The Appraisal Of Highway Subgrade Construction Examination Methods And Process Of Testing Data

At present, the highway is developing rapidly, not only do we need to complete roadbed further and improve the level standard of construction, but also put forward higher request for roadbed testing. No matter what pavement damages appear, the most probable reasons are due to the poor condition of the roadbed stability, overloading and insufficient strength in the road which result in an excess deformation. Therefore, testing of sub grade is necessary. After studying carefully the references, the relevant sub grade strength has been summarized, such as degree of compaction, deflection, elastic modulus, CBR value index examination method. Comparisons with practical examples are conducted. Appropriate methods in different actual engineering that can more accurately reflect roadbed quality are put forward.According to the arrangement of the sub grade detection methods, it is easy to find, because of indoor test limitations, that the indoor test index and field index are inconsistent. In addition, the artificial operations and the different instruments, and the different trigger detection on data processing method lead to the results that can not reflect the actual situation of roadbed for the actual examples of highway engineering testing process. Therefore, according to the evaluation of testing methods and the characteristics of actual engineering, this paper carries out a quality evaluation to the actual engineering based on the short cycle with limited data.The paper is based on Changde to Jishou project and systematically analysis and evaluates some existing problems in the methods of sub grade detection, such as sand filling method, ring knife method, a nuclear density measuring method and the apparatus of drop hammer spectrum for quick measuring the compactness of the roadbed. The paper puts forward appropriate testing and the evaluation method; Through analyzing the different deflection detecting data, we draw some laws between deflections measured with the bearing plate method, Beckman beam method and FWD method under the same condition and the adaptable conditions. Finally, by taking the test data of compaction degree index and deflection index as an example, we propose that a curve-fitting method should be taken in the test for an optimum moisture content and maximum dry density, and that the check criteria should be used of maximum dry density based on theory for roadbed deflection value. As a result, correction methods dealing with the limited experiment samples and testing data have been established for the current highway construction.