上覆荷载对改良膨胀土膨胀性影响研究

Research on Overlying Load Impact on the Expansion Characteristic of Improved Expansive Soil

研究了某一级公路膨胀土在分别掺入石灰、水泥、粉煤灰、风化砂改良后,在不同上覆荷载的作用下的膨胀变形特性,为膨胀土路基改良材料的选择以及覆土深度的确定提供了理论依据。对膨胀土分别加入石灰、水泥、粉煤灰及风化砂等改良材料,制作试件并经过养护后,在固结仪上通过施加0,12.5,25,37.5,50,75 kPa六级上覆荷载,分别测试其膨胀率,得到了同一上覆荷载作用下改良膨胀土的膨胀率与所掺改性材料比例之间的关系,以及同一比例的某种改良材料改良膨胀土,上覆荷载与膨胀率之间的关系。通过实验研究,可以得出,水泥、石灰、粉煤灰及风化砂均可以有效改良膨胀土,从抑制膨胀性的角度来看,掺石灰的效果最好,其次是掺水泥,掺粉煤灰抑制膨胀性的效果要差于上面二者但要优于风化砂。从施工的可操作性和路用性及环保的角度来看,采用风化砂要优于另外3种材料,为风化砂改良膨胀土提供了依据。

In this study, we used the expansive soil in a first class highway which improved by respec tively mixing with lime, cement, coal ash, weathered sand to study the action of expansion deformation characteristics in different overlying load, this provides a theoretical for the choice of materials and o verburden depth of expansive soil subgrade improved. To improve material of expansive soil which ad dition of lime, cement, coal ash and weathered sand, we made specimen and conserved, applied O, 12.5, 25, 37.5, 50, 75 kPa six levels of overlying load through oedometer, and then tested the ex pansion rate respectively. We got the same overlying loads modified expansive soil with the inflation rate and the relationship between the modified material proportion, and the relationship between overly ing load and the rate of expansion from the same percentage of some improved material modified expan sive soil. Through the experiment, it is concluded that cement, lime and fly ash and weathered sand all can effectively improved expansive soil. From the point of swelling inhibition, the best is mixinglime, followed by mixing cement, mixing coal ash inhibition swelling effect will send in the above two but is superior to weathered sand. From the point of the construction of the operability and environmen- tal protection, the weathered sand is superior to the other three kinds of materials, this provide the ba- sis for weathered sand improved expansive soil.