基于PHASE2D的充填开采工作面覆岩稳定性研究

为了研究不同开采步距及煤层厚度对充填开采工作面围岩稳定性影响,采用PHASE 2D有限元软件建立数值模型。结果表明:开采步距由3 m增至5 m时,工作面前方塑性区略为减小,直接顶下沉量减小6.4 mm,岩层垂直位移减小19%。煤层开采厚度由3 m增至5 m时,工作面前方塑性区显著增大,直接顶下沉量及岩层垂直位移分别增大29%和25%。研究显示适当加快开采速度或开采厚度较小能够降低煤壁破坏范围和提高围岩稳定性。

力学参数对围岩塑性变形影响的敏感性分析

不同力学参数对围岩塑性变形影响存在差异性,即存在参数影响的敏感性排序问题。若能确定各参数的敏感性排序,则可有针对性地对高敏感性力学参数予以精细化测定。基于大岗山水电站地下厂房区Ⅲ类围岩力学参数原始测试数据,在分析其概率分布特征后,以尾水调压室某横断面为例,应用敏感性分析方法,借助PHASE2D数值模拟软件详细探讨了围岩力学参数,如变形模量、泊松比、凝聚力、内摩擦角、抗拉强度等对围岩塑性变形的影响程度。结果表明,对围岩变形起控制性作用的影响因子为变形模量,而对塑性区范围起到控制性影响的则为凝聚力和内摩擦角。

高水平应力下大断面巷道围岩破坏机理及支护方案

为研究水平构造应力下大断面巷道围岩破坏机理,基于压力拱理论分析了巷道跨度对巷道围岩稳定的影响,并在理论上分析了水平构造应力对巷道顶板和两帮的影响,通过建立PHASE2D数值模型,分别模拟了不同巷道断面和水平应力下的巷道围岩应力和位移分布,表明巷道跨度的增大对巷道顶板两侧有较大影响,使其水平和垂直应力集中系数增大,强度系数减小,巷道顶板两侧围岩更易失稳破坏。随着侧压系数增大,巷道两帮强度系数大范围减小,表明水平应力的增大会使两帮煤体发生破坏。最后通过具体案列对理论分析结果进行了验证,提出了合理的支护方案。

Design of Overall Slope Angle and Analysis of Rock Slope Stability of Chadormalu Mine Using Empirical and Numerical Methods

In engineering projects associated with rock mechanic science like open pit mines, assessment and slope stability of mine walls is one of the important performance in generate of these structures. Estimating and knowledge of stable slope angle is one of main parts that should be occurring to special attention in open pit mines studies phase. Considering the importance of economic costs in mining issues, the need for appropriate design slope angle that can cause an adverse minimize project costs and throws the other hand, the stability conditions in the safe walls of the mine life will provide essential and seems obvious. Therefore, in this study to determine the optimal slope angle of overall and bench of west wall of the Chadormalu ore iron mine, has been trying, first, done field studies on the discontinuity of western wall, engineering classification and geomechanical properties of rock masses of wall, then assess the amount of optimal slope angle using empirical method. Finally, in order to ensure stability and accuracy of the wall slope angle based on the obtained (empirical method) tries to analysis is amount of Factor of Safety (FOS), displacements and mean stress condition atwalls calculated from drilling use Phase2D powerful software.

上覆荷载对采煤旧巷道稳定性影响状况分析

矿区采煤旧巷道错综复杂,上覆新修建筑物必对巷道稳定性产生显而易见影响,并直接关系上覆建筑物的服役寿命,亦是煤矿矿区安全状况的重要隐患,本文选取存在有典型地下采空区的煤矿矿区,详细分析新建建筑物建成后对地下采煤巷道稳定性的影响,采用有限元分析软件PHASE2D分析上覆荷载对地下采煤巷道稳定性状况的影响作用,并得出了有针对性的稳定性处置建议,根据现场钻探、物探检测及后期施工结果表明,本文分析结果合理、处置建议相对准确,该研究可为矿区研究上覆荷载对采煤旧巷道的稳定性状况影响分析具有一定借鉴意义。

A case study of multi-seam coal mine entry stability analysis with strength reduction method

In this paper,the advantage of using numerical models with the strength reduction method(SRM) to evaluate entry stability in complex multiple-seam conditions is demonstrated.A coal mine under variable topography from the Central Appalachian region is used as a case study.At this mine,unexpected roof conditions were encountered during development below previously mined panels.Stress mapping and observation of ground conditions were used to quantify the success of entry support systems in three room-and-pillar panels.Numerical model analyses were initially conducted to estimate the stresses induced by the multiple-seam mining at the locations of the affected entries.The SRM was used to quantify the stability factor of the supported roof of the entries at selected locations.The SRM-calculated stability factors were compared with observations made during the site visits,and the results demonstrate that the SRM adequately identifies the unexpected roof conditions in this complex case.It is concluded that the SRM can be used to effectively evaluate the likely success of roof supports and the stability condition of entries in coal mines.

Large bandgap oscillations in two-dimensional Dion–Jacobson phase perovskites caused by coherent longitudinal acoustic phonons [Invited]

Two-dimensional Dion–Jacobson(D-J)phase perovskites are prospective photovoltaic and optoelectronic materials.To study their mechanical properties and carrier-lattice interactions,we conduct femtosecond spectroscopic experiments on the films of a D-J perovskite.After optical excitation,a∼33 meV bandgap oscillation is observed in the film by transient absorption spectroscopy.With the help of transient reflection methods,we reveal that the oscillation originates from the transport of coherent longitudinal acoustic phonons through the film.Large bandgap oscillation indicates a strong coupling between carriers and lattice,and significant bandgap modulation by strains in D-J perovskites.

Molecular Scaffold Growth of Two-Dimensional, Strong Interlayer-Bonding-Layered Materials

Currently,most two-dimensional(2D)materials that are of interest to emergent applications have focused on van der Waals–layered materials(VLMs)because of the ease with which the layers can be separated(e.g.,graphene).Strong interlayer-bonding-layered materials(SLMs)in general have not been thoroughly explored,and one of the most critical present issues is the huge challenge of their preparation,although their physicochemical proper-ty transformation should be richer than VLMs and deserves greater attention.MAX phases are a classi-cal kind of SLM.

Real-time decay of fluorinated fullerene molecules on Cu（001） surface controlled by initial coverage

In this study, the evolution of C60F18 molecules on a Cu（001） surface was studied by means of scanning tunneling microscopy and density functional theory calculations. The results showed that fluorinated fuUerenes （tortoise-shaped polar C60F18） decay on Cu（001） surfaces by a step-by-step detachment of F atoms from the C60 cage. The most favorable adsorption configuration was realized when the F atoms of C60F18 pointed towards the Cu surface and six F atoms were detached from it. The results also showed that a further decay of C60F12 molecules strongly depended on the initial C60F18 coverage. The detached F atoms initially formed a two-dimensional （2D） gas phase which then slowly transformed into F-induced surface structures. The degree of contact between the C60F12 molecules and the Cu（001） surface depended on the density of the 2D gas phase. Hence, the life-time of fluorinated fullerenes was determined by the density of the 2D gas phase, which was affected by the formation of new F-induced structures and the decay of C60F12 molecules.