To assess the impact of solid waste phosphogypsum on the road performance of lime-fly ash-stabilized red clay, we conducted comprehensive tests on the road performance, swelling and shrinkage characteristics, and mechanical properties of lime-fly ash soil with varying phosphogypsum content and curing age. Additionally, we analyzed the microstructure and composition changes using scanning electron microscopy and X-ray diffraction tests. The results revealed that phosphogypsum significantly enhances the early strength and moisture stability of lime-fly ash soil. The mechanical properties of lime-fly ash soil continue to improve with increased curing age, with performance improvements tapering off after 60 days and eventually stabilizing. Moreover, as the phosphogypsum content increases, the unconfined compressive strength (UCS), splitting strength, and CBR value of the lime-fly ash soil initially increase and then decrease. The optimal mixing ratio was determined to be 4% phosphogypsum, resulting in a 7-day UCS increase of 67.2%, a 28-day UCS increase of 3 times, and a 28-day splitting strength increase of 4.3 times. The moisture stability coefficient also exhibited a 43% increase after 7 days, and its anti-disintegration ability was enhanced, reaching 0.91 after 28 days, which meets the specified standards. Microscopic analysis revealed that the addition of phosphogypsum improved the overall integrity of the lime-fly ash soil, and the formation of ettringite effectively filled the soil’s pores. However, excessive ettringite caused increased expansion and deformation. To optimize the use of phosphogypsum-modified lime-fly ash-stabilized red clay as subgrade filler, it is advisable to incorporate additives to further reduce swelling deformation.
城市轨道交通线路设计过程中不可避免地敷设小半径曲线来绕避敏感地段,因曲线地段存在着与通过速度不相匹配的超高,将产生较大的横向力作用,出现钢轨侧磨与扣件螺旋道钉断裂等问题,严重影响行车安全.结合北京地铁14 号线轨道维修实际情况,对小半径曲线地段扣件螺旋道钉断裂情况进行统计.建立地铁浮置板无砟轨道有限元分析模型,分析扣件螺旋道钉的剪切破坏特征.基于所建立的仿真分析模型,对现阶段通过增加垫圈的减缓螺栓断裂措施进行探讨,为科学指导地铁轨道维护养护维修工作提供参考.
Aiming at the problems of expressway construction in mountainous area, the paper puts forward the influencing factors and its system structure framework of casualty severity of Expressway in mountainous area; based on the interpretive structure model（ISM）,it establishes the hierarchical directed graph of influencing factors with certain logical relationship, and divides the influencing factors of casualty severity of Expressway in mountainous area into three levels: shallow level, middle level, deepest level and shallow level The influencing factors are driving time and environmental conditions, the middle influencing factors are road slippery snow, fatigue driving and road conditions, and the deepest influencing factors are accident severity and collision type, which directly affect the casualty severity of mountainous expressway.
以深圳海府路地下通道项目为依托,分析该路段复杂地质条件以及含有丰富地下水的特点,宜采用浅埋暗挖工艺施工,同时结合超前小导管辅助支撑工艺,使该方法更好地适用于软弱土层施工.施工过程中,地表沉降监测变化小于0.3 mm,累计变化范围在5.7～11.7 mm之间;地板隆起本期变化小于0.2 mm.累计变化范围在0.1～2.9 mm之间,均在安全值范围内.
铁路是国民经济大动脉、关键基础设施和重大民生工程,我国人口众多、幅员辽阔,铁路运输基于其运载量大、运行成本低、能耗少等特点,已成为我国最为重要的交通运输方式之一.受到铁路运输需求的影响,铁路工程建设行业快速发展,带来了更多的机遇和挑战,企业不断增强自身的项目管理能力,提升竞争力,具有重要的意义.现针对铁路工程项目管理,概述了精细化管理的内涵,分析了铁路工程项目管理存在的问题,提出了铁路工程项目精细化管理实施的策略.
