Experimental research of overburden movement and subsurface water seeping in shallow seam mining

Shallow seam coal field has the largest coal reserve in China. Mining in shallow depth causes serious problems, and sub- surface dewatering is a major issue. In this paper, the physical simulating models were prepared to study overburden movement and aquiclude stability in the shallow seam mining of Yushuwan Coalfield, China. According to the characteristic of clay aquiclude and bedrock in the overburden, the proper simulation materials for simulating the plastic clay aquiclude layers and brittle bedrock layers were determined by the stress-strain tests and hydrophilic tests. The physical simulating models of solid medium and two phases of solid-liquid medium were carried out to simulate the failure and caving process of the roof and overburden, as well as the subsurface water seeping. Based on the simulation, it was found that the movement of clay aquiclude follows the movement of the underlying bedrock layers. The stability of aquiclude is mainly affected by cracks in fracture zone. The tests also showed that the best way to control the stability of aquiclude is to reduce the subsiding gradient, and there is a possibility of ground water conservation under longwall mining in Yushuwan Mine. This research provides a foundation for further study on mining dewatering and water conserva- tion.     

Formative mechanism of preferential solution flow during dump leaching

1 INTRODUCTIONIn soil science ,the macropores ,such as insectcavity ,plant root and soil fissure can result in thepreferential flows in soil[1 4]. Not only the hydro-thermal condition and solute transfer in the soil ,but the validity and erosion of precipitation,irriga-ting water and nutrient are influenced by the pref-erential flows[5].In an ore heap for dumping leac-hing,there is great difference between the sizes ofthe ores . Some of ores size are up to 1 m whilesome are about several …     

Land deformation monitoring in mining area with PPP-AR简

The mining area deformation monitoring theory and method using precise point positioning (PPP) ambiguity resolution (AR) were studied, and an ambiguity fixing model with satellite and receiver combination phase delay (CPD) was proposed for zero-differenced PPP ambiguity fixing and its corresponding formula derivation was given. The data processing results for 1 h at six IGS stations in China show that 93% of ambiguities can be fixed within 10 min and all ambiguities can be fixed within 15 min. After ambiguity fixing, the positioning accuracy is improved by more than 85% in the E and N directions, with absolute positioning accuracy reaching millimeter level, and it was improved by 70% in the U direction, reaching centimeter level; the proposed zero-differenced ambiguity fixing model can effectively improve the convergence rate and positioning accuracy in PPP. Data monitoring continuously conducted for half a year at four CORS stations of Shanxi China Coal Pingshuo Group validated the feasibility of using PPP in mining area deformation monitoring.     

Characterization and precipitation mechanism of α-calcium sulfate hemihydrate growing out of FGD gypsum in salt solution

Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD) gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG-DSC), optical micrograph, X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometry (EDS), and scanning electron microscopy (SEM) have been employed to characterize the α-HH crystals, based on which the formation and growth mechanisms of the α-HH crystals have been discussed. The results show that FGD gypsum can be successfully transformed into high purity α-HH in salt solution under mild conditions, and that a dissolution-recrystallization route is most probably adopted by this transition. The growth of α-HH crystals in salt solution demonstrates a preferred direction along [001] and results in a bundle-of-sheets or bundle-of-raphide texture. The characteristics revealed in this study can help to understand and control the growth of the α-HH crystal from solution. Supported by the National High-Tech Research & Development Program of China (Grant No. 2006AA06Z385), New Century Excellent Talents in University (Grant No. NCET-04-0549), and the Project of Science and Technology Plan of Zhejiang Province (Grant No. 2007C23055)     

Modeling and simulation of crushing process of spiral mining head

1 INTRODUCTIONThe research of mining deep seabed cobalt-richcrust is a hotspot of international oceanology[1].Based on the mining manganese nodule ,lots of re-searches on mining cobalt crust have been madedeeply and many kinds of methods ,such as thei m-proved CLB, mining vehicle +lifting system +surface supporting ship have been put forward.Mining vehicle consists of collecting machine ,tracked treading machine and spiral mininghead[2 ,3].The first step of mining cobalt crust is tocrush…     

