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2017 Vol. 2, No. 4

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Waterproof pillar size design in steep coal seam
Xu Bin, Dong Shuning, Xu Yanling
2017, 2(4): 307-315.
Abstract(992) PDF(753)
Abstract:
According to different combinations of mining methods and water body positions in deep coal seam,three basic structural patterns were created and main basis of setting up reasonable waterproof coal pillar size for each pattern were proposed.The mechanics model of the stability of waterproof pillar was established,and formulas for critical value of stable length of waterproof pillar were derived.Based on different conditions for each coal mine,the optimization design theory on setting up reasonable waterproof coal pillar size was proposed.The above optimization design theory was applied to a mine in Tangshan.Results showed that the reasonable size of waterproof pillar could be 59.3m.Actually the steep mining face was safely and successfully exploited with 60m height of waterproof pillar,indicating that the theory could be useful for practical projects.
Study on the mechanism of remote sensing anomaly extraction and correlation analysis of ore controlling:Take the Qimantag metallogenic belt of Qinghai as an example
Tang Chao, Shao Longyi
2017, 2(4): 316-329.
Abstract(989) PDF(144)
Abstract:
Information extraction from remote sensing and the research of ore controlling factors has been in the two aspects isolated corrosion,the relationship between remote sensing anomaly extraction and deposit metasomatic alteration in the theory system has not yet been discussed,Combing the mineralization clues and altered minerals has discovered of Qimantag metallogenic belt according to the geological background of the work area,the paper has established the relationship of main alteration mineral-deposit genetic type-deposit type-type of remote sensing data and the geological and physical model through analyzing the relationship between the corresponding alteration characteristics of multi-source remote sensing data and spectral diagnosis mineral band,The combination analysis of remote sensing alteration information distribution and ore controlling factors of study areas,such as basic deposit types,stratigraphic and structural improved the correlation analysis method of remote sensing anomaly information and ore controlling ore and delineated the remote sensing anomaly packet,it has important significance for the 2D regional metallogenic prediction.
The effect of offset distance on dynamic fracture behavior of PMMA with double cracks
Yang Liyun, Zhang Yongjin, Sun Jinchao, Liu Ning, Cheng Tonglei, Chen Qifan
2017, 2(4): 330-335.
Abstract(884) PDF(324)
Abstract:
The influence of offset crack on dynamic impact fracture behavior is studied using the digital-leaser dynamic caustics system in conjunction with impact loading device.An inner mother crack along loading direction and its offset edge crack in PMMA were employed.The initiation and propagation behavior,as well as the caustics patterns of both cracks are observed.Some important dynamic fracture parameters of mother crack,such as the initiation time,maximum speed and dynamic stress intensity factor,are analyzed with different offset distance.The results show that the radio of crack spacing to crack offset distance is virtually important to the initiation time and maximum speed of mother crack,which are also influenced by the location of both cracks in the midline of the specimen.Moreover,the changes of dynamic intensity factor of mother cracks with different crack spacing are found to be similar,while the time of their maximum values are quite different.
Experimental study on water vapor absorption of rock and its influencing factors
Zhang Na, Zhao Fangfang, Zhang Haohao, Qiao Fengchao, He Manchao
2017, 2(4): 336-347.
Abstract(702) PDF(151)
Abstract:
Water absorption is one of the most important factors which can induce serious rock deformation and failure.Water vapor absorption experiments were carried out on rock samples collected from three different coal mines.Meanwhile,the mineral components,microstructure features and pore structure parameters were determined by means of X-ray diffraction,scanning electron microscopy and mercury intrusion porosimetry in order to comprehensively analyse the effects of clay minerals and micropore structure on water vapor absorption of the investigated rock samples.Results have shown that the patterns of the water vapor absorption curves of the three types of rocks were all characterized by a similar kind of dynamic process with decreasing water vapor absorption rate which could be well fitted by a negative exponential function.However,significant differences were found in water vapor absorption ability among the three types of rock samples which could be sorted in an order of Daqiang conglomerate > Shajihai mudstone > Halagou sandstone.Furthermore,the greater abundance of clay minerals contained in rock samples,especially smectite,the more and quicker water vapor absorption.Meanwhile,water vapor absorption is positively correlated with effective porosity,but is negatively correlated with fractional dimension which indicates that the bigger the effective porosity the greater the water vapor absorption ability and the more complicated the pore structures the weaker the water vapor absorption ability.
