为分析高海拔高寒缺氧环境对施工设备机械效率影响,利用柴油机机械效率数学模型计算分析高海拔地区各环境因素(大气压、温度、氧气浓度)对施工设备机械效率的影响程度和规律。研究结果表明:大气压力越低,机械效率越低,平均大气压力每降...为分析高海拔高寒缺氧环境对施工设备机械效率影响,利用柴油机机械效率数学模型计算分析高海拔地区各环境因素(大气压、温度、氧气浓度)对施工设备机械效率的影响程度和规律。研究结果表明:大气压力越低,机械效率越低,平均大气压力每降低20 k Pa,机械效率下降3%~5%;大气温度越高,机械效率略微升高,平均温度每升高5 K(相当于海拔升高1 km),有效功率降低2~4 k W;大气氧气含量越高,机械效率越高,平均氧气含量每上升3%,机械效率升高3%~5%。展开更多
The experimental study of air-entrained concrete specimens subjected to different cycles of freeze-thaw was completed. The dynamic modulus of elasticity, weight loss, the cubic compressive strength, compressive streng...The experimental study of air-entrained concrete specimens subjected to different cycles of freeze-thaw was completed. The dynamic modulus of elasticity, weight loss, the cubic compressive strength, compressive strength, tensile strength and cleavage strength of air-entrained concrete were measured after 0, 100, 200, 300, 400 cycles of freeze-thaw. The experimental results showed that the dynamic modulus of elasticity and strength decreased as the freeze-thaw was repeated. The influences of freeze-thaw cycles on the mechanical properties, the dynamic modulus of elasticity and weight loss were analyzed according to the experimental results. It can serve as a reference for the maintenance, design and the life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in northern cold regions.展开更多
文摘为分析高海拔高寒缺氧环境对施工设备机械效率影响,利用柴油机机械效率数学模型计算分析高海拔地区各环境因素(大气压、温度、氧气浓度)对施工设备机械效率的影响程度和规律。研究结果表明:大气压力越低,机械效率越低,平均大气压力每降低20 k Pa,机械效率下降3%~5%;大气温度越高,机械效率略微升高,平均温度每升高5 K(相当于海拔升高1 km),有效功率降低2~4 k W;大气氧气含量越高,机械效率越高,平均氧气含量每上升3%,机械效率升高3%~5%。
基金supported by part of the Key Project of the China Postdoctoral Science Foundation(Nos.20080430183 and 200801386)the Promotional Foundation for Excellent Middle-aged or Young Scientists of Shandong Province(No.2008BS08001)National Basic Research Program(No.2007CB714202)
文摘The experimental study of air-entrained concrete specimens subjected to different cycles of freeze-thaw was completed. The dynamic modulus of elasticity, weight loss, the cubic compressive strength, compressive strength, tensile strength and cleavage strength of air-entrained concrete were measured after 0, 100, 200, 300, 400 cycles of freeze-thaw. The experimental results showed that the dynamic modulus of elasticity and strength decreased as the freeze-thaw was repeated. The influences of freeze-thaw cycles on the mechanical properties, the dynamic modulus of elasticity and weight loss were analyzed according to the experimental results. It can serve as a reference for the maintenance, design and the life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in northern cold regions.
