阶段嗣后充填开采采场稳定性相似材料模型试验

根据司家营铁矿南区充填法开采设计,选取南区S16勘探线附近的采场,采用相似材料模型试验的研究方法,模拟了首采-450 m中段单盘的两步开采和充填过程,借助位移计、光纤传感器和压力盒等仪器监测了试验模型的地表沉降和围岩的变形及应力分布,分析了采场变形和应力变化规律及充填体的稳定性。试验结果表明,阶段嗣后充填法开采对地表影响不大,充填可以有效控制地表岩移;开采过程中采场整体稳定性较好,但二步回采后采场顶板和间柱变形均发生较大变化,回采后应及时对阶段空场进行充填,并适当提高充填体的强度。最终成果为开展多中段多盘区的矿体开采的进一步研究提供了基础依据。     

黄土-废石胶结充填体抗压强度试验研究

宝山矿2^#砂页岩矿体采用黄土-废石胶结充填法回采。为了确定其合适的配合比,采用RMT-150B岩石力学试验机对七种配合比的黄土-废石胶结充填体的标准试样进行了抗压强度测试,利用测试结果选择C组配合比的黄土-废石胶结充填体应用于该矿工业性试验采场进行充填,并对该试验采场的充填体进行了应力测试。研究结果表明:黄土-废石胶结充填体的破坏过程分为五个破坏阶段;黄土-废石胶结充填体的强度随黄土加入量的增加而减小,随水泥加入量的增加而增加;初期强度随水泥加入量的增加而提高;选用C组配合比的黄土-废石胶结充填体充填试验采场的应力为2.25 MPa,其龄期为60 d时为原岩体的抗压强度的47.4%,满足该矿对充填体强度的要求;研究成果为其它采场选用合适的胶结充填体的配合比提供了依据。     

大采高沿空留巷围岩稳定性及形变规律分析

为了研究云驾岭矿深部大采高沿空留巷围岩稳定性及形变规律,采用理论分析、现场实测和实验室测试综合研究手段和方法,确定了试验工作面巷旁充填体支护阻力和留巷参数,构建了能够反映沿空巷道受初次采动围岩形变规律的回归函数模型,对比分析了一次和二次开采扰动下围岩的应力应变状态,探究了充填体上方顶板岩层的应力传递规律。结果表明,采用弹塑性力学模型得出的巷旁充填体的临界支护阻力和充填体宽度分别为4.1MN/m和2.47 m,经实验室测试和工业性试验,能够保持高水材料充填体的稳定。受初次采动影响,沿空巷道围岩位移量与工作面至测站点距离之间符合Slogistic增长函数模型,求解了巷道顶板、底板和下帮的最大变形量、变形量最大时工作面的位置以及达到最大变形时工作面推过观测站的时间。对于沿空巷道,工作面超前支承压力波及范围至工作面煤壁前方约34 m,留巷顶板3.8 m以浅的采动裂隙可能会导致顶锚杆锚固失稳甚至失效,充填体切顶阻力的“波动性”能够反映顶板岩层的分层垮落特征。     

金属矿滨海基岩开采岩石力学理论与实践

三山岛金矿新立矿区是我国第一个进行滨海采矿的金属矿山,大量高强度海下开采势必破坏矿岩稳定性,有必要研究金属矿海底基岩开采相关岩石力学问题。从矿山开采工程实际出发,研究滨海矿床矿岩力学特性和海底黏性土微观结构与渗透性能,开发金属矿滨海基岩开采相似物理模拟试验平台,得出滨海基岩开采合理安全隔离层厚度,并进行数值模拟对比验证分析,验证试验模拟的准确性。采用正交试验方法,以岩体稳定性为原则建立目标函数,获得滨海基岩开采最佳采场结构参数。对阶段中盘区回采顺序进行优化,得出"隔二采一"的最佳开采顺序。分析矿岩性质和矿床产状等开采技术条件,提出岩层微扰框架式上向分层充填采矿技术。新立矿区为期3a的现场滨海开采试验和现场监测结果表明:合理安全隔离层厚度、低沉降框架式上向分层充填法和现场实时监测为海底基岩开采提供了技术保障。     

