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Development of a multivariate empirical model for predicting weak rock mass modulus

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International Journal of Mining Science and Technology 2015年第4期25卷 545-552页

作者： Kallu Raj R. Keffeler Evan R. Watters Robert J. Agharazi Alireza Department of Mining Engineering University of Nevada RESPEC Consulting and services University of Nevada Itasca Houston inc.

Estimating weak rock mass modulus has historically proven difficult although this mechanical property is an important input to many types of geotechnical analyses. An empirical database of weak rock mass modulus with associated detailed geotechnical parameters was assembled from plate loading tests per- formed at underground mines in Nevada, the Bakhtiary Dam project, and Portugues Dam project. The database was used to assess the accuracy of published single-variate models and to develop a multivari- ate model for predicting in-situ weak rock mass modulus when limited geoteehnical data are available. Only two of the published models were adequate for predicting modulus of weak rock masses over lim- ited ranges of alteration intensities, and none of the models provided good estimates of modulus over a range of geotechnical properties. In light of this shortcoming, a multivariate model was developed from the weak rock mass modulus dataset, and the new model is exponential in form and has the following independent variables：（1） average block size or joint spacing, （2） field estimated rock strength, （3） dis- continuity roughness, and （4） discontinuity infilling hardness. The multivariate model provided better estimates of modulus for both hard-blocky rock masses and intensely-altered rock masses.

关键词： In-situ modulus Weak rock mass Preliminary design Elastic deformation

A theoretical model for the intrusion of the Kuroshio across the continental shelf of East China Sea

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Science China Earth Sciences 2015年第12期58卷 2289-2295页

作者： ZHANG QingHua QU YuanYuan LI JianKe YIN XunQiang Key Laboratory of Marine Science and Numerical Modeling The First Institute of OceanographyState Oceanic Administration Marine services Digital Globe Inc.

Here we use a two-layer model to study the dynamics of the intrusion of the Kuroshio onto the continental shelf. Results show that the interaction of the Kuroshio water and shelf water produces a stable upwelling zone above 100 m depth northeast of Talwan, which provides a dynamical explanation to the presence of the cold core previously observed by satellite. The affected shelf water from the interaction has an onshore portion, which turns right and becomes a northward alongshore flow when it moves closer to shore. This implies that the Kuroshio water cannot penetrate deep onto the inner part of the continental shelf, but it generates a strong northward jet that is formed mainly by the shelf water.

关键词： Kuroshio continental shelf upwelling alongshore flow stratification

Investigation on microstructure evolution of clayey soils: A review focusing on wetting/drying process

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 269-284页

作者： Chao-Sheng Tang Qing Cheng Xuepeng Gong Bin Shi Hilary I.Inyang School of Earth Sciences and Engineering Nanjing UniversityNanjing210023China Global Education and Infrastructure services inc. CharlotteUSA

Variability in moisture content is a common condition in natural *** influences soil properties significantly.A comprehensive understanding of the evolution of soil microstructure in wetting/drying process is of great significance for interpretation of soil macro hydro-mechanical *** this review paper,methods that are commonly used to study soil microstructure are *** them are scanning electron microscope(SEM),environmental SEM(ESEM),mercury intrusion porosimetry(MIP)and computed tomography(CT)***,progress in research on the soil microstructure evolution during drying,wetting and wetting/drying cycles is summarized based on reviews of a large body of research papers published in the past several *** compacted on the wet side of op-timum water content generally have a matrix-type structure with a monomodal pore size distribution(PSD),whereas soils compacted on the dry side of optimum water content display an aggregate structure that exhibits bimodal *** drying,decrease in soil volume is mainly caused by the shrinkage of inter-aggregate *** wetting,both the intra-and inter-aggregate pores inc.ease gradually in number and *** in the characteristics of the soil pore structure significantly depend on stress state as the soil is subjected to *** wetting/drying cycles,soil structural change is not completely reversible,and the generated cumulative swelling/shrinkage deformation mainly derives from ***,based on this analysis and identified research needs,some important areas of research focus are proposed for future *** areas inc.ude innovative methods of sample preparation,new observation techniques,fast quantitative analysis of soil structure,integration of microstructural parameters into macro-mechanical models,and soil microstructure evolution charac-teristics under multi-field coupled conditions.

关键词： Soil microstructure Pore size distribution(PSD) Wetting/drying cycle Suction Volume change

A case study on the efficacy of different roof bolting schemes in Lhoist North America’s Crab Orchard Mine

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International Journal of Mining Science and Technology 2020年第1期30卷 99-104页

作者： Reece Kurre Gabriel Walton Stantec Consulting services inc. Walnut CreekCA 94597USA Department of Geology and Geological Engineering Colorado School of MinesGoldenCO 80401USA

