Determination of uncertainties of geomechanical parameters of metamorphic rocks using petrographic analyses

Geomechanical parameters of intact metamorphic rocks determined from laboratory testing remain highly uncertain because of the great intrinsic variability associated with the degrees of metamorphism.The aim of this paper is to develop a proper methodology to analyze the uncertainties of geomechanical characteristics by focusing on three domains,i.e.data treatment process,schistosity angle,and mineralogy.First,the variabilities of the geomechanical laboratory data of Westwood Mine(Quebec,Canada)were examined statistically by applying different data treatment techniques,through which the most suitable outlier methods were selected for each parameter using multiple decision-making criteria and engineering judgment.Results indicated that some methods exhibited better performance in identifying the possible outliers,although several others were unsuccessful because of their limitation in large sample size.The well-known boxplot method might not be the best outlier method for most geomechanical parameters because its calculated confidence range was not acceptable according to engineering judgment.However,several approaches,including adjusted boxplot,2MADe,and 2SD,worked very well in the detection of true outliers.Also,the statistical tests indicate that the best-fitting probability distribution function for geomechanical intact parameters might not be the normal distribution,unlike what is assumed in most geomechanical studies.Moreover,the negative effects of schistosity angle on the uniaxial compressive strength(UCS)variabilities were reduced by excluding the samples within a specific angle range where the UCS data present the highest variation.Finally,a petrographic analysis was conducted to assess the associated uncertainties such that a logical link was found between the dispersion and the variabilities of hard and soft minerals.

Evaluation of the effect of geometrical parameters on stope probability of failure in the open stoping method using numerical modeling

Stress-induced failure is among the most common causes of instability in Canadian deep underground mines.Open stoping is the most widely practiced underground excavation method in these mines,and creates large stopes which are subjected to stress-induced failure.The probability of failure(POF)depends on many factors,of which the geometry of an open stope is especially important.In this study,a methodology is proposed to assess the effect of stope geometrical parameters on the POF,using numerical modelling.Different ranges for each input parameter are defined according to previous surveys on open stope geometry in a number of Canadian underground mines.A Monte-Carlo simulation technique is combined with the finite difference code FLAC3D,to generate model realizations containing stopes with different geometrical features.The probability of failure(POF)for different categories of stope geometry,is calculated by considering two modes of failure;relaxation-related gravity driven(tensile)failure and rock mass brittle failure.The individual and interactive effects of stope geometrical parameters on the POF,are analyzed using a general multi-level factorial design.Finally,mathematical optimization techniques are employed to estimate the most stable stope conditions,by determining the optimal ranges for each stope’s geometrical parameter.

Effect of different quenching processes following solid-solution treatment on properties and precipitation behaviors of 7050 alloy

The effects of quenching in different ways following solid-solution treatment on properties and precipitation behaviors of7050 alloy were investigated by transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, selected areaelectron diffraction （SAED）, hardness and electrical conductivity tests. Results show that after quenching in different ways, electricalconductivity of the alloy decreases rapidly in the first 48 h of natural aging. The electrical conductivity of 7050 alloy in natural agingstate is determined by the size and density of GP zones, and the size of GP zones is the main factor. After natural aging for 70 d, thesize of GP zones is 1.8-2.6 nm in matrix of the immersion quenched sample and it is 1.4-1.8 nm in matrix of both water mist andforced air quenched samples. After natural and artificial peak aging, the hardness of the water mist quenched sample is HV 193.6 andits electrical conductivity is 30.5% （IACS） which are both higher than those of the immersion quenched sample. Therefore, watermist quenching is an ideal quenching method for 7050 alloy sheets after solid-solution treatment.

