A large-scale uniaxial compression test was conducted for two types of graded sand-grained materials from the overburden of a dam. The horizontal stress and vertical stress of sand-grained materials were measured using soil pressure boxes with parameters obtained from a calibration method, and then the at-rest lateral pressure coefficient(K₀)was calculated. By studying the applicability of the hydraulic and sand calibration methods, the reliability of the experimental results of K₀ was analyzed. The results show that the sand calibration method is a reliable calibration method for coarse-grained soil. When the vertical stress is large enough, the experimental error of K₀ can be ignored, and the value of K₀ is close to the actual value. The triaxial CD test was conducted for two types of graded sand-grained materials to measure the effective angle of internal friction, and then K₀ was calculated through the relevant empirical formula and compared with the test value to obtain an empirical formula that is suitable for coarse-grained soil. The results show that the relationship expression between the at-rest lateral pressure coefficient and the effective angle of internal friction, which was proposed by Federico and was based on the concept of a mobilized effective angle of internal friction proposed by Terzaghi, is appropriate for coarse-grained soil.