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.

In cold regions, the strength and deformation characteristics of frozen soil change over time, displaying different mechanical properties than those of conventional soils. This often results in issues such as ground settlement and deformation. To analyze the rheological characteristics of frozen soil in cold regions, this study conducted triaxial creep tests under various creep deviatoric stresses and established a corresponding Discrete Element Method (DEM) model to examine the micromechanical properties during the creep process of frozen clay. Additionally, the Burgers creep constitutive model was used to theoretically validate the creep deformation test curves. The research findings indicated that frozen clay primarily exhibited attenuated creep behavior. Under low confining pressure and relatively high creep deviatoric stress, non-attenuated creep was more likely to occur. The theoretical model demonstrated good fitting performance, indicating that the Burgers model could effectively describe and predict the creep deformation characteristics of frozen clay. Through discrete element numerical simulations, it was observed that with the increase in axial displacement, particle displacement mainly occurs at both ends of the specimen. Additionally, with the increase in creep deviatoric stress, the specimen exhibits different deformation characteristics, transitioning from volumetric contraction to expansion. At the same time, the vertical contact force chains gradually increase, the trend of particle sliding becomes more pronounced, and internal damage in the specimen progresses from the ends toward the middle.

To assess the geotechnical properties of soil, the pressuremeter test has been widely employed since its introduction in 1955. This test is instrumental in determining key parameters such as the limit pressure (Pl), creep pressure (Pf), and modulus of deformation (EM). The fundamental principle of the test involves inserting a radially expandable probe into a borehole, which is subsequently expanded through incremental loading steps, with the resulting volume variation being measured. Traditionally, each loading step is maintained for a duration of 60 s according to European and American standards. In the scope of this study, an investigation was conducted to evaluate the impact of varying the loading time, specifically extending it from 60 to 120 s. These tests were carried out across diverse soil types at four sites in Tunisia. The findings revealed that beyond the 60-s loading period, the soils exhibited continued deformation. Notably, the limit pressure demonstrated a decrease with the prolonged loading time for most of the tested soils. This reduction, ranging from 2% to 30%, was particularly pronounced in soft and sandy clays. Furthermore, the creep pressure, representing the threshold of the soil's pseudoelastic behavior, also experienced a decline with the increased loading time. The pressuremeter modulus EM2, which is obtained for a loading step of Delta t = 120 s, exhibited a reduction across all soil types, with this reduction being more prominent in fine soils characterized by low consistency.

Creep, once considered an inherent characteristic of granular materials, is primarily governed by time and the current stress state. However, recent studies indicate that creep development is also influenced by the loading history. To better reveal the creep revolution law of the rockfill under the influence of loading history such as historical stress rates, creep tests were conducted under oedometric loading. Alternative loading-creep steps, different stress increment sizes, and various precreep stress rates were considered. Independent of other factors, the development of the creep rate was governed by the recent precreep stress rate (the prior stress rate defined in this study). When the prior stress rate was higher than a threshold value, the relationship between the creep rate and time was double logarithmic linear; thus the creep strain-time relationship tended to converge on a power law (referred to as the creep baseline herein). However, when the prior stress rate was lower than the threshold value, the initial creep rate was lower than that of the creep baseline and did not decrease until several minutes after the start of the creep. The development of the creep rate with time in the initial stage can be generalized as a straight horizontal line, suggesting that the rate remains almost unchanged for a certain time, until the straight horizontal line approached the creep baseline. The inheritance and hysteresis of different strain rates in the initial stage of subsequent creep resulted in differences in the creep magnitude and time development process of the creep rate. The above findings are constructive for predicting the deformation of deep layers of rockfill, such as embankments, with more accuracy, especially for that with some large-sized rigid-structure buildings on its surface.

Numerous loess relic sites with cultural and historical values exist in the seasonally frozen ground region of Northwest China. Freeze-thaw action is an essential factor in inducing cracking and collapse of loess relic sites, and the creep behavior of loess also affects its long-term stability. Microbially induced calcium carbonate precipitation (MICP) technology has a promising application in earthen ruin reinforcement due to its environmental friendliness and good compatibility. To evaluate the feasibility of MICP technology for reinforcing loess relic sites in the seasonally frozen ground, triaxial compression tests, triaxial creep tests, and SEM tests were conducted on MICP modified loess after 0, 1, 3, 7, and 9 freeze-thaw cycles. Then, the changing laws of shear strength and creep properties of samples in the freeze-thaw conditions were analyzed. The results show that the MICP technology can enhance the mechanical properties and frost resistance of loess. The shear strength, cohesion, and long-term strength of MICP modified loess are enhanced by 27.8 %, 109 %, and 29.8 %, respectively, under 100 kPa confining pressure, and their reduction is smaller than that of the untreated loess after 9 freeze-thaw cycles; the internal friction angle fluctuates within 1 degrees. Finally, the reinforcement mechanism and freeze-thaw resistance mechanism of MICP technology were revealed. Microbially induced calcium carbonate can cement soil particles, fill interparticle pores, and inhibit the development of pores and cracks caused by freeze-thaw action. The results can provide a theoretical foundation and scientific basis for the long-term stability analysis of loess relic sites reinforced with MICP technology.