沿空留巷围岩结构模型的建立及其稳定性分析

综合考虑沿空留巷围岩变形、采场覆岩运动规律及巷旁支护结构的特点,将沿空留巷顶板结构简化为采空区矸石、巷旁充填体及巷帮煤体共同作用的弹性力学模型,计算了该条件下的支护反力,利用控制变量的方法分析了影响支护反力的主要因素是充填体宽度和充填体弹性模量,得出了巷旁充填体压缩量计算公式。在此基础上,通过UDEC数值模拟方法,模拟了沿空留巷顶板关键岩块在弹性支撑条件下的应力状态,分别得出了充填体宽度及弹性模量与顶板下沉量的关系。     

单轴拉伸条件下充填体的力学性能研究

对安庆铜矿特大型采场不同配比的充填体进行了单轴抗拉试验,根据试验测得的单轴抗拉强度、线性阶段弹性模量、峰荷应变结果,分析了这些力学性质的变化规律,对矿山提高充填体质量具有一定的指导意义,同时也对其它工程领域有一定的借鉴作用.     

密实充填矿压显现时空演化规律研究

建立和分析密实充填矿压显现时空演化力学模型,运用相似材料模拟方法研究充填开采条件下的采场矿压显现时空演化规律,并以邢台某矿充填实践为工程实例进行分析验证。研究结果表明:顶板下沉活跃期间,充填体受力与充填步距和推进时间呈正相关;在充填开采物理模拟中,顶板测点应力普遍经历了应力升高-急剧卸压-缓慢升压再到稳定的过程,且工作面前方顶板应力峰值和煤柱受力随着充填步距的增加而增大;充填体受力随着工作面推进而不断增加至趋于稳定,稳定后的顶板应力和充填体受力均小于原岩应力;停采后静置阶段,随着时间增长,充填区顶板依然存在缓慢下沉现象。某矿充填实测结果显示距离切眼15和40 m处的充填体压力为3.5和5.5 MPa,且顶板下沉和覆岩离层在工作面推进过程中均随着充填距离的增加和充填时间的推移表现出了规律性变化。     

不同温度养护后胶结充填体三轴卸围压力学特性试验研究EI北大核心CSCD

为研究胶结充填体在煤矿深部的高地温环境下发生卸荷的力学特性,采用RTX–4000型岩石动态三轴仪,对不同温度(20℃,35℃和50℃)养护后的胶结充填体进行不同初始卸荷围压下的常规三轴卸围压试验,得到胶结充填体三轴卸荷全过程的偏应力–应变曲线,分析其变形、破坏特征及强度准则。研究结果表明:50℃养护后的胶结充填体内部产生的有害热应力易使胶结充填体卸荷的应力–应变曲线在峰后阶段出现微破裂现象,进而使得变形模量在随围压卸载的过程中也出现突降和逆向增长。胶结充填体卸荷破坏形式主要为局部张拉裂纹、剪切裂纹以及由热损伤和力学损伤共同造成的错位裂纹。Mogi-Coulomb强度准则能更好地表征胶结充填体在增轴压卸围压条件下的卸荷破坏强度特征;随养护温度的升高,胶结充填体的黏聚力先减小后增大,内摩擦角先增大后减小,黏聚力的变化同卸荷峰值强度的变化规律一致,黏聚力越大,卸荷峰值强度越高,表明黏聚力为影响胶结充填体卸荷峰值强度的主要因素。     

大型疏浚土充填袋筑堤技术研究

为缓解砂石资源紧缺、保护生态环境、降低工程造价和高效利用航道疏浚土,以大型疏浚土充填袋筑堤技术应用于连云港港徐圩港区围堤建设为工程实例,通过稳定性分析计算、离心模型试验开展了大型疏浚土充填袋筑堤技术的理论可行性研究,并结合原型试验提出了新型配套施工工艺,形成了相关成套技术。研究表明:袋体土工织物加筋作用良好,堤体及地基稳定性能够满足安全设计;控制疏浚土充填料初始含水率、采用泥浆泵与浓浆泵串联接力的施工工艺,能够提升大型疏浚土充填袋筑堤施工效率,满足正常围堤建设强度需要;低含水率疏浚土充填料排水较快、袋体实际有效厚度较为理想、堤体地基较为稳定,大型疏浚土充填袋筑堤具有其技术可行性。     