Efficiency and mechanism of degradation of alachlor in water by O_3/H_2O_2 catalyst system

0　INTRODUCTIONThesedays ,someman madeorganiccompoundsandtheirdegradationproductsarefoundtobeharmfultohor mone secretinginbodyofbothpeopleandanimalsandtheycouldresultindisorderofincretion .Thesecom poundsarenowbedefinedasenvironmentalendocrinedisruptor[1] .Itiswell knownthatthesecompoundsareverydifficulttodegradebynatureprocess .Andbecausetheyarelipid soluble ,theyareeasytoamassinlipidandliverandhardtodischargeoutofbody .Thetoxicityissynergicanditssymptomshowspersisting ,slowandgrad ual.…     

On the tension necking of copper single crystal specimen under slip deformation mechanism

The tension necking of FCC copper single crystal specimen with a square cross section was analyzed under the slip deformation mechanism. The actual clamp manner of the specimen was modeled by setting correlative boundary condition,and the small angle deflection between tension loading axis and crystallography axis [100] was taken into account. The finite deformation numerical analysis of three-dimensional necking deformation for the specimen was performed by apply-ing crystal plasticity theory associated with a numerical algorithm suggested by the first author. According to the comparison with experimental observation,the fact was confirmed that the numerical results could describe the loading elongation curve of the copper single crystal specimen under large strain tension reasonably,and the method could be used to investigate the necking characteristic in neck shape and the effect due to the small angle deflection. Further,the investigation into the influence of specimen cross-section shape on necking was also performed;the results on mechanical response and neck profile evolution obtained through modeling of cylindrical specimen were compared with those obtained with square cross-section specimen.     

Optimization principle of combined surface and underground mining and its applications

The pit limit optimization is discussed, which is one of the most important problems in the combined mining method, on the basis of the economic model of ore-blocks. A new principle of the limit optimization is put forward through analyzing the limitations of moving cone method under such conditions. With a view to recovering as much mineral resource as possible and making the maximum profit from the whole deposit, the new principle is to maximize the sum of gain from both open-pit and underground mining. The mathematical models along the horizontal and vertical directions and modules for software package (DM&MCAD) have been developed and tested in Tonglushan Copper Mine. It has been proved to be rather effective in the mining practice.     

Characteristics of rockburst and its mining technology in mines

In order to resolve how to mine under the condition of high stress with rockburst, this paper analyzes the law of rockburst, and considers that most of the rockbursts occur in the high stress area of stope. A method of rockburst forecast and its steps are given, and three different stages of rockburst are identified. Furthermore, this paper considers that blasting energy can effectively control rockburst by changing the characteristics of rock mass, which decreases the probability of rockburst happening. According to characteristics of rockburst, two feasible mining techniques under rockburst conditions are put forward, that is stoping-and-filling method, and sublevel caving method of mining without any sills in hanging wall.     

厚松散层放顶煤开采条件下地表移动参数研究

用概率积分法预计地表移动与变形,其准确度关键在于地表移动参数的选取精度.而厚松散层条件下开采地表移动参数,有其明显的自身特点和规律.在鹤壁矿区实测资料的基础上,用数学方法分析了厚松散层放顶煤开采条件下地表移动参数的特点,并得出地表移动参数与地质采矿条件之间的函数关系式,对厚松散层下厚煤层"三下"开采及地表移动预计有一定指导意义.     

MATLAB与VB结合在开采沉陷中的应用

介绍了基于ActiveX控件的VB和MATLAB接口方法,利用VB的界面友好性和MATLAB提供的丰富稳定的数值计算及图形绘制功能,将两者结合应用在因开采沉陷引起的地表移动变形预计中,使复杂的计算过程变得具有直观性,结果具有可视性。     

煤矿开采对高速公路影响的评价

从煤矿井田中部穿过的高速公路在建设和运营过程中,必须及时掌握煤矿地下开采对其采动影响情况.根据煤矿地质采矿条件,对煤矿地下开采在高速公路沿线所引起的地表移动和变形进行预计,给出高速公路沿线地表移动变形值.由预计结果评价了煤矿开采对高速公路的损害程度.结果表明,煤矿开采后引起的地表变形值超过了高速公路的允许变形值,它对高速公路的采动损害程度明显.     

