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%.

Contract Mechanism of Water Environment Regulation for Small and Medium Sized Enterprises Based on Optimal Control Theory

The small and scattered enterprise pattern in the county economy has formed numerous sporadic pollution sources, hindering the centralized treatment of the water environment, increasing the cost and difficulty of treatment. How enterprises can make reasonable decisions on their water environment behavior based on the external environment and their own factors is of great significance for scientifically and effectively designing water environment regulation mechanisms. Based on optimal control theory, this study investigates the design of contractual mechanisms for water environmental regulation for small and medium-sized enterprises. The enterprise is regarded as an independent economic entity that can adopt optimal control strategies to maximize its own interests. Based on the participation of multiple subjects including the government, enterprises, and the public, an optimal control strategy model for enterprises under contractual water environmental regulation is constructed using optimal control theory, and a method for calculating the amount of unit pollutant penalties is derived. The water pollutant treatment cost data of a paper company is selected to conduct empirical numerical analysis on the model. The results show that the increase in the probability of government regulation and public participation, as well as the decrease in local government protection for enterprises, can achieve the same regulatory effect while reducing the number of administrative penalties per unit. Finally, the implementation process of contractual water environmental regulation for small and medium-sized enterprises is designed.

Recent advances in cobalt phosphide-based materials for electrocatalytic water splitting:From catalytic mechanism and synthesis method to optimization design

Electrochemical water splitting has long been considered an effective energy conversion technology for trans-ferring intermittent renewable electricity into hydrogen fuel,and the exploration of cost-effective and high-performance electrocatalysts is crucial in making electrolyzed water technology commercially viable.Cobalt phosphide(Co-P)has emerged as a catalyst of high potential owing to its high catalytic activity and durability in water splitting.This paper systematically reviews the latest advances in the development of Co-P-based materials for use in water splitting.The essential effects of P in enhancing the catalytic performance of the hydrogen evolution reaction and oxygen evolution reaction are first outlined.Then,versatile synthesis techniques for Co-P electrocatalysts are summarized,followed by advanced strategies to enhance the electrocatalytic performance of Co-P materials,including heteroatom doping,composite construction,integration with well-conductive sub-strates,and structure control from the viewpoint of experiment.Along with these optimization strategies,the understanding of the inherent mechanism of enhanced catalytic performance is also discussed.Finally,some existing challenges in the development of highly active and stable Co-P-based materials are clarified,and pro-spective directions for prompting the wide commercialization of water electrolysis technology are proposed.

A Study of the Rock Breaking Mechanism during Swirling Water Jet Drilling

Based on an analysis of the factors affecting rock breaking and the coupling between rock and fluid during water jet drilling, the rock damage model and the damage-coupling model suitable for the whole rock breaking process under the water jet is established with continuous damage mechanics and micro-damage mechanics. The evolvement of rock damage during swirling water jet drilling is simulated on a nonlinear FEM and dynamic rock damage model, and a decoupled method is used to analyze the rock damage. The numerical results agree with the test results to a high degree, which shows the rock breaking ability of the swirling water jet is strong. This is because the jet particle velocity of the swirling water jet is three-dimensional, and its rock-breaking manner mainly has a slopping impact. Thus, the interference from returning fluid is less. All these aspects make it easy to draw and shear the rock surface. The rock breaking process is to break out an annular on the rock surface first, and then the annular develops quickly in both the radial and axial directions, the last part of the rock broken hole bottom is a protruding awl. The advantage of the swirling water jet breaking rock is the heavy breaking efficiency,large breaking area and less energy used to break rock per unite volume, so the swirling water jet can drill in a hole of a large diameter.

A state‑of‑the‑art review on rock seepage mechanism of water inrush disaster in coal mines

Water inrush is one of the most dangerous disasters in coal mining.Due to the large-scale mining and complicated hydrogeological conditions,thousands of deaths and huge economic losses have been caused by water inrush disasters in China.There are two main factors determining the occurrence of water inrush:water source and water-conducting pathway.Research on the formation mechanism of the water-conducting pathway is the main direction to prevent and control the water inrush,and the seepage mechanism of rock mass during the formation of the water-conducting pathway is the key for the research on the water inrush mechanism.This paper provides a state-of-the-art review of seepage mechanisms during water inrush from three aspects,i.e.,mechanisms of stress-seepage coupling,fow regime transformation and rock erosion.Through numerical methods and experimental analysis,the evolution law of stress and seepage felds in the process of water inrush is fully studied;the fuid movement characteristics under diferent fow regimes are clearly summarized;the law of particle initiation and migration in the process of water inrush is explored,and the efect of rock erosion on hydraulic and mechanical properties of the rock media is also studied.Finally,some limitations of current research are analyzed,and the suggestions for future research on water inrush are proposed in this review.

