赵楼煤矿1 000 m深孔水压致裂地应力测量及其应力场研究

 赵楼煤矿是目前国内开采最深的非金属矿山之一,处于曹县-郓城活动断裂带上,区内地质构造较为复杂。为了掌握矿区原岩应力场分布规律,应用深孔水压致裂地应力测量技术开展地应力测量工作,获得该矿区2个钻孔中16个测段的应力状态。测量结果表明：矿区最大主应力随深度增加基本呈线性增大,且在800 m深度处应力值有所变化,最大水平主应力为28.45～45.75 MPa,方向NEE,反映出矿区地应力场以水平应力为主导的特点,测量结果可为矿山建设和开采设计提供科学依据。     

煤矿井下地质构造对地应力分布的影响

采用小孔径水压致裂地应力测量装置,在典型的急倾斜、特厚煤层矿区——甘肃华亭矿区的大型向斜构造附近进行14个测站地应力测量,以分析向斜构造不同部位的地应力变化。实测数据表明:华亭煤矿、砚北煤矿井下构造应力占绝对优势;在向斜翼部,水平应力较小;在向斜轴部,水平应力急剧增加,增加幅度远大于垂直应力;向斜构造对矿区地应力分布产生严重影响。基于山西晋城矿区的地应力实测数据,分析断层对地应力值与方向的影响。断层附近某些区域水平应力有所减小,大型断层会引起最大水平主应力方向的扭转。在实测数据基础上,采用FLAC3D数值计算软件,分析华亭矿区大型向斜构造周围地应力场分布,并与地应力实测数据进行对比。将地应力实测与数值模拟有机结合,是全面了解煤矿井下地应力场分布特征的有效途径。     

晋城矿区地应力场研究及应用

 随着矿井开采深度与强度的不断增加,地应力对围岩变形与破坏的影响更加突出,在煤矿矿区进行地应力测量,并分析地应力场分布特征具有重要意义。在晋城矿区,采用小孔径水压致裂地应力测量装置,进行10个煤矿、62个测点的二维与三维地应力测量。实测数据表明：晋城矿区原岩应力以水平应力为主,构造应力占绝对优势,属于典型的构造应力场类型;地应力值属于中等水平;矿区东部与西部水平主应力方向变化较大,主要原因是受晋获褶断带的影响。基于实测数据,绘制晋城矿区地应力分布图;采用回归方法分析地应力随埋藏深度的变化规律;论述水平主应力与垂直主应力的比值同埋藏深度的关系,并与霍克–布朗包线进行比较。选择典型矿井,将地应力测量结果应用于巷道布置与支护设计,根据地应力场分布特征提出合理的巷道轴线布置方向,并在井下应用中得到验证。井下地应力测量为晋城矿区提供了可靠的基础数据,对指导矿区井田开拓、巷道布置与支护设计、采煤方法的选择等工程实践具有重要参考价值。     

北岭煤矿地应力测量及其特征分析

为弄清北岭煤矿浅部应力状态及分布特征,采用空心包体应力解除法进行地应力测量。结果表明:该区的地应力以水平构造应力为主,且均为压应力;最大主应力位于近水平方向,为近东西向;各测点均有两个主应力接近水平方向,另一个主应力接近垂直方向,垂直主应力值基本等于自重应力;位于近水平面内的两个主应力值相差较大,三个测点近水平面内的两个主应力的比值分别为1.83、1.88、1.84;在同一平面内,地应力的大小和方向没有出现突变现象,说明矿区的地应力场比较均匀。此次地应力测量为矿区进行围岩稳定性分析及开挖设计科学化提供了理论依据。     

万福煤矿深部水压致裂地应力测量

为了克服煤田上覆冲击层厚度高达700m所造成的困难，保证超千米深部地应力测量的成功，对传统水压致裂法测量方法和设备进行改进，增加测量系统的耐压能力和测试系统的精度。在完成的7个钻孔、37个测点的现场实测中，6个钻孔的深度接近和超过1100m，最大测点深度为1105m，创造了我国水压致裂法测量地应力钻孔深度的新记录。通过实测，确定了矿区的地应力状态及其分布规律。研究结果表明，37个测点的最大水平主应力与垂直主应力的比值为1．441～3．224，平均为1．97，反映了矿区地应力场以水平应力为主导的特点。测量结果可为矿山建设和开采设计提供科学的依据。     

灰色建模理论在峨口铁矿地应力分布 规律研究中的应用

介绍了峨口铁矿地应力测量的结果，根据地应力实测数据，使用灰色建模理论建立了矿区地应力分布规律的模型。分析表明，在峨口铁矿使用水压致裂法和应力解除法两种不同方法所获得的测量结果服从相同的分布规律，具有良好的一致性     