Influence of TiB_2 nanoparticles on elevated-temperature properties of Al-Mn-Mg 3004 alloy

Two contents(1.5%and3%)of TiB2nanoparticles were introduced in Al?Mn?Mg3004alloy to study their effects on theelevated-temperature properties.Results show that TiB2nanoparticles were mainly distributed at the interdendritic grain boundarieswith a size range of20?80nm,which is confirmed by transmission electron microscopy(TEM)and X-ray diffraction(XRD).Therefore,the volume fraction of the dispersoid free zones is greatly reduced and the motion of grain boundaries and dislocations isinhibited more effectively at elevated temperature.After peak precipitation heat treatment,the yield strengths in the alloy with3%TiB2addition at room temperature and300°C were increased by20%and13%respectively,while the minimum creep rate at300°Cwas reduced to only1/5of the base alloy free of TiB2,exhibiting a considerable improvement of elevated-temperature properties inAl?Mn?Mg alloys.

Microstructure and high temperature tensile properties of Al-Si-Cu-Mn-Fe alloys prepared by semi-solid thixoforming

The differences in the microstructure and elevated temperature tensile properties of gravity die cast,squeeze cast,and semi-solid thixoformed Al-Si-Cu-Mn-Fe alloys after thermal exposure at 300℃were discussed.The results demonstrate that the elevated temperature tensile properties of semi-solid thixoformed alloys were significantly higher than those of gravity die cast and squeeze cast alloys,especially after thermal exposure for 100 h.The ultimate tensile strength(UTS)of semi-solid thixoformed alloys after thermal exposure at 300℃for 0.5,10 and 100 h were 181,122 and 110 MPa,respectively.The UTS values of semi-solid thixoformed alloys were higher than those of heat resistant aluminum alloys used in commercial applications.The enhanced elevated temperature tensile properties of semi-solid thixoformed experimental alloys after thermal exposure can be attributed to the combined reinforcement of precipitation strengthening and grain boundary strengthening due to thermally stable intermetallic phases as well as suitable grain size.

Development of fatigue analytical model of automotive dynamic parts made of semi-solid aluminum alloys

Automotive suspension control arm is used to join the steering knuckle to the vehicle frame. Its main function is to provide stability under fatigue stresses of loading and unloading in accelerating and braking. Conventionally, these parts were made of steel; however, fuel consumption and emission of polluting gases are strongly dependent on car weight. Recently, there is a try to develop and design much lighter and better fatigue resistant metal of semisolid A357 aluminum alloys. This work aims at a better understanding of identifying the fatigue strain-hardening parameters used for determining fatigue characteristics of aluminum suspension control arm using analytical and mathematical modeling. The most judicious method is to perform the fatigue tests on standardized test pieces and then plot two Wohler curves, mainly number of cycles as a function of the stress and as a function of the deformation. From these curves and following a certain mathematical and analytical methods, certain curves are plotted and then all of these coefficients are drawn. The new calculated parameters showed a clear improvement of the fatigue curve towards the experimental curve performed on the samples of aluminum alloy A357 compared with the same analytical curve for the same alloy.

Metallogeny of the Lannigou Sedimentary Rock-hosted Disseminated Gold Deposit in Southwestern Guizhou Province,China

The Lannigou deposit is a large-sized sedimentary rock-hosted disseminated gold （SRHDG） deposit located in the Youjiang Basin. It is hosted by the Middle Triassic turbidite. Wall rock alterations, including silicification, pyritization, arsenopyritization, carbonatization and argillization, commonly occur along fractures. PGE study demonstrates that either Permian basalts or Triassic ultrabasic intrnsives are unlikely to be the main source of gold mineralization. Coupled with the lack of other nmgmatic activity in the vicinity of the mining area, an amagmatic origin is proposed. Organic matter compositions and GC-MS analysis of the ores and host rocks show that the organics in the ores and the host rocks have a common source; the organic matter in the ores was mainly indigenous. The positive correlation between S2 and Au contents, along with the common occurrence of organic inclusions, suggest involvement of organic matter in the ore-forming process in terms of promoting Au leaching from the source rocks, making colloidal Au migration possible, as well as hydrocarbon reduction of sulphate. Geological and geochemical characteristics of the Lannigou deposit suggest that it was formed through circulation of meteoric water and probably less importantly organic bearing formation water driven by high geothermal gradient caused by late Yanshanian extension, which leached Au from the source bed, and then migrated as Au-bisnlfides and colloidal Au, culminating in deposition by reduction-adsorption and surface complexation of gold onto the growth surface of arsenlan pyrite.

