Numerical simulation for influence of excavation and blasting vibration on stability of mined-out area

Dynamic analysis steps and general flow of fast lagrangian analysis of continua in 3 dimensions(FLAC3D) were discussed. Numerical simulation for influence of excavation and blasting vibration on stability of mined-out area was carried out with FLAC3D. The whole analytical process was divided into two steps, including the static analysis and the dynamic analysis which were used to simulate the influence of excavation process and blasting vibration respectively. The results show that the shape of right upper boundary is extremely irregular after excavation, and stress concentration occurs at many places and higher tensile stress appears. The maximum tensile stress is higher than the tensile strength of rock mass, and surrounding rock of right roof will be damaged with tension fracture. The maximum displacement of surrounding rock is 4.75 mm after excavation. However, the maximum displacement increases to 5.47 mm after the blasting dynamic load is applied. And the covering area of plastic zones expands obviously, especially at the foot of right upper slope. The analytical results are in basic accordance with the observed results on the whole. Damage and disturbance on surrounding rock to some degree are caused by excavation, while blasting dynamic load increases the possibility of occurrence of dynamic instability and destruction further. So the effective supporting and vibration reducing measures should be taken during mining.

Study on the Water Surge Height Line of Landslide Surge of Linear River course Reservoir Based on FLOW-3D

The occurrence and transmission attenuation of surge is always a problem that researchers pay much attention to. The influence of the first wave height of landslide surge and the following transmission attenuation of surge are involved with many factors, which are mainly： landslide water entry angle, river course depth, river course geometrical properties and landslide mass and material, etc.. This thesis is mainly a research on the properties and transmission attenuation rules of landslide surge which is caused by linear narrow river course. Numerical value simulation will be applied in this thesis to discuss about the features and rules of the occurrence and transmission of surge in different landslide water entry angles and under different influences.

Numerical Study on Effect of Longwall Mining on Stability of Main Roadway under Weak Ground Conditions in Indonesia

The purpose of this research is to study the effect of longwall mining on the stability of main roadway in the underground coal mine. The PT GDM （Gerbang Daya Mandiri） underground coal mine in Indonesia, where the rocks are weak, was selected as a representative study site. To accomplish the objective of the research, the finite difference code software FLAC3D was used as a tool for the numerical simulations. The longwall mining of several panel and barrier pillar widths at various depths was simulated and discussed. Based on the simulation results, it indicates that the effect of coal panel extraction on the main roadway stability depends on the width of panel and barrier pillar. The greatest effect occurs when the large panel width and the small barrier pillar width are applied, whereas the smallest effect happens when the narrow panel width and the large barrier pillar width are adopted. In this paper, therefore, to maintain the stability of the main roadway with the aim of maximizing the coal recovery, the appropriate size of panel and barrier pillar width is proposed for each mining depth for this underground coal mine.

Linear stability theory with the equivalent spanwise wavenumber correction in 3D boundary layers

The prediction on small disturbance propagation in complex three-dimensional(3D) boundary layers is of great significance in transition prediction methodology, especially in the aircraft design. In this paper, the linear stability theory(LST) with the equivalent spanwise wavenumber correction(ESWC) is proposed in order to accurately predict the linear evolution of a disturbance in a kind of boundary layer flow with a vital variation in the spanwise direction. The LST with the ESWC takes not only the scale of the mean flow with the significant variation but also the wavenumber evolution of the disturbance itself. Compared with the conventional LST, the results obtained by the new method are in excellent agreement with those of the numerical simulations. The LST with the ESWC is an effective method on the prediction of the disturbance evolution in 3D boundary layers, which improves the prediction of the LST in the applications to complex 3D boundary layers greatly.