玲珑金矿深部地应力测量及矿区地应力场分布规律

 介绍玲珑金矿主矿区深部和浅部两期地应力测量的过程和结果。为提高测量结果的可靠性和准确性,采用完全温度补偿技术和实现完全温度补偿的空心包体应变计等一系列新的技术和方法,对传统的应力解除法进行重大改进。通过实测,获得矿区7个水平,18个测点的三维地应力大小和方向。根据实测结果,对玲珑金矿主矿区地应力场的分布规律进行定量的综合分析与研究。研究结果表明：(1) 玲珑金矿主矿区地应力场以水平构造应力为主导,最大水平主应力平均为自重应力的2.26倍;(2) 最大水平主应力的走向为NW向,基本与区域构造应力场最大主应力的方向相一致;(3) 垂直主应力值基本上等于或略大于自重应力值;(4) 深部与浅部相比,尽管岩性有较明显变化,但地应力场分布规律并没有显著改变;(5) 最大水平主应力、最小水平主应力和垂直主应力值均随深度呈几乎线性增长关系。     

深部矿井地应力测量方法研究与应用

目前地应力测量方法有很多种,可分为力学法、地球物理法及地质构造信息法等。在分析各种测量方法特点的基础上,介绍适用于深部煤矿巷道的地应力快速测量方法——小孔径水压致裂地应力测量法,包括小孔径水压致裂地应力测量原理、测量装置的组成部分和技术特征。在我国煤矿典型的深部矿区——新汶矿区井下巷道中,完成9个测点的地应力测量。其中5个测点的埋深超过1000m,最深达1220m。测量结果表明,7个测点的最大水平主应力大于垂直主应力;最大水平主应力高达42.1 MPa;最大水平主应力与垂直主应力的比值为1.004～1.550;新汶矿区超过1 000 m深井地应力以水平应力为主,最大水平主应力方向主要集中在N3°E～N43.5°W。通过井下实测,确定出所测区域地应力状态及其分布规律。同时证明,小孔径水压致裂地应力测量法可为深部矿井提供有效、快速的地应力测量手段,为深部巷道布置和支护设计优化提供可靠的基础参数。     

金川二矿区深部地应力测量及其分布规律研究

介绍了金川有色金属公司二矿区深部地应力测量的方法、过程和结果。通过现场实测获得二矿区深部３个水平１０个测点的三维地应力状态,揭示了二矿区深部地应力分布的基本规律     

应力解除法在某金矿地应力测量中的新进展

本文介绍了应力解除法在胶东某金矿地应力测量中的应用。在测量过程和结果计算中使用了改进型空心包体应变计，完全温度补偿技术，自动数据采集记录系统和双迭代法求解测点Ｋ系数、岩石弹性模量、泊松比和地应力的新方法，有效在保证了测量结果的精度。矿区地应力场实测结果和区域构造应力场显示了良好的一致性，有力地证明了实测结果的可靠性和正确性。     

深部高地应力巷道断面优化研究

巷道失稳和维护困难是困扰高地应力深部矿井的普遍问题,严重影响矿井的生产和经济效益的提高。深部矿井高地应力巷道有其自身的应力分布特点,对巷道的支护设计提出了更高的要求。研究从巷道断面优化着手,根据深部矿井高地应力巷道的地质赋存特征,结合淮南-780m水平现场地应力测试及室内岩石物理力学性质测试结果,运用FLAC3D三维显式有限差分法分析软件,建立巷道支护的三维数值计算模型,通过对几种方案巷道周边塑性区分布、应力场、位移场等的分析对比,得到了较为易于维持巷道稳定的巷道断面优化设计方案。     

Numerical modelling of ore dilution in blasthole stoping

The paper presents the results of a study of the factors causing stope wall overbreak or ore dilution in a blasthole stoping environment. A series of three-dimensional numerical models are developed and analyzed to examine the effect of mining depth, in situ stress as well as stope geometry and orientation on stope wall overbreak. A characteristic orebody and mine design configuration is adopted and used as a basis to carry out comprehensive model parametric study, from which a simple, graphical design tool is derived for the prediction of stope overbreak. It is shown that stope overbreak is significantly affected by the stope aspect ratio and the orientation of major principal in situ stresses with respect to the stope. The methodology presented in this paper can be adopted to develop mine-specific design tools for the estimation of ore dilution associated with a proposed mine design. This can be extremely helpful in the process of underground mine planning and optimization.     

Slope stability assessment of an open pit using lattice-spring-based synthetic rock mass (LS-SRM) modeling approach

Discontinuity waviness is one of the most important properties that influence shear strength of jointed rock masses, and it should be incorporated into numerical models for slope stability assessment. However, in most existing numerical modeling tools, discontinuities are often simplified into planar surfaces. Discrete fracture network modeling tools such as MoFrac allow the simulation of non-planar discontinuities which can be incorporated into lattice-spring-based geomechanical software such as Slope Model for slope stability assessment. In this study, the slope failure of the south wall at Cadia Hill open pit mine is simulated using the lattice-spring-based synthetic rock mass (LS-SRM) modeling approach. First, the slope model is calibrated using field displacement monitoring data, and then the influence of different discontinuity configurations on the stability of the slope is investigated. The modeling results show that the slope with non-planar discontinuities is comparatively more stable than the ones with planar discontinuities. In addition, the slope becomes increasingly unstable with the increases of discontinuity intensity and size. At greater pit depth with higher in situ stress, both the slope models with planar and non-planar discontinuities experience localized failures due to very high stress concentrations, and the slope model with planar discontinuities is more deformable and less stable than that with non-planar discontinuities.     