Deformation and failure mechanism of Yanjiao rock slope influenced by rainfall and water level fluctuation of the Xiluodu hydropower station reservoir

With the construction of the Xiluodu hydropower station on the Jinsha River,the reservoir impoundment began in 2013 and the water level fluctuates annually between 540 m and 600 m above sea level.The Yanjiao rock slope which is located on the left bank of the Jinsha River 75 km upstream of the Xiluodu dam site,began to deform in 2014.The potential failure of the slope not only threatens Yanjiao town but also affects the safe operation of the Xiluodu reservoir.This paper is to find the factors influencing the Yanjiao slope deformation through field investigation,geotechnical reconnaissance,and monitoring.Results show that the Yanjiao slope can be divided into a bank collapse area(BCA)and a strong deformation area(SDA)based on the crack distribution characteristics of the slope.The rear area of the slope has been experiencing persistent deformation with a maximum cumulative displacement(GPS monitoring point G4)of 505 mm and 399 mm in the horizontal and vertical directions,respectively.The potential failure surface of the slope is formed 36 m below the surface based on the borehole inclinometer.The bank collapses of the Yanjiao slope are directly caused by the reservoir impoundment while the deformation area of the slope is affected by the combination of the rainfall and reservoir water level fluctuation.Based on mechanism of the Yanjiao slope,prestressed anchor combined with the surface drainage and slope unloading are recommended to prevent potential deformation.

Geological conditions and key rock mechanics issues in the Western Route of South-to-North Water Transfer Project

In terms of special geological conditions of the Western Route of South-to-North Water Transfer Project, the classification method for surrounding rocks is discussed by combining with the construction method of tunnel boring machine （TBM）. The classification standard of surrounding rocks is put forward on the basis of physical simulations and engineering practices. Damage, deformation and evolution of surrounding rocks induced by TBM excavation are discussed. Meanwhile, the long-term deformation mechanisms and stability of surrounding rocks are also studied. On this basis, a three-dimensional constitutive model for interbedded sandstone slate and a fiat shell-joint element-foundation system for calculating internal forces of segment lining are established. The deformation features of surrounding rocks of deep and steep interbedded sandstone slate and their influences on internal forces of segment lining are presented. Finally, the design methods of segment lining constructed in deep and steep flysch are proposed.

Theoretical Study on Reaction Mechanism of Aluminum-Water System

A theoretical study on the reaction of aluminum with water in the gas phase was performed using the hybrid density functional B3LYP and QCISD（T） methods with the 6-311＋G（d,p） and the 6-311＋＋G（d,p） basis sets. The results show that there are three possible reaction pathways that involve four isomers, seven transition structures, and two possible products for the reaction of aluminum with water. The two most favorable reaction pathways were found, whose intermediates and products agreed quite well with experimental results. The enthalpy and Gibbs free energy change of the reaction between A1 and H2O at 298 and 2000 K were calculated. Some results are also in good agreement with the previous calculations or experimental results.

Turning mechanism problems of the Changjiang River diluted water

Some main ideas about the turning of the Changjiang River diluted water (CDW) and their deficiencies are reviewed in this paper. According to a large number of observation data it is pointed out that the turning phenomena of the CDW are related not only to the discharge of the Changjiang River but also to the sea surface slope and wind stress curl in the southeast coast of China. Exsistence of the sea surface slope reflects essentially the effect of the Taiwan Warm Currc (TWC) on the turning of the CDW.

Dual Mechanism and Reform Path of the Irrigation and Water Conservancy

The operating mechanism of farmland water conservancy in China was analyzed from the perspective of anthropology, and its dual mechanism characteristics and rules were exposed. The dual mechanism took different focus at different periods, thus there were some defaults. To carry out community-based water conservancy with the support of collective economy was an effective way to cope with the severe drought in the context of degraded dual mechanism.

The Mechanism of Lipids Extraction from Wet Microalgae Scenedesmus sp. by Ionic Liquid Assisted Subcritical Water

In this paper, the total sugar concentration, protein concentration, lipid yield and morphology characteristics of the algae residue were determined to explain the mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water. The results showed similar variation for the sugar, protein and lipid. However, the total sugar was more similar to lipids yield, so the results showed that the reaction between ionic liquid and cellulose and hemicellulose in cell wall was the most important step which determined the lipids extration directly. And the total sugar variation may be representing the lipids yield. For later lipids extraction, we can determine the total sugar concentration to predict the extraction end product.

