Abstract: This paper presents a case study of the stability evaluation of a waste soil dump site of a limestone quarry. The influencing factors of the stability are evaluated. The hierarchical structure, particle-size distribution of soils, the physico-mechanical property of waste soils, and the subsurface conditions of the dump site were obtained by technical means of geological mapping, geotechnical test borings, the heavy dynamic penetration tests and the laboratory tests on the remolded waste soils. Ultimately, the stability analysis and evaluation for this dump site were performed, and stability mitigation measures were proposed. In waste soils, the size of the crushed stone is gradually increased from the top to the bottom. The subsurface condition at the bottom of the dump site consists of moderately weathered karstic limestone with gravelly clay filled rock fissures at shallow karstic rock mass. Therefore, the foundation of the dump site is stable. The slopes within the dump site could be divided into four (4) different categories with the failure mode of short-range sliding mode within the waste soil body. The factor of safety is between 0.8 and 1.0 for all slopes by using Bishop Simplified Method, which indicate that the slopes are instable.

Key words: waste dump site, waste soil dumping process, particle size distribution, short-range sliding mode, bishop simplified method, stability evaluation