As the increasing demand for deep mineral resource extraction and the construction of deep vertical shafts by the artificial ground freezing method, the stability and safety of shaft that traverse thick alluvial depend significantly on their interaction with the surrounding deep frozen soil medium. Such interaction is directly conditioned by the mechanical properties of the deep frozen soil. To precisely capture these in-situ mechanical properties, the mechanical parameters tests using remodeled frozen specimens cannot ignore the disparities in consolidation history, stress environment and formation conditions between the deep and shallow soils. This study performs a series of long-term high-pressure K0 consolidation (where K0 represents the static earth pressure coefficient, describing the ratio of horizontal to vertical stress under zero lateral strain conditions), freezing under sustained load and unloading triaxial shear tests utilizing remodeled deep clay. This study presents the response of unloading strength and damage properties under varying consolidation stresses, durations, and freezing temperatures. The unloading strength increases sharply and then stabilizes with consolidation time. The unloading strength shows an approximate linear positive correlation with the consolidation stress, while a negative correlation with the freezing temperature. The strengthening rate of the unloading strength due to freezing temperature tends to decrease with increasing consolidation time. Additionally, an improved damage constitutive model was proposed and validated by incorporating the initial K0 stress state and a Weibull-based assumption for damage elements. Based on the back propagation (BP) neural network, a prediction method for the stress-strain curve was offered according to the consolidation stress level, initial stress state, and temperature. These results can provide references for improving the mechanical testing methods of deep frozen clay and revealing differences in mechanical properties between deep and shallow soils.

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 influence of seismic history on the liquefaction resistance of saturated sand is a complex process that remains incompletely understood. Large earthquakes often consist of foreshocks, mainshocks, and aftershocks with varying magnitudes and irregular time intervals. In this context, sandy soils undergo two interdependent processes: (i) partial excess pore water pressure (EPWP) generation during foreshocks or moderate mainshocks, where seismic loadings elevate EPWP without causing full liquefaction and (ii) incomplete EPWP dissipation between seismic events due to restricted drainage. These processes leave behind persistent residual EPWP, reducing the liquefaction resistance during subsequent shaking. A series of cyclic triaxial tests simulating these mechanisms revealed that liquefaction resistance increases when the EPWP ratio r(u) < 0.6-0.8 (peaking at r(u) similar to 0.4) but decreases sharply at higher r(u). Crucially, EPWP generation during seismic loading plays a dominant role in resistance evolution compared to reconsolidation effects. Threshold lines (TLs) mapping r(u), the reconsolidation ratio (RR), and peak resistance interval (the range of r(u) where the peak liquefaction resistance is located) indicates that resistance decreases above TLs and increases below them, with higher cyclic stress ratios (CSR) weakening these effects. These findings provide a unified framework for assessing liquefaction risks under realistic multi-stage seismic scenarios.

A novel framework for nonlinear thermal elastic-viscoplastic (TEVP) constitutive relationships was proposed in this study, incorporating three distinct thermoplasticity mechanisms. These four TEVP formulations, combined with an existing TEVP constitutive equation presented in the companion paper, were integrated into a coupled consolidation and heat transfer (CHT) numerical model. The CHT model accounts for large strain, soil selfweight, creep strains, thermal-induced strains, the relative velocity of fluid and solid phases, varying hydraulic conductivity and compressibility during consolidation process, time-dependent loading, and heat transfer, including thermal conduction, thermo-mechanical dispersion, and advection. The performance of CHT model, incorporating different TEVP constitutive equations, was evaluated through comparing the simulation results with measurements from laboratory oedometer tests. Simulation results, including settlement, excess pore pressure and temperature profiles, showed good agreement with the experimental data. All four TEVP constitutive relationships produced identical results for the consolidation behavior of soil that in the oedometer tests. The TEVP constitutive equations may not have a significant effect on the heat transfer in soil layers because of the identical performance on simulating soil compression. The CHT model, incorporating the four TEVP constitutive equations, was then used to investigate the long-term consolidation and heat transfer behavior of a four layer soil stratum under seasonally cyclic thermal loading in a field test, with excellent agreement observed between simulated results and measured data.