Roof bolting has long been used in underground mines across the world to provide ground *** roof bolts are cheap and easy to install with the use of specialized machines as a part of the production cycle. Lhoist North America’s Crab Orchard Mine is an underground room and pillar limestone mine that uses mechanically anchored roof bolts for ground support. The mine currently employs two different roof bolting patterns: a standard 1.5 × 1.5 m pattern, and another 0.8 × 0.8 m pattern for use in areas with particularly hazardous roof conditions. The purpose of this study is to evaluate the relative effectiveness of each bolting pattern. A series of numerical models were created using Roc Science’s RS2. The models were based on a symmetrical section of the mine at its deepest point, and were modeled using generalized Hoek-Brown failure criterion along with a discrete fracture network. A series of sensitivity analyses were performed on the models by varying parameters such as joint friction angle, crack persistence, joint randomization, and tensile strength of the limestone. Based on the results of the original models and sensitivity analyses, it appeared that the standard bolting pattern provided sufficient roof support capacity under almost all the expected conditions at the mine, sinc. safety factors below the design value of 1.5 were only found for individual bolts in a few of the worst test cases *** results can help improve the mine’s productivity and reduce operating costs without compromising safety.

关键词： Numerical modeling Mining Roof bolting Roof stability Analysis RocScience’s RS2 Underground stone

WHAT DOES ACCESS TO JUSTICE REQUIRE？ -- OVERCOMING BARRIERS TO INVOKE THE UNITED NATIONS CONVENTION ON THE RIGHTS OF PERSONS WITH DISABILITIES

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Frontiers of Law in China-Selected Publications from Chinese Universities 2016年第2期11卷 280-322页

作者： Kevin M. Cremin Columbia Law School MFY Legal services Inc. New York US

Persons with disabilities have a right to effective access to justice under the United Nations Convention on the Rights of Persons with Disabilities （UNCRPD）. This article provides insights on the parameters of that right, inc.uding a close examination of the history and text of Article 13, which directly addresses access to justice and other relevant UNCRPD provisions. In addition to the UNCRPD, this article discusses implementation guidance from the Committee on the Rights of Persons with Disabilities, inc.uding its guidelines for State Party reports and jurisprudence. The initial reports by eleven States Parties -- Argentina, Azerbaijan, China, Costa Rica, Croatia, Dominican Republic, Ecuador, Hungary, Mexico, Peru and Turkmenistan - are also considered. The Committee＇s feedback regarding implementation of Article 13 by these eleven States parties is critiqued for being limited and inc.nsistent. This article then attempts to clarify what effective access to justice actually requires. It does so by focusing on the insights that can be drawn from implementation of Article 13 sinc. the UNCRPD was adopted as well as implementation guidance from the Conference of States Parties, the International Disability Alliance, the World Network of Users and Survivors of Psychiatry and the National Center for Access to Justice. This article concludes with recommendations on how the Committee can improve its guidance on access to justice to help ensure that equal rights will not be illusory for persons with disabilities.

关键词： access to justice Convention on the Rights of Persons with Disabilities right tocounsel Committee on the Rights of Persons with Disabilities

Modeling displacement flow inside a full-length casing string for well cementing

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Petroleum Research 2024年第1期9卷 1-16页

作者： Hu Dai Ali Eslami Jason Schneider Gefei Liu Fred Schwering Pegasus Vertex Inc.USA Laval University Canada Sanjel Energy services Canada Athabasca Oil Corporation Canada

While computer modeling of annular displacement efficiency is widely applied in cementing engineering,modeling the displacement flow inside a casing or drill string for cementing operations has received less *** predicting displacement efficiency inside a full-length pipe is desired by cementing engineers,the attempt of developing a model with both efficiency and accuracy faces *** to computer simulators for this purpose is *** with annular flow,the displacement flow inside pipe,although within a simpler geometry and without eccentricity effect,is not simpler in physics,modelling strategy and predictability,because a variety of flow patterns and flow instabilities can develop to create complicated fluid *** this paper,we present an integrated numerical model developed to simulate displacement flows inside a full-length pipe,which connects an existing annulus model to enable complete displacement simulations of cementing *** model uses three-dimensional grid to solve fluid concentrations with degrees of mixing,and inc.rporates flow instability detection and flow regime *** in cementing,the model accounts for effects of pumping rate,well inc.ination,pipe rotation,fluid densities,rheological parameters and *** computationally efficient model does not rely on high-resolution mesh as often required by conventional Computational Fluid Dynamics models,thus it is suitable to be implemented in a cementing software for daily use by well cementing *** methodology of the model is discussed in detail in this *** validate the model,we examine simulation results against experimental results obtained in our laboratory tests and CFD simulations;acceptable agreement is found under different testing *** also presented two case studies of real cementing jobs with cement evaluation logs compared to simulation results,showing that the model can predict consistent displacement efficie

关键词： Inside pipe displacement Displacement efficiency Numerical model Primary cementing Displacement flow

Development and evaluation of corrosion resistant coating for expandable rock bolt against highly corrosive ground conditions

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International Journal of Mining Science and Technology 2018年第1期28卷 145-151页

作者： Kevin Jinrong Ma John Stankus Dakota Faulkner Keystone Mining services LLC of Jennmar Corporation Inc

