西藏拉洛水利枢纽大坝沥青混凝土心墙料三轴试验研究

Triaxial tests study on asphalt concrete core material in Laluo Hydro Project in Tibet

水工沥青混凝土具有良好的抗渗性和耐久性,近年来被广泛用于大坝建筑物中。针对不同性质的骨料沥青混凝土,开展了不同温度(4.8,12.7℃和28.2℃)和不同剪切速率(0.05,0.2,1 mm/min)下三轴固结排水剪切试验,分析了骨料性质、温度、剪切速率等对沥青混凝土力学性能的影响规律。试验结果表明:(1)辉绿岩作为骨料的沥青混凝土黏聚力较骨料为灰岩的大,摩擦角偏低;且在细骨料中加入不同比例的天然河砂对沥青混凝土的力学性能影响较小,但掺入河砂会影响体变,且有增大破坏应变的趋势;(2)随着温度增高,试样强度明显降低,破坏应变明显增大,且围压越低,强度降低的趋势越明显,破坏应变增大的越少;随温度增加,模量参数K值减小,初始切线泊松比G有减小趋势,但影响并不显著;(3)剪切速率越大,沥青混凝土强度越高,破坏应变越小,K值越大,R和F基本不受剪切速率影响。

Hydraulic asphalt concrete has good impermeability and durability, and has been widely used in dam buildings in recent years.In the light of different properties of aggregate asphalt concrete, triaxial consolidation drainage tests are carried out at different temperatures(4.8,12.7 ℃ and 28.2℃)and different shear rates(0.05,0.2,1 mm/min)to analyze the influence of aggregate properties, temperature and shear rate, etc.,on the mechanical properties of asphalt concrete.The test results showed that:(1) The cohesion of asphalt concrete with diabase as aggregate is higher than that of limestone as aggregate, and the friction angle is lower;in addition, adding different proportions of natural river sand to the fine aggregate has little effect on the mechanical properties of asphalt concrete, but adding river sand will affect the volume change and tend to increase the failure strain;(2) With the increase of temperature, the strength of the sample decreases significantly, the failure strain increases significantly and the lower the confining pressure, the more obvious the trend of strength reduction is, and the less the failure strain increases;with the increase of temperature, the value of the modulus parameter K decreases, and the initial tangent Poisson’s ratio G has a decreasing trend, but the effect is not significant;(3) The larger the shear rate, the higher the strength of the asphalt concrete, the smaller the failure strain, the larger the K value, and the Rand F are basically not affected by the shear rate.