采场老顶岩梁的超前破断与矿山压力

基于损伤力学的思想 ,建立了损伤基础梁的力学模型 ,并用该模型的结论分析了老顶岩梁超前破断对支承压力及其运动状态的影响 .分析认为 :损伤基础梁模型较弹性基础梁模型能够更真实地反映支承系统与老顶岩梁的相互作用关系 ,对提高顶板来压预测预报的准确性具有重要意义 ;老顶岩梁的超前破断与回转运动是“两个应力区”形成的必要条件 .

老顶岩块端角摩擦系数和挤压系数实验研究

通过岩块实验、相似模拟和计算模拟 ,研究了采场老顶岩块端角摩擦和端角挤压特性。得出老顶岩块端角摩擦角为岩石残余摩擦角 ,摩擦系数确定为 0 .5 ;端角挤压强度受弱面的影响明显且具有规律性 ,端角挤压系数确定为 0 .4。

深部岩浆流动形成的岩石的特征及其与糜棱岩、片麻岩的比较——以华北北缘隆化地区古生代晚期大光顶岩体为例

在片麻岩地区识别后期侵位的岩浆的流动特征,识别岩浆流动形成的岩浆岩、变质作用形成的片麻岩、韧性变形条件下形成的糜棱岩三者的差异和进行野外、室内不同环境下的判别,是现代岩石学、构造地质学需要重新审视的问题。通过对华北北缘大光顶岩体的塑性流动特征、相关的后期叠加韧性变形特征和区域变质片麻岩特征的比较,结合国内外对于岩浆塑性变形(magmatic flow)与韧性变形(solid-state flow)的比较研究,分析了在强变质岩石中如何分析和识别出岩浆的流动,这些岩浆的流动并不是区域变质作用形成的,也不是高温环境下韧性变形作用形成的,而是形成于岩浆侵位后期的冷却结晶作用。对于如何识别和分析岩浆流动提出了野外和室内的标志。

深部开采底板破坏与基本顶岩梁初次垮断的联动效应

深部承压水上开采基本顶初次垮断作为一种剧烈的矿压显现,往往造成底板大范围失稳破坏而诱发突水事故。为研究深部开采底板与基本顶初次垮断的联动破坏效应,应用相似材料试验分析了深部开采顶底板的初次断裂破坏特征,建立了基本顶岩梁初次垮断前后的顶板结构模型及底板力学模型,从应力增量角度研究了深部开采底板压剪、卸荷破坏与基本顶岩梁初次垮断的联动效应,应用离散元软件模拟了不同采深下基本顶初次垮断前后底板应力及变形的联动变化效应,并提出了预裂基本顶消除跨中触矸效应、提高支架工作阻力降低顶板垮断动载荷、降低底板应力卸荷起点与卸荷幅度等弱化顶底板联动效应的深部开采围岩控制技术。结果表明:深部开采基本顶初次垮断后,跨中触矸的采空区中部底板存在一压应力增高区域,其位移由垮断前向上鼓起转变为向下压缩;底板压力拱后拱脚位置由切眼煤壁端变换为触矸区域,底板压力拱由极限跨距的单一拱结构变换为两宽度约为极限跨距一半的双拱结构;采深越大,触矸区域底板水平应力增量越高,且垂直应力增量的影响深度高于水平应力;随最大应力变化量增大,底板最大变形量近似非线性指数增长,且垂直方向非线性增加最甚。

采场老顶岩梁的超前破断与矿山压力研究

为研究采场老顶岩梁的超前破断过程,工程师要在损伤力学的基础上,建立损伤基础岩梁的力学模型。通过分析损伤力学将初始来压前后的采场老顶岩梁,运用工程制图的方式简化为悬臂岩梁和固支岩梁,对采场老顶岩梁的超前破断进行实验模拟。

