The dry density of dam-building materials has strong gradation correlation, which is particularly affected by some grading characteristic parameters such as P5 content, maximum particle size and curvature coefficient. However, in practical engineering, the grading parameters of dam materials are usually obtained by screening the dam materials excavated from the quality test pit after the rolling construction. For a certain filling unit, there are few detected data from test pits in the filling construction area, so the existing compaction quality model of earthwork in the dam compaction monitoring system cannot effectively consider the impact of gradation characteristic parameters on compaction density. In view of this, in order to construct population distribution of the grading characteristic parameters of the dam filling material, this paper takes the small sample data of grading characteristic parameters obtained from test pits sampling of the asphalt concrete core sand-gravel dam of the Dashimen Water Conservancy Project as the research object. Firstly, the Weibull distribution was selected as the small sample data distribution through goodness-of-fit tests. Secondly, the parameterized Bootstrap method and the non-parametric kernel density estimation method were used to determine the prior distribution under small sample data. Furthermore, the posterior distribution of parameters is obtained by modifying the prior distribution with the Bayesian method combined with the excavation test data of a certain work unit quality inspection on site. Finally, the mixed Gibbs sampling method is used to simulate and solve the posterior distribution, and the estimation results of two-parameter posterior Weibull distribution based on Bayesian theory are obtained, which provides important data support for real-time and accurate evaluation of the compaction characteristics of sand-gravel dam materials during the construction of the dam. © 2022 China Water Power Press. All rights reserved.