Stress measurements from oriented core

A low-cost methodology that allows the estimation of in situ and induced stress using oriented rock core specimens has been investigated. The technique can be used to determine the stresses either during the early stages of a project, even in undeveloped areas of a mine, or to measure in situ and induced stress within active mine workings, such as stopes and pillars. The research aim was to compare the experimental results estimated by the Acoustic Emission and Deformation Rate Analysis methods with those estimated by conventional HI cell measurements. Data was collected from a number of sites with different geological environments and in most cases the core was obtained from the same hole in which a conventional stress measurement had been carried out. The studies have focused on the determination of the full stress tensor from a single oriented cored rock. In all cases, the rock core specimens recollected similar in situ stress values to those estimated using conventional overcoring methods.     

西石门铁矿地应力量测与应力场的反分析

本文通过西石门铁矿的地应力量测和应力场的反分析,对该矿区地应力场首次进行了系统的研究,提出了西石门铁矿的应力场是以水平应力为主的旋转压应力场,从南到北,其水平主应力方向为北东→北南→北西向;揭示了水平主应力随深度变化的规律以及平均水平主应力与垂直主应力之比“K”值随深度变化的规律;并从力学角度探讨了应力场与井下巷道稳定、采矿工程设计之间的关系,为地下采矿科学化提供了理论依据。     

Quantifying stresses and support requirements in the undercut and production level drifts of block and panel caving mines

A numerical modelling strategy has been developed in order to quantify the magnitude of induced stresses at the boundaries of production level and undercut level drifts for various in situ stress environments and undercut scenarios. The results of the stress modelling were in line with qualitative experiential guidelines and a limited number of induced stress measurements documented from caving sites.A number of stress charts were developed which quantify the maximum boundary stresses in drift roofs for varying in situ stress regimes, depths and undercut scenarios. This enabled many of the experiential guidelines to be quantified and bounded.A limited number of case histories of support and support performance in cave mine drifts were compared to support recommendations using the NGI classification system. The stress charts were used to estimate the Stress Reduction Factor for this system. The back-analyses suggested that the NGI classification system might be able to give preliminary estimates of support requirements in caving mines with modifications relating to rock bolt length and the support of production level intersections.     

Evaluation of earthquake impact on magnitude of the minimum principal stress along a shotcrete lined pressure tunnel in Nepal

In situ stress condition in rock mass is influenced by both tectonic activity and geological environment such as faulting and shearing in the rock mass.This influence is of significance in the Himalayan region,where the tectonic movement is active,resulting in periodic dynamic earthquakes.Each large-scale earthquake causes both accumulation and sudden release of strain energy,instigating changes in the in situ stress environment in the rock mass.This paper first highlights the importance of the magnitude of the minimum principal stress in the design of unlined or shotcrete lined pressure tunnel as water conveyance system used for hydropower schemes.Then we evaluated the influence of local shear faults on the magnitude of the minimum principal stress along the shotcrete lined high pressure tunnel of Upper Tamakoshi Hydroelectric Project(UTHP) in Nepal.A detailed assessment of the in situ stress state is carried out using both measured data and three-dimensional(3 D) numerical analyses with FLAC~(3 D).Finally,analysis is carried out on the possible changes in the magnitude of the minimum principal stress in the rock mass caused by seismic movement(dynamic loading).A permanent change in the stress state at and nearby the area of shear zones along the tunnel alignment is found to be an eminent process.     

复杂断层扰动下的原岩应力场的数值分析与评价

在分析复杂断裂构造扰动下的矿山区域原位多点实测地应力分布特点的基础上 ,通过建立适合矿山工程岩体地质特点的参数式数值分析模型 ,采用位移不连续法 (DDM)及基于有限实测点的逐次逼近相结合的方法模拟了工程区域的复杂断裂构造应力场 ,得到了与实测值良好吻合的结果。并通过对数值计算所得的水平面内的次主应力分布特征的分析 ,探讨了复杂断裂构造对区域岩体初始应力状态的影响。研究结果表明 :区域原岩应力状态宏观上主要受几何尺寸大的断层的支配 ,局部范围内受复合断层的叠加扰动影响 ,造成了原岩应力状态的各向异性及非均匀分布特征。     

三山岛金矿地应力场与地质构造关系分析

结合现场地应力测量，对三山岛金矿区地质构造进行了细致分析。研究了矿区地应力场分布规律及其与地质构造的关系．实测的三维地应力状态与区域构造应力场显示了良好的一致性，证明了实测结果的可靠性和正确性，对矿山开采设计具有重要的指导意义．