采动区建筑物下保护煤柱开采优化设计研究

采用岩层移动角进行留设保护煤柱的传统方法,增大了保护煤柱呆滞量,造成了煤炭资源的巨大浪费.为了探讨综放开采条件下保护煤柱留设的最优尺寸,基于潞安矿区王庄煤矿的地质采矿条件,提出了根据建筑物采动损害允许的临界变形值进行优化设计保护煤柱的新思路.按照概率积分法,预测计算开采工作面位于不同停采线位置时保护煤柱留设的合理尺寸,分析了不同开采方案下建筑物所受采动的影响面积、地表下沉程度及倾斜变形、拉伸变形等地表移动变形对建筑物采动损害的影响程度.通过11个方案的分析比较,结合经济与社会效益,给出了建筑物下保护煤柱留设的最优方案,为综放开采条件下建筑物压煤开采提供了科学依据.     

地表非连续变形破坏类型及特征分析

在分析大量实地调研和观测资料的基础上 ,将不同地质采矿条件下所形成的地表非连续破坏划分为四种类型 ,即拉伸型地表裂缝 ,滑动型地表裂缝 ,抽冒型地表裂缝 ,塌陷坑 .对不同类型地表非连续破坏的形成机理、形态特征及规律进行了分析研究 .     

考虑附加应力的采动沉陷区建筑物设计

针对地下矿产开采后形成采空区导致覆岩及地表沉陷,对地面建筑物造戍不同程度破坏的问题,以一栋四层砖混结构办公楼为模型,从理论上分析该模型在承受地表变形时,墙体和基础所受到的附加应力。以此为基础进行抗变形结构设计,分析Ⅰ～Ⅳ级地表变形对建筑物结构构件设置的影响,给出具体设计的墙壁圈梁配筋。     

MATLAB在开采沉陷预计可视化中的应用

采用VC 6 0面向对象技术来对预计点的移动变形值进行计算,先利用概率积分法来计算出工作面格网点的移动变形值,然后将其保存在数据文件中.针对地表移动和变形过程的特点和MATLAB强大的绘制和显示图形功能,将VC 6 0和MATLAB进行联编,实现了地表移动变形预计的可视化.     

盾构任意衬砌变形边界条件下复变函数弹性解

在Verruijt基本解法的基础上,假定Sagaseta通用变形模式为隧洞周边边界条件,推导了任意衬砌变形边界条件下复变函数弹性解答.利用复变函数解决孔口问题的基本方法,采用Mobius共形映射变换,将带孔口半无限空间映射为复平面下圆环域,该域下解析函数以Laurent级数展开,根据Muskhelishvili解法和给定边界条件,求得应力场和位移场.在此基础上分析了各分量对竖向位移和水平位移的影响,结果表明:衬砌椭圆化变形对位移场的影响远大于衬砌竖向沉降对位移场的影响.     

急倾斜煤层开采地表移动变形数值模拟

针对急倾斜煤层开采复杂的地质条件,对朝阳某煤矿分别选取了六种方案进行模拟,岩层依次变软,得出六种方案的水平和竖直方向的地表变形曲线及模型在x、y方向的等值线图.结果显示:方案一和方案二的最大值分别为0.026 85 m、0.049 39 m;方案三和方案四的最大值分别为0.066 75 m、0.089 4 m;方案五和方案六的最大值分别为0.134 1m、0.260 3 m.可以得出随着弹性模量的减小也就是随着上覆岩层的变软,地表水平和竖直方向的位移都逐渐增大,影响范围也逐渐变大;地表变形的最大值并不在采空区的正上方,而在采空区法线方向与地表的交点左右.可以为研究急倾斜煤层的开采及变形移动规律提供理论支持.     

开采引起的地表裂缝分布规律

通过研究，提出了开采引起的地表任意点动态应变分量的计算方法．将地表点的变形同地表土的力学性质结合起来，提出了地表裂缝分布规律动态计算模型，并用实例说明了模型的正确性．本文的成果弥补了用水平变形临界值或者裂缝角来判别裂缝区域之不足，具有普遍的适用性．