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Numerical simulation analysis of covering rock strata as mining steep-inclined coal seam under fault movement

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中国有色金属学会会刊：英文版 2011年第S3期21卷 556-561页

作者： MA Feng-hai, SUN Li, LI Dun college of civil and Architectural engineering, Dalian university, Dalian 116622, china college of civil and Architectural engineering Dalian University Dalian 116622 China

The fault is one important factor for the stability of overburden strata caused by steeply inclined coal seam. The stress and displacement change of overburden strata caused by steeply-inclined coal seam mining activity under faulting was simulated by FLAC2D finite differential program on the basis of Zhaogezhuang mining example belonging to Kailuan Mining Group. From the results, the stress and displacement clouding image after mining became complex because of the fault, that is, a kind of weak structural plane. The stress concentration region concentrated around the goaf, and also around the fault plane. As the mining depth increases, the stress and displacement within the fault zone change significantly. This movement and deformation characteristic of overburden strata can provide theoretical basis for the similar mining condition.

关键词： fault steep-inclined coal seam numerical simulation overburden distortion

Fracture analysis of a functionally graded interfacial zone between two dissimilar homogeneous materials

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Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 540-552页

作者： CHENG Zhanqi1,2 & ZHONG Zheng1 1. School of Aerospace engineering and Applied mechanics, Tongji university, Shanghai 200092, china 2. college of civil engineering, Zhengzhou university, Zhengzhou 450002, china School of Aerospace engineering and Applied mechanics Tongji University Shanghai China college of civil engineering Zhengzhou University Zhengzhou China

In this paper the plane elasticity problem for a functionally graded interfacial zone containing a crack between two dissimilar homogeneous materials has been considered. It is assumed that in the interfacial zone the reciprocal of the shear modulus is a linear function of the coordinate, while Possion’s ratio keeps constant. By utilizing the Fourier transformation technique and the transfer matrix method, the mixed boundary problem is reduced to a system of singular integral equations that are solved numerically. The influences of the geometric parameters and the graded parameter on the stress intensity factors are investigated. The numerical results show that the graded parameters, the thickness of interfacial zone, the crack size and location have significant effects on the stress intensity factors.

关键词： functionally graded material interfacial zone fracture stress intensity factor

CRITERION FOR JUDGING SATISFACTION OF CONSISTENCY CONDITIONS IN RATE-DEPENDENT CONSTITUTIVE RELATIONS

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Acta Mechanica Solida Sinica 1999年第4期12卷 356-364页

作者： Wang Zhe (college of civil engineering and Architecture,Northern Jiaotong university,Beijing 100044,china) Coll. of Civ. Eng. and Architecture Northern Jiaotong University Beijing 100044 China

Based on irreversible thermodynamics, the criterion for judging the satisfaction of consistency conditions in rate-dependent constitutive relationship is deduced by introducing four basic hypotheses. Formulas for solving internal variables are given. It makes the rate-dependent model applicable no matter whether the consistency conditions can be satisfied or not.

关键词： rate-dependent constitutive relations consistency condition irreversible thermodynamics

Three-dimensional elasticity solution of simple-supported rectangular plate on point supports, line supports and elastic foundation

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Science china(Technological Sciences) 2009年第3期52卷 584-589页

作者： XU YePeng1 & ZHOU Ding2 1 School of Science, Nanjing university of Science and Technology, Nanjing 210094, china 2 college of civil engineering, Nanjing university of Technology, Nanjing 210009, china School of Science Nanjing University of Science and Technology college of civil engineering Nanjing University of Technology

This paper studies the bending of simple-supported rectangular plate on point supports, line supports and elastic foundation. On the basis of three-dimensional elasticity theory, the exact expressions of the displacement functions, which satisfy the governing differential equations and the simply supported boundary conditions at four edges of the plate, are analytically derived. The reaction forces of the in- termediate supports are regarded as the unknown external forces acting on the lower surface of the plate. The unknown coefficients are then determined by the boundary conditions on the upper and lower surfaces of the plate. Comparing the numerical results obtained from the proposed method to those obtained from Kirchhoff plate theory, Mindlin plate theory and those obtained from the commer- cial finite element software ANSYS, the high accuracy of the present method has been demonstrated.

关键词： rectangular plate point support line support elastic foundation displacement stress three-dimensional elasticity solution

Modal identification of system driven by lévy random excitation based on continuous time AR model

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Science china(Technological Sciences) 2009年第12期52卷 3649-3653页

作者： DU XiuLi 1,2 &WANG FengQuan 1 1 college of civil engineering,Southeast university,Nanjing 210096,china 2 School of Mathematical Sciences,Nanjing Normal university,Nanjing 210097,china college of civil engineering Southeast University School of Mathematical Sciences Nanjing Normal University

Based on the continuous time AR model,this paper presents a new time-domain modal identification method of LTI system driven by the uniformly modulated lévy random *** structural dynamic equation is first transformed into the observation equation and the state equation(namely,stochastic differential equation).Based on the property of the strong solution of the stochastic differential equation,the uniformly modulated function is identified *** by virtue of the Girsanov theorem,we present the exact maximum likelihood estimators of ***,the modal parameters are identified by eigen *** results show that the method not only has high precision and robustness but also has very high computing efficiency.

