高低错位法高效疏放2601工作面采空积水

漳村煤矿2601工作面北部及中部采空区内存有积水,由于工作面顶板垮落后泥岩、砂岩等沉积导致低位探放钻孔出水不畅甚至堵塞,单孔放水量小、疏放水时间长,为此提出在2603进风巷实施高低错位法来疏放2601采空积水,低位钻孔距底板1.5~1.7 m,高位钻孔距底板2.2~2.5 m,钻孔与2601采空区钻透后继续向里钻进约3~4 m,保证钻孔与采空区放水通道的充分畅通,实施后最大程度地疏放了采空区水量,效果显著。

轨道接头激励下的桥式起重机大车振动特性分析

起重机在轨道上运行时的冲击程度和起重机的结构形式、车轮直径、运行速度和轨道接头的状态等有关。建立了2自由度起重机大车系统的垂向振动动力学模型及微分方程,考虑了大车运行轨道接头处的高低错位和间隙激励,基于Matlab/Simulink构建了仿真模型,分别研究了高低错位激励和间隙激励以及叠加激励下的大车振动特性。结果表明,轨道接头处高低错位激励对大车系统的垂向振动影响较大,而间隙激励对系统的影响可以忽略不计,大车运行速度对系统的振动加速度峰值影响不大,车体所受的振动冲击与车轮半径大致呈反比关系。

High density dislocations enhance creep ageing response and mechanical properties in 2195 alloy sheet

The creep strain of conventionally treated 2195 alloy is very low,increasing the difficulty of manufacturing Al-Cu-Li alloy sheet parts by creep age forming.Therefore,finding a solution to improve the creep formability of Al-Cu-Li alloy is vital.A thorough comparison of the effects of cryo-deformation and ambient temperature large pre-deformation(LPD)on the creep ageing response in the 2195 alloy sheet at 160℃with different stresses has been made.The evolution of dislocations and precipitates during creep ageing of LPD alloys are revealed by X-ray diffraction and transmission electron microscopy.High-quality 2195 alloy sheet largely pre-deformed by 80%without edge-cracking is obtained by cryo-rolling at liquid nitrogen temperature,while severe edge-cracking occurs during room temperature rolling.The creep formability and strength of the 2195 alloy are both enhanced by introducing pre-existing dislocations with a density over 1.4×10^(15)m^(−2).At 160℃and 150 MPa,creep strain and creep-aged strength generally increases by 4−6 times and 30−50 MPa in the LPD sample,respectively,compared to conventional T3 alloy counterpart.The elongation of creep-aged LPD sample is low but remains relevant for application.The high-density dislocations,though existing in the form of dislocation tangles,promote the formation of refined T1 precipitates with a uniform dispersion.

轨道接头缺陷对整机运行的影响分析

针对起重机轨道接头高低错位引起垂直冲击动力效应的问题,建立了起重机运行在高低错位接头轨道上所引起的动载荷轮一轨刚体动力学模型,分析轨道缺陷对起重机运行冲击的影响度。根据最大动能相等原理,对起重机整体系统等效转换为单自由度系统,利用等效单自由度系统应与整体系统具有相同的振动形式和频率得到其自振圆频率表达式·根据等效单自由度系统在接头高低错位处的响应建立轮-轨系统运动微分方程,获得等效单自由度系统在接头高低错位处的运行冲击表达式,并与ISO8686-1:2012《起重机载荷与载荷组合原则第一部分总则》中接头高低错位引起垂直冲击动力效应公式进行比对分析,进而为GB/T3811-2008《起重机设计规范》与ISO8686-1:2012《起重机载荷与载荷组合原则第一部分总则》方法的适用性提供理论依据。

客运专线整孔箱梁存梁技术

客运专线整孔箱梁体积大,长达32.6m,顶板宽达13.4m,高达3.0m,根据预制梁出场时间要求,要求梁场有很大的存梁场地,如何减少存梁用地,减少纵列式梁场提梁机纵向走行轨道长度和提梁机跨度,采用合适的存梁方式显得尤其关键。