## 1 Introduction  
With the rapid development of infrastructure in recent years, a considerable number of large fill projects have been initiated in China, many of which involve foundation construction in the southwestern regions, where coarse-grained soil is dominant. Due to large filling volume and large postconstruction settlement, an appropriate treatment should be performed. At present, the most popular approaches for treating fill foundation include dynamic compaction and geogrid reinforcement. Dynamic compaction (DC) has many advantageous characteristics such as simple equipment, convenient construction, faster construction work efficiency, and guarantee of quality. Some scholars have discussed the theory of DC ([PERSON] et al., 1984; [PERSON], 1992; [PERSON], 1975) [1; 2; 3]. Many researchers have investigated the densification effects of DC on sandy soils ([PERSON] et al., 2013; [PERSON] et al., 2012), deposits ([PERSON], 1980; [PERSON] et al., 2011), collapsible soils ([PERSON] et al., 2010), red clay soil ([PERSON] et al., 2008), and solid waste ([PERSON] et al., 2013) [4; 5; 6; 7; 8; 9; 10]. Based on a great deal of information from compaction tests on dry sand materials, researchers analyzed the relationship between the compacting energy and the compacting effect and indicated that the influence of the construction process is determined by the choice of equipment and relevant factors, including tamper weight, shape, dropping height, and interval between tamping point ([PERSON] and [PERSON], 1992) [11]. Many tests also indicated that there are many laws affecting soil reconsolidation and deformation, such as impact energy, peripheral pressure, soil properties, and so on ([PERSON], 2003) [12]. An improved but essentially empirical approach for selecting the operational parameters for DC has been suggested ([PERSON] et al., 1990) [13]. Some researchers also proposed a simplified model based on a one-dimensional wave equation to predict the crater depth associated with the dropped weight and to determine the depth and level of the improved soil beneath the impact zone ([PERSON] et al.,1992a, 1992b) [14; 15]. Additionally, characteristic design curves to select the optimum grid space in DC projects were also presented ([PERSON] et al., 1994) [16]. However, the design and application of DC are still empirical in practice, which relies heavily on the designer's experience and judgement ([PERSON] et al., 2005; [PERSON] et al., 2010) [17; 18]. The geogrid reinforcement method, which is an effective ground reinforcement method, reduces the lateral displacement, improves the deformation characteristics, and enhances the strength of the soil mass. Lots of model experiments showed that geogrid reinforcement does reduce the settlement of the foundation and the settlement reduction factor is a function of the depth of reinforcement ([PERSON] et al., 1998) [19]. A series of triaxial compression tests and cyclic triaxial tests were conducted on unreinforced and geogrid-reinforced crushed limestone samples to study the effects of geogrid type ([PERSON] et al., 2007) [20]. The effect of geogrid on controlling the stability and settlement of high railway embankments was also investigated using laboratory tests and finite element modeling ([PERSON] et al., 2018) [21]. Geogrid reinforcement reduces the lateral strains with the base and subgrade layers, reduces the vertical strains on top of subgrade layer, and hence significantly reduces the surface permanent deformation of pavement ([PERSON], 2011) [22]. Based on the computational results, the optimization design (geogrid modulus, reinforced layers, and reinforcement length) technology of geogrid-reinforced subgrade widening for highways is presented ([PERSON] et al., 2013) [23]. By choosing five main influential factors (such as tensile strength and geogrid modulus), the analysis on the sensitivity of geogrid reinforcement factors in mine-tailing slopes was conducted ([PERSON] et al., 2016) [24].