Adjustment mechanism of blasting dynamic-static action in the water decoupling charge

Water decoupling charge blasting excels in rock breaking,relying on its uniform pressure transmission and low energy dissipation.The water decoupling coefficients can adjust the contributions of the stress wave and quasi-static pressure.However,the quantitative relationship between the two contributions is unclear,and it is difficult to provide reasonable theoretical support for the design of water decoupling blasting.In this study,a theoretical model of blasting fracturing partitioning is established.The mechanical mechanism and determination method of the optimal decoupling coefficient are obtained.The reliability is verified through model experiments and a field test.The results show that with the increasing of decoupling coefficient,the rock breaking ability of blasting dynamic action decreases,while quasi-static action increases and then decreases.The ability of quasi-static action to wedge into cracks changes due to the spatial adjustment of the blast hole and crushed zone.The quasi-static action plays a leading role in the fracturing range,determining an optimal decoupling coefficient.The optimal water decoupling coefficient is not a fixed value,which can be obtained by the proposed theoretical model.Compared with the theoretical results,the maximum error in the model experiment results is 8.03%,and the error in the field test result is 3.04%.

Microscale mechanism of tailing thickening in metal mines

Water-locking flocs formed by ultrafine tailings particles will damage the thickener underflow concentration in the thickening process during paste preparation.The relationship between the mesostructure and seepage characteristics of tail mortar is typically ignored when investigating the deep dehydration stage.A shearing seepage test of an unclassified tailing-sedimentation bed was performed with copper tailings,and the morphology and geometric distribution of micropores were analyzed via X-ray computed tomography.Moreover,the shearing evolution of the micropore structure and seepage channel was investigated to evaluate the dewatering performance of underflow slurry using a three-dimensional reconstruction approach.The results show that porosity decreases considerably under shearing.The connected-pore ratio and the average radius of the throat channel reach peak values of 0.79 and 31.38μm,respectively,when shearing is applied for 10 min.However,the reverse seepage velocity and absolute permeability in the bed decrease to various extents after shearing.Meanwhile,the maximum flow rate reaches 1.537μm/s and the absolute permeability increases by 14.16%.Shearing alters the formation process and the pore structure of the seepage channel.Isolated pores connect to the surrounding flocs to form branch channels,which then become the main seepage channel and create the dominant water-seepage flow channel.

Study on Mechanical Properties of High Fine Silty Basalt Fiber Shotcrete Based on Orthogonal Design

In order to improve the comprehensive utilization rate of highfines sand(HFS)produced by the mine,full solid waste shotcrete(HFS-BFRS)was prepared with HFS asfine aggregate in cooperation with basaltfiber(BF).The strength growth characteristics of HFS-BFRS were analyzed.And thefitting equation of compressive strength growth characteristics of HFS-BFRS under the synergistic effect of multiple factors was given.And based on the orthogonal experimental method,the effects on the compressive strength,splitting tensile strength andflex-ural strength of HFS-BFRS under the action of different levels of influencing factors were investigated.The effect of three factors on the mechanical properties of HFS-BFRS,3,and 28 d,respectively,was revealed by choosing the colloidal sand ratio(C/H),basaltfiber volume fraction(BF Vol)and naphthalene high-efficiency water reducing agent(FDN)as the design variables,combined with indoor tests and theoretical analysis.The results show that the sensitivity of the three factors on compressive strength andflexural strength is C/H>FDN>BF Vol,and split-ting tensile strength is BF Vol>FDN>C/H.Finally,thefitting ratio of HFS-BFRS was optimized by the factor index method,and the rationality was verified by thefield test.For thefluidity of HFS-BFRS,the slump can be improved by 139%under the action of 1.2%FDN,which guarantees the pump-ability of HFS-BFRS.

