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At present , the rapid development of highway , not only to further improve the subgrade and pavement specifications to improve the level of construction , also put forward higher requirements for the detection of the subgrade and pavement . No matter in what pavement damage, mostly due to the deterioration of the roadbed stability , outside loads , insufficient strength , resulting in excessive deformation . Therefore, it is particularly necessary to detect on the roadbed . Through access to the extensive literature , synthesize the subgrade strength such as the degree of compaction , deflection , resilient modulus , CBR value of detection method , and compare the comparative analysis , combined with practical engineering examples proposed in different engineering what methods should be used in order to more accurately reflect the the roadbed quality . Finishing method of the roadbed detection means , and according to the instance is not difficult to find in the actual highway projects in the detection process is inconsistent , because the indoor detection limitations , as well as indoor detection indicators and indicators in that field control , coupled with human operational reasons , different equipment reasons , as well as data processing method , can not lead to the detection of the test results to better reflect the actual situation of the roadbed . Therefore, through the evaluation of the detection method , based on the practical engineering cycle is short , limited data on the actual quality evaluation . Relying on the Changde to Jishou project sections , system analysis and evaluation of the sand replacement method , cutting ring , Determination of the nuclear density , drop hammer spectrum roadbed compaction rapid determination of the instrument, such as the problems in the roadbed detection , and propose a suitable detection method and evaluation tools; through a comparative analysis of the different deflectometer detection data , in the same test conditions , come bearing plate method , of Beckman Beam law and FWD law bend the law between the sink and adapt to conditions ; Finally, in order to degree of compaction indicators and deflection indicators assay data , for example , proposed using curve fitting , the value of the correction of the deflection the subgrade deflection acceptance criteria based on the theoretical maximum dry density at the optimum moisture content and maximum dry density test in order to establish the current correction method the road test samples and testing data under limited circumstances .
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