Expandable rock bolts are widely used in hard rock mines as an efficient ground control ***, capacity and service life can be significantly reduced if the metallic body is subjected to *** some hard rock mines in the U.S., highly corrosive ground conditions exist, and it has been reported that inflatable rock bolts have corroded within a few months after *** provide mining industry a cost-effective inflatable bolt and combat the corrosion issues, Jennmar Corporation, inc.,and its subsidiary Keystone Mining services, LLC(KMS), analyzed corroded bolt samples, identified root causes, evaluated properties of various coating materials, and developed a new inflatable rock bolt,Python M3^(TM), that is protected with an innovative PyFlexU2^(TM)*** new generation Python M3^(TM) features improved steel chemistry for reliable performance, modified profile for better inflation, and surface preparation and coating *** PyFlexU2^(TM)is impervious to liquid and air, durable, and UV *** a flexible, adhesive, and highly corrosion-resistant undercoating, and a very hard sacrificial surface coating, the PyFlexU2^(TM)coating system provides the Python M3^(TM)superior protection against chemical corrosion and physical scratch *** under-coating has exceptional flexibility and adhesion to prevent coating micro-cracks or fractures after bolt inflation and possesses excellent corrosion resistance to acids(pH 11), fuels, and salt *** corrosion and scratch resistant PyFlexU2^(TM)coating offers very effective bolt protection for extra longevity in highly corrosive *** Python M3^(TM)coated with PyFlexU2^(TM)has been tested in the most challenging conditions,inc.uding laboratory corrosion tests in extreme acidic and basic solvents, rock slurry, and borehole scratch insertion *** demonstrated corrosion and scratch resistance, the product has been greatly welcomed by hard rock min

关键词： Rock bolt Hard rock Corrosive ground condition Bolt corrosion

Dissipative particle dynamics simulation of wettability alternation phenomena in the chemical flooding process

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Acta Mechanica Sinica 2009年第5期25卷 583-587页

作者： Xiaobo Li Yuewu Liu Jianfei Tang Shujiao Li DES Institute of Mechanics Chinese Academy of Sciences 100190 Beijing China Top-well services inc. 100101 Beijing China Greatwall Drilling Company 100101 Beijing China

Wettability alternation phenomena is considered one of the most important enhanced oil recovery （EOR） mechanisms in the chemical flooding process and induced by the adsorption of surfactant on the rock surface. These phenomena are studied by a mesoscopic method named as dissipative particle dynamics （DPD）. Both the alteration phenomena of water-wet to oil-wet and that of oil-wet to water-wet are simulated based on reasonable definition of interaction parameters between beads. The wetting hysteresis phenomenon and the process of oil-drops detachment from rock surfaces with different wettability are simulated by adding long-range external forces on the fluid particles. The simulation results show that, the oil drop is liable to spread on the oil-wetting surface and move in the form of liquid film flow, whereas it is likely to move as a whole on the waterwetting surface. There are the same phenomena occuring in wettability-alternated cases. The results also show that DPD method provides a feasible approach to the problems of seepage flow with physicochemical phenomena and can be used to study the mechanism of EOR of chemical flooding.

关键词： Wettability alternation Dissipative particledynamics - Enhanced oil recovery Chemical flooding -Mesoscopic mechanics

Quality of compounded topical 2% diltiazem hydrochloride formulations for anal fissure

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World Journal of Gastroenterology 2013年第34期19卷 5645-5650页

作者： Monil Shah Laura Sandler Vishwas Rai Charu Sharma Lakshmi Raghavan Ventrus Biosciences Inc. DermPathe Pharmaceuticals

AIM:To investigate the quality of topical 2%diltiazem formulations extemporaneously compounded by retail pharmacies openly offering drug-compounding ***:A participating healthcare professional wrote 12 prescriptions for compounded 2%diltiazem cream,with 2 refills allowed per *** 12sets of prescriptions were filled,at intervals of 1-2 wk between refills,at 12 different independent retail pharmacies that openly offer drug-compounding services in a major metropolitan *** 36 resultant preparations,provided as jars or tubes,were shipped,as soon as each was filled,at ambient temperature to the study core laboratory for high-performance liquid chromatography(HPLC)analysis,within 10 d of *** the HPLC analysis,8 different samples of the topical diltiazem,each approximately 1 g in weight,were taken from prespecified locations within each *** initiate the HPLC analysis,each sample was transferredto a 100 mL volumetric flask,to which methanol was *** HPLC analysis was conducted in accordance with the laboratory-validated method for diltiazem in cream,ointment,and gel *** main outcome measures were potency(percentage of label claim)and content uniformity of the compounded topical 2%diltiazem ***:Of the 36 prescriptions filled,30 were packaged in jars and 6 were packaged as *** prescriptions were specifically for cream formulations,but6 of the 12 pharmacies compounded 2%diltiazem as an ointment;for another pharmacy,which had inadequate labeling,the dosage form was *** United States Pharmacopoeia(USP)standard for potency is 90%-115%of label *** the 36 preparations,5(13.89%)were suprapotent and 13(36.11%)were *** suprapotent prescriptions ranged in potency from 117.2%to 128.5%of label claim,and the subpotent prescriptions ranged in potency from34.8%to 89.8%of label ***(38.9%)preparations lacked content uniformity according to the USP standard of 90%-110%pote

关键词： Anal fissure Pharmacy compounding Topical diltiazem Formulation potency Content uniformity