同构造岩浆流动与相对稳定环境下岩体侵位的差异性及其对华北北缘晚古生代晚期——早中生代构造演化的约束

花岗质岩浆岩是大陆地壳的重要组成部分,对华北北缘燕山地区构造变形、基本构造格架的分析已经做了大量研究,但对于花岗岩体侵位的动力学环境研究较少。与相对稳定构造环境下侵位的花岗岩不同,同构造岩浆流动通常发生在大陆边缘、造山带等构造活跃带,在强烈的构造应力场影响下,岩体特征、侵位过程、流动方向通常十分复杂。华北板块北缘在晚古生代期间有大量花岗质岩体侵入,其构造属性与成因分析为研究古亚洲洋的俯冲与华北板块破坏提供了关键证据。对华北板块北缘的大光顶岩体和盘山岩体从宏观到微观进行构造变形及岩石学特征分析,结合电子探针手段进行半定量的矿物学研究,并利用角闪石压力计来计算岩体形成的压力条件,得出岩体侵位的深度,探讨华北北缘不同动力学背景下的构造环境。大光顶花岗闪长岩在露头尺度上表现为大量轴面低角度北倾的无根褶皱,包体和捕虏体长轴平行于流动面理,显微镜下可见角闪石、黑云母等暗色矿物定向排列,具有典型的同构造变形特征,角闪石全铝压力计指示结晶压力为3.62~5.64 kbar,大致对应中地壳的深度(12.86~22.99 km),认为晚古生代(320~290 Ma)时期,华北板块北缘中下地壳重熔形成由北向南的同构造岩浆流动,同时也为中—深层次的应力传递提供媒介。中生代盘山花岗岩中的包体、捕虏体未发生变形,也无暗色矿物定向排列,岩体与围岩接触带发育热接触变质作用形成大理岩,属稳定构造环境下侵位的花岗岩。

三登云顶岩

每到一海岛,总想攀上这个岛的最高峰,浏览四周的景。到了台湾宝岛,上了阿里山;到了舟山群岛的普陀山,上了佛顶山。到了厦门岛的南普陀寺,上了寺后的五老峰。厦门岛上还有一座云顶岩,岩在云顶,一定很高峻,于是就上了云顶岩。

广西大瑶山地区大王顶花岗闪长斑岩年代学和地球化学特征

大王顶岩体出露于桂东南大瑶山地区,位于扬子陆块和华夏陆块交汇的钦杭成矿带西端,主要岩石类型为花岗闪长斑岩,岩石的LA-ICP-MS锆石U-Pb定年结果为463±5.0 Ma,属于加里东期岩浆活动产物。岩石地球化学研究表明:该岩体具有低硅、富钠、弱过铝质和钙碱性特征,微量元素主要富集Th、U、La、Zr和Hf,亏损Ba、Sr、Ta、Nb、P、Ti。稀土总量为(68.75~167.17)×10^(-6),轻稀土富集(LREE/HREE和(La/Yb)N分别为3.62~10.08和2.80~9.81),具弱Eu负异常,δEu为0.54~0.82。结合其他相关地质资料综合分析认为,大王顶花岗闪长斑岩为I型花岗岩,该岩体成因与其南侧的云开地块和北侧桂滇-北越地块拼贴碰撞有关。

鲁西蒙山龟蒙顶、云蒙峰岩体的锆石SHRIMP U-Pb测年及形成时代

蒙山主峰龟蒙顶为片麻状花岗闪长岩,原划为新太古代早期侵入岩。根据新测的2件样品锆石SHRIMP U-Pb年龄分别为(2 539±17)Ma,(2 544±15)Ma,其形成时代确定为新太古代晚期。蒙山北部云蒙峰为中粒二长花岗岩,锆石SHRIMP U-Pb年龄为(2 534±8)Ma,其侵入龟蒙顶岩体片麻状花岗闪长岩。龟蒙顶岩体属峄山岩套TTG质花岗岩,是地幔岩浆侵入混入地壳物质形成的。云蒙峰岩体属傲徕山岩套二长花岗岩,为上地壳物质重熔(深熔)作用形成。

沿空送巷的理论探讨

根据上覆岩层结构 ,建立了回采巷老顶岩梁的力学结构模型 ;利用数值分析法和流变学理论 ,导出了回采巷老顶岩梁的破断距及达到稳定状态时所需要的时间计算公式 。

基于损伤理论的煤层顶板破坏机理研究

基于损伤理论的思想,建立损伤基础梁的地质力学模型,并用该模型来分析煤层老顶岩梁的极限破断矩和压力情况。结果表明:该模型较传统的弹性模型更接近实际情况,能更准确的研究煤层开采上覆岩层的移动和矿山压力情况。