Analysis of stability of coal pillars with multi-coal seam strip mining

Strip mining is one of the efficient measures to control surface subsidence and mining damage. However, the researches on the laws of the geological mining factors to upper and lower pillar's stability are still deficient in multi-coal seam strip mining at present. Based on the three dimension fast Lagrangian analysis of continua (short for FLAC3D) numerical simulation software, the laws of the stress increasing coefficient on the coal pillar and its stability were systematically studied for different depths, different mining widths, different interlayer spacings, different mining thicknesses, different properties of interstratified rock and the spacial relations of the upper and lower pillars in vertical alignment in multi-coal seam strip mining. The function relation between the stress increasing coefficient of upper and lower pillars with the mining depth, mining widths, interlayer spacing, mining thickness, property of interstratified rock and the spatial relationship were obtained.

Beach stabilization by the laying of a drainage layer

In the present study, the stabilization effects of the laying of a drainage layer in a sandy beach were analyzed. The numerical model developed by Hur et al. （2011） was used to examine the characteristics of wave-sandy beach interaction with/without a drainage layer. This numericai model directly simulates Wave-Structure-Seabed/Sandy （WASS） beach interaction by consid- ering flow through a porous medium with inertia, laminar and turbulent resistances, and determines the eddy viscosity with the Large Eddy Simulation （LES） turbulent model in a 3-D wave field （LES-WASS-3D）. Based on the numerical results, it ap- pears that the installation of a drainage layer in the beach results in a decrease in both the mean groundwater level around the foreshore and the flow moving offshore on the beach surface. Spatial distributions of the mean groundwater level and wave setup around the foreshore with various arrangements of the drainage layer and conditions of the incident wave are also discussed in this paper.

考虑流固耦合作用的库岸滑坡变形失稳机制

当前,在库水位下降引起滑坡变形失稳机制的认识上,仍存在不足。基于渗流计算结果,采用有效应力法对边坡进行应力变形分析和稳定性计算的传统方法,仅考虑由水体自重渗流产生孔隙水压力,而没有考虑水位下降引起滑带处的超孔压,从而产生不切实际的变形分析和稳定性计算结果,对滑坡的变形和失稳机制产生错误的认识。在流固耦合理论基础上,以黄土坡滑坡前缘临江崩滑堆积体作为工程实例,通过对泄水下滑坡流固耦合作用的数值模拟,得到应力场、变形场及孔压场的变化规律,探讨考虑应力场与渗流场耦合作用的滑坡变形失稳机制,并进行非耦合和耦合计算方案下滑坡稳定性变化趋势。研究结果表明,库水位下降引起滑带附近的超孔隙水压力是诱使滑坡变形和失稳的重要原因。

西气东输管道工程EJ065桩附近边坡稳定性分析

西气东输管道工程EJ0 6 5桩附近边坡陡峻 ,并处于强震区 ,必须进行墩位地基所在岩体和岩壁边坡稳定性评价 (包括震动条件下 ) ,以评价跨越墩位的适宜性。通过野外地质调查确定研究区的区域地震活动、工程地质条件和受力边界条件 ,采集样品进行测试获取岩体的基本物理力学指标 ,作者进行了不同条件下 (天然、饱和、震动力 )的边坡三维模拟定量分析 ,评价了边坡的稳定性 。

露天转地下开采岩体稳定性三维数值模拟

露天转地下开采围岩应力和工程尺度同时影响着地下工程和露天边坡的稳定性.通过三维数值模拟,揭示了露天边坡内地下开采采场周围和边坡的力学环境,探讨了围岩移动变形、应力分布和破坏机理,分析了边坡稳定性状况.研究表明,在扰动边坡下进行地下开采,坡脚处的局部弧形破坏区将进一步恶化,但不会影响边坡的整体稳定性.由于边坡的卸荷作用,导致采场上覆岩层成拱机制减弱,采空区覆岩存在整体垮冒的可能性.

