斜拉桥施工控制中的温度影响分析

研究目的：研究温度场对斜拉桥施工控制的影响。研究方法：本文主要研究了斜拉桥的温度场的特点、类型和计算方法，结合云阳长江大桥工程实际，利用有限元方法建立空间模型，对其温度影响进行了计算并与实测值进行了对比分析。 研究成果：本文分析了结构体内温度场的规律性，表明日照等不均匀温差对斜拉桥结构的影响很大，并证明利用该方法得出的结果与实际比较吻合。 研究结论：本文提出的计算方法可以比较准确地计算斜拉桥施工控制中的温度影响，有利于施工中调整主梁的线形、应力，符合可靠性的要求。     

一种客车自动喷洒灭火装置的方案设计

介绍一种客车自动喷洒灭火装置的技术方案及实验验证。     

轨检仪轨距测量误差的温度影响与补偿

轨距参数的准确测量是铁路行车安全的有力保障,作为轨道几何参数测量的常用仪器,轨检仪在轨距测量过程中容易受温度影响,当传感器的标定温度与测量时环境温度相差较大时,误差体现更加明显。针对这一测量误差来源,提出温补因子的概念,从实验计算出温补因子大小,再从理论上验证了该温补因子的正确性。实验结果表明,增加温补因子后的轨距测量不再受标定温度及测量环境温度的温差影响,提高了轨检仪的轨距测量准确性,证明了温度补偿的必要性。     

浅析混凝土温差裂缝产生的原因与防治策略

结合工程实例，对混凝土温差裂缝产生的原因进行了分析，并提出了相应的预防措施及处理方法。     

青沙山隧道地温场测试与分析

采用埋入式铂金属热敏电阻测试方法,对地处青藏高原东部的青沙山公路隧道地温场进行现场实测与分析。结果表明:隧道洞口段,当环境温度较低时,地温差值分布明显,隧道进出口段衬砌背后出现相当长时间的负温;隧道洞内段,11月至次年3月,环境温度与所测地温相差很大,4月至7月,地温不稳定,围岩内各测点的温度曲线按位置重新进行调整,低温曲线上升到最高温处,高温的曲线则到达最低温处;7月至11月,隧道进口端地温下降曲线同隧道区环境温度变化同步,而隧道出口端地温比该处隧道内环境温度滞后;在冬季,衬砌内温度始终呈现倒U型,从隧道口向隧道中间,地温是上升的,地温上升呈现进口幅度小,出口幅度大,在低温度月份进口温度稍高于出口温度,在较高温月份进口温度低于出口温度;随着围岩深度的加深,温度是增加的,浅处的温度增量要大于深处;围岩内隧道径向存在某一比较稳定的温度边界条件。     

Long-term sea surface temperature baselines—time series, spatial covariation and implications for biological processes

Coastal areas such as estuaries, bays and fjords usually have hydrographic characteristics (e.g., temperature, salinity) which differ from those at larger spatial scales and in offshore areas. The differences can arise if the areas are subject to different climatic forcing or if they are relatively isolated from each other due to topographic and ocean circulation features which inhibit advective inputs of water mass properties. Local differences in hydrographic conditions can therefore potentially limit the applicability of existing long time series of coastally monitored temperatures for addressing questions at large spatial scales, such as the response of species distributions and phenologies to climate change. In this study we investigate the spatial synchrony of long-term sea surface temperatures in the North Sea–Baltic Sea region as measured daily at four coastal sites (Marsdiep, Netherlands; Torungen, Norway; Skagens Reef, Denmark; and Christiansø, Denmark) and in several large offshore areas. All time series, including two series reconstructed and intercalibrated for this study (Skagens Reef and Christiansø, Denmark), began during 1861–1880 and continue until at least 2001. Temperatures at coastal sites co-varied strongly with each other and with opportunistically measured offshore temperatures despite separation distances between measuring locations of 20–1200 km. This covariance is probably due to the influence of large-scale atmospheric processes on regional temperatures and is consistent with the known correlation radius of atmospheric fluctuations (ca. 1000 km). Differences (e. g, long-term trends, amplitude of seasonal variations) between coastal temperatures and those measured in adjacent offshore areas varied nonrandomly over time and were often significantly autocorrelated up to 2 years. These differences suggest that spatial variations in physical oceanographic phenomena and sampling heterogeneities associated with opportunistic sampling could affect perceptions of biological responses to temperature fluctuations. The documentation that the coastally measured temperatures co-vary with those measured opportunistically in offshore areas suggests that the coastal data, which have been measured daily using standardized methods and instruments, contain much of the variability seen at larger spatial scales. We conclude that both types of time series can facilitate assessments of how species and ecosystems have responded to past temperature changes and how they may react to future temperature changes.     

邵怀高速公路水泥稳定级配碎石半刚性基层非荷载作用裂缝控制

介绍了水泥稳定级配碎石基层强度的形成原理,对水泥稳定碎石基层裂缝的成因机理进行了系统研究。在综合运用试验条件下,统计了非荷载作用下水泥稳定级配碎石半刚性基层干缩应变、干缩系数与级配、失水率、环境温度之间关系,分析了影响水泥稳定级配碎石半刚性基层出现裂缝的主要因素,并在施工控制、配比设计、含水量控制、水泥剂量的控制、养生、压实度控制等施工工艺、工程措施方面提出了控制裂缝产生的措施。     

碳纤维布加固混凝土箱形墩柱温度自应力研究

考虑到碳纤维布(CFRP)与混凝土的热胀系数不同,该文建立了CFRP加同任意形状横截面混凝土构件因日照辐射或骤然降温引起的温度自约束变形求解方程,进而推导了CFRP加固混凝土箱形墩柱在均匀、线性和指数变化温度梯度下的温度自应力解析式。文章中与未加固混凝土箱形墩柱温度自应力解析式进行了对比分析,CFRP加固箱形墩柱即使在均匀和线性变化温度梯度下也会产生温度自应力,在指数变化温度梯度下CFRP中产生可观的温度自应力。所推导的自约束变形求解方程和温度自应力解析式既适用于CFRP加固混凝土构件也适用于未加同混凝土构件。采用ANSYS有限元软件对温度自应力进行仿真分析,与该文公式计算结果对照,说明文中推导的CFRP加固混凝土箱形墩柱温度自应力解析式具有足够的精度。     

大跨预应力混凝土连续箱梁桥日照温差效应

对某特大型预应力混凝土连续箱梁桥进行了连续4 d的温差效应观测,在实测数据的基础上论述了箱梁桥的温度场及其变化规律,继而提出了一种适合于中国中部地区的同时考虑箱梁竖向和横向温差的温度梯度模式,将该模式与实测资料进行了比较并分析了温差效应。结果表明:由该模式计算出的最大横向温差时刻与实测结果十分吻合,对箱梁桥日照温差效应的测试有参考价值。     

高墩大跨连续刚构桥施工控制分析

龙潭河特大桥采用连续刚构体系,其桥墩最高达178 m。为了分析桥墩及桩基础对桥梁结构的受力影响,建立考虑桩基作用及墩底固结两个不同的计算模型,计算和比较了箱梁施工预拱度及温度荷载作用下的结构控制截面的弯矩。