改良膨胀土筑堤压实度控制标准研究

Compaction degree control standard for stabilized expansive soil in embankment construction

针对宁淮高速公路石灰改良膨胀土路堤填筑过程中用干土法标准击实试验结果作为标准压实度难以达到要求的问题,进行了干土法和湿土法室内标准击实试验.试验结果表明干土法标准击实所得的最大干密度要大于湿土法标准击实所得的最大干密度,且有较大差别.根据宁淮高速公路实际施工状况,采用湿土法标准击实试验结果作为压实度控制标准是符合现场实际的.试验段碾压后现场CBR试验结果表明,改良土的CBR值满足规范要求,说明用湿土法标准击实试验结果作为宁淮高速公路路堤填筑控制标准能够满足工程质量要求.

The maximum dry densities obtained by two standard compaction methods, the watering method and water-reducing method, are of great differences. The agreement of the variation of moisture content in the expansive soil during the construction process with that in soil samples in laboratory test by water-reducing method indicates that only the result from the standard compaction test by the water-reducing method can be taken as the compaction degree control standard. Although the dry density obtained by the water-reducing method is smaller than that obtained by the watering method under the same compaction degree, the result of the field CBR test shows that the CBR strength of the stabilized soil meets the requirement of specifications. Results from laboratory and field tests demonstrate that the adoption of test results from standard compaction with the water-reducing method as the compaction degree control standard for expansive soil in embankment construction for Ninghuai Expressway can ensure the quality of the project.