Research Of Treatment On Ning-Hui Expressway Expansive Subgrade

In the course of the expressway surveying, design and construction, it should not be avoided to meet the weak soil such as the expansive soil. Constructing the expressway in the expansive soil area, how to guarantee the engineering stability and safety is the key of the engineering success or failure.The expansive soil is a high scattering and high expansive special clay. It is consist of Mengtuo stone or Yili stone. It has some speciality such as much more cranny, supper concretion and expanding with wet and contracting with dry. If it is treated with the improper method, it will endanger the engineering in the different extent, even the harm is very serious. The expansive soil subgrade is easy to slide and collapse, even to shrink, split, relax, flake and so on. And if the harm occurs, it is difficulty to deal with it.Ning-Hui highway is the third vertical way of the host skeleton of"Four vertical four horizontal four associations"planed by Jiangsu Province.It connects provincial capital Nanjing and Huai An, and is connected with the Xu–Huai-Yan highway.Along Ma-Wu section of Nanjing -Huai-an expressway the swelling soil was distributed . For the stabilization of the swelling foundation soil , the filling materials and the foundation soil were mixed with lime to improve the soil . The protections of subgrade drainage and borrow place drainage were strengthened and the compaction degree was controlled seriously during the construction period . It was found the water content of the subgrade section increased and degreased in the compaction degree , the roadbed resilience and the cracks appear on areas of 95% Compactness after roller compaction.Because the Huai highway is being at the construction stage, this article also showed the research of the Settlement observation and Deflection examination on roadbed construction have been given according to MaWu section.The paper will combine with the construction of the expansive soil of Ma-Wu section of Nanjing to Hui-an expressway in JiangSu Province which is in construction, and research the composition and the formation , the class and the judgment of expansive soil, and put forward the reasonable measure standard. On the other hand , synthetically research the prevention and cure measures on the subgrade damage of expansive soil according to the different situation, and bring forward the effective treatment scheme.The paper research the expansive soil combining with the engineering practice, and it can accumulate the experience for the similar engineering construction in the future.