房式采煤工作面的底板岩层应力分析

利用岩石力学中的半无限体理论，导出了受房式采煤工作面遗留煤柱影响的底板岩层的附加应力分布计算公式，该计算公式对于评价房式开采具有指导意义，并给出了一个具体的计算实例．图５，表１，参２．

巷旁深切缝对顶部岩层应力控制作用研究

当煤层顶板中存在1层或者数层坚硬岩层时,随着工作面采高的增加,侧向岩层应力集中范围增大,导致护巷煤柱宽度增大。为了减小护巷煤柱宽度,提出顶板切缝减小护巷煤柱宽度的技术原理。采用相似模拟和数值模拟实验,对巷旁顶板不同切缝深度的岩层应力传递控制作用进行了系统的研究,揭示了切缝深度对岩层破裂和顶板下沉的影响。结果表明:随着切缝深度的增加,煤柱上方岩层应力逐渐减小,层位越高,应力越小;工作面侧向采空区顶板下沉量增大,采空区岩层应力逐渐增加,层位越高,应力越大;煤柱上方10,20 m岩层应力峰值、峰值点距切缝边缘距离与切缝深度呈非线性反比关系;采空区上方10,20 m岩层应力与切缝深度呈指数关系,说明深度切缝可以有效控制岩层应力分布、应力峰值及峰值点距切缝边缘的距离。

监测采动岩层地应力变化预测矿井出水情况

为有效预测矿井出水状况，防止矿井突水事故的发生，采用天然电磁波法矿山采动岩层地应力变化监测系统对梧桐庄矿182101采煤工作面全程采煤过程中的地应力变化进行监测，结合区域地应力的变化作出了7次出水情况预测意见，结果显示在做出预报后的1～4d时间内，出水量有明显的增加，持续很短时间后开始下降，并分析了出现这种现象的原因．该方法也可以对某些矿井地质灾害的发生提前作出预报，为煤矿制定合理有效的突水治理方案提供依据．

高应力不良岩层矿石溜井施工

金川集团龙首矿1 340m中段矿石溜井,长度87.2m,净直径3m,布置在高应力不良岩层中,施工难度较大。根据施工条件及现场实际情况,对溜井施工机械化设备进行了合理化配套,并创新采用了光面爆破、临时喷射混凝土封闭围岩、一次锚网喷柔性支护和二次钢筋混凝土外加钢衬板刚性支护等技术,较好地解决了高应力不良岩层井筒掘支施工难题,实际效果很好。

软岩层厚度对关键层上载荷与支承压力的影响

本文简单介绍了岩层控制中关键层理论的基本概念，并运用有限元法详细分析了软岩层厚度对关键层上部的载荷及下部的支承压力分布规律的影响．研究结果表明：关键层上的载荷与支承压力分布一样，都受软岩层厚度变化的影响，一般不可视为均布状态。

主动承压式钻孔应力监测传感装置

为研究煤岩层应力演化规律,并据此预测煤岩体稳定性问题,通过分析研究煤岩体失稳变形原理和承压机构与煤岩体耦合接触条件,得出测量应力与煤岩体内应力成线性关系;基于静水压原理开发了主动承压式钻孔应力传感器,重点进行了应变感知机构设计,并在实验室对传感器进行加载试验;分析其基本误差均在全量程0.4%以内,可近似为相等。结果表明该应力监测装置测量结果可反映煤岩体真实应力演变趋势,为煤岩体应力状态研究及煤岩动力灾害预警和巷道支护设计提供现实数据依据。

“充填体煤柱”协同承载机理及煤柱合理尺寸留设

深部煤层充填工作面区段煤柱稳定性对控制覆岩运移、保护地表生态环境具有重要作用。以河南某矿充填工作面地质条件为背景,探究了地质条件、煤柱强度、采矿因素对工作面区段煤柱稳定性的影响,研究了充填前后煤柱及“充填体-煤柱”对顶板的支撑作用。通过FLAC3D对充填开采条件下不同宽度的煤柱进行稳定性分析。结果表明,当煤柱宽度为30 m及以上时,煤柱所受竖向应力为40~43 MPa,塑性区范围稳定,基本顶最大下沉量为33~35 cm。从提高资源采出率、保证地表生态环境、保持“充填体-煤柱”稳定性等方面综合考虑,确定合理的区段煤柱宽度为30 m。工作面区段煤柱钻孔应力监测表明,超前工作面32 m为峰值应力区,竖向应力为9.9 MPa,应力集中程度较小,表明“充填体-煤柱”协同承载有利于降低煤柱应力集中程度,提高煤柱稳定性。

