Surface movement and deformation characteristics due to high- intensive coal mining in the windy and sandy region

As China＇s energy strategy moving westward, the surface movement and deformation characteristics due to high-intensive coal mining in the windy and sandy region become a research hotspot. Surface movement observation stations were established to monitor movement and deformation in one super-large working face. Based on field measurements, the surface movement and deformation characteristics were obtained, including angle parameters, subsidence prediction parameters, etc. Besides, the angle and subsidence prediction parameters in similar mining areas are summarized; the mechanism of surface movement and deformation was analyzed with the combination of key stratum theory, mining and geological conditions. The research also indicates that compared with conventional working faces, uniform subsidence area of the subsidence trough in the windy and sandy region is larger, the trough margins are relative steep and deformation values present convergence at the margins, the extent of the trough shrink towards the goaf and the influence time of mining activities lasts shorter; the overlying rock movement and breaking characteristics presents regional particularity in the study area, while the single key stratum, thin bedrock and thick sand that can rapidly propagate movement and deformation are the deep factors, contributing to it.

THEORY OF STOCHASTIC MEDIUM AND ITS APPLICATION IN SURFACE SUBSIDENCE DUE TO EXCAVATION

Research on the stochastic theory and its application have been conducted in China for 40 years.This paper emphasizes on the basic theory of stochastic medium and its practice in predicting the ground movements and deformations induced by underground and open pit mining,near surface excavation of tunnel and so on.

基于改进Knothe时间函数的地表动态移动变形预测模型研究

目的为进一步探究地表动态移动变形特征,加深认识矿山开采沉陷基本规律,更好地服务于矿山安全绿色生产,方法针对原Knothe时间函数模型表达地表下沉及其速度变化规律的缺陷,基于矿山开采过程中地表下沉盆地动态形成机理,分析时间函数参数c对地表下沉量、下沉速度和下沉加速度影响规律;以地表下沉速度达到最大值时刻,将地表动态移动变形分为两个阶段,进一步改进Knothe时间函数模型,在此基础上,建立地表动态下沉、倾斜、曲率移动变形预测模型,并以某矿2201开采工作面为例,进行地表动态移动变形预测和精度分析。结果结果表明:改进后的Knothe时间函数形态与矿山开采沉陷地表动态移动变形一致,可以较好地描述采动地表“稳定→变化→稳定”全过程动态演化特征;参数c是该函数模型的重要参数,与覆岩力学性质、开采条件和开采速度等地质采矿条件有关,对描述地表动态移动变形量较敏感,随着参数c增大,地表下沉量和下沉速度显著增大;运用改进的Knothe地表动态移动变形预测模型计算,得到的地表下沉量误差为厘米级精度,倾斜值误差在5 mm/m以内,曲率误差在0.7 mm/m2以内,其相对误差均在6.0%以内,预测结果与实测结果较吻合。结论提出的预测模型具有一定可靠性与实用性,可较准确分析地表动态移动变形全过程的规律,从而为“三下”采煤及保护煤柱留设提供参考。

Earth Pressure Distribution and Sand Deformation Around Modified Suction Caissons(MSCs) Under Monotonic Lateral Loading

The modified suction caisson(MSC) is a novel type of foundation for ocean engineering, consisting of a short external closed-top cylinder-shaped structure surrounding the upper part of the regular suction caisson(RSC). The MSC can provide larger lateral bearing capacity and limit the deflection compared with the RSC. Therefore, the MSC can be much more appropriate to use as an offshore wind turbine foundation. Model tests on the MSC in saturated sand subjected to monotonic lateral loading were carried out to investigate the effects of external structure sizes on the sand surface deformation and the earth pressure distribution along the embedded depth. Test results show that the deformation range of the sand surface increases with the increasing width and length of the external structure. The magnitude of sand upheaval around the MSC is smaller than that of the RSC and the sand upheaval value around the MSC in the loading direction decreases with the increasing external structure dimensions. The net earth pressure in the loading direction acting on the internal compartment of the MSC is smaller than that of the RSC at the same embedded depth. The maximum net earth pressure acting on the external structure outer wall in the loading direction is larger than that of the internal compartment, indicating that a considerable amount of the lateral load and moment is resisted by the external skirt structure.

