改良膨胀土施工技术与改良土的性质研究

黄淮河冲积平原区广泛分布弱～中等膨胀土,用这种土作为高等级公路路堤填筑材料时,必须用掺石灰的方法对土体进行改良,以提高土体的强度,降低土体的胀缩性。改良膨胀土施工采用二次掺灰工艺、合适的石灰拌和方法和碾压机械组合对提高改良土的碾压质量很重要。系列现场和室内试验研究表明:采用二次拌灰工艺能够使石灰均匀并易于碾压。尽管压实天然土的CBR强度不满足规范的要求,但改良土的CBR强度高,自由膨胀率低,无压膨胀量小。改良土的微观结构与天然土明显不同,土粒间连接增强,基本看不到单粒形态。

STUDY ON CONSTRUCTION TECHNIQUES AND CHARACTERISTICS OF LIME-STABILIZED EXPANSIVE SOIL

Weak and medium expansive soils are widely distributed in the area of the Huanghuai Plain,China.The soil must be stabilized when it is used as the filling of the expressway embankment to improve its strength and reduce its expansion and shrinkage.The two-stage lime adding methodt,he suitable mixing process and the combination of rolling machine are the key aspects for the construction of lime-stabilized soil.The test results show that the two-stage lime adding method is good for soil pulverizing and compacting.The California bearing ratio(CBR) of stabilized soil is very high although the CBR of the compacted natural soil is such low that it could not satisfy the requirement of the construction code.The free expansive ratio and the expansion of the stabilized soil are very low.The microstructure of the stabilized soil has significant difference to the natural soil.The connection of the particles of stabilized soil is strong and single particles almost could not be found in the stabilized soil.