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Analysis of coal pillar stability(ACPS): A new generation of pillar design software

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International Journal of Mining Science and Technology 2019年第1期29卷 87-91页

作者： Christopher Mark zach Agioutantis Technical Support Mine Safety and Health Administration Department of Mining Engineering University of Kentucky

Thirty years ago, the analysis of longwall pillar stability(ALPS) inaugurated a new era in coal pillar *** was the first empirical pillar design technique to consider the abutment loads that arise from full extraction, and the first to be calibrated using an extensive database of longwall mining case *** was followed by the analysis of retreat mining stability(ARMPS) and the analysis of multiple seam stability(AMSS). These methods incorporated other innovations, including the coal mine roof rating(CMRR), the Mark-Bieniawski pillar strength formula, and the pressure arch loading model. They also built upon ever larger case history databases and employed more sophisticated statistical ***, these empirical methods are used in nearly every underground coal mine in the US. However,the piecemeal manner in which these methods have evolved resulted in some weaknesses. For example,in certain situations, it may not be obvious which program is the best to use. Other times the results from the different programs are not entirely consistent with each other. The programs have also not been updated for several years, and some changes were necessary to keep pace with new developments in mining practice. The analysis of coal pillar stability(ACPS) now integrates all three of the older software packages into a single pillar design framework. ACPS also incorporates the latest research findings in the field of pillar design, including an expanded multiple seam case history data base and a new method to evaluate room and pillar panels containing multiple rows of pillars left in place during pillar *** also includes updated guidance and warnings for users and features upgraded help files and graphics.

关键词： Pillar design Ground control Stability Empirical methods

Towards multiple hazard resilient bridges:a methodology for modeling frequent and infrequent time-varying loads Part I,Comprehensive reliability and partial failure probabilities

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Earthquake Engineering and Engineering Vibration 2012年第3期11卷 293-301页

作者： zach Liang George C.Lee Department of Mechanical and Aerospace Engineering University at Buffalo Department of Civil Structural and Environmental EngineeringUniversity at Buffalo

The current AASHTO load and resistance factor design （LRFD） guidelines are formulated based on bridge reliability, which interprets traditional design safety factors into more rigorously deduced factors based on the theory of probability. This is a major advancement in bridge design specifications. However, LRFD is only calibrated for dead and live loads. In cases when extreme loads are significant, they need to be individually assessed. Combining regular loads with extreme loads has been a major challenge, mainly because the extreme loads are time variables and cannot be directly combined with time invariant loads to formulate the probability of structural failure. To overcome these difficulties, this paper suggests a methodology of comprehensive reliability, by introducing the concept of partial failure probability to separate the loads so that each individual load combination under a certain condition can be approximated as time invariant. Based on these conditions, the extreme loads （also referred to as multiple hazard or MH loads） can be broken down into single effects. In Part II of this paper, a further breakdown of these conditional occurrence probabilities into pure conditions is discussed by using a live truck and earthquake loads on a bridge as an example. There are three major steps in establishing load factors from MH load distributions：（1） formulate the failure probabilities; （2） normalize various load distributions; and （3） establish design limit state equations. This paper describes the formulation of the failure probabilities of single and combined loads.

关键词： multiple hazards bridge probability-based design comprehensive reliability partial failure probability

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Development of a new algorithm for implementing the edge effect offset for subsidence calculations

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International Journal of Mining Science and Technology 2018年第1期28卷 61-66页

作者： Joshua Hescock Christopher Newman zach Agioutantis Department of Mining Engineering University of Kentucky

The surface deformation prediction system(SDPS) program has been developed as an engineering tool for the calculation of subsidence deformation indices through the implementation of various prediction *** basic user-defined input parameters, SDPS can determine subsidence indices, such as mining induced displacements, strains, tilt, etc., at any elevation between the seam and the horizontal or varying surface topography.A fundamental parameter in obtaining reliable ground deformation results is the determination of the edge effect *** value assigned to the edge effect offset corresponds to a virtual offsetting of boundary lines delineating the extracted panel to allow for roof cantilevering over the mined-out *** objective of this paper is to describe the methods implemented in updating the edge effect offset algorithm within *** proven geometric equations, the newly developed algorithm provides a more robust calculation of the offset boundary of the extracted panel for simplistic as well as more complex mining *** that an extracted panel is represented by a closed polyline, the new edge offset algorithm calculates a polyline offset into the extracted panel with respect to the user defined edge effect offset *** deformations are then calculated using this adjusted panel *** Matlab program was utilized for development and testing of the new edge effect offset *** completing rigorous testing regimes, the new offset algorithm will be integrated into SDPS further increasing the speed and reliability of the program resulting in a retrospective increase in capability and flexibility.