Hazard development mechanism and deformation estimation of water solution mining area

Based on the hazard development mechanism, a water solution area is closely related to the supporting effect of pressure-bearing water, the relaxing and collapsing effect of orebody interlayer, the collapsing effect of thawless material in orebody, filling effect caused by cubical expansibility of hydrate crystallization and uplifting effect of hard rock layer over cranny belt. The movement and deformation of ground surface caused by underground water solution mining is believed to be much weaker than that caused by well lane mining, which can be predicted by the stochastic medium theory method. On the basis of analysis on the engineering practice of water solution mining, its corresponding parameters can be obtained from the in-site data of the belt water and sand filling mining in engineering analog approach.

Estimation of Ground Deformation Caused by the Earthquake (M7.2) in Japan,2008,from the Geomorphic Image Analysis of High Resolution LiDAR DEMs

In this study, a new method for quantitative and efficient measurement for the ground surface movement was developed. The feature of this technique is to identify geomorphic characteristics by image matching analysis, using the intelligent images made from high resolution DEM(Digital Elevation Model). This method is useful to extract the small ground displacement where the surface shape was not intensely deformed.

Numerical Simulation of Current Density Distribution in Keyhole Double-Sided Arc Welding

In the double-sided arc welding system (DSAW) composing of PAW+TIG arcs, the PAW arc is guided by the TIG arc so that the current mostly flows through the direction of the workpiece thickness and the penetration is greatly improved. To analyze the current density distribution in DSAW is beneficial to understanding of this process. Considering all kinds of dynamic factors acting on the weldpool, this paper discusses firstly the surface deformation of the weldpool and the keyhole formation in PAW+TIG DSAW process on the basis of the magnetohydrodynamic theory and variation principles. Hence, a model of the current density distribution is developed. Through numerical simulation, the current density distribution in PAW+TIG DSAW process is quantitatively analyzed. It shows that the minimal radius of keyhole formed in PAW+TIG DSAW process is 0.5 mm and 89.5 percent of current flows through the keyhole.

Analysis of the Impact on Hydraulic Facilities Due to Underground Mining Based on the Influence Function Method

A mathematical model based on influence function method was established to predict the surface movement and deformation due to underground mining, and the impact on the upper hydraulic facilities in one coal mine was analyzed used the model. The analysis indicates: the maximum surface subsidence reaches 3.5 m, and the predicted maximum horizontal surface deformation reaches 7.0 mm/m, which would result in crack, deformation and uneven settlement in the soil foundation of the upper hydraulic facilities and influence the quality directly. Therefore, reasonable engineering measurements should be adopted to ensure the safe operation.

融合DT和SDFPT的时序InSAR矿区形变监测与分析

煤矿高强度开采会导致严重的地面形变及次生地质灾害。时序合成孔径雷达干涉(synthetic aperture Radar interferometry,InSAR)具有较强的形变监测能力,但在开采核心及周边低相干区域时无法监测到足够的目标点。该文尝试将分布式目标(distributed target,DT)和缓慢去相关滤波相位目标(slowly-decorrelating filtered phase target,SDFPT)进行联合,以提高矿区形变监测点的密度和覆盖度。分别采用快速同质点选取(fast statistically homogenous pixel selection,FaSHPS)法和振幅离差指数法选取DT和SDFPT候选点,分别对2类点进行相位优化和稳定性分析,筛选出符合条件的DT和SDFPT形成融合点集,并对其进行三维相位解缠、恢复相位时间序列和时空滤波,最终得到融合点集的形变时间序列和年均形变速率。选取2018年4月—2020年4月获取的覆盖布尔台煤矿的60景Sentinel-1影像进行形变监测,结果表明,融合DT和SDFPT后形变点密度和覆盖度显著提升,可监测最大形变量级也随之增加。实验区域内存在5处形变漏斗,最大累积形变量达到-309.76 mm;形变影响范围和不同年份时序形变量的差异与矿区开采活动密切相关。

