堆石料湿化变形特性试验研究

Experimental study of the characteristics of wetting deformation of rockfill materials

湿化变形是土石坝的主要后期变形之一,对坝体的应力变形性状具有显著影响。采用糯扎渡高心墙堆石坝的弱风化花岗岩堆石料进行了常规三轴试验、不同围压和应力水平条件下的流变-湿化组合试验和快速湿化三轴试验等,分析了流变-湿化组合试验各阶段的变形特征,重点研究了堆石料湿化变形的过程、特性及发生机制。结果表明,可将堆石料湿化变形划分为湿化瞬时变形和湿态流变变形两个部分。其中,湿化瞬时变形是堆石料随浸水饱和过程发生的变形,其应变增量的方向平行于相应应力状态下应力加载应变增量的方向,且具有非硬化特性;湿态流变变形是堆石料试样在饱和浸水完成后发生的随时间的变形,和一般堆石料的流变变形具有相类似的特性。湿化变形是堆石料浸水后所导致的物态弱化变形。可将堆石料湿化看作一种广义的荷载。

The wetting deformation is one of the leading long-term deformations of the earth-rockfill dam,which significantly influences the stress-deformation behaviours of the dams.In this paper,the rockfill material of weakly weathered granite from the Nuozhadu high earth-rockfill dam was studied by conventional triaxial tests,combined creep-wetting tests,and quick-wetting (without creep stage) tests under different confining pressures and stress levels.The deformation behaviours at all stages of the combined creep-wetting tests were analysed,and the evolution process,characteristics,and mechanism of wetting deformation were investigated.Results show that the wetting deformation of the rockfill material can be classified as the instantaneous wetting deformation and the wet-state creep deformation.The instantaneous wetting deformation occurs during the process of wetting and saturating of the rockfill material and shows non-hardening characteristics.Moreover,the strain increment direction is parallel to the direction of the loading-induced strain increment at the same stress state.The wet-state creep deformation occurs after the rockfill material is saturated and has similar characteristics to the general creep deformation of rockfill materials.The wetting deformation is induced by the weakening of physical state after the rockfill material is wetted by water,and thus the wetting of rockfill material can be considered as a generalised load.