Research on Ground Movement Laws for Strip Mining Under Thick Alluvium

With the discrete element method, the simulation and analysis of a series of numerical models were made. This research revealed ground movement laws for strip mining under thick alluvium and gave calculation formulae for the maximum ground subsidence and horizontal movement as a function of basement rock thickness and mining width, thus providing sound evidence for future strip mining under thick alluvium.     

Surface Movement Regularity of Super-Wide Mining Face With Top-Coal Caving

No.4326 super-wide panel of Wangzhuang Coal Mine ( in which the fully-mechanized top-coal caving longwall mining method was used) was monitored for dynamic characteristic of surface movement. The dynamic surface movement in and after mining was predicted by using the Mining Subsidence Prediction System. The results indicate that after mining, the surface above the super-wide panel reaches a state of full subsidence, making the No.309 national highway above the panel be located on the flat bottom of the subsidence basin so that the influence of mining activity in both sides of 4326 panel on the national highway is the smallest.     

Time series ground subsidence inversion in mining area based on CRInSAR and PSInSAR integration

The subsidence of the mining area was monitored by analyzing the phase of permanent scatters （PS） which maintained high coherence in magnitude of SAR images.A hew method of spatial unwrapping was presented which used the subsidence rates calculated on comer reflector （CR） points as constraints for PS network to perform the spatial unwrapping using the parametric adjustment method.The algorithm achieved the integration of CR data and PSInSAR algorithm.The colliery dense distributed area around Baisha reservoir was chosen as the study area in the experiment.The time series of subsidence from February in 2007 to February in 2010 is successfully inversed by using the periodic function to simulate the linear and nonlinear components of the deformation.The simulation results show that the accuracy can be ± 2.1 mm with the leveling data being used as the external validation data.     

Prediction of ground surface displacement caused by grouting

Ground surface displacement caused by grouting was calculated with stochastic medium theory. Ground surface displacement was assumed to be caused by the cavity expansion of grouting, slurry seepage, and slurry contraction. A prediction method of ground surface displacement was developed. The reliability of the presented method was validated through a comparison between theoretical results and results from engineering practice. Results show that the present method is effective. The effect of parameters on uplift displacement was illustrated under different grouting conditions. Through analysis, it can be known that the ground surface uplift is mainly caused by osmosis of slurry and the primary influence angle of stratum β determines the influence range of surface uplift. Besides, the results show that ground surface uplift displacement decreases notably with increasing depth of the grouting cavity but it increases with increasing diffusion radius of grout and increasing grouting pressure.     

Subsidence over room and pillar retreat mining in a low coal seam

The objective of this paper is to study the behavior of a low thick and low depth coal seam and the overburden rock mass. The mining method is room and pillar in retreat and partial pillar recovery. The excavation method is conventional drill and blast because of the small production. The partial pillar recovery is about 30% of the previous pillar size, 7 m × 7 m. The roof displacement was monitored during retreat operation; the surface movement was also monitored. The effect of the blasting vibration on the final pillar strength had been considered. Due to blasting, the pillar reduced about 20%. The consequence is more pillar deformation and roof vertical displacement. The pillar retreat and ground movement were simulated in a three-dimensional numerical model. This model was created to predict the surface subsidence and compare to the subsidence measured. This study showed that the remaining pillar and low seam reduce the subsidence that was predicted with conventional methods.     

MINING INDUCED INFLUENCE ON THE ROADWAYS IN WEAK SURROUNDING ROCK AND ITS CONTROLLING MEASURES

The application of destressing method can change the distribution patterns of the stress field in the weak rock surrounding openings, locate the openings in the zone of low stress level, thus improve their loading and maintaining conditions. Such method is considered as a new way of opening maintenance in weak rock and has caused extensive interests in mining industry both at home and abroad. The results of theoretic research and lab experiments of utilizing topdestresslng trough to maintain the opening affected by mining activities in weak rock, as well as its practical application in a coal mine are introduced in this paper. The research results indicate that the deformation and floor heaving of the opening in weak rock can be effectively controlled, and long-term stability of the opening can be realized by applying destressing method as long as the destressing plan and concerned parameters are carefully determined.     

