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A large area of continuous solid shallow-buried goaf group created by open-stope method, under the influence of space-time effects exerted by slow creep of the pillar-roof system, will wholly collapse driven by partly instability of pillar and roof collapse until the whole mine collapses, showing a domino effect. The dynamic process is ignored in the traditional analysis of mechanical stability. Based on analysis for the domino effect and disaster-relief mechanism in the mining goaf, the mechanical method combined with Voronoi graph method has been adopted to establish the dynamic analysis on the pillar-roof system stability. It seems more in line with the actual situations, and can help to more accurately predict the time and location of disaster. The conclusion is of great value on study of rock mechanics and mining companies’ safety production. 相似文献
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小震震源机制P轴取向的预报应用 总被引:1,自引:1,他引:0
采用Snoke的振幅比方法,利用江苏台网和山东台网记录到的数字化波形资料,计算了发生在江苏及其附近地区的33个地震的震源机制解,并由此计算了其相应的P轴取向。结果表明:南黄海北部凹陷地区M_L5.1地震发生前2个月内、长江口地区显著小震群发生之前2个月内,在震中所在区域的附近地区有震源P轴取向小于100°的异常地震发生;盐城附近及其近海海域在本文研究的时段内未曾出现震源P轴取向小于100°的地震,该区域也没有发生中强地震或显著小震群事件。由此说明震源P轴取向具有一定的短临前兆意义,但这种情况与大地震事件所表现出来的规律并不完全相同。茅山断裂附近地区出现的2次震源P轴取向小于100°的事件与该地区重力异常结果是一致的,说明2002年前后茅山断裂曾活动过。 相似文献
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Xiaoyong Liu Mingshi Wang Xiaole Pan Xiyue Wang Xiaolong Yue Donghui Zhang Zhigang M Yu Tian Hang Liu Shandong Lei Yuting Zhang Qi Liao Baozhu Ge Dawei Wang Jie Li Yele Sun Pingqing Fu Zifa Wang Hong He 《环境科学学报(英文版)》2021,33(5):20-32
The region along the Taihang Mountains in the North China Plain (NCP) is characterized by serious fine particle pollution. To clarify the formation mechanism and controlling factors, an observational study was conducted to investigate the physical and chemical properties of the fine particulate matter in Jiaozuo city, China. Mass concentrations of the water-soluble ions (WSIs) in PM2.5 and gaseous pollutant precursors were measured on an hourly basis from December 1, 2017, to February 27, 2018. The positive matrix factorization (PMF) method and the FLEXible PARTicle (FLEXPART) model were employed to identify the sources of PM2.5. The results showed that the average mass concentration of PM2.5 was 111 μg/m3 during the observation period. Among the major WSIs, sulfate, nitrate, and ammonium (SNA) constituted 62% of the total PM2.5 mass, and NO3? ranked the highest with an average contribution of 24.6%. NH4+ was abundant in most cases in Jiaozuo. According to chemical balance analysis, SO42?, NO3?, and Cl? might be present in the form of (NH4)2SO4, NH4NO3, NH4Cl, and KCl. The liquid-phase oxidation of SO2 and NO2 was severe during the haze period. The relative humidity and pH were the key factors influencing SO42- formation. We found that NO3? mainly stemmed from homogeneous gas-phase reactions in the daytime and originated from the hydrolysis of N2O5 in the nighttime, which was inconsistent with previous studies. The PMF model identified five sources of PM2.5: secondary origin (37.8%), vehicular emissions (34.7%), biomass burning (11.5%), coal combustion (9.4%), and crustal dust (6.6%). 相似文献
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摆动辗压过程中锥形摆头与坯料接触面积是一个十分重要的参数,此文从辗压过程中坯料螺旋式送进的事实出发,首次给出了环形坯料,接触区域轮廓坐标的数值求解过程,为正确计算接触面积提供了精确的计算方法。 相似文献
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Liu Daicheng Wang Yan Tao Yinhua College of Life Science Sh ong Normal University Jinan Sh ong China 《中国人口.资源与环境(英文版)》2008,(2)
Acetone,which is volatile,flammable,toxic,expen- sive and causing serious air pollution,is often used as extracting solvent in the production of powdery soy phospholipid.Recycling and reusing acetone is the key of reducing the cost of production. Therefore,saving energy and reducing emission when recycling acetone are the most important technologies during the production of phospholipid.On the basis of the productivity of powdery phospholipid being 2.4 t every day,43.2 t acetone is reused every 8 h and t... 相似文献
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Xiaoyong Liu Xiaole Pan Jie Li Xi Chen Hang Liu Yu Tian Yuting Zhang Shandong Lei Weijie Yao Qi Liao Yele Sun Zifa Wang Hong He 《环境科学学报(英文版)》2022,34(5):465-473
Cross-boundary transport of air pollution is a difficult issue in pollution control for the North China Plain. In this study, an industrial district (Shahe City) with a large glass manufacturing sector was investigated to clarify the relative contribution of fine particulate matter (PM2.5) to the city's high levels of pollution. The Nest Air Quality Prediction Model System (NAQPMS), paired with Weather Research and Forecasting (WRF), was adopted and applied with a spatial resolution of 5 km. During the study period, the mean mass concentrations of PM2.5, SO2, and NO2 were observed to be 132.0, 76.1, and 55.5 μg/m3, respectively. The model reproduced the variations in pollutant concentrations in Shahe at an acceptable level. The simulation of online source-tagging revealed that pollutants emitted within a 50-km radius of downtown Shahe contributed 63.4% of the city's total PM2.5 concentration. This contribution increased to 73.9±21.2% when unfavorable meteorological conditions (high relative humidity, weak wind, and low planetary boundary layer height) were present; such conditions are more frequently associated with severe pollution (PM2.5 ≥ 250 μg/m3). The contribution from Shahe was 52.3±21.6%. The source apportionment results showed that industry (47%), transportation (10%), power (17%), and residential (26%) sectors were the most important sources of PM2.5 in Shahe. The glass factories (where chimney stack heights were normally < 70 m) in Shahe contributed 32.1% of the total PM2.5 concentration in Shahe. With an increase in PM2.5 concentration, the emissions from glass factories accumulated vertically and narrowed horizontally. At times when pollution levels were severe, the horizontally influenced area mainly covered Shahe. Furthermore, sensitivity tests indicated that reducing emissions by 20%, 40%, and 60% could lead to a decrease in the mass concentration of PM2.5 of of 12.0%, 23.8%, and 35.5%, respectively. 相似文献