为改善非对称高墩预应力混凝土变截面连续刚构桥成桥后墩顶产生较大偏位带来的不利影响,常在中跨合龙前实施合龙口顶推施工.以安家山河预应力连续刚构桥中跨跨中合龙口施工为研究背景,考虑边、中跨不平衡荷载、收缩徐变、合龙温差等因素确定顶推位移,基于结构力学推导了合龙口顶推力解析式,验证合龙口顶推力解析式的正确性.对比施加非对称顶推力、对称顶推力和未施加顶推力对刚构桥主梁线型、桥墩受力和主梁受力的影响.结果表明:施加对称顶推力比施加非对称顶推力对主梁控制下挠作用更加明显,使得顶推后主梁和桥墩应力水平处于合理的范围内.该研究对大跨度预应力混凝土连续刚构桥合龙施工提供理论与实践依据.

太阳辐射作用下,混凝土薄壁桥塔内外表面易产生较大的温度应力,从而导致结构内外表面出现裂缝.以某悬索桥混凝土薄壁桥塔截面为研究对象,基于现场实测温度数据,利用ABAQUS软件计算分析了不同保温隔热措施下混凝土薄壁桥塔的温度场、应力场随时间变化规律,计算结果表明,施加保温板和涂层能显著降低塔壁内外表面日照温差,减小塔壁温差应力;采用保温隔热板时,板厚小于35 mm时,隔热效果显著,厚度大于35 mm时,隔热效果不明显;采用白色或浅色的保温涂层降低塔壁内外表面日照温差的效果优于其他颜色的涂层.

为了研究截面几何参数对混凝土薄壁桥塔温度应力的影响,基于某悬索桥混凝土桥塔实测日照温差,通过有限元方法分析了不同塔壁厚度、塔壁长宽比和塔壁内外表面角隅处倒角等条件下桥塔截面的温度应力,结果表明:改变塔壁厚度、塔壁长宽比和塔壁内侧角隅处倒角对桥塔温差应力均有不同程度的影响;在塔壁内外正温差条件下,桥塔内表面角隅处的温度应力随塔壁厚度的增加而增大;负温差条件下,塔壁外表面的温度应力随塔壁厚度的增加而减小;改变塔壁截面长宽比对改善塔壁截面温度应力的效果不明显;正温差条件下,在塔壁内侧截面角隅处设置倒角,可有效降低塔段内表面的温度应力,在考虑混凝土体积与抗压刚度的情况下,其倒角尺寸建议在0.3 m×0.3 m～0.5 m×0.5 m之间;负温差作用下,塔壁厚度比是重要设计参数,其取值不宜太大,较大的塔壁厚度比可以降低桥塔中心处温度应力,但同时会导致角隅处温度应力集中,混凝土体积增加,塔壁长宽比变小,从而导致桥塔的抗压刚度降低.在设计柱状薄壁箱形结构截面时,满足结构承载能力和工程造价的前提下,要充分考虑日照温差应力对薄壁箱型结构的影响,其研究成果可推广应用于其他桥型的混凝土空心薄壁箱型桥塔或桥墩截面设计中.

The seismic design of bridge engineering is generally carried out on the basis of static design. Through the design of seismic design and seismic isolation of a four-span continuous girder bridge, the principle of these two methods is explored, and the characteristics of the method are analyzed. These two methods are compared to obtain their scope and provide examples for the seismic design manual method.

从煤矿企业应急能力建设可持续改进的角度出发,提出PDCA-CMEC(Coal Mine Emergency Capability)建设模型.依据此模型,以煤矿应急计划能力、应急执行能力、应急检查能力、应急处理能力为基础,构建了由4个一级指标和18个二级指标组成的煤矿应急能力评价指标体系.并使用ANP网络层次分析法,研究各评价指标间的依存反馈关系,建立ANP-CMEC(Coal Mine Emergency Capability)结构模型,分析其超级矩阵,借助SD软件对煤矿应急能力评价指标进行权重计算,得出了各评价指标的权重值.

To rationally choose the evaluation method is of great significance for a coal mine enterPrise to recognize the Present situation of its emergency caPability and enhance the level of its emergency caPability. In order to carry out the evaluation of coal mine emergency caPability and strengthen the construction of its emergency caPability,analysis and combination were made on the advantages of both Analytic Network Process( ANP)and Back ProPagation( BP)neural network,and ANP-BP evaluation method was ProPosed by taking the evaluation results of ANP as the training samPle data of BP neural network. In addition,study was made on the imPlementation of ANP-BP method in coal mine emergency caPability evaluation,and its aPPlicability and oPerability were Proved.

教风学风建设既是一项系统工程,也是一项长期的任务,是学校校风建设和校园文化建设工作的重要内容,是学校的立校之本,其结果直接关系到学校的办学质量和学生的健康成长成才。本文对陕西某高校土木工程专业进行了调研,针对本专业的教风与学风提出了解决问题的几点建议。

Through the analysis of the Xi'an metro interzone tunnel which across the earth fissure,we introduce some construction scheme about it.The subway structure will adjust itself to the distortion and development of the earth fissure after it used the construction scheme,it can keep the traffic and the subway normalization when the earth fissure moved.