M-CM-GA-BP算法的地表移动变形参数预测模型

针对复杂的开采沉陷预测问题,研究22个工作面采动地表移动变形参数变化规律,提出了一种基于M-CM-GA-BP算法求取地表移动变形参数的预测模型。通过线性加权组合预测方法和遗传算法优化BP神经网络的权值和阈值,融合多元回归模型来提高地表移动变形参数的求取精度,以地表下沉系数q为例,将该模型与其他预测模型预测性能进行对比分析,验证模型的准确性。结果表明,该模型能够有效地提高地表移动变形参数的预测精度,模型的平均相对误差为1.294、均方根误差为0.013,为地表移动变形参数预测提供了一种可行方法。

Lower Crustal Flow and Its Relation to the Surface Deformation and Stress Distribution in Western Sichuan Region, China

The channel flow model was gradually being accepted with the more important multidisci- plinary evidences from geology and geophysics, but how the lower crustal flow influenced the surface deformation quantitatively was unknown. Here, we develop a three-dimensional viscoelastic model to explore the mechanical relations between the lower crustal flow and the surface deformation in western Sichuan. Based on numerous tests, our results show that the modeled results fit well with the observed GPS data when the lower crust flows faster than the upper crust about 11 mm/a in the rhombic block, which can be useful to understand the possible mechanism of the surface deformation in western Siehuan. Moreover, taking the Xianshuihe fault as an example, we preliminarily analyze the relation between the active fault and stress field, according to the boundary constraints that deduced from the best model. The results show that the maximum shear stress on the Xianshuihe fault zone is mainly located in the fault terminal, intersections and the bend of the fault geometry, the stress level on the northwestern segment that has the high slip rate is relatively high. Additionally, with the reduction of the Young＇s modulus in the fault zone, it＇s conducive to generate the greater strain distribution, hence forming the high stress level.

无人机低空遥感裂缝识别与采动地表变形指标的相关性研究

山西煤炭资源丰富,随着煤炭资源大规模开采利用诱发了一系列地质灾害,地表裂缝即为地质灾害的主要表现形式之一。目前对地表裂缝监测多采用人工野外调查识别和卫星影像解译识别方法,存在成本高、效率低、分辨率低、易受天气影响等不足。利用飞马D2000无人机对山西省华阳二矿某地质灾害易发区进行了航空摄影测量,得到了测区数字正射影像模型(DOM)、数字表面模型(DSM)和三维点云模型(3DPCM),基于这3种模型数据解译得到地表裂缝发育与分布特征。同时,根据地质采矿条件进行地表移动变形预计,分析了地表变形指标与采动裂缝分布之间的关系。结果表明:利用DOM与3DPCM模型数据可以高效、准确地识别地表裂缝,且裂缝分布情况与采动引起的地表曲率变形、水平变形高度相关。研究结果对于预测评估开采引起的地表裂缝发育情况具有参考意义。

基于地表沉陷实测数据的覆岩内部移动变形预计方法

覆岩内部移动变形实测数据少、预计难度大、可靠性低。基于几何相似特征构建了依据地表沉陷实测数据预计覆岩内部移动变形的方法,该方法考虑了煤矿开采后覆岩移动变形导致的膨胀压缩。研究表明:预计离地表较近覆岩内部的移动变形时,可以不考虑覆岩的膨胀压缩,而预计离开采煤层较近覆岩内部的移动变形时,需要考虑覆岩的膨胀压缩;在开采边界附近,预计覆岩内部的移动变形可以不考虑膨胀压缩,而在开采中心附近则需要考虑膨胀压缩。研究结果有助于煤矿绿色安全开采。