Effect of Water Absorption on the Mechanical Property and Failure Mechanism of Hollow Glass Microspheres Composite Epoxy Resin Solid Buoyancy Materials

To study the water absorption of hollow glass microspheres(HGMs)composite epoxy resin solid buoyancy materials in the marine environment and its effect on the mechanical properties,the water absorption was measured by immersing the material in distilled water for 36 days at ambient temperature and fitted to Fick’s second law.The strength of materials before and after water absorption were tested by uniaxial experiments,and the effects of the filling ratio and water absorption on the mechanical properties of the materials were analyzed and explained.Finally,the failure modes and mechanism of the hollow glass microspheres composite material were explicated from the microscopic level by scanning electron microscope(SEM).This research will help solve the problems of solid buoyancy materials in ocean engineering applications.

Observational characteristics and dynamic mechanism of low-salinity water lens for the offshore detachment of the Changjiang River diluted water in August 2006

The Changjiang River diluted water(CDW)spreads into the East China Sea(ECS)primarily in a plume pattern,although in some years,low-salinity water lenses(LSWLs)detach from the main body of the CDW.In-situ observations indicate that in August 2006,a LSWL detached from the main body of the CDW near the river mouth.In this paper,the effects of winds,tides,baroclinity and upwelling on LSWLs are explored with a threedimensional model.The results show that:(1)winds play a crucial role in these detachment events because windinduced northerly Eulerian residual currents impose an uneven force on the CDW and cut it off,thus forming a LSWL;(2)upwelling carries high-salinity water from the lower layer to the upper layer,truncating the low-salinity water tongue vertically,which is conducive to the detachment and maintenance of LSWLs;and(3)upwelling during the evolution of a LSWL is caused by the combined effects of winds and tides.The influences of windinduced upwelling are mainly near the shore,whereas the upwelling along the 30 m isobath is predominantly affected by tides,with the effect increasing from neap tide to spring tide.

Theoretical and experimental study on the rheological properties of WIS grout and the dispersion and sealing mechanism

Recently a new grout material called water inflow sealing(WIS) was invented for sealing water inflow in tunneling and underground constructions. In this study, a special experimental method called intubated counter grouting(ICG) was proposed to investigate the influence of water dispersion on the rheological properties of the grout during the grouting process, and to testify the sealing performance of the grout,such as instant gelling ability(IGA) and anti-dispersion ability(ADA). In the experiment, dispersion was restricted in the downstream of the channel with a high turbulence intensity. The influences of ADA and IGA were therefore decoupled and evaluated separately. Experimental results revealed two distinctive sealing mechanisms of WIS. For a low initial velocity of water, WIS turned the shear flow of water into an overall movement of a plug by absorbing water into the particles. For a high initial velocity and the situation that the particles reached the outlet before sufficiently expanding, WIS modified the rheology of the water in the channel and reduced its velocity till the static state. The distinctive feature of WIS brings a reformation on the sealing mechanism and provides an effective way to control water inflow with high pressure and velocity.

Failure mechanism of a large-scale composite deposits caused by the water level increases

The failure of slope caused by variations in water levels on both banks of reservoirs is common.Reservoir landslides greatly threaten the safety of reservoir area.Taking large-scale composite deposits located on the Lancang River in Southwest China as a study case,the origin of the deposits was analyzed based on the field investigation and a multi-material model was established in the physical model test.Combined with numerical simulation,the failure mechanism of the composite deposits during reservoir water level variations was studied.The results indicate that the deformation of the large-scale composite deposits is a staged sliding mode during the impoundment process.The first slip deformation is greatly affected by the buoyancy weight-reducing effect,and the permeability of soil and variation in the water level are the factors controlling slope deformation initiation.The high water sensitivity and low permeability of fine grained soil play an important role in the re-deformation of deposits slope.During the impoundment process,the deformation trend of the deposit slope is decreasing,and vertical consolidation of soil and increasing hydrostatic pressure on the slope surface are the main reasons for deformation attenuation.It is considered that the probability of large-scale sliding of the deposits during the impoundment period is low.But the damage caused by local bank collapse of the deposit slope still needs attention.The results of this paper will further improve our understanding of the failure mechanism of composite deposits caused by water level increases and provide guidance for the construction of hydropower stations.