Pattern synthesis optimization of 3-D ODAR based on improved GA using LSFE method

Pattern synthesis in 3-D opportunistic digital array radar(ODAR) becomes complex when a multitude of antennas are considered to be randomly distributed in a three dimensional space.In order to obtain an optimal pattern,several freedoms must be constrained.A new pattern synthesis approach based on the improved genetic algorithm(GA) using the least square fitness estimation(LSFE) method is proposed.Parameters optimized by this method include antenna locations,stimulus states and phase weights.The new algorithm demonstrates that the fitness variation tendency of GA can be effectively predicted after several "eras" by the LSFE method.It is shown that by comparing the variation of LSFE curve slope,the GA operator can be adaptively modified to avoid premature convergence of the algorithm.The validity of the algorithm is verified using computer implementation.     

NONLINEAR ANALYSES OF VOID DIFFUSION MODEL AND ITS APPLICATION TO SUBSIDENCE PREDICTION

The void diffusion model for mining-effected strata can be analyzed by means of a nonlinear finite element method. This paper presents the fundamental principles of the analyses. The key to the analyses is the determination of roof subsidence and the nonlinear relationship between diffusion coefficient and subsidence. This paper discusses these problems and determines the coefficient for Pingdingshan mining district, with which several profiles are predicted. It is found that the predicted profiles are coincident with the corresponding field profiles.     

Subsidence History of the Eastern Depression in the North Yellow Sea Basin

Using a back-stripping method, our paper simulated the subsidence history of the eastern depression in the North Yellow Sea Basin. The subsidence history curve pattern and the subsidence chorisogram during every subsiding period were exposed. Combining with the regional geologic background and the distribution features of the subsiding centers in every period, a contrasting study of the pattern and the classical subsidence history curves shows the subsidence history is made up of Mesozoic （J3-K1） and Cenozoic （E2-Q） subsiding cycles. The two subsiding cycles are separated by the late Cretaceous and Paleocene （K2-E1） uplift denudation. Both subsiding cycles have the characteristics of an extension basin. The rapid subsidence during the late Jurassic and Eocene is equivalent to the initial subsiding phases in both cycles.. The slow subsidence of both, the early Cretaceous and Neogene, can be regarded as thermal subsidence phases.     

煤矿开采沉陷有效控制的新途径

开采沉陷是造成矿区环境地质灾害的直接根源，有效控制和减轻地面沉陷程度是减轻或避免开采沉陷环境灾害的根本之路，针对这一问题，分析了充填开采、条带开采和覆岩离层注浆岩层控制技术的优缺点，根据荷载置换原理，提出了“条带开采一注浆充填固结采空区—剩余条带开采”的三步法(二次条带式)开采沉陷控制的新思路，进行了三步法开采沉陷控制的可行性研究，初步分析表明，采用三步法开采可以实现对岩层移动和地表沉陷的有效控制，地表下沉系数可控制在0．25左右，煤炭采出率可达到80％～90％，可基本实现地面建筑物不搬迁和大幅度减轻土地塌陷灾害。     

村庄下双对拉工作面开采的地表和房屋变形

通过北宿煤矿村庄下双对拉工作面开采的地表移动观测,探讨了地表移动变形与房屋变形及其裂缝发育宽度之间的关系,获得了预测房屋裂缝宽度的典型曲线．该曲线可以对房屋裂缝的发育规律作出较为精确的定量预测,对房屋将出现的最大破坏程度有充分的估计．最后,给出了动态下沉系数和水平移动系数的修正公式．     