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.

Soil creep is a slow type of mass movement that, despite its low velocity, can significantly influence slope stability and landscape evolution over time. Understanding its mechanisms and spatial variability is essential for assessing slope stability. However, obtaining high-quality long-term data on creep activity remains a challenge. Dendrogeomorphic methods offer a promising approach to reconstruct past creep movements, but their application to shallow creep processes still requires further refinement. Therefore, this research undertakes a dendrogeomorphic analysis of shallow creep movements on flysch rock slopes, utilizing tree-ring eccentricity as an indicator of this geomorphic process. A total of 136 increment cores from 68 Norway spruce (Picea abies (L.) H. Karst.) trees were analysed, revealing the spatio-temporal dynamics of shallow creep and its relationship with slope morphometry and weathering mantle thickness. The eccentricity values were spatially interpolated to visualize the evolution of creep activity over decades, which showed its significant spatial variability. Statistical analyses, including Pearson's and Spearman's correlation coefficients, were employed to examine the relationships between tree-ring eccentricity and various environmental factors. Results indicated that tree age influences the sensitivity to creep signals, with older trees showing increased eccentricity, suggesting a heightened response to creep movements. The study also explored the impact of precipitation on creep activity, identifying a weak, non-significant positive relationship. This comprehensive analysis enhances the understanding of shallow creep mechanisms and contributes to the broader field of dendrogeomorphology.

Landslides commonly evolve from slow, progressive movements to sudden catastrophic failures, with saturation and displacement rates playing significant roles in this transition. In this paper, we investigate the influence of saturation, displacement rate, and normal stress on the residual shear strength and creep behaviour of shear-zone soils from a reactivated slow-moving landslide in the Three Gorges Reservoir Region, China. Results reveal a critical transition from rate-strengthening to rate-weakening behaviour with increasing displacement rates, significantly influenced by the degree of saturation. This transition governs the observed patterns of slow movement punctuated by periods of accelerated creep, highlighting the potential for exceeding critical displacement rates to trigger catastrophic failure. Furthermore, partially saturated soils exhibited higher residual strength and greater resistance to creep failure compared to nearly and fully saturated soils, underscoring the contribution of matric suction to shear strength.

Setting an expandable polystyrene (EPS) board on box culverts can reduce the vertical earth pressure (VEP) acting on the culvert roof. However, long-term backfill load will induce creep in both the EPS board and the surrounding soil, resulting in a change in the stress state of the culvert-soil system. A mechanical model for the long-term interaction of backfill-EPS board-box culvert was established, and theoretical formulas were derived for calculating the earth pressure around the culvert. Numerical simulation was employed to validate the accuracy of the proposed theoretical approach. Research indicates that, with EPS board, the VEP decreases rapidly then slightly increases with time and eventually approaches an asymptotic value, ultimately decreasing by 33%. However, the horizontal earth pressure (HEP) shows the opposite pattern and ultimately increases by 15%. The foundation contact pressure (FCP) increases nonlinearly and reaches a stable value, ultimately increasing by 10.2%. Without the EPS board, the VEP and HEP are significantly different from those with the EPS board. Although EPS boards can reduce the VEP on the culvert, attention should be paid to the variation of HEP caused by the creep of the EPS board and backfill.

A large-strain model was developed to study the consolidation behavior of soil deposits improved with prefabricated vertical drains and subjected to surcharge and vacuum preloading. The smear effect resulting from the installation of drains was incorporated in the model by taking the average values of permeability and compressibility in the smear zone. The dependence of permeability and compressibility on void ratio and the effects of non-Darcian flow at low hydraulic gradients were also incorporated in the model. The creep effect was also taken into account for secondary consolidation of soft soil deposits. The model was applied to two different embankments located at Suvarnabhumi International Airport, Thailand, and Leneghan, Australia. It was observed that the creep effect led to an additional settlement of 12%-17% after the primary consolidation phase. The study further demonstrated that creep settlements increased with the non-Darcian effect. The difference between surface settlement results with and without the creep effect increased from about 12% to 15% when the non-Darcian parameter (n) increased from 1 to 1.6. However, beyond a threshold value of n >= 1.6, the influence of non-Darcian flow on creep settlement diminished. The value of average and actual effective stresses increased by about 13% and 17%, respectively, when the value of n increased from 1 to 2. However, the impact of n on effective stresses became negligible for values of n >= 2.5. The rate of consolidation decreased approximately by about four times when the permeability ratio ((k) over tilde (u)/(k) over tilde (s)) increased from 1 to 5.