Soft soil subgrades often present significant geotechnical challenges under cyclic loading conditions associated with major infrastructure developments. Moreover, there has been a growing interest in employing various recycled tire derivatives in civil engineering projects in recent years. To address these challenges sustainably, this study investigates the performance of granular piles incorporating recycled tire chips as a partial replacement for conventional aggregates. The objective is to evaluate the cyclic behavior of these tire chip-aggregate mixtures and determining the optimum mix for enhancing soft soil performance. A series of laboratory-scale, stress-controlled cyclic loading tests were conducted on granular piles encased with combi-grid under end-bearing conditions. The granular piles were constructed using five volumetric proportions of (tire chips: aggregates) (%) of 0:100, 25:75, 50:50, 75:25, and 100:0. The tests were performed with a cyclic loading amplitude (qcy) of 85 kPa and a frequency (fcy) of 1 Hz. Key performance indicators such as normalized cyclic induced settlement (Sc/Dp), normalized excess pore water pressure in soil bed (Pexc/Su), and pile-soil stress distribution in terms of stress concentration ratio (n) were analyzed to assess the effectiveness of the different mixtures. Results indicate that the ordinary granular pile (OGP) with (25 % tire chips + 75 % aggregates) offers an optimal balance between performance and sustainability. This mixture reduced cyclic-induced settlement by 86.7 % compared to the OGP with (0 % TC + 100 % AG), with only marginal losses in performance (12.3 % increase in settlement and 2.8 % reduction in stress transfer efficiency). Additionally, the use of combi-grid encasement significantly improved the overall performance of all granular pile configurations, enhancing stress concentration and reducing both settlement and excess pore water pressure. These findings demonstrate the viability of using recycled tire chips as a sustainable alternative in granular piles, offering both environmental and engineering benefits for soft soil improvement under cyclic loading.

Granular columns have been used widely over the years to improve the load-bearing capacity of soft soils. Conventional granular columns are composed of stone aggregates, a non-renewable natural resource. Meanwhile, the global stockpile of plastic waste poses another serious threat to the sustainable existence of lives on our planet. This paper highlights the results of laboratory model tests performed on an embankment supported over a soft clay bed improved with granular columns (GC) and plastic granular columns (PGC). The model embankment was subjected to static and cyclic loading tests. The cyclic loading was applied in a 4-stage varying amplitude and single-stage loading. The experimental results show that the vertical load-bearing capacity of the soil bed improved by the granular column is increased by 71-135 % under static loading, respectively. The stresses induced in the column and soil bed were measured using earth and pore pressure transducers. Using GC and PGC, the cyclic load-induced settlements were reduced for both floating and end-bearing conditions compared to unreinforced soil. Using geosynthetic encasement further enhances the loading-bearing capacity, stress concentration ratio, and excess pore water pressure dissipation of the soil bed. The excess pore water pressure in unreinforced clay beds is reduced significantly. The stress concentration ratio (n) of the encased column improved bed is 1.51 and 1.50 times that of the non-encased end-bearing and floating columns. Geosynthetic encasement of GC and PGC significantly contributes to cyclic load-bearing capacity. The application of GC and PGC in soft clay improvement for the development of transportation routes and railway embankments is wellsuited based on the findings of this study.

The stone column encasement is a widespread ground improvement technique that effectively improves the engineering characteristics of weak and compressible soils with excessive settlement problems under vertical loadings. Despite the extensive use of stone columns, the settlement response of sandy soils reinforced with various geosynthetic encasement configurations under cyclic loading conditions remains unexplored. This study aimed to understand the settlement response of sandy soils reinforced with dual-layer geosynthetic-encased stone columns (DLGESCs), single-layer geosynthetic-encased stone columns (SLGESCs), and ordinary stone columns (OSCs) under cyclic loading conditions. The effects of cyclic loading amplitude, frequency, and geosynthetic encasement on settlement behavior were investigated using PLAXIS-3D (version 21) software with the hardening soil small constitutive model, and geosynthetic encasements with variable axial stiffness and tensile strength were studied. The study results indicated that higher cyclic loading amplitudes and frequencies increase the settlement of the stone column. DLGESC outperformed SLGESC with a 5.8%-11.2% settlement reduction, while SLGESC reduced settlement by 40.9%-47.8% compared to OSC. Geosynthetic GT3 (800 kN/m axial stiffness, 70 kN/m tensile strength) decreased settlement by 7.6%-13.6% compared to GT1. This research emphasizes ground improvement techniques and demonstrates the way DLGESC reduces settlement and improves structure stability on stone column-reinforced sandy soils. This study can help design resilient and stable foundations for pavements, railroad tracks, and offshore structures under cyclic vertical loading characteristics and suitable encasement configurations.

The application of sites containing low-strength soil deposits is of great concern concerning the rapid increase in urbanization and industrialization. To overcome such difficulties in construction, ground improvement techniques are frequently practiced. So, the provision of the stone column is one of the well-known approaches to improve the weak soil properties. Moreover, the application of reinforced stone columns is chosen over the conventional method of stone columns to enhance the strength and durability parameters of weak soils to a greater extent. In this context, the present article presents a state-of-art review of reinforced stone columns and analyzes their developments, Performance, and Prospects concerning future aspects. This comprehensive analysis includes the most relevant existing studies based on experimental, analytical, and field testing for static and cyclic loading conditions. The present study presents the review chronologically from the beginning of the research on geosynthetic reinforced stone columns. The main aim of this study is to collect the existing outcomes from various research and accumulate them in one resource which will be helpful for future researchers to proceed with the new development with this easily accessible information and data.