煤巷复合顶板变形破坏规律分析

基于现场实测巷道顶板变形规律提出了一个更为切合实际的煤巷复合顶板的概念。基于煤巷复合顶板破坏前及破坏的临界状态各岩层的变形曲率相同条件下,将顶板所受的荷载分配到各岩层中,进而分析复合顶板各岩层的受力状态。根据复合顶板的受力特征及其变形破坏规律,一般认为,复合顶板中软弱夹层因其自身强度低、厚度薄,巷道开挖后先将破坏,降低了顶板的整体刚度,使顶板结构弱化,从而产生较大的二次变形,随着顶板中的其他岩层应力变化,若顶板能够承受围岩荷载,则经应力变化顶板变形趋于稳定;若顶板不能够承受围岩荷载,则经应力变化顶板剧烈变形并失稳,提出了复合顶板有经过结构承载调整—结构刚度弱化—结构失稳的变形破坏规律。

煤层开采覆岩变形与破坏试验研究

顶底板赋存含水层的煤系地层在采煤影响下可能因导水裂隙的发育而导致突水危险。采用平面模拟的方法,通过实验室相似模拟试验,对某井田采煤过程中覆岩变形与破坏规律进行了模拟试验研究,获得了上覆岩层应力的分布以及随开采面推进的发展规律,结果表明,在本模拟条件下煤层开采导致上部覆岩破裂带触及上部含水层,因此需采取必要措施,以确保安全生产。

巷道底鼓的综合治理

长期以来,底鼓一直是煤矿开采等地下工程中难以解决的问题,巷道底鼓后,断面缩小,影响运输、通风和人员行走,不利于矿井安全生产。随着采深的增加和巷道断面的增大,巷道底鼓现象越来越突出,底鼓已成为该类巷道矿压显现的重要特征,是急待解决的技术难题。文章分析了巷道底鼓的主要因素,为有效防治底鼓措施提供了理论依据。

复杂地质条件下综放工作面双倾斜大倾角回采施工工艺实践

文章通过对综放工作面双倾斜大倾角回采工艺探索实践,解决了在超前应力作用下,巷道顶板下沉、底板鼓起、工作面倾斜、持续上山仰斜大倾角回采,上覆煤岩层应力集中,导致采煤机倾倒,割煤“割飘”,液压支架倾斜倾倒压架,输送机倾斜拉底煤严重,造成频繁断链等等,困难重重条件下的回采难题,探索并实践出一种双倾斜大倾角综放工作面安全合理高效的回采工艺。

极软岩厚煤层回风巷支护技术

介绍铁法煤业集团公司大平煤矿在高应力、强膨胀围岩、临近采空区条件下对N1N1工作面回风巷进行的支护技术,采用锚网喷、36U钢双层金属支架复合支护技术在软岩支护中取得良好效果。

岩巷高效快速掘进工艺及设备的优化

为进一步提升煤矿生产效率和安全性,要求岩巷掘进效率与煤巷的开采效率相匹配。以324岩巷为例,在研究其岩层特性及断面基本结构的基础上,对当前325岩巷所采用的掘进工艺下的掘进问题进行总结分析,并结合理论计算初步确定两种优化掘进方案,结合数值模拟最终确定掘进工艺中对应爆破方案的掏槽眼的具体参数。

探究固体密实充填采煤的矿压控制理论与运用

在生态环保与可持续发展理念下,当前煤炭企业面前最重要的问题是解决煤炭生产过程中资源浪费严重与生态环境破坏的问题。应用固体密实充填采煤及时是缓解煤炭企业发展与环境矛盾的有效途径之一。在应用此技术下,不仅可以提升资源猜出率,还可以延长矿井使用寿命,同时对土地、水体及生态资源等起到有效的保护作用,将矿区排放的矸石、粉煤灰等固体废弃物应用到采煤操作中,以此有效避免这些固体废弃物对环境造成的污染及采空区的灾害发生隐患。

浅谈某煤矿深部巷道支护技术的应用

本文以曲江-850m东大巷为例,对该巷道的变形和破坏机理进行分析,探究适应于曲江矿深部巷道支护的最佳方案。有效地预防和控制了曲江公司在高应力软岩层巷道掘进中的岩层脱落及冒顶事故的发生。

Study on fault induced rock bursts

In order to study the rules of rock bursts caused by faults by means of mechanical analysis of a roof rock-mass balanced structure and numerical simulation about fault slip destabilization, the effect of coal mining operation on fault plane stresses and slip displacement were studied. The results indicate that the slip displacement sharply increases due to the decrease of normal stress and the increase of shear stress at the fault plane when the working face advances from the footwall to the fault itself, which may induce a fault rock burst. However, this slip displacement will be very small due to the increase of normal stress and the decrease of shear stress when the working face advances from the hanging wall to the fault itself, which results in a very small risk of a fault rock burst.

