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.

A group of earthquakes typically consists of a mainshock followed by multiple aftershocks. Exploration of the dynamic behaviors of soil subjected to sequential earthquake loading is crucial. In this paper, a series of cyclic simple shear tests were performed on the undisturbed soft clay under different cyclic stress amplitudes and reconsolidation degrees. The equivalent seismic shear stress was calculated based on the seismic intensity and soil buried depth. Furthermore, reconsolidation was conducted at the loading interval to investigate the influence of seismic history. An empirical model for predicting the variation of the accumulative dissipated energy with the number of cycles was established. The energy dissipation principle was employed to investigate the evolution of cyclic shear strain and equivalent pore pressure. The findings suggested that as the cyclic stress amplitude increased, incremental damage caused by the aftershock loading to the soil skeleton structure became more severe. This was manifested as the progressive increase in deformation and the rapid accumulation of dissipated energy. Concurrently, the reconsolidation process reduced the extent of the energy dissipation by inhibiting misalignment and slippage among soil particles, thereby enhancing the resistance of the soft clay to subsequent dynamic loading.

The foundation soil below the structure usually bears the combined action of initial static and cyclic shear loading. This experimental investigation focused on the cyclic properties of saturated soft clay in the initial static shear stress state. A range of constant volume cyclic simple shear tests were performed on Shanghai soft clay at different initial static shear stress ratios (SSR) and cyclic shear stress ratios (CSR). The cyclic behavior of soft clay with SSR was compared with that without SSR. An empirical model for predicting cyclic strength of soft clay under various SSR and CSR combinations was proposed and validated. Research results indicated that an increase of shear loading level, including SSR and CSR, results in a larger magnitude of shear strain. The response of pore water pressure is simultaneously dominated by the amplitude and the duration of shear loading. The maximum pore water pressure induced by smaller loading over a long duration may be greater than that under larger loading over a short duration. The initial static shear stress does not necessarily have a negative impact on cyclic strength. At least, compared to cases without SSR, the low-level SSR can improve the deformation resistance of soft clay under the cyclic loading. For the higher SSR level, the cyclic strength decreases with the increase of SSR.

Pile penetration in soft ground involves complex mechanisms, including significant alterations in the soil state surrounding the pile, which influence the pile negative skin friction (NSF) over time. However, the pile penetration process is often excluded from finite element analysis. This paper investigates the impact of pile penetration on the generation of NSF and dragload. A stable node-based smoothed particle finite element method (SNS-PFEM) framework is introduced for two-dimensional axisymmetric conditions and coupled consolidation, incorporating the ANICREEP model of soft soil with a modified cutting-plane algorithm. A field case study with penetration process is simulated to verify the numerical model's performance, followed by a parametric analysis on the effect of penetration rate on NSF during consolidation. Results indicate that without the pile penetration process in NSF analysis can result in an unsafely low estimation of NSF and dragload magnitudes. The penetration rate affects dragload only at the initial consolidation stage. As consolidation progresses, dragload converges to nearly the same magnitude across different rates. Additionally, current design methods inadequately predict the beta value (where beta is an empirical factor correlating vertical effective stress of soil with the pile skin friction) and its time dependency, for which a new empirical formula for the time-dependent beta value is proposed and successfully applied to other field cases.

Horizontal frost heave disasters frequently occur in cold-region engineering projects, making it essential to understand water migration mechanisms along horizontal directions during freezing processes. Using a selfdeveloped one-dimensional visualization horizontal freezing apparatus, unidirectional horizontal freezing tests were conducted on soft clay under varying temperature gradients, and the development process of the cryostructures was continuously observed. The results indicate that the thermal-hydraulic processes, including temperature evolution, water content variation, pore-water pressure dynamics, and soil pressure changes, demonstrate similarities to vertical freezing patterns, with temperature gradients primarily influencing the magnitude of parameter variations. Under the influence of gravity, the freezing front forms an angle with the freezing direction, attributed to differential freezing rates within soil strata. Post-freezing analysis showed dualdirectional water redistribution (horizontal and vertical), with horizontal migration dominating. Maximum water content was observed 1-3 cm from the freezing front. Distinct cryostructures formed in frozen zones were identified as products of tensile stresses generated by low-temperature suction and crystallization forces. The study highlights the coupling of water transfer, thermal changes, mechanical stresses, and structural evolution during freezing and suggests that water migration and cryostructure formation are interrelated processes. This research provides robust experimental evidence for advancing the theoretical framework of horizontal water migration mechanisms in frozen soil systems.

The long-term settlement of subsea pipelines on a clayey seabed is crucial for the on-bottom stability of the pipelines, especially in deep waters. In this study, a poro-elasto-viscoplastic finite element analysis is performed for predicting long-term settlement of subsea pipelines by incorporating a rheological constitutive model. A method for identifying the creep-settlement (Sc) from the total-embedment (Sk) is proposed on the basis of the obtained linear relationship between the secondary consolidation coefficient (C alpha e) of the clayey soil and the total-embedment (Sk) of the pipe. The identifying method is validated with the existing theoretical solutions and experimental data. Parametric study is then performed to investigate the key influential parameters for long-term settlement of subsea pipeline. A non-dimensional parameter Gc is introduced to quantitatively characterize the soil rheology effect on pipeline settlement. The relationship between the proportion of creep-settlement in the total-embedment (Sc/Sk) and Gc is eventually established for identifying whether the proportion of creep-settlement in the total-embedment is remarkable.

