放顶煤工作面巷道长距离超前支护系统研究

放顶煤工作面巷道需要进行长距离超前支护。单体支柱支护工作效率低、劳动强度大,成组式超前支架对巷道顶板反复支撑造成顶板破碎,无法协调支撑可靠性与对顶板破坏之间的矛盾。通过数值模拟,分析了地质条件及开采工艺下巷道超前支承压力分布特点,结合成组式支架与单元式支架的优势,提出长距离超前支护系统。在高压区采用成组式超前支架,利用较大工作阻力维护巷道顶板稳定;在稳压区采用单元式支架,凭借其循环移架方式提升巷道支护效率,通过单轨吊式空中移架避免底鼓、巷道变形等因素对移架过程的影响。综合两者优势,保证巷道顶板支护效果的同时,减少对顶板的反复支撑破坏,完成复杂地质条件下工作面巷道的长距离超前支护。     

李雅庄煤矿2-607综采工作面上隅角瓦斯治理技术

为确保采面生产安全,降低上隅角瓦斯集聚给煤岩回采影响,对2-607综采工作面上隅角瓦斯治理展开研究。由于开采的2^#煤为自燃煤层,将采空区埋管抽采口布置在散热带内,可避免埋管抽采增加遗煤自燃。现场应用后,上隅角瓦斯浓度控制在0.45%以内,采面日产量也由2000t提升至2800t,取得显著应用成果。     

胥虹桥上部结构计算分析

胥虹桥为三孔刚架拱桥，主孔净跨为６０ｍ，全桥长度为１５５．９８ｍ，该桥于１９９２年６月建成，从竣工后延续至今，相继出现桥面裂缝，拱肋开裂，墩台变位，桥面下沉等病害。本文着重分析该桥病害发生的上部结构的原因。     

桥台台背土压力试验研究

高速铁路桥台台后填土从填料选择、施工控制、质量监测等方面均不同于常规铁路,但是对桥台台背土压力研究并不多见,再加上影响土压力的因素比较复杂,目前的土压力理论还难以准确地反映土压力分布的实际情况。基于此,结合现场试验对高速铁路桥台台背土压力进行长时间观测,根据实测结果分析土压力随时间的变化,土压力随填土高度变化以及填土完成后台背土压力的大小和分布情况。分析结果表明,台背土压力沿桥台深度方向呈非线性分布,土压力随着距离桥台顶部距离的增大而增加,但到达一定深度后随深度的增大土压力反而减小;土压力合力作用点要比理论上的土压力合力作用点有所上移,在0.41倍填土高度处。     

基于离心模型试验的路桥变形耦合特性数值模拟研究

基于离心模型试验,采用有限差分仿真法建立路桥过渡段三维数值分析模型。通过数值模拟计算结果和离心模型试验结果的对比分析,证明了所建立的模型可合理预测路、桥台变形耦合特性。数值分析结果表明:①距台背不同位置过渡段路基面沉降均随过渡段地基处理程度的加强而减小,离台背距离越近,路基面的沉降坡度越大;②桥台沉降稳定后再填筑路基有利于减小桥台自身的水平位移及台背处的差异沉降值。填筑时应注意填筑速率,重点关注桥台及过渡段路基的整体稳定性和过度的不均匀下沉,防止地基因填土堆载发生滑动破坏及路基层状几何形态的变坏所引起的路基刚度的急剧下降;③不同地基处理程度情况下路桥衔接处均存在差异沉降,因此,有必要在桥头设置搭板将路桥交界处的台阶式跳跃沉降变成斜坡式连续沉降;④过渡段路基收敛沉降值与桥台的水平位移和倾角成正相关性,在数值计算的基础上提出了台后20m处过渡段路基收敛沉降值这一控制指标,并将台后过渡段填料的容许剪应变引入到过渡段设计中。     

浅谈桥梁下部结构设计

简单介绍了桥梁墩台的组成、作用及设计原则,分别探讨了桥墩、桥台、墩台基础三个部位的设计方法及注意事项,并结合具体实例阐述了桥梁下部结构设计要点,以指导实践。     

钢管混凝土异形柱与U形钢-混凝土组合梁穿心式连接抗震性能试验研究

为研究异形钢管混凝土柱与U形钢-混凝土组合梁穿心式连接的破坏特征和抗震性能,进行了3个足尺边节点试件低周反复循环加载试验,试验参数为节点域构造和轴压比,考察了试件的受力过程及破坏特征,分析了节点的荷载-位移滞回曲线、承载力、刚度和强度退化性能、耗能能力以及延性等力学指标。研究表明：该类型连接的典型破坏形态为节点域钢管柱壁鼓屈、节点域连接槽钢拉裂和组合楼板压溃;试件的滞回曲线较饱满;3个试件的层间位移延性系数μ为1.43~2.02,弹性层间位移角θy为1/62~1/48,弹塑性层间位移角θu为1/39~1/30,等效黏滞阻尼系数ξeq为0.140~0.170,节点的变形能力较好,也具有一定耗能能力;梁底布置贯穿节点域的钢筋能提高节点正向的承载力和刚度;提高轴压比可以提高该类型节点的耗能能力。     

Field investigation of using water injection through inseam gas drainage boreholes to control coal dust from the longwall face during the influence of abutment pressure

Coal dust is a primary contributor to underground coal-mining disasters and is also a major factor in adversely affecting the occupational health of mine workers. Pre-wetting the coal seam with water injection is widely considered as one of the effective means of mitigating coal dust generation during mining. Injecting water through inseam long boreholes parallel to the working face is a commonly used technique. However, for most fully-mechanised top-coal caving working faces, inseam gas drainage boreholes are drilled to extract gas from the gassy seam prior to mining. Therefore, there is neither enough time nor space at the working site for an elaborated water injection process. Based on the mining conditions at Panel 9801 of the Yangquan coalfield, this study designed a water injection system through the inseam gas drainage boreholes to control dust arising from the longwall face. Under the influence of abutment pressure, water injection through a set of inseam gas drainage boreholes was experimentally investigated to offset the conflict between water injection and gas drainage in terms of the time and space availability. The relations between the amount of injected water, the injection rate, the seam moisture content and the coal dust level at the working space were investigated. The effect of water injection for dust control at different distances ahead of working face was assessed. With the change of abutment pressure, the effect of water injection to inseam gas drainage and gas emission at working face was revealed and a space-time balance between gas drainage and dust control by water injection was established. The results indicate that under the influence of abutment pressure, water injection through inseam gas drainage boreholes wetted the seam and decreased the dust level at the working face. Water injection only has marginal influence on inseam borehole drainage and has a negligible impact on the gas level produced at the working face. Under the influence of abutment pressure, the optimum area for water injection through the inseam boreholes was the primary fracture opening zone and the secondary fracture development zone.     

放顶煤开采顶煤变形与破碎特征

以放顶煤开采现场实测为基础,着重探讨了顶煤的变形特征、顶煤变形与支承压力的关系;对比分析了“卸载降架－拉架－支撑”和“带压移架”不同移架方式对顶煤破碎效果的影响,结果表明,支架的反复支撑对煤具有明显的破碎作用。     

坝肩岩体地震残余变形对小湾拱坝安全影响

用有限元模拟拱坝坝体、非连续接触单元模拟坝肩，计算了在设计地震荷载作用下小湾拱坝坝肩残余位移和坝体应力。以拉应力达到坝体混凝土抗拉强度为控制标准，得出坝肩岩体的动力稳定安全系数。计算结果表明，小湾拱坝坝肩仍具有一定的安全度。