Zonal disintegration phenomenon in rock mass surrounding deep tunnels

Zonal disintegration is a typical static phenomenon of deep rock masses. It has been defined as alternating regions of fractured and relatively intact rock mass that appear around or in front of the working stope during excavation of a deep tunnel. Zonal disintegration phenomenon was successfully demonstrated in the laboratory with 3D tests on analogous gypsum models, two circular cracked zones were observed in the test. The linear Mohr-Coulomb yield criterion was used with a constitutive model that showed linear softening and ideal residual plastic to analyze the elasto-plastic field of the enclosing rock mass around a deep tunnel. The results show that tunneling causes a maximum stress zone to appear between an elastic and plastic zone in the surrounding rock. The zonal disintegration phenomenon is analyzed by considering the stress-strain state of the rock mass in the vicinity of the maximum stress zone. Creep instability failure of the rock due to the development of the plastic zone, and transfer of the maximum stress zone into the rock mass, are the cause of zonal disintegration. An analytical criterion for the critical depth at which zonal disintegration can occur is derived. This depth depends mainly on the character and stress concentration coefficient of the rock mass.

In-situ stress measurements and stress change monitoring to monitor overburden caving behaviour and hydraulic fracture pre-conditioning

A coal mine in New South Wales is longwall mining 300 m wide panels at a depth of 160–180 m directly below a 16–20 m thick conglomerate strata. As part of a strategy to use hydraulic fracturing to manage potential windblast and periodic caving hazards associated with these conglomerate strata,the in-situ stresses in the conglomerate were measured using ANZI strain cells and the overcoring method of stress relief. Changes in stress associated with abutment loading and placement of hydraulic fractures were also measured using ANZI strain cells installed from the surface and from underground. Overcore stress measurements have indicated that the vertical stress is the lowest principal stress so that hydraulic fractures placed ahead of mining form horizontally and so provide effective pre-conditioning to promote caving of the conglomerate strata. Monitoring of stress changes in the overburden strata during longwall retreat was undertaken at two different locations at the mine. The monitoring indicated stress changes were evident 150 m ahead of the longwall face and abutment loading reached a maximum increase of about7.5 MPa. The stresses ahead of mining change gradually with distance to the approaching longwall and in a direction consistent with the horizontal in-situ stresses. There was no evidence in the stress change monitoring results to indicate significant cyclical forward abutment loading ahead of the face. The forward abutment load determined from the stress change monitoring is consistent with the weight of overburden strata overhanging the goaf indicated by subsidence monitoring.

THE STUDIES OF THE STRESS WAVE THEORY ON ROCKBURST UNDER HIGH STRATA STRESS

Through the analysis of the occurring and developing process of the rockburst under the high strata stress, it points out that the action of stress wave is the key factor to affect the rockburst process. The characteristics of stress wave as well as its relation with the strata stress and the mechanism of its causing rockburst are explained. Finally, the preventing measures of the rockburst caused by the stress wave are put forward.

Movement and deformation laws of the overlying strata in paste filling stope

We combined the similar simulation with numerical simulation to analyze the movement and deforma- tion features of overlying strata caused by paste backfill mining, study the movement and deformation laws of the overlying strata in paste backfill mining, structural movement of the stope strata as well as the stope stress distribution laws. Furthermore, authors also explored the key factors to the movement and deformation of the overlying strata in paste backfill mining. The results indicate that a caving zone existed in the bending zone only in the overlying strata of the paste backfill mining. Compared with the roof caving mining, the degree of stress concentration and area of influence in the paste filling stope were apparently smaller. And the degree of destruction and area of the overlying strata decreased prominently. Also, there was no apparent strata behavior in the working face. Lastly, the filling ratio was the key to control the movement and deformation of the overlying strata. Combined with a specific engineering example, the author proved the reliability of the simulation results and provided a theoretical basis for the further extension of the paste backfill mining.