In practical engineering, earthquake-induced liquefaction can occur more than once in sandy soils. The existence of low-permeable soil layers, such as clay and silty layers in situ, may hinder the dissipation of excess pore pressure within sand (or reconsolidation) after the occurrence of liquefaction due to the mainshock and therefore weaken the reliquefaction resistance of sand under an aftershock. To gain more mesomechanical insights into the reduced reliquefaction resistance of the reconsolidated sand under aftershock, a series of discrete element simulations of undrained cyclic simple shear tests were carried out on granular specimens with different degrees of reconsolidation. During both the first (mainshock) and second (aftershock) cyclic shearing processes, the evolution of the load-bearing structure of the granular specimens was quantified through a contact-normal-based fabric tensor. The interplay between mesoscopic structure evolutions and external loadings can well explain the decrease in reliquefaction resistance during an aftershock.

The solidification of dredged marine sediments with high water content is important for maintenance dredging and reclamations. To reduce the carbon emission of solidification, low-carbon recycled wastes such as incinerated sewage sludge ash (ISSA) and ground granulated blastfurnace slag (GGBS) have been recently adopted as binding materials to replace conventional Portland cement. For soil slurry with ultra-high water content, using the consolidationsolidification combined method is an effective way to reduce the volume and improve the final mechanical properties. However, it is unclear how the consolidation interacts with solidification using the binding materials. In this study, a series of laboratory tests were conducted on dredged Hong Kong marine deposit slurry mixed with ISSA and GGBS with alkali activation by lime. The elemental consolidation tests controlled with different constant rates of strain and multistage loadings demonstrate that the rate of consolidation has significant effects on volume reduction and yielding stress development during consolidation-solidification treatment. Consolidationsolidification achieves higher volume reduction and yielding stress than pure solidification. As the rate of consolidation decreases, there is a smaller volume reduction at the same effective stress and less yielding stress enhancement at the same curing time. A scanning electron microscope with energy dispersive spectrometer was used to investigate hydration products and soil fabric after treatment. The slower rate of consolidation causes the looser structure and finer needleshaped products with the same curing period, which can explain the mechanical properties observed from the element tests.

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.

The long-term compression behavior of clay is significantly affected by temperature paths. However, most studies on temperature paths focus on short-term changes in volume and pore pressure, with limited research on how temperature paths affect soil secondary consolidation characteristics. To experimentally investigate the time-dependent compression behavior of lateritic clay under different temperature paths, a series of temperaturecontrolled isotropic consolidation tests from 5 to 50 degrees C were conducted with consideration of heating/cooling rate and thermal cycle paths. The results indicate that the accumulation of thermal-induced pore water pressure increases with the rate of temperature variations, but a faster rate leads to smaller volumetric changes. Moreover, thermal cycling does not cause irreversible thermoplastic volumetric strain with a suitable heating/cooling rate, and the cycle paths do not influence this outcome. Furthermore, the creep rate of heated samples increases significantly, and the heating/cooling rate also affects the creep rate: a slower heating rate results in a faster creep rate. Additionally, the creep behavior ceased after the thermal cycle, and it appears that the thermal cycle paths have no effect on the creep rate. Finally, this study summarizes the mechanism of the influence of temperature on the creep behavior of clay, and reasonable explanations are proposed for the thermo-mechanical behavior caused by different temperature paths.

Offshore structures typically experience multiple storms during their service life. The soil around the foundations of offshore structures is subjected to cyclic loading during storm and reconsolidates between storms. Therefore, it is essential to understand the fundamental soil behaviour under episodic cyclic loading and reconsolidation to evaluate the long-term serviceability of offshore foundations. This paper presents experimental results of a comprehensive suite of cyclic DSS tests on a normally consolidated silty clay. The tests explore the soil response under different cyclic loading patterns (e.g., one-way or two-way), different cyclic amplitudes and number of cycles. A theoretical model, which combines the conventional cyclic contour diagram approach and principles of the critical state soil mechanics, is proposed and validated for predicting the cyclic soil response during undrained cyclic loading and hardening after reconsolidation. The model proposed in this paper paves a critical step for developing long-term soil-structure interaction models that are fundamentally linked to soil element level responses.

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.