充填体和围岩–充填体界面剪切特性对比试验研究

拱效应理论模型在剪切力学参数(黏聚力c和内摩擦角φ)的选取上采用了等效原则。为了区分剪切参数的选取对拱效应理论模型的影响,首先,采用三轴测试方法,开展常侧向约束条件下围岩-充填体界面的三轴剪切和充填体的三轴压缩试验。基于Mohr-Coulomb强度理论框架,对不同养护时间下充填体和围岩-充填体界面的剪切力学参数进行对比和量化分析。然后,利用电子扫描电镜(SEM)和热差异分析(TG/DTG)的分析手段,充分解释充填体和围岩-充填体界面剪切参数的差异性。最后,依据试验测试结果,对Terzaghi理论模型的工程应用进行讨论。研究表明,随侧向约束的增加,围岩-充填体界面的剪切位移-剪切应力曲线呈现出多峰值现象,且充填体的轴向应变-偏应力曲线呈现出明显的弹性强化阶段。充填体的剪切力学参数(c_b,φ_b)要明显大于相应围岩—充填体界面的参数(c_i,φ_i)。两者的黏聚力比值(c_b/c_i)相差了 2.26～2.67倍,内摩擦角比值(φ_b/φ_i)相差了 1.65～2.76倍。且采用围岩-充填体界面的剪切参数(c_i,φ_i)进行充填采场竖向应力(σ_v)的预估能有效地克服Terzaghi理论模型的局限性。研究结论可为充填采场拱效应的预估和数值分析中力学参数的选取提供一定的参考。     

拉伸状态下充填体损伤演化及本构方程研究

1引言抗拉强度是充填体的重要力学性能之一。充填体中存在有微裂隙,如裂纹、气泡、孔穴和离析等,这些内部的微观缺陷或不连续现象对充填体宏观力学性能起决定性作用。对于矿山胶结充填体的内部微开裂和由微开裂引起的各类力学行为的研究很少。为计算和预测安庆铜矿大体积充填体     

Stability analysis of large-scale stope using stage subsequent filling mining method in Sijiaying iron mine

To improve mining production capacity, a stage subsequent filling mining(SSFM) method is employed for Sijiaying iron mine. The height of the stage stope is approximately 100 m. As there are farmlands and villages on the surface of the mine, the surface deformation should be controlled when the ore is mined out for the purpose of stope stability and minimizing surface subsidence. In this paper, according to the site-specificgeological conditions, the self-stability of the stagefi lling body was analyzed, and the failure mechanism of back filling body was defined. Thus the relationship between the exposed height of filling body and the required strength was obtained. Next, the stability of back filling body and the characteristics of surface subsidence due to mining of 450 m level were analyzed using physical modeling.Finally, a three-dimensional numerical model was established using FLAC3 D, with which the surface subsidence and the stability of stope were achieved. The results show that the stope basically remains stable during the two-step recovery process. The maximum magnitude of the incline is 10.99 mm/m, a little larger than the permissible value of 10 mm/m, and the horizontal deformation is 5.9 mm/m,approaching the critical value of 6.0 mm/m, suggesting that the mine design is feasible for safety mining.     

