Pipe installation following excavation of pavement and subsoils induces settlements, cracks and bad roughness near utility cut. This study is to use PMT and LDWT in order to evaluate stiffness and/or degree of compaction of sublayers and backfill in utility cut section because no specially designed efforts for evaluating stiffness condition of the substructures below new pavement after pipe installation are offered for the sections. From test results of PMT, comparable stiffness and/or degree

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... compaction in recompaction process is not obtained comparing to that of the existing sublayers before excavation. It is verified that LDWT comparing to PMT is effective only to get stiffness and/or degree of compaction within limited depth from surface of refill materials, but it is not useful to know stiffness of substructures in full-depth in case of utility cut. A numerical study is performed also for getting information about behavior of utility cut section with changing stiffness of the sublayers.