Flocculated unclassified tailings settling efficiency improvement by particle collision optimization in the feedwell

Efficient thickening of tailings is a prerequisite for the metal mine tailings backfill and surface disposal operation.The effective collision of ultrafine tailings particles in suspension with flocculant molecules is essential for flocs aggregates formation and settling.Unreasonable feeding speed and flocculant adding method will lead to the failure of effective dispersion of flocculant and high particle content in thickener overflow.In this work,the effect of turbulence intensity and flocculant adding method on floc size,strength,and movement characteristics are analysed.Aiming to solve the turbidity increased,a pilot-scale continuous thickening test was carried out.Taking a single particle and multiple flocs of full tailings as the research object,the particle iterative settlement model of flocs was established.The influence of turbulence intensity on collision effect is studied by tracking and simulating particle trajectory.The results show that in the process of single particle settlement,chaos appears in the iterative process owing to particle adhesion which caused by micro action.When the turbulence intensity is 25.99%,the maximum particle size of tailings floc is 6.21 mm and the maximum sedimentation rate is 5.284 cm·s^(−1).The tailings floc presents a multi-scale structure of particle-force chain system when hindered settling,and the interweaving of strong and weak force chains constitutes the topological structure of particles.The results are applied to a thicker in plant,the flocculant addition mode and feed rate are optimized,and the flocs settling speed and overflow clarity are improved.

Numerical simulations for gas-structure interaction in inflated deployment of folded membrane boom

It is very important for gas-structure interaction between compressible ideal gas and elastic structure of space folded membrane booms during the inflatable deployment. In order to study this gas-structure interaction problem, Arbitrary Lagrangian-Eulerian （ALE） finite element method was employed. Gas-structure interaction equation was built based on equilibrium integration relationship, and solved by operator split method. In addition, numerical analysis of V-shape folded membrane booms inflated by gas was given, the variation of inner pressure as well as deployment velocities of inflatable boom at different stage were simulated. Moreover, these results are consistent with the experiment of the same boom~ which shows that both ALE method and operator split method are feasible and reliable methods to study gas-structure interaction problem.

Research on Monitoring Area Division of Quality Grade Changes in County Cultivated Land and Technology of Deploying Monitoring Point

It is an important means in management of improving both the quality and quantity of cultivated land to monitor grade changes in cultivated land quality. How to deploy monitoring network system and its point reasonably and roundly are the key to the technology of monitoring grade changes in cultivated land quality by monitoring grade changes in cultivated land quality dynamically in order to obtain the information to the index of cultivated land quality and its changes based on the existing achievements of farmland classification and grading. Spatial analysis method is used to demarcate monitoring area and deploy monitoring point according to ARCGIS,of which the result can meet the demand for monitoring grade changes in cultivated land.

A Novel Gymnosperm Wood from the Lopingian(Late Permian)in Zhangzi,Shanxi,North China and Its Paleoecological and Paleogeographic Implications

The Permian-Triassic transition saw extreme climatic changes that severely impacted the terrestrial ecosystem.Fossil plants,particularly fossil woods,are sensitive to climatic changes,and they,therefore,are unique materials revealing extreme environmental and climatic changes on land at that time.Abundant conifer woods were discovered in the Lopingian(Late Permian)strata of the Sunjiagou Formation in Shanxi Province,North China.The newly finding permineralized woods record the unique landscape of Lopingian North China.They represent a new conifer genus and species:Shanxiopitys zhangziensis gen.et sp.nov.Analyses of growth pattern and anatomical characteristics of the fossil woods indicate these trees grew under optimal growing conditions,and without seasonal growth cessation.However,climate signals from leaf fossils,vertebrate fossils and sedimentary evidences indicate a strongly seasonal climate in North China during the Lopingian.Thus,it is speculated that these trees likely lived in the gallery forests,which were distributed along the paleo-rivers within a seasonal landscape in the central North China block during the Lopingian.