关键词： modal identification uniformly modulated function CAR model lévy process exact maximum likelihood estimator

Research on forecasting model of sandstone deformation rate during sine wave loading segment under the lag effect

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Science china(Technological Sciences) 2010年第5期53卷 1442-1449页

作者： LIU Jie1,2,LI JianLin1,2,QU JianJun1,ZHOU JiFang3,ZHANG ChaoFeng3 & LI JianWu1 1Key Laboratory of Geological Hazards on Three Gorges Reservoir Area,Ministry of Education,china Three Gorges university,Yichang 443002,china 2college of civil and Hydropower engineering,china Three Gorges university,Yichang 443002,china 3Er’tan Hydropower Development Company,Ltd.Chengdu 61000,china Key Laboratory of Geological Hazards on Three Gorges Reservoir Area Ministry of Education China Three Gorges University college of civil and Hydropower engineering China Three Gorges University

To reduce data variance caused by individual differences of different samples,a new experimental method is proposed by loading and unloading the axial forces with different frequencies and different waves of a certain load amplitude to the same rock sample without damaging *** time segments are defined and fractionized into segments I and Ⅱ.Criterions for seg-mentation,definitions of relevant parameters and empirical analysis are also offered *** the course of sinusoidal loading,the serious peak value dislocation of the displacement variation rate and the loading rate is defined as peak ***,the definition of the apparent tangent modulus is put forward and the linear relation between it and the vertical force in the frequency of 0.1,0.2,0.5 Hz sinusoidal loading segment is confirmed to be ever-present on the basis of the test *** the calculating formula of the deformation rate in non-lag time is *** is thus suggested that the deformation rate should be codetermined by the loading rate df/dt and instant load f(t),which well explains the peak dislocation of the time-variable curve peak value of dl/dt and deformation rate of df/*** the lag time derivation model is established and by comparing the calculated values with the measured ones,it is demonstrated that the above formula offers a better simulation of the sandstone deformation rate in the sinusoidal loading segment,with the load amplitude being 96 kN and the frequency ranging from 0.1 Hz to 0.5 Hz.

关键词： lag time segments peak shifting phenomenon apparent tangent modulus deformation rate

In-Tunnel Blast Pressure Empirical Formulas for Detonations External, Internal and at the Tunnel Entrance

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Transactions of Tianjin university 2006年第B09期12卷 177-181页

作者： LI Xiudi ZHENG Yingren Department and Architecture and civil engineering Logistical Engineering University Chongqing 400041 China

In order to define the loading on protective doors of an underground tunnel, the exact knowledge of the blast propagation through tunnels is needed. Thirty-three scale high-explosive tests are conducted to obtain in-tunnel blast pressure for detonations external, internal and at the tunnel entrance. The cross section of the concrete model tunnel is 0.67 m2. Explosive charges of TNT, ranging in mass from 400 g to 4 600 g, are detonated at various positions along the central axis of the model tunnel. Blast gages are flush-installed in the interior surface of the tunnel to record side-on blast pressure as it propagates down the tunnel. The engineering empirical formulas for predicting blast peak pressure are evaluated, and are found to be reasonably accurate for in-tunnel pressure prediction.

关键词： mechanics of explosion empirical formulas scale tests airblast

粗糙裂隙渗流的超立方和次立方定律及其试验研究

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水利学报 2003年第3期34卷 74-79页

作者：许光祥张永兴哈秋舲重庆交通学院河海工程系重庆400074 重庆大学土木工程学院重庆400045 中国长江三峡开发总公司技术委员会北京100062

在充分总结和认真分析了裂隙渗流现有研究成果以后发现,采用平均隙宽代替水力隙宽后,裂隙单宽渗流量与平均隙宽之间存在两种截然相反的幂指数关系,一种是指数大于3的超立方关系,而另一种是指数小于3的次立方关系。基于理想裂隙渗流遵循... 详细信息

在充分总结和认真分析了裂隙渗流现有研究成果以后发现,采用平均隙宽代替水力隙宽后,裂隙单宽渗流量与平均隙宽之间存在两种截然相反的幂指数关系,一种是指数大于3的超立方关系,而另一种是指数小于3的次立方关系。基于理想裂隙渗流遵循的立方定律,提出可以采用超立方定律和次方立定律来反映粗糙裂隙的渗流规律。并通过多种人工裂隙的试验研究,证明了该两种定律在粗糙裂隙渗流中可能同时存在,并初步提出了临界判别的定性标准。结果表明:吻合粗糙裂隙符合次立方定律,而非吻合粗糙裂隙遵循超立方定律。

关键词：粗糙裂隙渗流立方定律超立方定律次立方定律临界条件

Computational theory of cavitating flows for hydraulic turbomachinery with consideration of influence of water quality

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Science china(Technological Sciences) 2010年第12期53卷 3341-3348页

作者： WANG Lei1,2 & CHANG JinShi2 1 Huadian Electric Power Research Institute, Hangzhou 310030, china 2 college of Water Conservancy and civil engineering, china Agricultural university, Beijing 100083, china Huadian Electric Power Research Institute college of Water Conservancy and civil engineering China Agricultural University

Previously it was assumed that the pressure within the cavity or on the cavity surface remained constant and the vapor pressure of clean water at 20°C and 0 m altitude was utilized as the computational boundary for cavitating flows in hydraulic turbomachinery. Cavitation was confused with vaporization, and the effect of water quality on cavitation pressure characteristics was not taken into account. In recent years, lots of experiments of cavitation pressure characteristics of different water qualities including different sand concentrations of sand water and different altitudes of clean water have been performed by the authors, and the important influences of water quality on cavitation pressure characteristic have been validated. Thus the water quality should be involved in the cavitating flows computation. In the present paper, the effect of water quality on the cavitation pressure characteristic is analyzed and the computational method and theory of cavitating flows for hydraulic turbomachinery that considers the influence of water quality are proposed. The theory is suitable for both the potential flow method and the two-phase flow method for cavitating flows simulation. Finally, the validation results for cavitating flows in a hydraulic tur- bine indicate the significant influences of water quality on the cavitating flow performance.

关键词： cavitating flows cavitation pressure water quality hydraulic turbomachinery