Direct shear tests on cemented paste backfill-rock wall and cemented paste backfill-backfill interfaces

This paper presents the results of the shear strength(frictional strength) of cemented paste backfillcemented paste backfill(CPB-CPB) and cemented paste backfillerock wall(CPB-rock) interfaces. The frictional behaviors of these interfaces were assessed for the short-term curing times(3 d and 7 d) using a direct shear apparatus RDS-200 from GCTS(Geotechnical Consulting & Testing Systems). The shear(friction) tests were performed at three different constant normal stress levels on flat and smooth interfaces. These tests aimed at understanding the mobilized shear strength at the CPB-rock and CPB-CPB interfaces during and/or after open stope filling(no exposed face). The applied normal stress levels were varied in a range corresponding to the usually measured in-situ horizontal pressures(longitudinal or transverse) developed within paste-filled stopes(uniaxial compressive strength, s c 150 k Pa). Results show that the mobilized shear strength is higher at the CPB-CPB interface than that at the CPB-rock interface. Also, the perfect elastoplastic behaviors observed for the CPB-rock interfaces were not observed for the CPB-CPB interfaces with low cement content which exhibits a strain-hardening behavior. These results are useful to estimate or validate numerical model for pressures determination in cemented backfill stope at short term. The tests were performed on real backfill and granite. The results may help understanding the mechanical behavior of the cemented paste backfill in general and, in particular, analyzing the shear strength at backfillebackfill and backfill-rock interfaces.     

下向分层胶结充填采场失稳机理及顶板垮塌模式研究

以某矿下向分层胶结充填法采场发生大面积失稳事故为工程背景,通过分析地表及井下工程破坏情况得出采场顶板发生了“下部充填体散体冒落+上部充填体及覆岩整体陷落”的复合垮塌模式,并进行了理论计算验证。数值模拟研究结果表明,随着采场中采空进路数量的增加,各间柱上的垂向压力不断叠加,若有一个间柱因承压达到极限而失稳,压力便向周边间柱转移导致其他间柱失稳,进而引发“多米诺效应”式的间柱连锁失稳现象,空区顶板在拉应力作用下发生散块冒落,空区边缘部位在集中剪应力作用下发生整体剪切滑落,最终发生直通地表的大规模垮塌事件。结合矿山实际生产问题,提出了一系列采场失稳风险防控措施,可为类似矿山提供借鉴。     

Numerical investigation of the stresses in backfilled stopes overlying a sill mat

Backfill is commonly used in underground mines to help increase the ore recovery rate and reduce the ore dilution. The use of a part of mine waste as underground backfill material also helps reduce the environmental impact of mining operations. After all, backfill is used to provide a working platform or safer working space. Its primary and most important role is to improve the rock mass stability around mine openings. However, most available solutions to stress analyses were developed for an isolated stope, without taking into account the influence of mine depth, or of adjacent stopes. In this paper,results from a numerical study carried out to evaluate the stresses in backfilled stopes overlying a sill mat are presented. Mine depth and excavation of the underlying stope below the sill mat(horizontal pillar)are both taken into consideration. The influence of stope geometry, backfill, sill mat and rock properties on the stresses is also evaluated. Compared with the case of a single isolated backfilled stope, the numerical results show that the stress magnitudes in the overlying backfill are considerably increased due to the excavation of the underlying stope. In general, the stresses also increase with mine depth and backfill stiffness, while these tend to decrease with an increase in the surrounding rock mass stiffness.These results suggest that existing solutions for backfill design may need to be revised.     

基于尖点突变理论的充填体下采空区安全顶板厚度计算模型

 充填体下采空区顶板结构普遍存在于利用充填体进行回采的矿山。为了保证矿山的作业安全,合理确定充填体荷载作用下顶板厚度参数具有重要意义。在分析充填体下采空区顶板结构形成及破坏机制的基础上,建立该顶板结构的稳定性力学模型,应用尖点突变理论分析其失稳的力学机制。依据顶板结构尖点突变模型失稳的充分条件和必要条件,推导得到充填体下采空区顶板极限厚度值表达式。结合某铅锌矿工程实例,计算得到矿山安全顶板厚度应大于11.48 m,在数值模拟验证和实际生产中,取顶板厚度值为12 m。验证结果表明：尖点突变理论可以有效阐释充填体下采空区顶板结构失稳的力学机制,而将其运用到顶板或类似结构的稳定性分析和参数设计中是合理可行的。