Determining relative block structure rating for rock erodibility evaluation in the case of non-orthogonal joint sets

The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resistance. This capacity is evaluated using Kirsten's index, which was initially developed to evaluate the excavatability of earth materials. For rocky material, this index is determined according to certain geomechanical factors related to intact rock and rock mass, such as compressive strength of intact rock, rock block size, discontinuity shear strength and relative block structure. To quantify the relative block structure, Kirsten(1982) developed a mathematical expression that accounts for the shape and orientation of the blocks relative to the direction of flow. Kirsten's initial concept for assessing the relative block structure considers that the geological formation is mainly fractured by two joint sets forming an orthogonally fractured system. An adjusted concept is proposed to determine the relative block structure when the fractured system is non-orthogonal where the angle between the planes of the two joint sets is greater or less than 90°. An analysis of the proposed relative block structure rating shows that considering a non-orthogonally fractured system has a significant effect on Kirsten's index and, as a consequence, on the assessment of the hydraulic erodibility of rock.

A reliability study of springback on the sheet metal forming process under probabilistic variation of prestrain and blank holder force

This work deals with a reliability assessment of springback problem during the sheet metal forming process. The effects of operative parameters and material properties, blank holder force and plastic prestrain, on springback are in- vestigated. A generic reliability approach was developed to control springback. Subsequently, the Monte Carlo simula- tion technique in conjunction with the Latin hypercube sam- pling method was adopted to study the probabilistic spring- back. Finite element method based on implicit/explicit al- gorithms was used to model the springback problem. The proposed constitutive law for sheet metal takes into account the adaptation of plastic parameters of the hardening law for each prestrain level considered. Rackwitz-Fiessler al- gorithm is used to find reliability properties from response surfaces of chosen springback geometrical parameters. The obtained results were analyzed using a multi-state limit reli- ability functions based on geometry compensations.

Static and Vibration Analysis of an Aluminium and Steel Bus Frame

The transport sector is increasing day by day to satisfy the global market requirement. The bus is still the main mode of intercity transportation in Canada. Despite, an essentially unchanged conception, the total weight of the bus has increased by over 25% during the last three decades. To solve this problem, industrialists have moved to the use of light metals in the transportation field. Therefore, use of lightweight materials, such as aluminum is essential to reduce the total weight of bus. In this study, the focus is on the bus frame as it represents 30% of the total weight and it is the most stressed part of the bus. Its life duration is more important compared to that of all other elements. Thus, a study of the static and vibratory behavior would be very decisive. In this article, two types of analysis are carried out. First is the modal analysis to determine the natural frequencies and the mode shapes using a developed dynamic model of the bus. Because if any of the excitation frequencies coincides with the natural frequencies of the bus frame, then resonance phenomenon occurs. This may lead to excessive deflection, high stress concentration, fatigue of the structure and vehicle discomfort. In this case, the results analysis shows that the natural frequencies are not affected by the change of material. The second type of analysis is the linear static stress analysis to consider the stress distribution and deformation frame pattern under static loads numerically. For the numerical method, the frame is designed using SolidWorks and the analysis is made using Ansys WorkBench. The maximum Von Mises stress obtained for the static loading is in the same order for the three chassis frames studied. But in the case of the aluminium frame, the weight of 764 kg was reduced.

