上覆荷载对重塑粉质黏土补水冻胀特性影响

Influence of Load on Frost Heaving Characteristics of Remolded Silty Clay

在冻胀融沉预测与控制问题中,外荷载特别是较大荷载抑制冻胀的作用及冻胀变形规律是预测与控制冻胀变形的关键。通过补水条件下荷载对重塑粉质黏土冻胀试验,研究不同荷载水平对重塑粉质黏土冻胀特性的影响及演变规律。结果表明:不同荷载作用试样降温规律类似,主要分为恒温、温度迅速下降、温度缓慢降低和温度稳定4个阶段,总体表现为荷载越大,温度下降速度越快;不同荷载作用下冻结锋面随时间变化的发展曲线均呈对数增长趋势,随荷载增大,冻结前期冻结锋面发展速度加快,中后期锋面发展速度减慢,锋面位置高度随荷载增大而降低;随荷载增大,起始冻胀量出现的时间延后,冻胀量发展达到稳定的时间缩短,冻胀量发展速率减小,且冻胀量减小,无荷载作用下土样最终冻胀量为200 kPa下的6.4倍;冻胀率随上覆荷载的增大呈指数规律递减,无荷载作用下土样最终冻胀率为200 kPa下的5.6倍。

In the prediction and control of frost heave and thaw settlement,the effect of external load,especially large load,on inhibiting frost heave and the law of frost heave deformation are the key to predict and control frost heave deformation.Through the frost heave test of remolded silty clay in the condition of water replenishment,the influence and evolution law of different load levels on the frost heave characteristics of remolded silty clay were studied.The results showed that the cooling law of samples with different loads was similar,which was mainly divided into four stages:constant temperature,rapid temperature drop,slow temperature drop and temperature stability.The overall performance was that the greater the load,the faster the temperature drop.The development curves of freezing front with time with different loads showed a logarithmic growth trend.With the increase of load,the development speed of freezing front in the early stage of freezing was accelerated,and the development speed of front in the middle and late stages was slowed down.The height of front position decreased with the increase of load.With the increase of load,the time when the initial frost heaving amount appeared delayed,the time when the frost heaving amount reached stable development shortened,the development rate of frost heaving amount decreased,and the frost heaving amount decreased.The final frost heaving amount of soil sample without load was 6.4 times that under 200 kPa.The frost heaving ratio decreased exponentially with the increase of the overlying load,and the final frost heaving ratio of soil samples with no load was 5.6 times that under 200 kPa.