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The Representation of Soil Moisture−Atmosphere Feedbacks across the Tibetan Plateau in CMIP6

Advances in Atmospheric Sciences 2023年第11期40卷 2063-2081页

作者： joshua TALIB Omar V.MÜLLER Emma j.barton Christopher M.TAYLOR Pier Luigi VIDALE U.K.Centre of Ecology and Hydrology WallingfordOX108BBU.K. National Centre for Atmospheric Science ReadingRG66BBU.K. Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET) Centro de Estudios de Variabilidad y Cambio Climático(CEVARCAM)Facultad de Ingeniería y Ciencias HídricasUniversidad Nacional del LitoralSanta FeArgentina National Centre for Earth Observation WallingfordOX108BBU.K. Department of Meteorology University of ReadingReadingRG66BBU.K.

Thermal processes on the Tibetan Plateau(TP)influence atmospheric conditions on regional and global *** this,previous work has shown that soil moisture−driven surface flux variations feed back onto the *** soil moisture is a source of atmospheric predictability,no study has evaluated soil moisture−atmosphere coupling on the TP in general circulation models(GCMs).In this study,we use several analysis techniques to assess soil moisture−atmosphere coupling in CMIP6 simulations including:instantaneous coupling indices;analysis of flux and atmospheric behaviour during dry spells;and a quantification of the preference for convection over drier *** these metrics we partition feedbacks into their atmospheric and terrestrial *** with previous global studies,we conclude substantial inter-model differences in the representation of soil moisture−atmosphere coupling,and that most models underestimate such *** on dry spell analysis,most models underestimate increased sensible heat during periods of rainfall *** example,the model-mean bias in anomalous sensible heat flux is 10 W m−2(≈25%)smaller compared to *** dry-spell sensible heat fluxes lead to a weaker atmospheric *** also find that most GCMs fail to capture the negative feedback between soil moisture and deep *** poor simulation of feedbacks in CMIP6 experiments suggests that forecast models also struggle to exploit soil moisture−driven *** improve the representation of land−atmosphere feedbacks requires developments in not only atmospheric modelling,but also surface processes,as we find weak relationships between rainfall biases and coupling indexes.

关键词： model evaluation land-atmosphere feedbacks Tibetan Plateau precipitation surface energy balance

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改进烯烃厂热回收的节能工艺

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齐鲁石油化工 1989年第5期17卷 55-57页

作者： j.barton 荣德显

1.前言在许多国家,一般都是通过石脑油或者重柴油热裂解制取用于聚合的乙烯和丙烯。热裂解反应是在800到850℃的温度下进行.在乙烯装置中,从热裂解气中回收热量的最普通的方案如图1所示。

关键词：烯烃厂热回收节能

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提高舒适性的吸湿整理

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国外纺织技术（纺织针织服装化纤染整） 2003年第4期 26-28页

作者： j.barton 刘玉莉

近期,研究人员已经开发出了多种'微气候调节'整理产品.生产商已经意识到了消费者对具有户外和运动功能的休闲服装的要求,所以不断投入资金进行新品开发,以满足消费者对舒适性越来越高的要求.

关键词：舒适性吸湿整理织物合成纤维运动服微气候调节整理

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Understanding the need for pre-injection from permeability measurements: What is the connection?

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journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 576-597页

作者： Nick barton Eda Quadros Nick barton & Associates OsloNorway BGTech Soil and Rock Engineering Ltd. Sao PauloBrazil

Pre-grouting ahead of tunnels has three main functions:to control water inflow into the tunnel,to limit groundwater drawdown above the tunnel,and to make tunnelling progress more predictable since rock mass quality is effectively *** helps to avoid settlement damage caused by consolidation of clay deposits beneath built-up areas,since towns tend to be built where terrain is more flat,due to the clay *** are so many instances of settlement damage that the profession needs to take note of the need for high-pressure pre-grouting,to use micro-cements and micro-silica *** use of highpressure injection may cause joint jacking,but this is local in extent when the rapid pressure decay away from an injection hole is *** effect is variable and depends on the geometrical parameters of the *** pressure-decay advantage must not be violated by maintaining high pressure when grout flow from the injection hole has *** latter can cause damage to the grouting already *** methods of estimating mean hydraulic apertures(e)from Lugeon testing are described,and from more sophisticated three-dimensional(3D)permeability *** estimation of the larger mean physical joint apertures(E)is based on the joint roughness coefficient(jRC).Comparison is then made with the empirical aperture-particle size criterion E>4d95,where d95 represents almost the largest cement particle *** on joint set orientations and on the available micro-cements,the decision must be made of which range of pre-injection pressure should be aimed for,using successive reductions of the water-cement ratio w/*** simple estimation of permeability,also with depth dependence,can be made with the empirical link between a modified rock mass quality Q and permeability,which is termed *** value of this parameter can be based on core-logging or intunnel face *** 3D before-and-after-grouting permeability measurements have been use

关键词： Pre-grouting Micro-cement Hydraulic apertures Physical joint apertures joint roughness Particle size Anisotropic permeability

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Risk of shear failure and extensional failure around over-stressed excavations in brittle rock

