# Integrated Plug High-Strength Geocell Reinforcement in Foundation Design for Square Footing
## 1 Introduction  
The geocell, with its intricate three-dimensional honeycomb-like structure crafted from interconnected synthetic strips, serves as a robust solution for reinforcing foundations [1]. Within this structure, soil experiences heightened lateral stresses, effectively limiting the movement of soil particles and enhancing shear strength. The confinement provided by adjacent cells further bolsters resistance against external loads passively, aided by the geocell's high loop strength, which restricts lateral expansion (Figure 1) [2, 3]. Such structural integrity, often established through methods like extrusion or adhesion, significantly mitigates the intrusion of base materials into soft soil foundations, thereby fortifying weakened substrates and minimizing settlement occurrences [4, 5, 6, 7]. Consequently, the bearing capacity of geocell-reinforced foundations is intricately linked to factors like cell wall tensile strength, cell opening size, and joint characteristics [8, 9, 10, 11]. The interlock-enhanced integral geocell (IPGC), as depicted in Figure 2, represents a notable advancement in high-strength geocell technology. The IPGC wall exhibits significantly higher strength in the horizontal direction than in the vertical direction. This discrepancy leads to stress concentrations at cut locations, increasing the likelihood of horizontal tearing. Consequently, such tearing can compromise the integrity of the overall connection points. The confining effect of the geosynthetic structure is limited by these connections, likely due to localized eccentric effects that occur under real-world conditions. In contrast to traditional counterparts, the IPGC wall is polypropylene, with a longitudinaltensile strength of \(\geq\)244 MPa, an elongation at break of \(\leq\)15%, and a tensile strength at the plug-in joint of \(\geq\)244 MPa. The thickness of the cell wall is (0.45 \(\pm\) 0.1) mm, and the height is 50 mm. The integration of plug-in joints, formed by pins with a diameter of \(\geq\)2.5 mm inserted into geocell wall cuttings, further enhances its structural integrity. Both model tests [12] and finite element analysis [13] have underscored IPGC's reliance on the high strength and stiffness of its geocell wall, which effectively confines the infill soil. [PERSON] et al. (2014) [12] and [PERSON] et al. (2019) [14] conducted model experiments to compare the bearing capacity and deformation characteristics of sand foundations with those reinforced by IPGC under varying conditions. The schematic diagram of the IPGC-reinforced foundation under a square footing is presented in Figure 3. The scale ratio is about 1:12 for the testing application [12,15]. However, it is essential to note that additional tests and discussions on scale ratios are necessary if the results are to be applied to real projects. A square footing with a width of \(B\) is positioned in the center of the model box. \(D_{\text{u}}\) is the top space of IPGC from the bottom of the footing. \(h\) is the height of the cell wall. \(d_{0}\) is the diameter of the maximum cell size. \(p\) is the overburden loading. The study found that foundations reinforced with IPGC have significantly higher initial stiffness and more than double the bearing capacity of foundations on a sand base. bution, enhancing the performance of the soil foundation. [PERSON] et al. [13; 17] also found that geocells effectively prevent soil particle displacement under load due to their sidewalls. The 3D network structure with apertures permits soil particle penetration from one side of the cell to the other, thereby restraining lateral deformation and potential strain within the soil. Consequently, the applied load is distributed over a wider area, increasing the composite system's shear strength and enhancing the foundation's load-bearing capacity. [PERSON] et al.