Determination of Coke,Pitch and Pores/Cracks in Green Anode by Image Analysis

Carbon anodes are an essential part of the primary aluminum production. They are made of coal tar pitch, calcined petroleum coke, recycled anodes and butts. As pitch acts as a binder for the anode, its proper distribution in a green anode has a great impact on the properties of the baked anode. Information on cracks in anodes is important for the quality of the baked anode. There is presently no reliable method available to analyze and quantify the amount of coke, pitch and pores/cracks in a green anode sample. In this article, an image analysis technique has been described, that can analyze as well as quantify the area percentage of pores/cracks and weight percentages of pitch and coke. The novelty of the method is its capacity to differentiate the different components of anode.

Formation of Strata-bound Ore Deposits in China:Studies on Fluid Inclusions

Fluid inclusion studies were made on the basis of the geological data on the strata-bound ore de-posits of China including those of Pb,Zn,Au,Ag,Sb,U,Hg,W,quartz-crystal and sparry-calcite.An attempt was made to approach the model of formation for each type of ore depos-its by considering the material sources,the migration of fluids and the conditions of mineralization.It is found that ore-forming fluids (especially H2O)originate as heated underground water reacts with the wallrocks and dissolves Na^+,Ca^2+,K^+,Cl^+,HCl^- and Mg^2+ .The ore fluids are mainly of NaCl-Ca-HCO3-H2O system with salinities ranging from 4to 14wt.%.NaCl equivalent and densities ranging from 0.9 to 1.0g/cm^3.It may be concluded that the deposits were formed at temperatures ranging from 150 to 250℃ under pressures from 300 to 1000 bars.Ore deposition may have been controlled by temperature and pressure or by the mixing among different fluids.

Periodicity of Element Changes in the Upper Devonian Strata of Dachang Area, Southern China——A Case Study of Spectral Analysis

Power spectral analysis is discussed and an exmple of its application to a geochemical stratigraphic profile is presented.In the Dachang area,all major elements,as well as the maximal sedimentary trend factor(MSTF),demonstrate consistent change periodicity,but are out-of-step with cach other.This can be explained by sedimentogecochemical consideration.The results of power spectral analysis enable geochemists to group elements on the basis of the distribution of their changed periods,and to interpret some special geological and geochemical situations.

Confirmation of 24 h 50 min Lunar Periodicity, Apparently Inexplicable by Classical Factors, in Precession of Allais Pendulum

During 36 days the motion of two pendulums, which were restarted every hour, was continuously recorded. 869 “runs” were thus made, providing each time the precession during the run, as well as other parameters of the motion. Spectral analysis of precession and ellipticity revealed a lunar component of 24 h 50 min, which can only result from an astral action, through mechanisms yet to be discovered. Indeed, an analysis was carried out of the influence of all classical perturbing factors: direct or indirect action of classical gravity, temperature, Earth’s magnetic field, etc.… None of them can explain this component, given its amplitude and phase. Its amplitude excludes also an explanation by general relativity. This is consistent with a major result that Allais claimed to have obtained during each one of the six continuous one-month-long experiments he carried out from 1954 to 1960. The numerous and very precise data provided by an automatic alidade give additional information to those gathered by Allais. All that confirms all the scientific interest that there would be to resume long-duration pendulum observations on a much more important scale: continuous observations for at least 2 years, and if possible more.

Study on Weathering Behavior of Jack Pine Heat-Treated under Different Conditions

It is of considerable importance to investigate the influence of weathering on the degradation processes of heat-treated wood. Kiln-dried （untreated）jack pine （Pinus banksiana） and jack pine heat-treated at three different temperatures （190 ℃, 200 ℃, and 210 ℃） were exposed to artificial weathering for different periods in order to understand the degradation processes due to weathering. Before and after exposure, their color and wettability by water were determined. Structural changes and chemical modifications at exposed surfaces were also investigated using SEM （scanning electron spectroscopy）, FTIR （Fourier transforms infrared spectroscopy）, and XPS （X-ray photoelectron spectroscopy）. The results revealed that the photo-degradation of lignin and the presence of extractives play important roles in color change and wetting behavior of heat-treated wood surfaces during weathering. The structural changes also influence the wettability. The effects of weathering for woods heat-treated under different conditions were similar, but different from those for untreated wood.