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journal of Rock Mechanics and Geotechnical Engineering 2017年第2期9卷 210-225页

作者： Nick barton Baotang Shen Nick barton&Associates OsloNorway CSIRO Energy BrisbaneAustralia

The authors investigate the failure modes surrounding over-stressed tunnels in *** lines of investigation are employed:failure in over-stressed three-dimensional(3D) models of tunnels bored under 3D stress,failure modes in two-dimensional(2D) numerical simulations of 1000 m and 2000 m deep tunnels using FRACOD,both in intact rock and in rock masses with one or two joint sets,and finally,observations in TBM(tunnel boring machine) tunnels in hard and medium hard massive *** reason for 'stress-induced' failure to initiate,when the assumed maximum tangential stress is approximately(0.4-0.5)σ_c(UCS,uniaxial compressive strength) in massive rock,is now known to be due to exceedance of a critical extensional strain which is generated by a Poisson's ratio ***,because similar 'stress/strength' failure limits are found in mining,nuclear waste research excavations,and deep road tunnels in Norway,one is easily misled into thinking of compressive stress induced *** of this,the empirical SRF(stress reduction factor in the Q-system) is set to accelerate as the estimated ratio σ_(θmax)/σ_c >> *** mining,similar 'stress/strength' ratios are used to suggest depth of *** reality behind the fracture initiation stress/strength ratio of '0.4' is actually because of combinations of familiar tensile and compressive strength ratios(such as 10) with Poisson's ratio(say0.25).We exceed the extensional strain limits and start to see acoustic emission(AE) when tangential stress σθ ≈ 0.4σc,due to simple *** combination of 2D theoretical FRACOD models and actual tunnelling suggests frequent initiation of failure by 'stable' extensional strain fracturing,but propagation in 'unstable' and therefore dynamic *** the case of very deep tunnels(and 3D physical simulations),compressive stresses may be too high for extensional strain fracturing,and shearing will dominate,both ahead of the face and following the *** shallower,the conc

关键词： Fracture propagation Tension Shear Poisson’s ratio Break-out Rock burst Deep tunnels FRACOD model

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Shear strength criteria for rock,rock joints,rockfill and rock masses:Problems and some solutions

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journal of Rock Mechanics and Geotechnical Engineering 2013年第4期5卷 249-261页

作者： Nick barton Nick barton & Associates OsloNorway

Although many intact rock types can be very strong,a critical confining pressure can eventually be reached in triaxial testing,such that the Mohr shear strength envelope becomes *** critical state has recently been better defined,and correct curvature or correct deviation from linear Mohr-Coulomb（MC） has finally been *** shear testing procedures for rock joints,using multiple testing of the same sample,in case of insufficient samples,can be shown to exaggerate apparent *** rough joints do not have any cohesion,but instead have very high friction angles at low stress,due to strong *** masses,implying problems of large-scale interaction with engineering structures,may have both cohesive and frictional strength ***,it is not correct to add these,following linear M-C or nonlinear Hoek-Brown（H-B） standard *** is broken at small strain,while friction is mobilized at larger strain and remains to the end of the shear *** criterion ＇c then σn tan φ＇ should replace ＇c plus σn tan φ＇ for improved fit to *** of principal stresses to a shear plane seems to ignore mobilized dilation,and caused great experimental difficulties until *** seems to be plenty of room for continued research,so that errors of judgement of the last 50 years can be corrected.

关键词： Rock masses Critical state Rock joints Shear strength Non-linear friction Cohesion Dilation Scale effects Numerical modelling Stress transforms

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Advances in joint roughness coefficient (jRC) and its engineering applications

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journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3352-3379页

作者： Nick barton Changshuo Wang Rui Yong Nick barton&Associates Fjordveien 65cHavik Oslo1363Norway School of Civil Engineeing Shijiazhuang Tiedao UniversityShijiazhuang050043China Rock Mechuanics Institute Ningbo UniversityNingbo315211China

The joint roughness coefficient (jRC), introduced in barton (1973) represented a new method in rock mechanics and rock engineering to deal with problems related to joint roughness and shear strength estimation. It has the advantages of its simple form, easy estimation, and explicit consideration of scale effects, which make it the most widely accepted parameter for roughness quantification since it was proposed. As a result, jRC has attracted the attention of many scholars who have developed jRC-related methods in many areas, such as geological engineering, multidisciplinary geosciences, mining mineral processing, civil engineering, environmental engineering, and water resources. Because of such a developing trend, an overview of jRC is presented here to provide a clear perspective on the concepts, methods, applications, and trends related to its extensions. This review mainly introduces the origin and connotation of jRC, jRC-related roughness measurement, jRC estimation methods, jRC-based roughness characteristics investigation, jRC-based rock joint property description, jRC's influence on rock mass properties, and jRC-based rock engineering applications. Moreover, the representativeness of the joint samples and the determination of the sampling interval for rock joint roughness measurements are discussed. In the future, the existing jRC-related methods will likely be further improved and extended in rock engineering.