露天矿最终边坡角的数值模拟研究

为了合理确定露天矿最终边坡角,在岩石力学试验和工程地质调查研究的基础上,分别应用三维弹性有限元程序ANSYS、三维弹塑性有限元程序PHASE2和三维黏弹塑性有限元程序EVP模拟最终边坡角为42°、50°、53°的开挖模式。建立计算模型时,最终台阶坡面角取65°;按照《矿山安全规程》,台阶高度12 m时,安全平台宽度取4 m,清扫平台宽度取6 m;台阶高度14m时,安全平台宽度取5 m,清扫平台宽度取8 m。结果表明,上帮最终边坡角不超过48°,下帮最终边坡角不超过50°,端帮最终边坡角不超过49°。较原有设计上帮可增大6°,下帮可增大8°～10°。

东坪金矿采空区开挖过程的三维有限元数值模拟

结合东坪金矿南山采区1号空区的工程实际,采用Plaxis 3D Tunnel对其建立三维数值模型,并对其不同开挖顺序的开挖过程进行数值模拟。通过对开采过程中的地压活动规律和围岩稳定性进行分析,论证了地下采空区开挖方案的可行性,揭示了采空区不同开挖阶段应力的集中部位和围岩的潜在破坏部位。计算表明该空区由上向下开挖顺序较为有利,其开挖过程总体可以保持稳定,但也存在不安全隐患。计算结果对该矿山的安全生产具有指导意义。

龙滩水电站地下厂房主支洞交叉处稳定性分析

根据龙滩水电站地下厂房巨型地下洞室群的布置情况,结合洞室围岩为顺层断层和节理发育的高陡倾角层状岩体的地质特点,建立了三维有限元计算模型,并针对主支洞交叉处岩体的稳定性分析进行了分步开挖下的弹塑性数值模拟。计算结果表明:主支洞交叉处的岩体是应力松弛和塑性区的主要分布区域,该处岩体变形量大,具有明显的非对称性。现有的加固方案是有效、安全的,这一结果可供工程参考。

土石坝坡三维随机有限元整体可靠度分析

考虑边坡工程中土的物理力学参数在三维空间上分布的随机变异特性,建立了抗剪强度折减法和蒙特卡罗法相结合的随机有限元法,用以计算边坡的整体稳定可靠度。以某心墙土石坝为例,对土料的容重、凝聚力和内摩擦角的三维空间随机场进行了模拟,计算了整体稳定可靠度。计算结果表明,该方法用于边坡整体稳定可靠度分析是切实可行的。

三维可压缩混合层中扰动演化的研究

为了利用被动控制增强可压缩混合层中混合效率,本文用数值模拟的方法研究了三维可压缩混合层中扰动向下游的演化。通过在入口处引入不同的不稳定T-S波,给出了扰动随空间的演化过程,及马赫数对扰动演化的影响。计算结果表明在马赫数较小时,扰动波增长很快,当马赫数增大时,扰动所形成的流向涡的强度会减弱。这一结论与流动稳定性分析结果是一致的。

基于ArcGIS和ICMP的矿山边坡自动数值建模与分析研究

以晋宁磷矿露采边坡为例,利用ArcGIS软件建立了边坡三维地层可视化模型,开发了转化插件;从三维地层模型截取典型二维地质断面,导出二维断面地层几何信息及材料信息;利用独立覆盖无网格质点法实现了从ArcGIS地层模型到数值计算模型的自动建模,并对该露采边坡典型断面进行了稳定性分析。应用实例验证了研究方法的正确性、实用性,及其良好的工程应用前景。

深埋软岩输水隧洞变形控制技术

泥岩及砂质泥岩均为典型的软弱围岩,受水浸泡后力学性质严重恶化。某隧洞在里程K4+000～K4+350段围岩以泥岩、砂质泥岩为主,埋深232～286 m。隧洞在向上游掘进过程中,由于含水量明显增大,围岩稳定性降低并出现塌方。随后加强支护参数,施工方法由全断面法改为台阶法,并采用数值方法进行施工过程的数值模拟,分析了锚杆、钢架、喷层的应力分布特征。三维数值计算分析结果和现场隧洞断面变形监测结果均表明,加强后的支护参数和施工方法能够保证隧洞施工安全。