Settlement performance and prediction model of rock-filled subgrade constructed by explosive replacement method

The explosive replacement method(ERM) is one of the effective methods to treat the deep soft soil in coastal area. The model tests of explosive replacement were carried out to investigate the post-explosion settlement evolution pattern, and a integrated rockfill was used to represent the crushed rock to reduce the measurement error caused by the randomness. The settlement behavior of the rockfill with different rockfill sizes and blasting design parameters was analyzed. Then, the settlement prediction methods were discussed. The research results indicate that the wider or higher the rockfill cross-section, the greater the post-explosion settlement of the rockfill, and the deeper the treated silt depth, but the longer the settlement stabilization delay. The greater the depth of explosive burial, the post-explosion settlement of rockfill tends to decrease. There is an optimal depth of explosive burial. Combining the results of field measurements of a subgrade project of S201 Trunk road of Nation and Province in Ningde, Fujian Province, China, the predicting method of post-explosive settlement of the subgrade was proposed by taking the coefficient of determination, prediction error, and final settlement as the indicators of the method validity assessment based on on-site measurements. The field and experimental settlement results were compared and analyzed to verify the reasonableness of the prediction model. The study can provide technical guidance for relevant engineering practice.