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Ground reaction curves for circular excavations in non-homogeneous,axisymmetric strain-softening rock masses 被引量:7
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作者 J.González-Cao F.Varas +1 位作者 F.G.Bastante L.R.Alejano 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2013年第6期431-442,共12页
Fast methods to solve the unloading problem of a cylindrical cavity or tunnel excavated in elasto-perfectly plastic, elasto-brittle or strain-softening materials under a hydrostatic stress feld can be derived based on... Fast methods to solve the unloading problem of a cylindrical cavity or tunnel excavated in elasto-perfectly plastic, elasto-brittle or strain-softening materials under a hydrostatic stress feld can be derived based on the self-similarity of the solution. As a consequence, they only apply when the rock mass is homogeneous and so exclude many cases of practical interest. We describe a robust and fast numerical technique that solves the tunnel unloading problem and estimates the ground reaction curve for a cylindrical cavity excavated in a rock mass with properties depending on the radial coordinate, where the solution is no longer self-similar. The solution is based on a continuation-like approach(associated with the unloading and with the incremental formulation of the elasto-plastic behavior), fnite element spatial discretization and a combination of explicit sub-stepping schemes and implicit techniques to integrate the constitutive law, so as to tackle the diffculties associated with both strong strain-softening and elasto-brittle behaviors. The developed algorithm is used for two practical ground reaction curve computation applications. The frst application refers to a tunnel surrounded by an aureole of material damaged by blasting and the second to a tunnel surrounded by a ring-like zone of reinforced(rock-bolted) material. 展开更多
关键词 Tunnel convergence Ground reaction curves Strain-softening rock masses Tunnel with an aureole of a different material
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Deformability characteristics of jointed rock masses under uniaxial compression 被引量:45
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作者 Chen Xin Liao Zhihong Peng Xi 《International Journal of Mining Science and Technology》 2012年第2期213-221,共9页
We investigated the combined influence of joint inclination angle and joint continuity factor on deforma- tion behavior of jointed rock mass for gypsum specimens with a set of non-persistent open flaws in uni- axial c... We investigated the combined influence of joint inclination angle and joint continuity factor on deforma- tion behavior of jointed rock mass for gypsum specimens with a set of non-persistent open flaws in uni- axial compression. Complete axial stress-strain curves were classified into four types, i.e., single peak, softening after multi-peak yield platform, hardening after multi-peak yield platform and multi-peak dur- ing softening. Observation of crack evolution on the specimen surface reveals that the deformation behavior is correlated to the closure of pre-existing joint, development of fractures in rock matrix and teeth shearing of the shear plane. To investigate the brittleness of the specimens, the ratio of the residual strength to the maximum peak strength as well as the first and last peak strains were studied. At the same joint inclination angle, the ratios between residual strength and the maximum peak strength and the last peak strains increased while the first peak strain decreased with the increase of joint continuity factor. At the same joint continuity factor, the curves of the three brittleness parameters vs. joint inclina- tion angle can either be concave or convex single-oeak or wave-shaoed. 展开更多
关键词 Rock massJoint inclination angleJoint connectivityUniaxial compression testAxial stress-strain curve
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Temperature field distribution of burnt surrounding rock in UCG stope 被引量:10
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作者 Xin Lin Wang Zuotang +4 位作者 Huang Wengang Kang Guojun Lu Xuefeng Zhang Peng Wang Jianhua 《International Journal of Mining Science and Technology》 SCIE EI 2014年第4期573-580,共8页
In order to study temperature field distribution in burnt surrounding rock and to determine ranges of burnt surrounding rock, coal-wall coking cycle and heat influence in the underground coal gasification(UCG) stope, ... In order to study temperature field distribution in burnt surrounding rock and to determine ranges of burnt surrounding rock, coal-wall coking cycle and heat influence in the underground coal gasification(UCG) stope, based on the Laplace transform and inversion formula, we studied the temperature analytical solution of one-dimensional unsteady heat conduction for multi-layer overlying strata under the first and the forth kinds of boundary conditions, and we also carried out a numerical simulation of twodimensional unsteady heat conduction by the COMSOL multiphysics. The results show that when the boundary temperature of surrounding rock has a linear decrease because of a directional movement of heat source in the UCG flame working face, the temperature in surrounding rock increases first and then decreases with time, the peak of temperature curve decreases gradually and its position moves inside surrounding rock from the boundary. In the surrounding rock of UCG stope, there is an envelope curve of temperature curve clusters. We analyzed the influence of thermophysical parameters on envelope curves and put forward to take envelope curve as the calculation basis for ranges of burnt surrounding rock, coal-wall coking cycle and heat influence. Finally, the concrete numerical values are given by determining those judgement standards and temperature thresholds, which basically tally with the field geophysical prospecting results. 展开更多
关键词 Underground coal gasification (UCG) Temperature distribution Laplace transform Envelope curve Burnt surrounding rock Coking cycle
