The widespread utilisation of vacuum-assisted prefabricated vertical drains (PVD) for managing clayey soft ground has led to the development of numerous consolidation models. However, these models have limitations when describing the filtration behaviour of soil under high water content conditions, without the formation of a particle network. To effectively address this issue, in this work, based on the compressional rheology theory, a two-dimensional axisymmetric model incorporating the compressive yield stress Py(phi) and a hindered setting factor r(phi) was developed to couple the filtration and consolidation of soil under vacuum preloading. A novel approach for determining the unified phi-Py-r relationships was introduced. The equation governing such fluid/solid and solid/solid interactions was solved using the alternative direction implicit (ADI) method, and the numerical solutions were validated against the 1-D filtration cases, 3-D laboratory model tests, and large-scale field trials. Further parametric analysis suggests that the radius of the representative unit and r(phi) exclusively affect the dewatering rate of the clayey slurry, while the gel point and Py(phi) influence both the dewatering rate and the final deformation.

In cold regions, and considering the increasing concerns regarding climate change, it is crucial to assess soil stabilisation techniques under adverse environmental conditions. The study addresses the challenge of forecasting geotechnical properties of lime-stabilised clayey soils subjected to freeze-thaw conditions. A model is proposed to accurately predict the unconfined compressive strength (UCS) of lime-stabilised clayey soils exposed to freeze-thaw cycles. As the prediction of UCS is essential in construction engineering, the use of the model is a viable early-phase alternative to time-consuming laboratory testing procedures. This research aims to propose a robust predictive model using readily accessible soil parameters. A comprehensive statistical model for predicting UCS was developed and validated using data sourced from the scientific literature. An extensive parametric analysis was conducted to assess the predictive performance of the developed model. The findings underscore the capability of statistical models to predict UCS of stabilised soils demonstrating their valuable contribution to this area of study.

The current study focuses on the long term strength reduction in lime stabilised Cochin marine clays with sulphate content. By introducing 6% lime and 4% sulphates to untreated Cochin marine clay, the research aims to investigate the effect of sulphates in these clays. Unconfined compression tests were conducted on lime treated clay both with and without additives, immediately after preparation and over 1 week, 1 month, 3 months, 6 months, 1 year and 2 years of curing. Test results indicated that both sodium sulphate and lithium sulphate has a negative impact on the strength gain of lime stabilised clay. To address this issue, Barium hydroxide, in both its pure laboratory form and the commercial product known as baryta, was incorporated into the lime stabilised soil. The study showed a consistent increase in shear strength with the addition of both barium hydroxide and baryta. When twice the predetermined quantity of baryta was added to lime stabilised clay, it outperformed pure barium hydroxide in terms of strength enhancement. Results of SEM and XRD analysis align with the strength characteristics. The cost-effective use of baryta offers a practical solution to counteract strength loss in lime stabilised, sulphate bearing Cochin marine clays.

The construction industry is increasingly focusing on sustainability, creating a need for innovative materials. This comprehensive review examines the potential of calcined clays and nanoclays in enhancing construction materials and promoting resilient infrastructure. It emphasises their role in improving performance and supporting environmental conservation in sustainable development. The review discusses how varying proportions of calcined clays and nanoclays impact the performance of pavement materials, especially when combined with bitumen in asphalt mixtures. It highlights their benefits, including reduced chloride penetration, enhanced water resistance, and improved soil conductivity. Overall, the review suggests that the strategic integration of calcined clays and nanoclays into construction materials can enhance durability, optimise resource use, and support environmental sustainability.