Recent Progresses on Dopant-Free Organic Hole Transport Materials toward Efficient and Stable Perovskite Solar Cells

As the third generation new battery,the power conversion efficiency(PCE)of metal halide perovskite solar cells(PsCs)has increased from 3.8%in 2009 to 25.8%currently certified,which fully shows that they have great research value and development prospect.As one of the main components of high-efficiency PSCs,hole transport materials(HTMs)play an important role in extracting and transporting holes and inhibiting charge recombination.However,commonly used HTMs require doping,and the hygroscopicity and corrosiveness of the dopants will destroy the stability of PsCs and hinder their commercialization.Therefore,it is of great significance to develop dopant-free HTMs.

Precipitation and hot deformation behavior of austenitic heat-resistant steels: A review

The austenitic heat resistant-steels have been considered as important candidate materials for advanced supercritical boilers, nuclear reactors, super heaters and chemical reactors, due to their favorable combination of high strength, corrosion resistance, perfect mechanical properties, workability and low cost.Since the precipitation behavior of the steels during long-term service at elevated temperature would lead to the deterioration of mechanical properties, it is essential to clarify the evolution of secondary phases in the microstructure of the steels. Here, a summary of recent progress in the precipitation behavior and the coarsening mechanism of various precipitates during aging in austenitic steels is made. Various secondary phases are formed under service conditions, like MX carbonitrides, M_（23）C_6 carbides, Z phase, sigma phase and Laves phase. It is found that the coarsening rate of M_（23）C_6 carbides is much higher than that of MX carbonitrides. In order to understand the thermal deformation mechanism, a constitutive equation can be established, and thus obtained processing maps are beneficial to optimizing thermal processing parameters, leading to improved thermal processing properties of steels.

Characteristics and Sources of Organic Matter from the Early Cambrian Niutitang Formtion and Its Preservation Environment in Guizhou

The Early Cambrian Niutitang Formation on the Yangtze Block is a set of high-quality marine source rock.However,hydrocarbon-forming organisms of these organic-rich shales was poorly understood.In this paper,the results of palynofacies analysis and hydrocarbon-forming organism characteristics of the Niutitang Formation from the Yangtze Block are reported for the first time,and the sedimentary environment is discussed in combination with geochemical data.Palynofacies analysis show that the organic matter(OM)of the Niutitang Formation is mainly composed of amorphous organic matter(AOM),with a small amount of structural organic matter(STOM)and palynomorphs(PL).The results of CONISS(stratigraphically constrained incremental sum of squares)cluster analysis show that the PL can be divided into three zones in the ascending order:Leiosphaeridia-Micrhystridiumfungal zone,algal bloom zone and fungal development zone,corresponding to three stages:transgression,high-stand and regression,respectively.The principal component analysis(PCA)shows that the main hydrocarbon-forming organisms include planktonic green microalgae or dinoflagellates that are related to Leiosphaeridia and Microcystidium.Palynofacies analysis and geochemical data show that the Niutitang Formation was deposited under anoxic or dysoxic condition which was favorable to the enrichment of organic matter.

Permineralized Calamitean Axes from the Upper Permian of Xinjiang, Northwest China and Its Paleoecological Implication

Two anatomically preserved calamitean axes are reported for the first time from the Late Permian Wutonggou Formation in the southern Bogda Mountains, Xinjiang Uygur Autonomous Re- gion, Northwest China. Based on the anatomical features, these axes are assigned to Arthropitys. A new species Arthropitys taoshuyuanensis sp. nov. is established. A. taoshuyuanensis sp. nov. possesses a large pith and comprises large pith cavity and a narrow perimedullary zone at the nodes and diaphragms at the internodes. Carinal canals are circular and surrounded by a single layer of metaxylem tracheids. Secondary xylem is divided into interfascicular rays and fascicular wedges. Interfascicular rays are ini- tially four to five cells wide and taper abruptly centrifugally. Fascicular wedge consists of thick-walled tracheids and thin-walled fascicular ray cells. Radial tracheid walls have uniseriate or biseriate circular pits, or scalariform pits. The absence of growth rings in the Arthropitys specimens indicates that they probably lived in the wetland area under stable annual temperature and water sufficient conditions.