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Integrative method in lithofacies characteristics and 3D velocity volume of the Permian igneous rocks in H area, Tarim Basin 被引量:1
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作者 Yang Haijun Liu Yongfu +3 位作者 Xie Huiwen Xu Yongzhong Sun Qi Wang Shuangshuang 《International Journal of Mining Science and Technology》 SCIE EI 2013年第2期179-184,共6页
This paper introduces horizon control, seismic control, logging control and facies control methods through the application of the least squares fitting of logging curves, seismic inversion and facies-controlled techni... This paper introduces horizon control, seismic control, logging control and facies control methods through the application of the least squares fitting of logging curves, seismic inversion and facies-controlled techniques. Based on the microgeology and thin section analyses, the lithology, lithofacies and periods of the Permian igneous rocks are described in detail. The seismic inversion and facies-controlled techniques were used to find the distribution characteristics of the igneous rocks and the 3D velocity volume. The least squares fitting of the logging curves overcome the problem that the work area is short of density logging data. Through analysis of thin sections, the lithofacies can be classified into eruption airfall subfacies, eruption pyroclastic flow subfacies and eruption facies. 展开更多
关键词 Characteristics of igneous rocks Fitting of logging curves Seismic inversion Velocity volume Seismic facies
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Floating-zone growth and property characterizations of high-quality La_(2-x)Sr_xCuO_4 superconductor crystals
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作者 慎晓丽 李正才 +4 位作者 申彩霞 陆伟 董晓莉 周放 赵忠贤 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第7期2893-2897,共5页
We have grown underdoped (х = 0.11, 0.12) and optimally doped (x = 0.16)La2-хSrхCuO4 single crystals by the traveling-solvent floating-zone technique.In order to prepare good quality cuprate crystals,we have ma... We have grown underdoped (х = 0.11, 0.12) and optimally doped (x = 0.16)La2-хSrхCuO4 single crystals by the traveling-solvent floating-zone technique.In order to prepare good quality cuprate crystals,we have made much effort to optimize the preparation procedures.For example,we haveadopted the sol-gel route to prepare a highly fine and homogeneous La2-хSrхCuO4 precursor powder for fabricating a very dense ceramic feed rod used for the floating-zone growth,and we have also used quite a slow growth rate. The high quality of the grown crystals has been verified by double-crystal x-ray rocking curves,with the full-width-at-half-maximum being only 113-150 arcseconds, which are the best data reported so far for La2-хSrхCuO4 crystals.The superconducting critical temperatures of the grown crystals are 30, 31 and 38.5 K for х = 0.11, 0.12 and 0.16 samples, respectively,according to magnetic measurements. 展开更多
关键词 floating-zone crystal growth sol-gel chemistry x-ray rocking curves SUPERCONDUCTIVITY
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Retrieval of multiple scattering contrast from x-ray analyzer-based imaging
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作者 Heng Chen Bo Liu +2 位作者 Li-Ming Zhao Kun Ren Zhi-Li Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第1期600-604,共5页
We present a moment-based alternative approach to retrieve multiple scattering contrasts from x-ray analyzer-based imaging. By use of the properties of moments of convolutions, the multiple-image radiography approach ... We present a moment-based alternative approach to retrieve multiple scattering contrasts from x-ray analyzer-based imaging. By use of the properties of moments of convolutions, the multiple-image radiography approach is theoretically validated. Furthermore, higher order moments of the object scattering distribution, inaccessible in multiple-image radiography, are simultaneously provided by this alternative approach. It is experimentally demonstrated that the skew and kurtosis information related to the distribution of sub-pixel features within the object can be obtained from those complementary contrasts. Finally, the sensitivity of the retrieved multiple scattering contrasts is investigated experimentally. The finding that the sensitivity is inversely proportional to the square root of the detected photon number essentially indicates that the retrieval of moments with an order higher than two can be achieved without increasing exposure time or dose. The presented alternative approach provides an access to the exploitation of multiple scattering contrasts, which is expected to be useful in biomedical research, materials science, security screening, etc. 展开更多
关键词 x-ray imaging analyzer-based imaging rocking curve moment analysis
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Medical application of diffraction enhanced imaging in mouse liver blood vessels 被引量:1
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作者 张汐 袁清习 +5 位作者 杨欣荣 李海清 陈雨 陈绍亮 朱佩平 黄万霞 《Chinese Physics C》 SCIE CAS CSCD 2009年第11期986-990,共5页
Neovascularization is correlative with many processes of diseases, especially for tumor growth, invasion, and metastasis. What is more, these tumor microvessels are totally different from normal vessels in morphology.... Neovascularization is correlative with many processes of diseases, especially for tumor growth, invasion, and metastasis. What is more, these tumor microvessels are totally different from normal vessels in morphology. Therefore, observation of the morphologic distribution of microvessels is one of the key points for many researchers in the field. Using diffraction enhanced imaging (DEI), we observed the mirocvessles with diameter of about 40 μm in mouse liver. Moreover, the refraction image obtained from DEI shows higher image contrast and exhibits potential use for medical applications. 展开更多
关键词 diffraction enhanced imaging blood vessel rocking curve image contrast
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