基于物理模拟试验的房柱式采空区变形特征研究

房柱式采空区具有采出率较小、留设煤柱较大的特点,其覆岩移动规律及地表变形规律与长壁式采空区差别较大,在煤柱失效情况下,地表会产生较大变形,威胁地面建构筑物的安全。为研究浅埋缓倾房柱式采空区覆岩和松散层的变形发育机制,基于PIV图像处理技术和模块化组装思路,在室内建立物理模型开展物理模拟试验,反演了房柱式采空区覆岩和松散层的变形发育过程,分析了房柱式开采和煤柱失稳条件下覆岩和松散层的变形机制。研究结果表明:①房柱式开采条件下,浅埋缓倾采空区覆岩变形可划分为3个区域:“条带状”变形区域、“梯形状”变形区域和“倒漏斗型”变形区域。松散层中的变形呈“梯形状”发育。②煤柱失稳条件下,覆岩变形规律保持不变,松散层变形特征由“梯形状”发育为“漏斗型”,且随着失稳煤柱的增加,松散层变形增大,“漏斗型”变形区域由中心向两端逐渐扩展。③房柱式开采结束后,采空区顶板受力可简化为承受均布荷载的简支梁,在煤柱持续失稳的情况下,覆岩和松散层的静载将导致采空区顶板达到极限平衡状态,顶板破坏模式为拉破断,在拉应力作用下产生裂缝,但顶板并未完全断裂,采空区顶板形成一种带裂缝的悬臂梁结构。浅埋缓倾房柱式采空区煤柱失稳对地表变形影响剧烈,松散层变形与覆岩变形基本处于同一量级。

营盘壕煤矿深部多煤层开采地表移动变形规律及最优错距研究

鄂尔多斯东胜煤田为侏罗系含煤地层,诸多深部矿区2-2煤层和3-1煤层全区可采,并且煤层间距较小。以营盘壕煤矿为地质原型,通过FLAC3D和UDEC数值模拟软件构建研究区域数值模型,围绕2-2煤层和3-1煤层开采引起的地表移动变形及应力场演化规律进行研究。结果表明:多煤层重复采动将引起沉陷盆地中心投影向下煤层采空区方向移动,进而逼近煤层初采中心投影,并最终越过之;两煤层连续开采后,地表最大下沉值小于两煤层单独开采最大下沉值之和,煤层复采下沉系数小于初采下沉系数;煤柱错距与地表移动参数关联密切,错距系数与地表下沉系数、水平移动系数和主要影响角正切分别呈对数正态函数、凹抛物线和凸抛物线函数关系,并且与宽深比作为共同因子对煤层初采及复采表征参数的比值产生耦合影响;另外,同时随着错距的增大,地表沉陷盆地范围先减小后增大的趋势发展,水平移动近盆地等值线由椭圆形向梭子形演化;综合卸压错距经验公式、地表损伤程度及煤柱卸压效果确定的研究区域多煤层开采最优错距为30 m。

我国开采沉陷学70年研究综述及技术展望

从覆岩破坏规律、地表移动变形规律,以及技术标准和学术专著等方面,回顾了开采沉陷学科的发展历程和取得的重要研究成果。在覆岩破坏规律方面,我国学者提出了岩体响应采动理论、关键层理论等,并总结归纳了裂隙带的形态特征和发育高度;在地表移动变形规律方面,我国学者提出了负指数函数法、概率积分法等计算方法,尤其是概率积分法广泛应用于地表沉陷预计;在技术标准和学术专著方面,我国开展了较为系统的建设工作,几经系统修订并实施,并出版了一系列学术专著。本文归纳总结了目前开采沉陷学研究中存在的难点问题,包括围岩介质属性、概率积分法局限性、综采(综放)“两带”高度和形态、地表残余移动变形特征与规律、动态地表移动变形特征和计算方法、地表观测站观测频率、相关规程对同一事项的技术要求不一致的问题。提出了学科今后研究工作的发展方向及建议,包括以覆岩运动全过程可视化为主要手段揭示开采沉陷的本质机理、以空间信息技术为主要手段完成数据的采集与处理。研究认为,只有认识到“采场矿压-岩层移动-开采沉陷”是一个有机统一的整体,才能准确地理解和描述开采沉陷。在不断继续补充完善已有研究成果的同时,有必要以新理论和新思想审视开采沉陷学,以新技术和新方法研究开采沉陷学,不断推动学科的深入发展。