Deep soil mixing (DSM) is a widely used ground improvement method to enhance the properties of soft soils by blending them with cementitious materials to reduce settlement and form a load-bearing column within the soil. However, using cement as a binding material significantly contributes to global warming and climatic change. Moreover, there is a need to understand the dynamic behavior of the DSM-stabilized soil under traffic loading conditions. In order to address both of the difficulties, a set of 1-g physical model tests have been conducted to examine the behavior of a single geopolymer-stabilized soil column (GPSC) as a DSM column in soft soil ground treatment under static and cyclic loading. Static loading model tests were performed on the end-bearing (l/h = 1) GPSC stabilized ground with Ar of 9 %, 16 %, 25 %, and 36 % and floating GPSC stabilized ground with l/h ratio of 0.35, 0.5, and 0.75 to understand the load settlement behavior of the model ground. Under cyclic loading, the effect of Ar in end-bearing conditions and cyclic loading amplitude with different CSR was performed. Earth pressure cells were used to measure the stress distribution in the GPSC and the surrounding soil in terms of stress concentration ratio, and pore pressure transducers were used to monitor the excess pore water pressure dissipated in the surrounding soil of the GPSC during static and cyclic loading. The experimental results show that the bearing improvement ratio was 2.28, 3.74, 7.67, and 9.24 for Ar of 9 %, 16 %, 25 %, and 36 %, respectively, and was 1.49, 1.82, and 2.82 for l/h ratios of 0.35, 0.5, and 0.75 respectively. Also, the settlement induced due to cyclic loading was high under the same static and cyclic stress for all the area replacement ratios. Furthermore, the impact of cyclic loading is reduced with an increase in the area replacement ratio. Excess pore water pressure generated from static and cyclic loads was effectively decreased by installing GPSC.

The soilbags reinforcement has been widely used for soft soil foundation improvement due to its high compressive strength and deformation modulus considering the time limit of many projects and the characteristics of the reclaimed soil. However, despite the strength and deformation properties of soilbags reinforcement, the drainage characteristics of soilbags reinforcement is a crucial factor that creates a large challenge to foundation improvement for soft soil. Thus, this study developed a four-staged surcharge preloading on soilbags-reinforced soft soil foundation and focused on its drainage consolidation effectiveness. The contrasting laboratory tests were performed in four identical experimental boxes with clayey soil from the Nanjing, China. Four-staged preloading were applied on the soilbags-reinforced testing model, respectively, the data of the settlement and water discharge during the test are monitored, and after the tests, the water content and shear strength at different positions are measured. And three contrasting tests considering the possible drainage channels of soilbags reinforcement were also conducted. The results show that the consolidation effect is achieved with the soilbags reinforcement in terms of the settlement, pore water pressure, water content and shear strength after consolidation.

This study investigates the influence of unsymmetrical surcharge on the piles of a bridge located in a coastal soft soil area, aiming to elucidate the deformation characteristics of the piles. The impact of some key parameters, including soft soil properties and unsymmetrical surcharge, on pile deformations is evaluated through 3D finite element numerical analysis and parameter sensitivity analysis. The results show that unsymmetrical surcharge significantly influences the displacement of both the piles and the surrounding soil, with both being affected by the soil arching effect. The parameter sensitivity analysis reveals that Poisson's ratio of the soft soil, and the stiffness of the piles have minimal impact on horizontal displacement. In contrast, the elastic modulus, cohesion, and internal friction angle of the soft soil, as well as the height and slope of the unsymmetrical surcharge, have significant effects on the piles. When the unsymmetrical surcharge is applied parallel or perpendicular to the bridge, the parallel surcharge has a relatively minor impact on the pile. The horizontal displacement of the pile follows an exponential relationship with L/B, D/h, and B/d. A functional relationship can be established between these parameters to predict the pile's horizontal displacement.

This study developed all-solid-waste-based curing agents using industrial solid wastes-ground granulated blastfurnace slag (GGBS), carbide slag (CS), and sulfate solid wastes (electrolytic manganese residue (EMR), desulfurized-gypsum (DG), and phosphogypsum (PG))-to stabilize engineering sediment waste (ESW). Based on the simplex centroid design, three ternary curing agents (GGBS-EMR-CS (GEC), GGBS-DG-CS (GDC), and GGBSPG-CS (GPC)) were prepared. The optimal ratios for GEC, GDC, and GPC are 60:12:28, 70:27:3, and 70:21:9, respectively. Compared to ordinary Portland cement (OPC), the unconfined compressive strength (UCS) of ESW stabilized with these curing agents increased by 78 %, 178 %, and 98 %, respectively. Sulfate components synergistically activates GGBS and CS, promoting needle-like ettringite (AFt) formation, which fills pores and enhances strength. Meanwhile, COQ emissions and costs were reduced up to 99 % and 73 %, respectively. This study developed all-solid-waste-based curing agents with excellent mechanical performance, low costs, and near net-zero emissions, which provided a sustainable solution for ESW stabilization.