广西大瑶山南部大佛顶Ⅰ型花岗岩体的岩石成因及构造意义

为厘定广西大瑶山南部大佛顶花岗岩体的形成时代、岩石成因,探讨其源区属性及大地构造意义,进行了高精度的LA-ICP-MS锆石U-Pb定年、锆石原位Hf同位素分析和全岩地球化学研究。大佛顶岩体的侵位年龄为158~157 Ma;εHf(t)值为-10.77~3.44,以负值为主,二阶段年龄模式(T_(DM2))为1.86~1.16 Ga,指示岩浆主要来源于中元古代古老地壳,且有少量的幔源物质加入。该岩体富铝(Al2O317.75%~17.82%)、高钾(K2O 2.49%~2.66%)、低钙(CaO 4.07%~4.30%),Mg#为37~39;稀土总量较低(88.62×10^(-6)~121.62×10^(-6)),轻重稀土分馏中等(LaN/YbN=12.41~12.69),δEu=0.92~0.98;富集Ba、K、Sr等大离子亲石元素和U、Pb、Nd等高场强元素,Ti、P、Ta、Th、Nb等元素表现为负异常,Zr+Nb+Y+Ce含量、10000×Ga/Al值和A/CNK值较低,属典型的准铝质I型花岗岩。具岛弧型特征的大佛顶I型花岗岩体,为保存于古俯冲带岛弧底部(下地壳)的玄武质岩石,在燕山早期岩石圈拉张-伸展背景下发生部分熔融,并有少量幔源物质加入的条件下上升侵位而形成,因而“遗传”了上一代岛弧岩石的地球化学基因,与古太平洋板块向华南大陆之下俯冲的扰动有关。

MECHANICAL BEHAVIOUR OF MAIN FLOOR FOR WATER INRUSH IN LONGWALL MINING

In this paper a new mechanica1 medel indicating the mechanical behaviour of main floor in longwall mining is proposed. In the medel the unfractured rnain floor is considered as an elasto plastic plate, and the combination of fractured blocks as a voussoir beam. Using the plastic hmit theory of plates, th limit load acting on rnain floor and the position of its largest deformation are gotten. The stability conditions for the key blocks of the voussoir beam are analysed by "S-R" stability theory. The results of the theoretical analysis are important for the study on the water inrush from seam floor.

The relation between modes of lithologic association and interlayer-gliding structures in coal mine

As a case study of the Panji No.1 Coal Mine in Anhui Province, based on thesite measured and statistical data, summarized the lithologic associations, characteristicsand distribution laws of interlayer-gliding structures and tectonic coal in the No.11-2 coalseams.The results show that 9 modes of lithologic association can form interlayer-glidingstructures.It is more easy for rock slip to occur when the lithologic associations are mainroof + coal seam + immediate floor type, compound roof+immediate roof + coal seam +immediate floor type and immediate roof + coal seam + immediate floor type.Lithologicassociations of roof and floor are the precondition to the formation of interlayer-glidingstructures.

Rock mechanical investigation of strata loading characteristics to assess caving and requirement of support resistance in a mechanized powered support longwall face

Longwall mining is one of the most acclaimed and widely used in underground method for coal extraction. The interaction of powered supports with the roof is the key issue in strata mechanics of longwall mining. Controlled caving of rock mass is a prerequisite pro thriving exploitation of coal deposits by longwall retreat with caving technique and support resistance has evolved as the most promising and effective scientific tool to predict various aspects related to strata mechanics of such workings. Load density,height of caving block, distance of fractured zone ahead of the face, overhang of goaf and mechanical strength of the debris above and below the support base have been found to influence the magnitude of load on supports. Designing powered support has been attempted at the different countries in different methods. This paper reviews the mechanism of roof caving and the conventional approaches of caving behaviour and support resistance requirement in the context of major strata control experiences gained worldwide. The theoretical explanation of the mechanism of roof caving is still continuing with consistently improved understanding through growing field experiences in the larger domain of geo-mining conditions and state-of-art strata mechanics analysis and monitoring techniques.

Effect of a single weak lithological structure on the height of a collapsing roof in a deep soft rock roadway

Besides the cross sections of roadways and the tendency and obliquity of roadway axes, the major controlling factors affecting the height of a collapsing roof include the weak lithological structure of surrounding rocks. This thesis analyzes the effect of two single and weak lithological structures of both sides and the roof on the height of a collapsing roof in a deep soft rock road- way. Using the two-dimensional UDEC3.1 software, a numerical structures of both sides of a roadway and of two weak lithological simulation was carried out on the models of weak lithological structures of roof of different depths. We reconstruct the overall processes from a break-away layer, bending, subsidence and the cracking of a collapsing roof. We also illustrate the distribution characteristics of displacement fields in the surrounding rock after the roof collapse in a deep soft rock roadway. The results of our numerical simulations indicate that the form of a roof collapse is side-expanding when the roadway is a weak structure at both sides The height of the roof collapse is related to the lithological combination of the roof when the roadway is a weak structure of the roof.