关键词： Subsidence Coal mining Influence function Edge effect

Bridge pier failure probabilities under combined hazard effects of scour, truck and earthquake. Part Ⅰ: occurrence probabilities

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Earthquake Engineering and Engineering Vibration 2013年第2期12卷 229-240页

作者： zach Liang George C. Lee Department of Mechanical and Aerospace Engineering Unidersity at Buffalo Depart of Civil Structural and Environmental EngineeringUniversity at Buffalo

In many regions of the world, a bridge will experience multiple extreme hazards during its expected service life. The current American Association of State Highway and Transportation Officials （AASHTO） load and resistance factor design （LRFD） specifications are formulated based on failure probabilities, which are fully calibrated for dead load and nonextreme live loads. Design against earthquake loads is established separately. Design against scour effect is also formulated separately by using the concept of capacity reduction （or increased scour depth）. Furthermore, scour effect cannot be linked directly to an LRFD limit state equation, because the latter is formulated using force-based analysis. This paper （in two parts） presents a probability-based procedure to estimate the combined hazard effects on bridges due to truck, earthquake and scour, by treating the effect of scour as an equivalent load effect so that it can be included in reliability-based bridge failure calculations. In Part I of this series, the general principle of treating the scour depth as an equivalent load effect is presented. The individual and combined partial failure probabilities due to truck, earthquake and scour effects are described. To explain the method of including non-force-based natural hazards effects, two types of common scour failures are considered. In Part 11, the corresponding bridge failure probability, the occurrence of scour as well as simultaneously having both truck load and equivalent scour load are quantitatively discussed.

关键词： multi-hazards load and resistance factor design bridge scour

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Towards establishing practical multi-hazard bridge design limit states

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Earthquake Engineering and Engineering Vibration 2013年第3期12卷 333-340页

作者： zach Liang George C.Lee Department of Mechanical and Aerospace Engineering Unidersity at Buffalo Depart of Civil Structural and Environmental Engineering University at Buffalo

In the U.S., the current Load and Resistance Factor Design （LRFD） Specifications for highway bridges is a reliability-based formulation that considers failure probabilities of bridge components due to the actions of typical dead load and frequent vehicular loads. Various extreme load effects, such as earthquake and vessel collision, are on the same reliability-based platform. Since these extreme loads are time variables, combining them with not considered frequent. non- extreme loads is a significant challenge. The number of design limit state equations based on these failure probabilities can be unrealistically large and unnecessary from the view point of practical applications. Based on the opinion of AASHTO State Bridge Engineers, many load combinations are insignificant in their states. This paper describes the formulation of a criterion to include only the necessary load combinations to establish the design limit states. This criterion is established by examining the total failure probabilities for all possible time-invariant and time varying load combinations and breaking them down into partial terms. Then, important load combinations can be readily determined quantitatively,

关键词： multi-hazards load and resistance factor design re.liability based bridge design specifications design limit state equations

Principal axes of M-DOF structures PartⅡ:Dynamic loading

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Earthquake Engineering and Engineering Vibration 2003年第1期2卷 39-50页

作者： zach Liang GeorgeC.Lee Department of Civil Structural and Environmental Engineering University at BuffaloState University of New YorkBuffaloNew YorkUSA Research Associate Professor Multidisciplinary Center for Earthquake Engineering Research University at BuffaloState University of New YorkBuffaloNew YorkUSA Samuel P.Capen Professor of Engineering

This paper is the second in a two-part series that discusses the principal axes of M-DOF structures subjected to static and dynamic *** primary purpose of this series is to understand the magnitude of the dynamie response of structures to enable better design of structures and response modification devices/*** idealized design condi- tions,the structural responses are obtained by using single directinn input ground motions in the direction of the intended response modification devices/systems,and by assuming that the responses of the structure is deconpleable in three mutual- ly perpendicular *** standard practice has been applied to both new and retrofitted structures using various seis- mic protective *** limited information is available on the effects of neglecting the impact of directional couplings (cross effects of which torsion is a component)of the dynamic response of *** order to quantify such effects,it is necessary to examine the principal axes of structures under both static and dynamic *** this twn-part series,the first paper is concerned with static loading,which provides definitions and fundamental formulations,with the conclusion that cross effects of a statically loaded M-DOF structure resulting from the lack of principal axes are of insignificant magnitude. However,under dynamic or earthquake loading,a relatively small amount of energy transferred across perpendicular direc- tions is accumulated,which may result in significant enlargement of the structural *** paper deals with a formu- lation to define the principal axes of M-DOF structures under dynamic loading and develops quantitative measures to identify cross effects resuhing from the non-existence of principal axes.