MOLECULAR DYNAMICS SIMULATIONS OF FILLED AND EMPTY CAGE-LIKE WATER CLUSTERS IN LIQUID WATER AND THEIR SIGNIFICANCE TO GAS HYDRATE FORMATION MECHANISMS

Molecular dynamics simulations are performed to observe the evolutions of 512 and 51262 cage-like water clusters filled with or without a methane molecule immersed in bulk liquid water at 250 K and 230 K. The lifetimes of these clusters are calculated according to their Lindemann index δ (t) using the criteria of δ≥0.07. For both the filled and empty clusters, we find the dynamics of bulk water determines the lifetimes of cage-like water clusters, and that the lifetime of 512 62 cage-like cluster is the same as that of 512 cage-like cluster. Although the methane molecule indeed makes the filled cage-like cluster more stable than the empty one, the empty cage-like cluster still has chance to be long-lived compared with the filled clusters. These observations support the labile cluster hypothesis on the formation mechanisms of gas hydrates.

The Effect of Temperature on Irreducible Water Saturation of Water-wet Cores

The conventional measurement of a relative permeability curve (RPC) is usually conducted at room temperature, which is much lower than the reservoir temperature. Previous research work on high temperature relative permeability mainly take oil-wetted cores as objective. In this paper, laboratory test and measurement are conducted using water-wet cores from the Lunnan Oilfield. Since irreducible water saturation (Swi) is a critical factor that affects and controls the relative permeability curve, special tests are conducted to measure Swi at different temperatures for water-wet cores in the course of the experiment of relative permeability. The experimental results indicate that for the water-wet cores Swi decreased with the increasing temperature from ambient to 105℃,and the relative permeability curve shifted in a low water saturation direction, i.e. moved toward the left, while it moved toward the right for oil wetness reservoirs. Seen from both macroscopic and microcosmic view, the reasons and mechanisms of relative permeability change with temperature are discussed, and factors including core wetness, viscosity force, capillary forces, contact angle, interfacial tension change are considered.

An analysis on the formation mechanism of the distributionof high content of chlorophyll-a in the continentalshelf edge waters of East China Sea

On the basis of the data obtained from the comprehensive Kuroshio surveys in 1987-1988,this paper analyses the oceanographic characteristics in the area (125°-130° E,27°-31° N) of the continental shelf edge of the East China Sea (E. C. S. ) and its adjacent waters and discusses the effects of the Kuroshio front,thermocline and upwelling of the Kuroshio subsurface water on the distribution of standing stock of phytoplankton (chlorophyll-a). The distribution of high content of chlorophylly-a has been detected at 20-50 in depth in the water body on the left side of the Kuroshio front in the continental shelf edge waters of the E. C. S. The high content of chlorophyll-a spreads from the shelf area to the Kuroshio area in the form of a tongue and connects with the maximum layer of subsurface chlorophyll-a of the Kuroshio and pelagic sea. The author considers that the formation of the distribution of high content chlorophyll-a in this area results from the bottom topography and oceanic environment and there are close correlations between the high content of chlorophyll-a and the light-nutrient environment.

A Preliminary Study on Mechanisms of Well Water Temperature Responses Based on the Modes of Stress Loading

Based on the studies of the predecessors, and contrasting the modes of stress loading with water level and water temperature response characteristics of a well-aquifer system, this paper draws a preliminary conclusion on the mechanisms of water temperature responses in a well caused by three modes of stress loading, i.e. gas escape, heat dispersion and cold water penetration mechanisms for elastic seismic wave stress loading; the fracture seepage mechanism for seismic wave stress loading and the hydrodynamic mechanism for earth tide stress loading and stress-dissipative heat mechanism for long period slow stress loading in the earthquake preparation stage. This paper illustrates the typical observation examples for each mode of stress loading and makes a preliminary study on their mechanisms.

Study on the Operation Mechanism and Effect of the Yellow River Water and Sediment Regulation System

In order to scientifically deal with the problems of less water and more sediment in the Yellow River and the uncoordinated relationship between water and sediment,it is necessary to establish a perfect water and sediment regulation system.Through the calculation of the sediment transport capacity of the Yellow River and the application of the water and sediment regulation system,it is found that the sediment transport efficiency of the Yellow River will increase with the increase of water flow,and there will be an obvious inflection point near the flat discharge.The joint regulation of the backbone reservoir group can discharge the large discharge close to the minimum flat discharge of the downstream river,which improves the sediment transport capacity of the river and alleviates the problem of sediment deposition.In this paper,through the introduction of the Yellow River water and sediment regulation project system,regulation indicators and mechanisms,the author discusses in detail the Yellow River water and sediment regulation scheme and its operation effect,hoping to provide help promote the improvement of the Yellow River governance effect.