关键词： joint roughness coefficient(jRC) Rock joints Roughness Shear strength Scale effect

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Real-time ore sorting using color and texture analysis

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International journal of Mining Science and Technology 2023年第6期33卷 659-674页

作者： David G.Shatwell Victor Murray Augusto barton Hochschild Mining PLC La Colonia 180Lima 15023Peru Department of Electrical Engineering Universidad de Ingenieria y Tecnologia-UTECLima 15063Peru john A.Paulson School of Engineering and Applied Sciences Harvard UniversityCambridge 02134USA Department of Electrical and Computer Engineering University of New MexicoAlbuquerque 87131USA

Sensor-based ore sorting is a technology used to classify high-grade mineralized rocks from low-grade waste rocks to reduce operation *** ore-sorting algorithms using color images have been proposed in the past,but only some validate their results using mineral grades or optimize the algorithms to classify rocks in *** paper presents an ore-sorting algorithm based on image processing and machine learning that is able to classify rocks from a gold and silver mine based on their *** algorithm is composed of four main stages:(1)image segmentation and partition,(2)color and texture feature extraction,(3)sub-image classification using neural networks,and(4)a voting system to determine the overall class of the *** algorithm was trained using images of rocks that a geologist manually classified according to their mineral content and then was validated using a different set of rocks analyzed in a laboratory to determine their gold and silver *** proposed method achieved a Matthews correlation coefficient of 0.961 points,higher than other classification algorithms based on support vector machines and convolutional neural networks,and a processing time under 44 ms,promising for real-time ore sorting applications.

关键词： Ore sorting Image color analysis Image texture analysis Machine learning

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A photogrammetric approach for quantifying the evolution of rock joint void geometry under varying contact states

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International journal of Mining Science and Technology 2024年第4期34卷 461-477页

作者： Rui Yong Changshuo Wang Nick barton Shigui Du Institute of Rock Mechanics Ningbo UniversityNingbo 315211China Nick barton&Associates Fjordveien 65cHøvik 1363Norway

Accurate measurement of the evolution of rock joint void geometry is essential for comprehending the distribution characteristics of asperities responsible for shear and seepage ***,existing techniques often require specialized equipment and skilled operators,posing practical *** this study,a cost-effective photogrammetric approach is ***,local coordinate systems are established to facilitate the alignment and precise quantification of the relative position between two halves of a rock ***/pull tests are conducted on rock joints with varying roughness levels to induce different contact states.A high-precision laser scanner serves as a benchmark for evaluating the photogrammetry *** certain deviations exist,the measured evolution of void geometry is generally consistent with the qualitative findings of previous *** photogrammetric measurements yield comparable accuracy to laser scanning,with maximum errors of 13.2%for aperture and 14.4%for void *** joint matching coefficient(jMC)measurement errors are below 20%.Larger measurement errors occur primarily in highly mismatched rock joints with jMC values below 0.2,but even in cases where measurement errors exceed 80%,the maximum jMC error is only ***,the proposed photogrammetric approach holds promise for widespread application in void geometry measurements in rock joints.

关键词： Rock joint Void geometry evolution Photogrammetry Aperture Void volume joint matching coefficient

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An approximate nonlinear modified Mohr-Coulomb shear strength criterion with critical state for intact rocks

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journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 645-652页

作者： Baotang Shen jingyu Shi Nick barton State Key Laboratory of Mining Disaster Prevention and Control Shandong University of Science and TechnologyQingdaoChina CSIRO Energy QCAT1 Technology CourtPullenvaleQLD4069Australia Nick barton&Associates OsloNorway

In this paper, the Mohr-Coulomb shear strength criterion is modified by mobilising the cohesion and internal friction angle with normal stress, in order to capture the nonlinearity and critical state concept for intact rocks reported in the literature. The mathematical expression for the strength is the same as the classical form, but the terms of cohesion and internal friction angle depend on the normal stress now,leading to a nonlinear relationship between the strength and normal stress. It covers both the tension and compression regions with different expressions for cohesion and internal friction angle. The strengths from the two regions join continuously at the transition of zero normal stress. The part in the compression region approximately satisfies the conditions of critical state, where the maximum shear strength is reached. Due to the nonlinearity, the classical simple relationship between the parameters of cohesion, internal friction angle and uniaxial compressive strength from the linear Mohr-Coulomb criterion does not hold anymore. The equation for determining one of the three parameters in terms of the other two is supplied. This equation is nonlinear and thus a nonlinear equation solver is needed. For simplicity, the classical linear relationship is used as a local approximation. The approximate modified Mohr-Coulomb criterion has been implemented in a fracture mechanics based numerical code FRACOD,and an example case of deep tunnel failure is presented to demonstrate the difference between the original and modified Mohr-Coulomb criteria. It is shown that the nonlinear modified Mohr-Coulomb criterion predicts somewhat deeper and more intensive fracturing regions in the surrounding rock mass than the original linear Mohr-Coulomb criterion. A more comprehensive piecewise nonlinear shear strength criterion is also included in Appendix B for those readers who are interested. It covers the tensile, compressive, brittle-ductile behaviour transition and the

关键词： Shear strength Modified Mohr-Coulomb criterion Critical state Intact rock

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