Abstract: This paper presents a case history of foundation type selection for a residential building development project in the backfilled area of a former sand quarry site. The subsurface geotechnical conditions of the project site, including, soil stratigraphy, geological conditions as well as physical and mechanical properties, are introduced in detail. Different foundation types and their associated ground improvement methods are evaluated and compared.The advantages, disadvantages, and applicability of each scheme are analyzed, and the safety, economy, rationality, and construction feasibility are also considered. The shallow foundation with soil-cement mixing piles is selected as the optimized method for this project. The ground improvement design method for the project is briefly presented. The static load tests were performed on both single soil-cement mixed piles and composite ground. The test results indicates that the bearing capacity of the improved ground meet the design requirements and the selected ground improvement method is feasible for the project. It’s can provide reference for foundation design and foundation treatment schemes of similar sites.

Key words: Sand Quarry, Ground Improvement, Foundation Design, Design Approach Comparison, Soil-Cement Mixing Piles