the system stiffness ratio(stiffness ratio of fault to surroun-ding rock) β is the important parameter that affects the occurrence of earthquakes.Earthquake instability occurs only when β < 1,and the sudden stress jump appears at the displacement turning point of the equilibrium path curve.The expression of three important parameters for earthquakes(fault half-dislocation distance after earthquake,earthquake stress drop and elastic energy release) is also given.When β≥1,the earthquake does not occur and the fault only slips slowly without an earthquake.
基金supported by the National Natural Science Foundation of China (Grant No. 11190023)the National Basic Research Program (Grant Nos. 2011CBA00103 and 2012CB927404)the Fundamental Research Funds for the Central Universities of China
文摘Impurity scattering in a superconductor may serve as an important probe for the nature of superconducting pairing state. Here we re- port the impurity effect on superconducting transition temperature Te in the newly discovered Cr-based superconductor K2Cr3As3. The resistivity measurements show that the crystals prepared using high-purity Cr metal （≥99.99%） have an electron mean free path much larger than the superconducting coherence length. For the crystals prepared using impure Cr that contains various non- magnetic impurities, however, the Tc decreases significantly, in accordance with the generalized Abrikosov-Gor＇kov pair-breaking theory. This finding supports a non-s-wave superconductivity in K2Cr3As3.
文摘Lenin＇s theory of imperialism, which was based on a combination of Marxist theory with active reference to and dialectical critique of the theories of classical imperialism current at the time, provides an empirical analysis of the historical logic and laws of motion of capitalism. It realizes the sublation of theory and ideology by means of critical, explanatory and constructive logic, displaying a unique theoretical originality. Lenin＇s theory of imperialism offers a theoretical reflection on the development of capitalism and its historical trends; it is a practical response to the world structural contradictions arising from imperialism, an epochal reflection that vigorously explores and constructs the value claims of a new civilization and provides in-depth Marxist view of world history. The methodology and general principles of Lenin＇s study of imperialism are based on the materialist view of history. They are not out of date, nor are the propositions in his theory of imperialism, based as they are on research into monopoly. At the same time as it declared war on the values, systems and practices of the old world, Lenin＇s theory provided a completely new cognitive method, philosophical attitude and ideal values for the future society. This has become the precious wealth of mankind, wealth that transcends historical time and space.
