Effectiveness of high-energy dynamic compaction on Layered soil-rock mixture geomaterials based on field test

Dynamic compaction (DC) method is an effective ground improvement technique for various soil conditions. However, there has been limited investigation into the application of high-energy DC for deep layered backfill beyond the once influence depth of DC. This study presents a field investigation of DC using a maximum energy level of 15,000 kN·m on large thickness backfills with soil-rock mixtures geomaterials in Chongqing city, China. The site utilizes layered backfill and tamping, primarily consisting of gravels with low uniformity and density. To meet engineering construction requirements and determine optimal DC parameters, representative areas were selected for field testing. The testing mainly included point tamping at energy levels of 6000 kN·m, 10,000 kN·m, and 15,000 kN·m in different layers, with subsequent analysis of tamping settlement and crater deformation. The study identified the optimal number of drops for various energy levels. Super-heavy dynamic penetration tests (SH-DPT) and plate load tests (PLT) were conducted to assess site reinforcement effects. Following DC, the results indicated that the maximum reinforcement depth, allowable ground-bearing capacity, and deformation modulus were all greater than 15 m, 200 kPa, and 15 MPa, respectively, meeting engineering requirements.