海岛地区海水混浆短纤维加筋水泥土的试验特性研究

Experimental Investigate on Fiber-Reinforced Cement Stabilized Soil Mixing with Seawater in Island

沿海滩涂围垦区软土常通过纤维加筋水泥土进行固化后加以利用。由于海岛地区缺乏淡水,采用海水作为加筋水泥土的水源具有广泛应用前景。通过实验研究和数值模拟方法揭示了纤维加筋机理。首先基于单纤维拉拔试验,获得了不同龄期下和不同纤维埋置长度下纤维拉拔力与位移关系曲线,表明不同纤维埋置长度下单纤维最大拉拔力随龄期的发展逐渐增加,纤维越长,最大拉拔力越大,但超过10 mm时拉拔力增长幅度减低,说明纤维加筋长度存在一个合理长度;然后建立了单纤维与水泥土基体相互作用的三维有限元模型,完成了不同接触条件下单纤维拉拔数值模拟,并与试验结果进行了对比,研究表明粘性界面接触条件对单纤维与水泥土基体相互作用特性有重要影响。

Soft soils in reclamation areas often need to be solidified by mixing with fiber and cement before they can be used.Meanwhile,due to the lack of fresh water in the island area,using seawater as the water resource of fiber-reinforced cement stabilized soil is a method with wide application prospects.Failure mechanism of short fiber-reinforced cement-stabilized silty clay depends on the interaction between the fiber and the cement-stabilized soil matrix.Firstly,the relationships between the tensile force and displacement at the fiber tip are obtained by using single fiber pullout test with three fiber lengths under different curing age.The experimental results show that the curves of tensile force and displacement can be divided into three phases and there is a residual force due to friction between fiber and matrix.The results show that the maximal tensile force of single fiber under different embedding lengths increases with the development of age.The longer the fiber,the greater the maximum pulling force,but more than 10mm,the increasing rate of drawing force decreases.The length of fiber embedded has obvious influence on pull-out curve.Too long or too short fiber is not reasonable for fiber reinforcement.At last,a three-dimensional finite element method model is used to simulate the interaction between single fiber and cement-stabilized soil based on cohesive model.Numerical analyses are carried out under several different contact conditions.The comparisons of theoretical results,numerical results and experimental results discover that viscous interface parameters have vital effects on the interaction between single fiber and cement-stabilized matrix.Introducing the cohesive model,numerical results agree well with the experimental results better.This research has reference significance for the engineering utilization of seawater in the reclamation project in the island.