初始含水率对崩岗土体抗拉特性的影响

Effect of Initial Moisture Content on Tensile Resistance of Collapsed Soil

针对花岗岩发育的崩岗土体崩壁失稳等问题,通过单轴抗拉试验,研究了湖北通城地区不同初始含水率的崩岗土体抗拉强度特性。结果表明:初始含水率对崩岗土壤抗拉强度影响明显。土壤抗拉强度特征曲线为单峰型,表土层、红土层和红砂过渡层抗拉特征曲线在含水率W C(24.4%)附近出现抗拉强度峰值,而砂土层在W C(25.8%)出现抗拉强度峰值。崩岗不同层次土壤轴向拉伸长和径向收缩长随初始含水率呈现正相关关系,且土壤轴向拉伸率和径向收缩率与初始含水率拟合出相关系数较高的线性函数关系(除砂土层的径向收缩率与初始含水率呈指数函数关系)。低(18%~22%)、中(22%~30%)、高(30%~饱和)3种初始含水率区间下崩岗土壤持水机制分别为土壤毛细管持水机制、团粒水桥联结持水机制与团粒持水机制。研究结果可为崩岗科学防治提供一定的科学依据。

Aiming at the problems instability of collapsed hill soil deveoped by granite,the tensile strength characteristics of collapsed hill soil with different initial water contents were studied by uniaxial tensile test in Tongcheng area of Hubei Province.The results showed that the initial moisture contents had a significant effect on the tensile strength of the collapsed soil.The characteristic curve of soil tensile strength appeared as a unimodal curve.The peak values were obtained at the water content of W C(24.4%)for the surface soil,laterite and red sand transition layer,while W C(25.8%)for the sandy layer.The axial and radial shrinkage lengths of different soil layers were positively correlated with the initial water contents,and the linear relationships between the axial and radial shrinkage of soil and the initial water contents were fitted with a higher correlation coefficient(the radial shrinkage of sand removal layer is exponentially correlated with the initial water contents).The mechanisms of water holding in soils with three initial water contents ranging from low(18%~22%),medium(22%~30%)to high(30%~saturation)was analyzed,which were soil capillary water holding mechanism,aggregate water bridge water holding mechanism and aggregate water holding mechanism respectively.These research results could provide a scientific basis for the scientific prevention and control of collapsed hill.