2023年土耳其“双大震”InSAR同震形变观测及断层滑动分布反演

为研究2023-02-06东安纳托利亚断裂系中“双大震”地震序列的同震形变及发震断层滑动特征,对欧空局发布的Sentinel-1 A影像进行D-InSAR和POT处理,获取此次地震序列的同震形变场,并基于“四叉树”法进行数据降采样,以构建的分布式滑动模型为基础进行发震断层的几何形态及精细化滑动分布反演研究。结果表明,“双大震”同震形变场的形变态势呈现相反的变化趋势,发震断层均位于以左旋走滑为主的东安纳托利亚断裂系中,M W7.8地震破裂在主断裂带上,最大滑动量约10.5 m,平均滑动角为3.74°;M W7.5地震破裂以索尔古分支断层为主,最大滑动量约11.8 m,平均滑动角为1.05°。与USGS和GCMT的震源机制解联合分析可知,两次大震均表现为左旋走滑为主兼少量倾滑分量,此次地震序列的发生是东安纳托利亚断裂带现今构造运动的一大重要体现。

基于FLAC^(3D)和概率积分法的公路下伏采空区变形影响分析与评价

某矿S3102工作面上方地表有市政二级公路,工作面开采造成部分路面下沉塌陷损毁。为了对公路损毁程度进行准确评估,分别用FLAC^(3D)数值模拟方法和概率积分法对地表移动变形进行预测计算,计算结果与实测数据进行对比分析。FLAC^(3D)数值模拟结果和概率积分法计算结果分别显示,公路地表最大下沉值分别为4979 mm和4880 mm,与实测公路地表最大下沉值4870 mm十分接近,最大误差在2%左右。研究结果表明,利用三维数值模拟软件模拟和概率积分法研究复杂采空区影响地表移动变形规律是可行的,能够较为准确地预测地表移动变形情况,可为采空区地表稳定性评估提供技术支持,供类似矿区道路塌陷预测研究借鉴。

工作面开采对污水池影响程度分析及保护方案研究

新郑煤电公司12203工作面地表存在一垃圾填埋场污水池,为最大程度地回收煤炭资源,同时有效保护污水池,对工作面开采对污水池的影响程度进行了研究,并提出了相应的方案措施。采用垂直剖面法确定了污水池的保护煤柱范围,并结合采动地表移动变形角值影响范围计算,分析工作面开采对污水池的影响程度。采用概率积分法对工作面整体不同厚度开采、限定采厚不同宽度开采和限定宽度不同厚度开采3种方案的地表移动变形进行了计算分析,提出了工作面采取局部区域限厚2.8 m开采的措施,限厚开采区域:倾向为自运输巷向上山方向30 m,走向为距开切眼70~170 m区域。并通过建立污水池移动变形观测站,监视地表移动变形情况,分析工作面开采对污水池的影响程度,并采取相应技术措施提供技术参考。

基于InSAR数据的山沟地貌地表岩移特征研究

因煤矿开采而引起的地表沉降对附近居民生活具有较大的影响,矿区地表沉降数据的获取对矿井生产布置至关重要。通过哨兵一号卫星获取覆盖平舒煤业15302工作面的30景影像,使用短基线集干涉测量技术对矿区地表沉降进行监测,获得了近2年的监测数据,计算了地表岩移主要参数,经计算可知:工作面走向方向的沉降量随时间不断增大,矿区整体平均沉降速率大于-30 mm/a,最大沉降速率为-108.87 mm/a,最大曲率为-0.1234 mm/m^(2),岩石移动角为78.2°。结果表明,该区域的地表倾斜与曲率均在允许值范围内,15302工作面的开采周边环境影响较小。