Control technology and coordination deformation mechanism of rise entry group with high ground stress

Based on engineering practices of Wuyang Coal Mine, we carried out X-ray diffract researches on No. 3 coal; and the rocks of its roof and floor by XRD meter, and simulated the interactive effect of the surrounding rock deformation by FLAC2DS.0 numerical simulation software under the condition of different tunneling method of multimine roadway in parallel. The internal structures of the surrounding rocks of 76 belt roadway were monitored by borehole observation instruments： and then, we analyzed the reason of fhilure and deformation of surrounding rocks of several rise entry, and proposed the technical mea- sures for controlling interactive effect of several rise entry surrounding rock deformation at last. For the thickness seam rise roadway, two conclusions were drawn： one is that the co-deformation among roadway groups mainly reflect on that both shear failure and deformation in coal pillar among roadways have decreased the width of pillar core region and clamping action of coal pillar to roof strata, increased the actual span of roof strata, intensified the flexural failure of roof strata and prized the bed separation of roof deep rock strata. The other conclusion is that the factors controlling the interactive deformation among roadways is obvious when appropriate re-adjustment in construction sequence of the tunneling of multimine parallel roadways because the construction sequence among roadways also has great effects on deformation of the surrounding rock in roadway.

Feasibility analysis of gob-side entry retaining on a working face in a steep coal seam

Based on the decline in exploitation of coal resources, steep coal seam mining and mining face tensions continue to explore the feasibility analysis of steeply inclined faces in the gob. One of the key factors in utilizing the technology of gob-side entry retaining in steep coal seams is to safely and effectively prevent caving rock blocks from rushing into the gob-side entry by sliding downwards along levels. Using theoretical analysis and field methods, we numerically simulated the mining process on a fully-mechanized face in a steep coal seam. The stress and deformation process of roof strata has been analyzed, and the difficulty of utilizing the technology is considered and combined with practice in a steep working face in Lvshuidong mine. The feasibility of utilizing the technology of gob-side entry retaining in a steep coal seam has been recognised. We propose that roadways along the left lane offshoot body use a speciallymade reinforced steel dense net to build a dense rock face at the lower head. The results show that the lane offshoot branch creates effective roof control, safe conditions for roadway construction workers, and practical application of steeply inclined gob.

Theoretical analysis on the deformation characteristics of coal wall in a longwall top coal caving face

Against the background of analyzing coal wall stability in 14101 fully mechanized longwall top coal caving face in Majialiang coal mine,based on the torque equilibrium of the coal wall,shield support and the roof strata,an elastic mechanics model was established to calculate the stress applied on the coal wall.The displacement method was used to obtain the stress and deformation distributions of the coal wall.This study also researched the influence of support resistance,protective pressure to the coal wall,fracture position of the main roof and mining height on the coal wall deformation.The following conclusions are drawn:(1) The shorter the distance from the longwall face,the greater the vertical compressive stress and horizontal tensile stress borne by the coal wall.The coal wall is prone to failure in the form of compressive-shear and tension;(2) With increasing support resistance,the revolution angle of the main roof decreases linearly.As the support resistance and protective force supplied by the face guard increases,the maximum deformation of the coal wall decreases linearly;(3) As the face approaches the fracture position of the main roof,coal wall horizontal deformation increases significantly,and the coal wall is prone to instability;and(4) The best mining height of 14101 longwall face is 3.0 m.

Prediction of representative deformation modulus of longwall panel roof rock strata using Mamdani fuzzy system

Deformation modulus is the important parameter in stability analysis of tunnels, dams and mining struc- tures. In this paper, two predictive models including Mamdani fuzzy system （MFS） and multivariable regression analysis （MVRA） were developed to predict deformation modulus based on data obtained from dilatometer tests carried out in Bakhtiary dam site and additional data collected from longwall coal mines. Models inputs were considered to be rock quality designation, overburden height, weathering, unconfined compressive strength, bedding inclination to core axis, joint roughness coefficient and fill thickness. To control the models performance, calculating indices such as root mean square error （RMSE）, variance account for （VAF） and determination coefficient （R^2） were used. The MFS results show the significant prediction accuracy along with high performance compared to MVRA results. Finally, the sensitivity analysis of MFS results shows that the most and the least effective parameters on deformation modulus are weatherin~ and overburden height, respectively.