金川镍矿Ⅱ号矿体深部地应力场及工程稳定性研究

【作者】 刘卫东；

【导师】 李峰；

【作者基本信息】 昆明理工大学 ， 矿产普查与勘探， 2013， 博士

【摘要】 金川镍矿区由于受到过多次地质历史时期构造运动影响,矿区范围内断裂、节理、裂隙十分发育,加之目前金川镍矿区仍处于构造活动期,给地面和地下工程的稳定带来极为不利的影响。矿区内的Ⅱ号矿体进入深部开采后,随着多中段同时开采以及扩能改造工程的逐步实施,采动影响越来越剧烈,巷道围岩碎胀蠕变明显,岩体整体性、稳定性极差,地表裂缝扩展,地面沉降加剧,应力值增大,深部巷道和采场稳定性控制问题日愈突出。及时掌握采场及周边的应力分布变化规律和变形规律,适时地提出保障矿山安全生产的合理化建议,为矿山工程的设计和巷道支护方法的选择以及充填体强度选择提供科学依据,是迫在眉睫的问题。本论文以金川集团公司重大科研项目《金川矿区应力场与岩石力学研究》及科技攻关项目《金川矿山深部高强度采掘条件下的岩石力学研究》为依托,针对金川镍矿Ⅱ号矿体深部开采过程中遇到的岩石力学及工程问题而开展工作。首先对金川镍矿区地质条件及岩体深部变形特征进行系统的调查分析及研究；其次系统的收集、整理、分析了金川镍矿区近几十年来地应力测量工作及取得的成果,在此基础上选取具有代表性的工作区域进行地应力实测,获得矿区深部地应力重要数据,开展矿区浅部与深部地应力特征的对比分析研究；然后,根据金川镍矿Ⅱ号矿体深部开采情况,选取Ⅱ号矿体F17断层以西的1000m、1150m和F17断层以东的1200m中段进行地应力现场实际测量；最后结合Ⅱ号矿体深部应力分布及变形特征,通过FLAC3D软件对Ⅱ号矿体深部大面积连续开采矿柱及深部巷道稳定性进行分析。通过上述工作获得以下主要成果：1、提出最大主地应力值随深度的变化是非线性的,浅部变化曲线的斜率较小,最大主应力随深度增加而增大的较快,深部变化曲线的斜率较大,最大主应力随深度增加而增大的较慢,深浅部应力变化的拐点大致在埋深400m的位置。2、研究发现矿区深部地应力分布与地质构造密切相关,而且明显受开采扰动的影响,造成深浅部最大主应力方向有所不同,浅部最大主应力方向以NNE-NE向为主；深部最大主应力方向以SSW-SW向为主,更加趋于复杂化；3、Ⅱ号矿体深部最大主应力倾角和中浅部相比明显不同。中浅部测点最大主应力倾角较小,最大主应力基本为近水平状态,矿体深部最大主应力倾角明显增大。本次测量深部多数最大主应力为倾斜状态,倾角已接近或超过40。,说明水平应力的主导性在深部采区中在逐渐减弱；矿体深部最大主应力量值与最小主应力量值的差值增大,剪应力增大,剪切破坏强度加大,这对矿山深部工程稳定具有十分不利的影响；4、在矿体深部地应力测量基础上,采用FLAC3D软件对Ⅱ号矿体深部大面积连续开采时,双中段开采水平矿柱及垂直矿柱稳定性进行了对比分析研究。5、对高地应力条件下深部巷道破坏及巷道支护机理分析探讨表明：随着巷道埋深的增加、围岩压力逐渐增大,巷道水平压力大于垂直压力；巷道不对称变形破坏严重,巷道一帮侧压内挤变形量常常大于另一帮；垂直压力为主的地段,巷道两侧形成剪切滑移体,侧墙易于产生不规则开裂及拱顶压坏现象；巷道底鼓现象显著。由于金川镍矿区地应力较高,矿岩破碎,单纯采用巷道支护的方式来控制巷道地压具有明显的局限性,因此,提出采用人工卸压和巷道支护相结合的巷道地压控制措施,对于控制巷道变形、维护巷道的稳定具有重要的指导借鉴意义。更多还原

