下游常水位后浮箱水力自动控制闸门的设计

后浮箱水力自控闸门在突尼斯麦-崩水渠已运行20多年,发挥了很好的调节控制作用。本文结合工作实践,从闸门的工作原理、结构特点、闸门选型等方面,对该闸门进行了简明的技术分析和造型介绍及设计体会、认识。

Numerical Simulation of Coal Floor Fault Activation Influenced by Mining

By means of the numerical simulation software ANSYS, the activation regularity of coal floor faults caused by mining is simulated. The results indicate that the variation in horizontal, vertical and shear stresses, as well as the horizontal and vertical displacements in the upper and the lower fault blocks at the workface are almost identical. Influ- enced by mining of the floor rock, there are stress releasing and stress rising areas at the upper part and at the footwall of the fault. The distribution of stress is influenced by the fault so that the stress isolines are staggered by the fault face and the stress is focused on the rock seam around the two ends of the fault. But the influence in fault activation on the upper or the lower fault blocks of the workface is markedly different. When the workface is on the footwall of the fault, there is a horizontal tension stress area on the upper part of the fault; when the workface is on the upper part of the fault, it has a horizontal compressive stress area on the lower fault block. When the workface is at the lower fault block, the maximum vertical displacement is 5 times larger then when the workface is on the upper fault block, which greatly in- creases the chance of a fatal inrush of water from the coal floor.

Stress spatial evolution law and rockburst danger induced by coal mining in fault zone

In order to explore the influence of coal mining disturbance on the rockburst occurring in fault zone, this research constructed a mechanical model for the evolution of fault stress, and analyzed the influence of the ratio of horizontal stress to vertical stress on the stability of fault, and the spatial distribution of the stress in fault zone as well as its evolution rule. Furthermore, the rockburst danger at different spatial areas of fault zone was predicated. Results show that: when both sides of the working face are mined out, the fault zone in the working face presents greater horizontal and vertical stresses at its boundaries but exhibits smaller stresses in its middle section; however, the ratio of horizontal stress to vertical stress is found to be greater at middle section and smaller at boundaries. As the working face advances towards the fault, the horizontal and vertical stresses of the fault firstly increases and then decreases; conversely,the ratio of horizontal stress to vertical stress keeps decreasing all the time. Therefore, if the fault zones are closer to the goaf and the coal wall, the stress ratio will be smaller, and the fault slip will be more prone to occur, therefore rockburst danger will be greater. This research results provide guidance for the rockburst prevention and hazard control of the coal mining in fault zone.

Regeneration of grinding wheel active surface using high-pressure hydro-jet

The possibility of applying a high-pressure hydro-jet for renewal of the grinding wheel cutting ability was presented.This work was conducted in the internal cylindrical grinding process of the Titanium Grade 2 alloy,which belongs to the group of hard-to-cut materials.The analysis shows that the impact on the erosion effectiveness of the grinding wheel active surface(GWAS)depends upon the hydro-jet inclination angle and working pressure.Experimental results reveal that application of hydro-jet working pressure of 25 MPa allows for effective cleansing of the grinding wheel surface.Depending on the initial GWAS condition and the level of its smearing with chips of machined material,it is possible to increase the number of grinding wheel unevenness apexes by as much as 4.5 times.

Determining areas in an inclined coal seam floor prone to water-inrush by micro-seismic monitoring

The failure depth of the coal seam floor is one important consideration that must be kept in mind when mining is carried out above a confined aquifer.Determining the floor failure depth is the essential precondition for predicting the water-resisting ability of the floor.We have used a high-precision microseismic monitoring technique to overcome the limited amount of data available from field measurements. The failure depth of a coal seam floor,especially an inclined coal seam floor,may be more accurately estimated by monitoring the continuous,dynamic failure of the floor.The monitoring results indicate the failure depth of the coal seam floor near the workface conveyance roadway（the lower crossheading） is deeper and that the failure range is wider here compared to the coal seam floor near the return airway（the upper crossheading）.The results of micro-seismic monitoring show that the dangerous area for water-inrush from the coal seam floor may be identified.This provides an important field measurement that helps ensure safe and highly efficient mining of the inclined coal seam above the confined aquifer at the Taoyuan Coal Mine.