关键词： principal axes of M-DOF structures structural response couplings cross effect theoretical base dynamic loading peak response estimation

Development of a web-platform for mining applications

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International Journal of Mining Science and Technology 2018年第1期28卷 95-99页

作者： Christopher Newman zach Agioutantis Nathaniel Schaefer Department of Mining Engineering University of Kentucky

‘‘Web ground control"(web GC) provides users with instantaneous access to mine design applications anywhere, at any time, through a web *** a web-based multiple-tier architecture, users are able to easily access ground control designs, perform on-demand calculations in the field, as well as facilitate project collaborations across multiple users, devices, and operating ***, the web GC platform contains five ground control related design applications previously developed and distributed by the US National Institute of Occupational Safety and Health(NIOSH), that is, analysis of roof bolt stability(ARBS), analysis of longwall pillar stability(ALPS), analysis of retreat mining stability(ARMPS), analysis of retreat mining stability–highwall mining(ARMPS-HWM), and analysis of horizontal stress in mining(AHSM).With respect to design decisions made by the web GC development team, the web GC platform will be able to further integrate future mine design applications providing the mining industry with one of a kind umbrella suite of ground control related software available at ones *** following paper provides a detailed overview on the current state of the web GC platform with discussions ranging from back-end database development and design to the front-end user-platform *** on current progress in platform development as well as beta testing results, the web GC platform is scheduled for release in the fall of 2018.

关键词： Ground control Stability Web application Cloud computing

On similitude law of sub-systems

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Earthquake Engineering and Engineering Vibration 2006年第1期5卷 133-142页

作者： zach Liang George C.Lee Department of Civil Structural and Environmental Engineering University at BuffaloState University of New YorkBuffaloNew YorkUSA Multidisciplinary Center for Earthquake Engineering Research University at BuffaloState University of New YorkBuffaloNew YorkUSA

Based on Buckingham＇s π-Theorem, dimensional analysis has achieved considerable success over the past near-century. Model testing has long been a powerful tool in both scientific studies and engineering applications. However, the prototype objects are becoming more and more complicated nowadays, and many of the prototype systems can contain several sub-systems. The conventional theories on model-prototype similarity and dimensional analysis have only limited application since the π-Theorem itself does not distinguish between the original system and subsystems. This is particularly true in the field of structural dynamics, where the structure is often modeled as a multi-degree-of-freedom system. In this paper, we attempt to show that, if a system can be decoupled into several nontrivial subsystems, then, in each subsystem, the number of π-terms will be reduced and therefore simplify the model testing. On the other hand, if a system cannot be decoupled into subsystems, then using model testing with reduced π-term analysis, both experimentally and theoretically, may introduce severe errors.

关键词： similitude law Buckingham's π-theorem model testing sub-systems

Lofty Expectations and Bitter Reality： Chinese Interpreters for the US Army during the Second World War, 1941-1945

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Frontiers of History in China 2017年第4期12卷 566-598页

作者： zach Fredman John Sloan Dickey Center for International Understanding Darthmauth College Hanover NewHampshire 03755 USA

Between 1941 and 1945, the Nationalist government supervised a program that trained more than 3,300 male college students and recent graduates to serve as interpreters for the US military in the China-Burma-India （CB1） Theater. These interpreters made the Sino-US alliance a reality by enabling American servicemen to communicate with other Chinese. But despite the program＇s operational success, interpreters suffered from intractable morale problems. Interpreters began their service with lofty expectations. Senior officials and intellectuals encouraged them to see themselves as central figures in China＇s struggle for nafonal rejuvenation. They would uplift the country by convincing American servicemen to see Chinese as equals and by introducing American technology, traits, and habits to the Chinese Army. It all sounded glorious to cadets undergoing training, but actual interpreter service proved bitterly disappointing to most young men. They found their monotonous duties unworthy of their position The Nationalist government, for its part, lacked the capacity to keep them clothed, paid, and fed. Their own compatriots--soldiers and civilians alike--regarded them with suspicion. Most frustrating of all, American soldiers refused to treat them as equals. By examining interpreter morale problems in China fronl 1941 to 1945, this article enriches our understanding of wartime interpreting, China in a global World War II, and sources of friction in the Sino-US alliance

关键词： nationalism US-China relations interpreters Anti-Japanese War World War II wartime translation and interpreting Huang Renlin