细粒土的全压实曲线与压实土体的强度特性研究

对3种细粒土在3种击实功作用下的全压实曲线(含水量变化从零到土体趋于饱和),以及沿击实曲线的无侧限抗压强度、饱水与不饱水状态下的CBR强度特性进行了试验研究。试验研究表明:细粒土压实曲线具有两个重要的边界特征,即当含水量较小时,细粒土在一定击实功作用下的干密度值随含水量改变而变化的幅度很小,而当土体含水量较高时,随着含水量的增大,土体在不同击实功作用下的击实曲线均趋向合一,且土样的饱和度基本维持在某一定值;压实土样的最大干密度与最优含水量与击实功的常用对数分别呈线性递增和递减关系;沿全压实曲线,击实土样在最优含水量的干侧出现无侧限抗压强度峰值,且其强度值维持较高水平的含水量范围与塑限的大小有关;沿压实曲线,土样的不饱水CBR强度(单轴灌入强度)随含水量的增大而单调减小,当土样含水量较大时,重型击实功作用下土样的不饱水CBR强度反而低于采用中间和轻型击实功制备的土样的强度,而饱水CBR强度在最优含水量的湿侧的某一含水量范围内还呈递增趋势。实际工程中,应充分掌握和利用细粒土的这些压实和强度特性,制定出合理的压实控制指标和标准。

The Compaction and Strength Behaviors of fine-grained soils and the Compaction Standard of Clay Embankments in Moisture Area

By the tests of compaction and CBR,this paper discusses compaction characteristics and strength behaviors of fine-grained soils from Hunan Province under 3 different tamping efforts.The testing results show that the maximum dry densities and the optimum water contents of compacted fine-grained soils are linear to logarithm of the tamping efforts.Beyond the optimum water contents,the compaction curves are almost lapped over under different tamping efforts,and the saturation of compacted soils are been maintaining a fixed value.the un-soaking CBR values under modified proctor efforts are lower than the values under proctor and middle efforts when the water content of soils is high.These reveal that there should be establishing a rational tamping efforts to the moist soils,which can avoid wasting the tamping energy and damaging the structural.Along the compaction curve,the un-soaking CBR values are gradually depressed,while the soaking ones have a peak value when the water content of soils is beyond the optimum water contents.In order to obtain the stable engineering behaviors,the water content should be consistent with the one which the soaking CBR values is maximal in practical embankment construction.