Growth mechanism of original crack facing the blasting side of adjacent tunnel under the blasting load
Guo Dongming, Liu Kang, Luo Lang, Yang Jun, Wang Hao, Xiao Zhengxin
2017, 2(4): 348-356.
Abstract(785) PDF(142)
Abstract:
The method of dynamic caustics is adopted to investigate the mechanism of original crack existing in the surrounding rock of adjacent tunnel under the action of blasting load.Conclusions are drawn as follows.Under the action of blasting load,dynamic fraction toughness of pre-crack is not related to the dip angle of pre-crack and the free surface of tunnel.However,the existence of free surface makes pre-crack initiation in advance.In general,the propagation path of pre-crack facing the blasting side of adjacent tunnel under the action of blasting load is related to the propagation path of principal crack from the blast-hole,the free surface of tunnel as well as its section form.Initial propagation path presents approximate vertical upward because of the action of tension wave reflected by the free surface of tunnel.The middle and later periods of pre-crack propagation,the propagation path of principal crack and the stress distribution characteristics of free surface have great effect on the propagation path of pre-crack.The stress distribution characteristics of surrounding rock facing the blasting side are analyzed through the LS-DYNA.From the base angle of side wall to vault facing the blasting side of tunnel,effective stress presents the variation rule of decreasing-increasing-decreasing,of which the maximum points lie to the base angle and the location between sprung arch and vault,the minimum point lie to the side wall.As a result,the pre-crack propagation path is partial to the arch parts and arrest at certain location between the sprung arch and vault.
The prediction of PM2.5 concentration based on the adaptation related-combinatorial mode GCM(1,N)
Lü Chen, Wu Zongzhi, Fu Gui, Jia Shuze
2017, 2(4): 357-363.
Abstract(743) PDF(264)
Abstract:
There is a relationship between the variations of PM2.5 concentration and the happen of disaster weather as the haze,the accurate prediction of the changed trend of PM2.5 concentration plays an important guiding role in the effective prevention and control of the wide range of disaster weather as the haze.Considering the gray characteristics of PM2.5 concentration is disturbed by the various factors,the article adopts the way of the same dimension gray recurrence and supplies the new gray information in time,establishes the gray relational computing model of the main factors of PM2.5.At the same time,the GM(1,N) is improved by introducing the gray control parameters,which can meet accurate prediction on the condition of multi-effects factors.The above approaches are combined,the adaptation related-combinatorial mode GCM(1,N) is established and can be applied for different metadata N.By the analysis of the measured data obtained in Beijing,the precision of the calculation and prediction model GCM(1,N) has reached to 89.75%~96.44%,the relative error of the prediction of PM2.5 concentration is between 7.32% and 15.21%,the results are satisfactory.
The research on mining along next goaf technology of double gateways excavation in super-long forward distance working face
Wang Zhiqiang, Wang Jianming, Guo Lei, Xu Jie
2017, 2(4): 364-370.
Abstract(605) PDF(257)
Abstract:
With theoretical analysis and field measurement,the research is conducted on mining along next goaf technology of double gateways excavation in super-long forward distance working face.Mining along next goaf technology of double gateways excavation is proposed to solve larger leaved protective coal pillar caused by ventilation and auxiliary haulage in double gateways excavation in super-long forward distance.On this basis,a method is given to determined larger pillar in double gateways excavation,small coal pillar in gob-side entry driving and dip separation of driving direction in driving face along next goaf to the first mining face and continuous face.Finally,we propose the technology in 5000m super-long forward distance where skip-mining is impossible to apply and give critical technical parameter.The technology application not only improves present situation of roadway maintenance difficultly,but also helps to mine more than 1.01million t coal between two faces,generating significant economic and social benefits.
Stability study and field observation of coal pillar between goaf and unmined top-coal caving face
Wei Zhen, Li Jinping, He Fulian, Zhang Shoubao
2017, 2(4): 371-378.
Abstract(958) PDF(260)
Abstract:
The stability of coal pillar between goaf and unmined mining face is the guarantee of safety and success in long wall mining.In recent years,with increasing high-intensity production,the opposite mining and excavation is commonly found in coal mining,which results in twice mining dynamical influences of section coal pillar.It impacts the pillar stability and bring challenges to roadway ground control,especially in top-coal caving face.This paper gives theoretical derivation and field observation of abutment pressure distribution law of section pillar between goaf and unmined thick coal seam top-coal caving face.Taking the 20 meters coal pillar between 922 and 923 mining face in Dongpo coal mine for engineering background,firstly,the evolution process of abutment pressure is analyzed after the formation of section coal pillar,the limit equilibrium zone formulas of gob-side and roadway-side of pillar are deduced and the minimum width of stable pillar is calculated; secondly,with the field observation,the area and peak data of pillar abutment pressure before present mining face are found.The data shows that there is an elastic core in 20 meters coal pillar which helps to keep roadway stable.The discovery also help to propose the possibility of coal pillar size optimization and recovery rate improvement.