THE MODEL TEST RESEARCH OF HORIZONTAL FORCE ON RIGID SHAFT FURNITURE IN DEEP MINE

The state of deep mine rigid shaft fUrniture horizontal force calculation in China is introduced and the calculating model of horizontal force is determined. Based on the interaction between hoisting vessel and shaft furniture, the vertical mobel test device is built and a large number of model tests and analyses are carried out. At last, the relationship between horizontal force and hoisting end load, hoisting speed or bunton level interval is gained. The three parameters horizontal force calculating equation of beep mine rigid shaft furniture is given and it can guide the design and calculation of shaft engineering.

Experimental Study on Thermal Interaction of LBE and Lead Droplet with Subcooled Water

Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） and three kinds of interaction zones （solidification, deformation and fragmentation） were observed during LBE droplet/water interaction and lead droplet/water interaction, respectively. The fragmentation zone （FZ） could be identified exactly by two border lines： spontaneous nucleation temperature and minimum film boiling temperature. Within fragmentation zone, 10% to 35% tiny debris （diameter 〈 1 mm） of LBE and 5 to 8 kPa peak pressure generated with increasing the LBE temperature and no effect with increasing the subcooling of water. Only 2%-4% tiny debris （diameter 〈 1 mm） of lead and 2 kPa peak pressure generated regardless of lead and water temperature.

Analysis of insidious fault activation and water inrush from the mining floor

Based on the stress field distribution rule of the mining floor under abutment pressure, we have established a simplified mechanical model, which contains multiple factors relating to activation and evolution of insidious water-conductive faults. The influence of normal and shear stresses on fault activation and effective shear stress distribution in the fault plane was acquired under mining conditions.Using fracture mechanics theory to calculate the stress intensity factor of an insidious fault front, we have derived the criterion for main fault activation. Results indicate that during the whole working face advance, transpressions are exerted on fault planes twice successively in opposite directions. In most cases, the second transpression is more likely to lead to fault activation. Activation is influenced by many factors, predominant among which are: burial depth of the insidious fault, friction angle of the fault plane, face advance direction and pore water pressure. Steep fault planes are more easily activated to induce a sustained water inrush in the face.

A New Method in Determining Potential Region of Precipitation Enhancement Above Coastal Land

To ensure the effectiveness of the operation of artificial precipitation enhancement, a potential region for the operation should be determined in advance.As cloud microphysical measurements needed for the determination of the potential region of cloud seeding are not available before the operation of routine precipitation enhancement, a new method based on the growth process of ice crystal is put forward for determining the potential region using the numerical weather prediction model output.The ice supersaturation, accumulated water vapor within minus temperature layer (≥9 mm), and upward water vapor transportation are adopted as criteria to determine the potential time, height and region of cloud seeding, and the real-time radar images are applied to make decisions on the seeding commanding.The criteria and Doppler radar images are studied in a case of precipitation enhancement characterized by significant water vapor supply from the north part of a tropical cyclone in the northwest Pacific, which shows that the ocean plays a crucial role in the advection transportation of water vapor to the potential region of the coastal area.The study presents a new method to determine the potential region of precipitation enhancement using macro-physical quantities under ice crystal growth environment.The method possesses a clear physical significance and can be readily applied with the required and easily predicted parameters.

Coefficient of consolidation by end of arc method

One of the most important issues in geotechnical engineering is excess pore pressure caused by clay soil loading and consolidation. Regarding uncertainties and complexities, this issue has long been the subject of attention of many researchers. In this work, a one-dimensional consolidation apparatus was equipped in a way that pore water pressure and settlement could be continuously read and recorded during consolidation process under static loading. The end of primary consolidation was obtained using water pressure changes helping to present a new method for determining the end of primary consolidation and consolidation coefficient. This method was then compared with two classical theory methods of lg t and t. Using Terzaghi's theory, the way of pore pressure dissipation for lg t, t and the new method was found and compared with experimental results. It is concluded that the new method has better results.

Role of Dams and Hydro as Renewable Energy in China

As the largest developing country, China has been under great pressure of harnessing nature resources to meet its ever-growing demand for energy. China's energy relies mainly on coal. This paper gives a brief introduction to the basic conditions and present development status of water potentials in China, indicates that reservoirs and dams are playing an important role in power supply and optimization of energy structure and economic and social development, and the Paper also points out that the future prospects and challenges of hydropower development in China.