【Abstract】 The fault, joint and fissure are very developed in the Jinchuan large scale Ni orefield owing to the effect of many times of structural movement in the geological historic period. Moreover, this area is still in the structure active period at present time, which also has very disadvantageous influence on the stability of surface and underground engineering. After the beginning of deep mining of ore body II in the orefield, the mining influence becomes more and more violent because of the simultaneous mining on several level and the progressive carrying out the expansion and reformation of production ability. The fracture, expansion and creep deformation of wall rock in tunnel are very evident. The completeness and stability of rock body are very bad. The surface fissure expands, surface sinking intensifies, stress value increases. The stability control problem of deep tunnel and mining area becomes more and more prominent. The emergency problems are to put forward the timely rationalization proposal to ensure safety in mining production and to provide the scientific foundation for selection of mine engineering design and support method of tunnel.In this paper, we aim at the lithomechanics and engineering problems in deep mining process of ore body II in Jinchuan Ni orefield basing upon the important scientific project 《The Study on the Stress Field and Lithomechanics of Jinchuan Orefield》 of Jinchuan Company(Group) and scientific project of tackling key problems《The Study on the Lithomechanics under Deep High Intensity Mining Conditions of Jinchuan Mine》. First, the geological condition of Jinchuan Ni orefield and deep deformation characteristics of rock body are systematically surveyed, analyzed and studied; second, the crustal stress measurements in Jinchuan Ni orefield in recent scores of years are gathered, put in order and analyzed, then select the representative area for the survey on the spot based upon the working mentioned above in order to achieve the important data of deep crustal stress of orefield and carry out the comparison, analysis, study of surface and deep crustal stress characteristics of orefield. Afterwards, we select the level1000m,1150m west of F17of ore body II and the level1200m east of F17for the survey on the spot according to the deep mining situation of ore body II in Jinchuan Ni orefield. Finally, the stability of deep large area continuous mining mine pillar and deep tunnel is analyzed with the software FLAC3D in combination with the deep stress distribution and deformation characteristics of ore body II. Thus, we have achieved the following important results:1. We propose that the variation of maximum principal stress value in company with the depth change is nonlinear, which is varied approximately in the cube form. The slope of shallow variation curve is gentle. The maximum principal stress increases rapidly in company with the depth. Nevertheless, the slope of deep variation curve is steep. The maximum principal stress increases slowly in company with the depth. The inflection point of stress variation from the deep to the shallow is approximately at the depth underground400m.2. According to the study, the deep crustal stress distribution of orefield is in close relation not only to geological structure but also evidently influenced by the mining disturbance, which causes the difference of maximum principal stress direction of the deep from that of the shallow. The shallow maximum principal stress direction is mainly in NNE-NE, whereas the deep one is mainly in SSW-SW, ie, it is more complicated.3. The deep maximum principal stress dip angle of ore body II is evidently different from middle-shallow ones. The maximum principal stress dip angle of middle-shallow measuring point is gentle, the maximum principal stress is basically in nearly horizontal state. The deep maximum principal stress dip angle of ore body increases clearly. In this measurement, most deep maximum principal stress data are inclined and the dip angles approach or exceed40°, which shows that the dominance of horizontal stress has been weakened progressively in the deep mining area. The difference between maximum and minimum principal stress value increases, ie, the shear stress increases. The increase of shear damage intensity has a very disadvantageous influence on the stability of deep mining workings.4. Basing upon the deep crustal stress measurement of ore body, the stability of horizontal and vertical mine pillar of dual-level mining in deep large area continuous mining of ore body II is compared, analyzed and studied with the software FLAC3D.5. The analysis of and probe into damage and support mechanism of deep tunnel under high crustal stress show that the wall rock P progressively increases in company with the increase of tunnel depth, the horizontal P higher than vertical P of tunnel, the tunnel unsymmetrical deformation damage serious, the side extruding deformation of one wall often more intense than the other in the tunnel, the shear slide body formed on both sides of tunnel in the area mainly under the vertical P, the irregular fracture on side wall and arch roof pressure damage take place easily, tunnel bottom distension evident. Because of the high crustal stress in Jinchuan Ni orefield, ore and rock fracture, the tunnel crustal P control is limited by the tunnel support form alone. Therefore, we propose the tunnel crustal P control measures combining manual P discharge and tunnel support, which have the important guide and reference significance for the tunnel deformation control and the protection of tunnel stability.更多还原