A series of undrained cyclic triaxial tests were carried out on loose sand specimens, including encased and non-encased granular columns, to evaluate the cyclic behavior and liquefaction resistance of the ground improved by granular columns. It was found that using geogrid encasements could effectively reduce cumulative settlements and mitigate the liquefaction potential when its tensile stiffness was high enough. Another finding was the inefficiency of flexible geosynthetic encasements to delay and mitigate the liquefaction in granular columns with the possibility of clogging. Findings indicated that the improvement of a loose ground with encased granular columns not only decreased the liquefaction-induced ground deformation but also significantly reduced the effect of earthquake magnitude on the ground deformation. It was also found that using the granular column and encasing it with a high-stiffness encasement not only slowed down the rate of ground softening during the cyclic loading experience but also decreased the dissipation of energy.

The efficiency of geosynthetics has been proven in stone column -reinforced foundations. In this paper, loading tests were conducted on three stone column -reinforced foundations, experiencing four freeze -thaw cycles. The effects of geosynthetic encasement and lateral reinforcement were investigated on the behavior of ordinary stone column (OSC) - reinforced and geosynthetic encased stone column (GESC) - reinforced foundation. The results showed that particles of OSCs spread into foundation soil during freezing and thawing, and top of OSCs were replaced by foundation soil. The temperature gradient along the depth in OSC-reinforced foundation was smaller than in GESC-reinforced foundations, resulting in a lower negative pore pressure at the beginning of freezing. However, it was found that geosynthetic encasement helped maintain the integrity of GESCs, and increased the stress concentration ratio (SCR) during thawing, which led to a lower excess pore pressure in GESC-reinforced foundations. The lateral reinforcement was also found to not only reduce the differential settlement between GESCs and soil during thawing, but also restrain the frost heave during freezing. The tensile membrane effect of lateral reinforcement redistributed the stress and the overburden pressure throughout the freeze -thaw process. More water moved upwards during freezing in the OSC-reinforced foundation, leading to a larger amount of frost heave. However, the moisture migration became complex in the OSC-reinforced foundation, as OSCs were damaged by freeze -thaw cycles.

The current study addresses the dual challenges of improving the performance of soft soil beds subjected to static and cyclic stresses and managing the environmental impact of waste tire disposal. This research contributes valuable insights into the sustainable use of recycled tire chips in granular pile construction, coupled with the efficacy of combi-grid encasement for improved soft ground under static and cyclic loading conditions. A series of laboratory model tests were carried out on a group of granular piles to examine the principal parameters, such as the selection of geosynthetic materials and cyclic loading characteristics, including cyclic loading amplitude (qca) and cyclic loading frequency (f). The granular pile composition consists of (25% tire chips + 75% aggregates). The performance of granular piles on improved ground is assessed based on the settlement reduction ratio (Sc,r), accumulation of excess pore water pressure (Pexc), and stress concentration ratio (n). The key findings from static model tests are that the load-bearing capacity is significantly increased with installing a group of ordinary granular piles (= 58%) and substantially increased with combi-grid encasement (= 335%). The effectiveness of ordinary granular piles (OGP) in enhancing the performance of a soft soil bed becomes greater when subjected to lower cyclic loading frequencies (f) and smaller cyclic loading amplitudes (qca). The incorporation of combi-grid encasement greatly enhanced the cyclic performance of a group of granular piles by substantially minimizing cyclic-induced settlement (Sc) across both principle parameters f and qca. This study also examines the increased cyclic stresses on the improved soft bed, resulting in the accumulation of excess pore water pressure (Pexc) development, which is reduced to a greater extent with the help of combi-grid encasement across both principle parameters.

The performance of encased granular piles subjected to heavy cyclic loading presents a significant concern in the current context. Meanwhile, global waste tire management poses a major challenge because it has a detrimental effect on the environment. To address both difficulties, this research utilizes recycled tire chips derived from endof-life tires (ELTs) and substituting traditional aggregates in granular pile construction. This study summarizes laboratory model tests investigating the performance of geosynthetic encased granular piles designed for soft soil improvement under vertical cyclic loading. The composition of the granular pile comprised (25 % tire chips + 75 % aggregates). Various cyclic loading parameters were scrutinized, including the selection of encasement material and the best configuration for granular piles, cyclic loading frequency (f), cyclic loading amplitude (qca), length-to-diameter (L/D) ratios, granular pile end conditions, and strength of surrounding soft soil. The novel feature of this research is the evaluation of the cyclic induced settlement (Sc) - excess pore water pressure (Pexc) coupled performance for all considered factors and its effects on the encased granular piles improved soft ground under vertical cyclic loading. Key findings include ordinary granular piles (OGP) illustrated optimal performance when subjected to lower frequency and amplitude loading, smaller L/D ratios, and end bearing conditions. The provision of Combi-grid encasement notably improved the cyclic performance of granular piles by substantially reducing the cyclic induced settlement (Sc) on improved soft beds across all examined factors. This research also discusses the increased cyclic stress on the surrounding soft soil initiated excess pore water pressure (Pexc) development and is reduced to a greater extent with the help of Combi-grid encasement across all test cases.