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公路工程中,对高程的测量贯穿了公路设计及施工的各个阶段,在进行公路测量和设计时,需要沿线路布设四等或等外水准路线,以满足设计和施工的需求。本文主要介绍了公路高程控制测量的特点、基本要求,主要从GPS控制网的布设方面对公路高程控制测量技术做了分析和阐述。 相似文献
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Fatigue tests were conducted on tapered plain concrete prism specimens under triaxial constant-amplitude tension-compression cyclic loading. The low stress of the cyclic loading was taken as 0.2fc and the upper stress ranged from 0.20ft to 0.65ft. Three constant lateral pressures were 0.1fc, 0.2fc and 0.3fc respectively. Based on the results, the three-stage evolution nile of the fatigue stiffness, maximttm(minimum) longitudinal strain and damage were analyzed, and a unified S-N curve to calculate fatigue strength factors was worked out. The results show that the fatigue strength and fatigue life under triaxial constant-amplitude tension-compression cyclic loading are smaller than those under uniaxial fatigue condition. Moreover, the secondary strain creep rate is related to the fatigue life, a formula for describing their relation was derived. The investigation of this paper can provide information for the fatigue design of concrete structures. 相似文献
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