采动覆岩隔离注浆充填技术在淮北矿区的应用

针对淮北矿区村庄压煤严重、迁村采煤困难这一难题,结合淮北矿区地质采矿条件,开展了“采动覆岩隔离注浆充填技术”试验与应用。分析了注浆充填的技术原理、设计方法与工程控制原则,将分析结果成功应用于刘店煤矿1044工作面注浆充填工程中。通过实施注浆充填,共注入粉煤灰67340 t,压实注采比达29％。实测地表最大下沉0．149 m,注浆充填减沉率85．1％,建筑物没有任何损坏,表明隔离注浆充填技术在不迁村采煤中有重要的应用前景。目前,该项技术已在淮北矿区全面推广应用。     

利用固体充填开采方法保护建筑群安全的研究

我国煤矿建筑物下压煤量占总压煤量的69%,同时每年要向地面排放4.5亿t以上的固体废弃物,因此,研究利用固体废弃物充填开采方法,在保证地表建筑物安全性的基础上,高效开采出下压煤炭资源意义重大.文章应用数值模拟方法,对建筑物下压煤开采所引起的岩层移动过程进行模拟,系统分析了采场围岩塑性区分布及地表沉陷量变化规律,由计算结果分析得知,应用固体充填开采法与无充填直接开采相比,采场围岩破坏单元数较少,围岩稳定性受影响较小,减少地表沉陷量效果明显.以数值模拟结果作为参考,研制了长臂综采矸石充填开采工艺的配套设备,并在某矿建筑物下压煤炭开采的实际应用中取得良好效果,有效控制了地表变形,保证了建筑物的安全性和资源的高效开采.     

开采沉陷数据的可视化研究

利用C#语言实现了煤矿开采地表移动与变形等值线（下沉、倾斜、曲率、水平移动、水平变形）的绘制,在此基础上进行了影响区域任意两点间的剖面线的绘制,基本实现了开采沉陷数据的可视化,可对采区上方建筑物进行了破坏等级划分,从而判别建筑物是否受到地下开采的影响以及受到开采影响的程度。     

采动区建筑物地基、基础和结构协同作用模型

受采动影响建筑物的移动变形和附加应力分布规律十分复杂，与建筑物的长度、高度、建筑材料、结构、刚度、地基性质、地下开采情况、建筑物所处的位置等多种因素有关．本综合采用矿山开采沉陷学、矿山岩体力学、数理科学等多学科的知识，建立了采动区建筑物地基、基础与结构协同作用力学模型．该模型可以计算采动区建筑物移动变形和各种附加内力，并采用可视化VB语言编制了相应的计算程序，通过计算示例进行了验证，为今后采动区建筑物的保护和设计提供了理论基础和计算工具．     

采动区可升降点式基础房屋抗变形理论探讨

提出了采动区可升降点式基础建筑物在地表移动和变形作用下的设计思想,导出了其附加作用力计算的基本公式,进行了可升降点式基础的设计．通过对比分析,此方案改善了传统的“条形基础抗采动房屋”的结构性能,使得建筑物能更有效地吸收和抵抗地表移动和变形．     

采动区地基、独立基础与框架结构共同作用的力学模型

根据采动区地表变形的规律和独立基础框架结构受力和变形特点，采用合理的地基模型、基础与上部结构共同作用模型和开采沉陷模型，综合应用结构力学、矿山开采沉陷学、土力学、材料力学等相关理论，建立了采动区地基-独立基础-框架结构共同作用的理论计算模型，该计算模型综合考虑了开采盆地形成过程中地表变形对建筑物的动态影响，从理论上揭示了建筑物位于下沉盆地不同位置时，地表变形与建筑物附加变形和附加内力的关系，并推导出计算采动区建筑物附加变形和附加内力的计算公式，通过计算实例进行了验证，为采动区上方框架结构建筑物的保护、加固和设计提供了理论计算依据．     

宁东采煤区地表沉陷数值模拟计算与规律

在概述宁东采煤区基本情况的基础上，对其地表沉陷进行了数值模拟分析计算，给出了采区沉陷各变形量的计算公式，总结了其沉陷规律，简析了地表沉陷的成因与特点，为综合治理提供依据．