Full Dynamic Model for Liquid Sloshing Simulation in Cylindrical Tank Shape

This study presents a comprehensive full dynamic model designed for simulating liquid sloshing behavior within cylindrical tank structures. The model employs a discretization approach, representing the liquid as a network of interconnected spring-damper-mass systems. Key aspects include the adaptation of liquid discretization techniques to cylindrical lateral cross-sections and the calculation of stiffness and damping coefficients. External forces, simulating various vehicle maneuvers, are also integrated into the model. The resulting system of equations is solved using Maple Software with the Runge-Kutta-Fehlberg method. This model enables accurate prediction of liquid displacement and pressure forces, offering valuable insights for tank design and fluid dynamics applications. Ongoing refinement aims to broaden its applicability across different liquid types and tank geometries.

The occurrence of gold in pyrite from the Liulincha gold ore belt,western Hunan Province,China

In this study,an electron microprobe analyzer(EMPA) was used to map the spatial distribution and the occurrence of invisible gold in pyrite from the Liulincha gold ore belt.EPMA data show that gold mainly occurs as submicroscopic-microscopic inclusions.From the contrast of the major guide elements of pyrite from the Liulincha gold ore belt and those from four hydrothermal-type gold deposits in the Jiaodong region,we can see the pyrites were formed in two stages:the pyrite from wall rock is mainly sedimentogenic,with simple structure;and the pyrite from ore body experienced early sedimentary process to late hydrothermal activity,the pyrite is regular in crystal form and exhibits fractured structure.

Development of Analytical Model for Modular Tank Vehicle Carrying Liquid Cargo

The study of dynamics of tank vehicles carrying liquid fuel cargo is complex. The forces and moments due to liquid sloshing create serious problems related to the instability of tank vehicles. In this paper, a complete analytical model of a modular tank vehicle has been developed. The model included all the vehicle systems and subsystems. Simulation results obtained using this model was compared with those obtained using the popular TruckSim software. The comparison proved the validity of the assumptions used in the analytical model and showed a good correlation under single or double lane change and turning manoeuvers.

Recycling of Silicone Rubber from Composite Insulator with Pyrolysis Method

Composite insulators have been widely used in transmission lines.After being removed from transmission lines,their housing silicone material cannot degrade naturally.To tackle this problem,this paper proposes an effective method to recycle waste insulators by pyrolysis to obtain mullite(3Al_(2)O_(3)·2SiO_(2))with high purity and compact structure.The recycling process studied will not generate toxic products.The thermal degradation process of housing material is investigated by analyzing its degradation products including the gas and residues in detail.The experimental results indicate that the colorant agent Fe2O3 inside the housing material is beneficial for the generation of mullite by decreasing the temperature of mullitization.Besides,since the transitional alumina generated by the dehydration of aluminum hydroxide(ATH)has a smaller diameter and can better dissolute into the silica phases,ATH is a better choice as the additional aluminum resource.By comparing the components,structure,and particle size of grains formed at different calcination temperatures,the proposed pyrolysis temperatures of the two stages are 1400◦C and 1600◦C,respectively.

流体相分离的深度(压力)-温度场特征及其对热液矿床定位的意义

大量的流体包裹体研究表明,流体相分离作用是造成热液矿床矿质沉淀的重要机制之一。本文对几种常见的成矿流体相分离深度-温度场特征进行了讨论,包括不同流体体系在不同深度、温度条件下的相分离曲线的特征,盐类及二氧化碳对流体相分离场的影响以及不同压力状态下相分离场的差异。在此基础上,通过一些钨锡矿床的流体包裹体研究实例,讨论了流体相分离深度-温度场对矿床的定位(尤其是矿床的产出部位与岩体接触带的距离)的意义。