Prospect for hybrid DC power system in coal mine
Wang Yanwen, Guo Lin, Gao Feng, Gao Yan
2017, 2(4): 379-388.
Abstract(911) PDF(235)
Abstract:
According to the electrical load characteristics in the coal mine,a sequence of the hybrid DC power system voltage is proposed,and the analysis indicates its rationality from the power supply capacity and power supply distance.A coal mine Hybrid DC power supply network topology is put forward to enhance the reliability of distribution network in coal mine power system.In addition,the key technologies for building hybrid DC power supply system in coal mine are summarized and analyzed,such as distribution modes,connection modes,grounding modes,key equipment,operation control strategies and relay protection technologies.Finally,the feasibility of implementing a hybrid DC power supply system in coal mine is briefly analyzed.
A fast numerical method based on static reduction for the solution of the contact problem of the piston ring
Liu Yuwei, Li Heyan, Ye Fuhao
2017, 2(4): 389-394.
Abstract(946) PDF(267)
Abstract:
This paper provides a fast method based on static reduction for the solution of the displacements of the piston ring’s contact nodes.The nodal displacements and the corresponding nodal forces of the contact nodes are connected by the contact stiffness matrix which is obtained through performing static reduction on a finite element description of the two dimensional model of the piston ring in an internalcombustion engine.Given applied loads,the displacements of the contact nodes can be quickly obtained,and vice versa.The numerical result is compared with that of analytical and the error is less than 2% which indicating the accuracy of this numerical method.Using this method,free shape of the piston ring can be easily designed to ensure the requirements of the contact pressure of the piston ring,which will improve wear resistance and service life of the piston ring.
Directional synthesis of zeolites with silicon and aluminum dissolved from fly ash
Jiang Xiaolin, Xie Qiang
2017, 2(4): 395-401.
Abstract(578) PDF(259)
Abstract:
Two fly ashes were sampled from Wuhai Wuyun power plant and Hohhot Huyi power plant,respectively.Dissolution characteristics of Si and Al from these fly ash samples at hydrothermal synthesis circumstance were studied,and then they were used as a guide to adjust the SiO2/Al2O3 molar ratio of gel system,as a result A-zeolite and X-zeolite were synthesized directionally by hydrothermal synthesis method.X-ray diffraction （XRD） was used to identify the type of zeolite.Effect of alkalinity on the synthesis of zeolite was investigated.The results show that the amount of Si and Al dissolved from fly ash are much less than that in the chemical composition of fly ash;with the increase of dissolution time,amount of dissolved Si increases,while amount of dissolved Al rises first and drops later.Higher alkalinity is beneficial to the formation and growth of A-zeolite crystal nucleus.Besides,X-zeolite also can be synthesized directionally.It could be concluded that it is the Si and Al dissolved from fly ash at hydrothermal circumstance that are available components in the hydrothermal synthesis of zeolite,under guide of which a variety of zeolites can be synthesized directionally.
Hydraulic and mass transfer characteristics of DFG oriented grid structured packing tower
Cai Weibin, Chen Meng, Qian Jianbing, Wang Yujun, Yang Yunhui, Zhu Shenlin
2017, 2(4): 402-408.
Abstract(899) PDF(236)
Abstract:
The hydraulic and mass transfer characteristics of a new type DFG oriented grid structured packing in a 100mm diameter extraction column were studied.MIBK (methyl isobutyl ketone) and DIPE (diisopropyl ether) were selected as extractants,which were widely used in solvent extraction for coal chemical industry wastewater phenols removal.Result indicated that the hydraulic of the two extraction systems can be well described by an improved correlation;compared to the traditional packing,the extraction column with DFG structured packing can greatly improve the operation loadings.Within the experiment range,the max flooding loading is as high as 150m3/（m2·h）.The mass transfer performance is similar to traditional structured packing,the height equivalent to theoretical stage （He） is between 2.2 and 3.1m.The DFG structured packing holds good integrated performances,which can meet the need of high throughput phenol removal extractors for the increasing large-scaled coal chemical industry.

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