This paper aims to develop geopolymer concrete (GPC) with flash-calcined soils cured under ambient conditions. Flash calcination is a heat thermal technique used to eliminate pollutants and organic content in excavated soils and allow them to be used in cementitious formulations. To develop GPC, the materials used in the development of the GP precursor binder should be rich in silicon (Si) and Aluminum (Al) that can react with alkaline silicates to yield Si-O-Al bonds that would form cementitious materials. The GP precursor binder is composed of Metakaolin (MK), flash-calcined soils, and granulated blast furnace slag (GBFS). The thermally treated soils are flash-calcined dredged sediments (FCS) and flash-calcined excavated clays (FCC) while potassium silicate is used as the alkaline reagent. This study aims to use the materials above to develop GPC cured under ambient conditions with high strength, good durability, and microstructure properties. Seven formulations are done to evaluate the effect of replacing MK with either FCS or FCC and GBFS on the mechanical compressive strength, water absorption, and freeze-thaw test. The findings reveal that using only metakaolin (MK0) in the formulation yielded the highest compressive strength. These results align with the porosity test outcomes, which show correlations between micropore and macropore percentages. Analysis of the durability freeze-thaw test suggests that as the proportion of macropores increases, formulations incorporating FCS and FCC exhibit improved resistance to extreme temperatures. Conversely, an increase in GBFS content leads to a finer microstructure and reduced resistance. Water absorption testing indicates that formulations with FCS and FCC display favorable sorptivity coefficients compared to MK0, with increased GBFS content enhancing durability. SEM/EDS and calorimetry tests were conducted to investigate the impact of substituting FCS and FCC for MK within the geopolymer matrix.

Marine soft clays are known for their poor engineering properties, which, when subjected to prolonged static and dynamic loading, can lead to excessive settlement of offshore pile foundations and subsequent structural instability, resulting in frequent engineering failures. This study examines the bearing and deformation behavior of jacked piles in these clay deposits under both static and cyclic loading conditions using a custom-designed model testing apparatus. Emphasizing the time-dependent load-carrying capacity and accumulated cyclic settlement of piles, the research uses artificially structured clay to more accurately simulate stratum conditions than traditional severely disturbed natural clays. Model pile testing was carried out to analyze the effects of soil structure and cyclic loading patterns on the long-term response of jacked piles. Key factors investigated include initial soil structure, pile jacking-induced destruction, soil reconsolidation post-installation, disturbed clay's thixotropic effects, and cyclic loading's impact during service. Results show that increasing the cement content within the clays from 0 % to 4 % nearly doubled pile penetration resistance, led to a more significant accumulation of excess pore water pressure (EPWP), and accelerated its dissipation rate. Additionally, the ultimate load-carrying capacity of jacked piles also doubled. Higher cement content slowed pile head settlement rates and reduced stable cumulative settlement values, requiring more cycles to reach instability. Under high-amplitude, low-frequency cyclic loads, hysteresis loops of the model piles became more pronounced and rapid. This study enhances understanding of the long-term cyclic behavior of jacked piles in soft soils, providing valuable insights for designing offshore piles.

Accurately predicting pile penetration in marine soft clays is crucial for effective construction, load-bearing design, and maintenance of offshore pile foundations. A semi-analytical solution employing the combined expansion-shearing method (CESM) is introduced to model pile penetration in soft clays. This method innovatively simplifies the Pile penetration into undrained cavity expansion and vertical shearing. Using the S-CLAY1S model, which incorporates the anisotropy and structure of natural soft clays, an exact semi-analytical solution was developed to describe soil behavior around the pile under undrained vertical shearing, expanding upon existing undrained cavity expansion solutions. The accuracy and innovation of the CESM were validated through the results of field tests and finite element simulations. Additionally, a comprehensive parametric study highlighted the significant impact of soil's initial structure and stress state on pile penetration response. The study findings strongly align with theoretical calculations, field Measurements, and numerical simulations. Compared to the conventional cavity expansion method, CESM excels in resolving soil stresses at the pile shaft, albeit with a slight limitation in evaluating excess pore water pressure of soils at the pile shaft. The proposed solution considers the fundamental properties of soft clays, including their anisotropy and structural behavior, while incorporating the vertical shearing experienced by the soil during pile installation, thereby providing a simplified yet precise theoretical framework for addressing pile penetration challenges.

Accurately predicting the setup of jacked piles in marine soft clays is crucial for effective construction, load- bearing design, and maintenance of offshore foundations. This paper integrated UMAT subroutines into the ABAQUS platform using two numerical integration methods: the cutting plane algorithm (CPA) and the NewtonRaphson iterative algorithm (NRIA), to simulate the entire life cycle of jacked piles in marine soft clays. The study incorporates the advanced elastoplastic constitutive model (S-CLAY1S) and the elastoviscoplastic constitutive model (ANICREEP), addressing soil fabric anisotropy, structural effects, and, specifically, soil creep effects in the ANICREEP model. A two-dimensional axisymmetric model is established for jacked piles in marine soft clays, involving unloading and consolidation stages, followed by static load tests on test piles at various post- installation rest periods to assess their time-dependent bearing performance. Finite element modeling enables simulations of field and laboratory pile tests, validating models against measurements. Parameter analysis includes variations in excess pore water pressure (EPWP), ultimate skin friction resistance, and pile bearing capacity in both soil models, examining the impact of initial soil structure ratio on pile performance. Key findings reveal differences in EPWP dissipation rates and long-term bearing capacity evolution between elastoplastic and elastoviscoplastic soils, highlighting the ANICREEP model's capability to capture both short-term and creep- induced long-term effects. Integrating complex soil mechanics into ABAQUS enhances the ability to predict and optimize jacked pile performance in various geotechnical engineering applications.

It has been well recognized that sand particles significantly affect the mechanical properties of reconstituted sandy clays, including the hosted clay and sand particles. However, interrelation between the permeability and compressibility of reconstituted sandy clays by considering the structural effects of sand particles is still rarely reported. For this, a series of consolidation-permeability coefficient tests were conducted on reconstituted sandy clays with different sand fractions (ass), initial void ratio of hosted clays (ec0) and void ratio at liquid limit of hosted clays (ecL). The roles of ass in both the relationships of permeability coefficient of hosted clay (kv-hosted clay) versus effective vertical stress (s0v) and void ratio of hosted clay (ec-hosted clay) versus s0v were analyzed. The results show that the permeability coefficient of reconstituted sandy clays (kv) is dominated by hosted clay (kv 1/4 kv-hosted clay). Both ass and ec0 affect the kv of sandy clays by changing the ec-hosted clay at any given s0v. Due to the partial contacts and densified clay bridges between the sand particles (i.e. structure effects), the ec-hosted clay in sandy clays is higher than that in clays at the same s0v. The kv - ec-hosted clay relationship of sandy clays is independent of ec0 and ass, but is a function of ecL. The types of hosted clays affect the kv of sandy clays by changing the ecL. Based on the relationship between permeability coefficient and void ratio for the reconstituted clays, an empirical method for determining the kv is proposed and validated for sandy clays. The predicted values are almost consistent with the measured values with kv-predicted=kv-measured 1/4 0.6-2.5. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

This study introduces a novel methodology to address consolidation under long-term cyclic loading. The approach simplifies analysis by neglecting cyclic load induced fluctuations and by decomposing the cyclic load into a static load and a vibratory load without net tensile or compressive tendency over time. One-dimensional vibration consolidation tests are proposed to investigate the consolidation behavior of normally consolidated soil under vibratory loading. These tests yield a normal vibration consolidation line, which visually represents the consolidation effect of a given vibratory load on normally consolidated soil under different consolidation pressures. Based on these test results, a mathematical model is developed. This model incorporates a constitutive relationship that accounts for both the decrease in effective stress due to the structural damage caused by the vibratory load and the increase in effective stress due to the compression of the soil skeleton. The governing equation, with void ratio and effective stress as dependent variables, comprehensively describes the state change process of soil elements during vibration consolidation. Numerical solutions are then employed to analyze this process in detail.