The sulphated gravel embankment in seasonal frozen soil regions may experience deformation problems such as salt expansion, frost heave, and settlement under rainfall percolation conditions and changes in environmental temperature, affecting considerably its normal use. In response to these issues, relying on the renovation and expansion project of an international airport in northwest China, this paper used a self-designed temperature control testing device and conducted indoor constant temperature tests and freeze-thaw cycle tests using on-site natural embankment filling, and conducted numerical simulation tests using the COMSOL Multiphysics software programme. This paper investigated the characteristics of temperature variation, moisture, salt migration, and deformation of sulphated gravel in seasonal frozen soil regions under rainfall percolation conditions. The results indicated that under environmental temperature changes in the range of- 10-25 degrees C, the temperature at which sulphated gravel salt expansion and frost heave occur was approximately-8 degrees C, and the deformation sensitive depth range from 0 to 200 mm. The moisture and salt contents of soil samples would experience a sudden increase due to rainfall percolation, with the sudden increase in moisture in the soil sample with a salt content of 0.9 % lagging that of the soil sample with a salt content of 0.5 % by one freeze-thaw cycle. Rainfall percolation significantly enhanced the settlement deformation of sulphated gravel during freeze-thaw cycles. The primary causes of soil deformation include the upward migration of water vapour, the downward percolation of moisture, and rainfall. These factors contribute to the destruction of the soil structure and alter the contact modes between soil particles, resulting in soil loosening and settlement deformation.

Polypropylene fiber and cement were used to modify iron tailings and applying it to roadbed engineering is an important way to promote the sustainable development of the mining industry. However, the existing studies are mostly concerned with the static mechanical properties, and lack the deformation characteristics of cyclic loading under different loading modes. The effects of fiber content, dynamic-static ratio (Rcr) and curing age on the deformation characteristics of fiber cement modified iron tailing (FCIT) under different cyclic loading modes were explored through dynamic triaxial tests. The research results show that: (1) Polypropylene fibers significantly reduced the cumulative strain of FCIT. Under intermittent loading, the cumulative strain decreased by 36 similar to 43 %, and under continuous loading, the cumulative strain decreased by 48 similar to 55 %. (2) The deformation behavior of FCIT under both intermittent and progressive loading was in a plastic steady state with cumulative strain <= 1 %. (3) The cumulative strain variation of FCIT with intermittent loading of 0.316 % was significantly lower than that with continuous loading of 0.417 %, and the resilience modulus was higher with intermittent loading. (4) The stress history effect of step-by-step loading can be eliminated by the translational superposition method, and the strain evolution law under continuous loading is predicted based on the progressive loading data, and the minimum error between the expected and actual results is 6.5 % when Rcr is 0.1.

Ground subsidence is a common urban geological hazard in several regions worldwide. The settlement of loess fill foundations exhibits more complex subsidence issues under the coupled effects of geomechanical and seepage-driven processes. This study selected 21 ascending Sentinel-1 A radar images from April 2023 to October 2024 to monitor the loess fill foundation in Shaanxi, China. To minimize errors caused by the orbital phase and residual flat-earth phase, this research combined PS-InSAR technology with the three-threshold method to improve the SBAS-InSAR processing workflow, thereby exploring time-series deformation of the loess fill foundation. Compared with conventional SBAS-InSAR technology, the improved SBAS-InSAR technique provided more consistent deformation time-series results with leveling data, effectively capturing the deformation characteristics of the fill foundation. Additionally, geographic information system (GIS) spatial analysis techniques and statistical methods were employed to analyze the overall characteristics and spatiotemporal evolution of the ground surface deformation in the study area. On the other hand, the major drivers of the subsidence in the study area were also discussed based on indoor experiments and engineering geological data. The results showed gradual and temporal shifts of the subsidence center toward areas with the maximum fill depths. In addition, two directions of uneven subsidence were observed within the fill foundation study area. The differences in the fill depth and soil properties caused by the building foundation construction were the main factors contributing to the uneven settlement of the foundations. Foundation deformation was also positively and negatively affected by surface water infiltration. This study integrates remote sensing and engineering geological data to provide a scientific basis for accurately monitoring and predicting loess fill foundation settlement. It also offers practical guidance for regional infrastructure development and geological hazard prevention.

Unlike uniform soils, soft clays with sand interlayers in coastal soft clays, can affect their mechanical properties, potentially impacting underground-construction safety and stability. Consolidated undrained cyclic triaxial tests were conducted to study the dynamic properties and deformation behavior of clay, focusing on how the thickness ratio between the sand and clay layers and the cyclic-stress ratio influence the pore pressure, axial strain, shear-modulus ratio, and normalized damping ratio. The results indicate that higher thickness ratios and cyclic-stress ratios lead to a faster decay of the shear-modulus ratio, quicker increases in pore pressure, faster strain accumulation, and fewer cycles to failure. The normalized damping ratio has three different forms: decreasing, decreasing then increasing, and increasing. However, at a cyclic-stress ratio of 0.2 and thickness ratio of 0.25, the samples exhibit better dynamic characteristics. Soft clay with sand layers exhibits characteristics in line with the stability theory. At low thickness and cyclic-stress ratios, purely elastic and elastically stable phases are observed. As the thickness and cyclic-stress ratios increase, it transitions to plastic stability and incremental failure.

This paper uses a simplified assessment method based on the excavated-induced ground movement to examine the coupling effect between adjacent excavations during construction. The finite element numerical model is established to simulate and analyze the deformation of adjacent excavations at each stage of construction. Distinct construction sequences are employed to explore the dissimilarities in the deformation characteristics of the surrounding soil and envelope after excavation. The results indicate that when adjacent excavations are excavated simultaneously, their interactions affect the soil and envelopes' deformation. The maximum ground settlement occurs at a certain distance from the edge of the excavation. As the excavation depth increased, the enclosure exhibited a more pronounced deformation. The deformation of the enclosure structure can be significantly inhibited by the spatial effect at the corners of the excavation. When adjacent pits are constructed in different construction sequences, the enclosure structure on the first constructed excavation often experiences greater deformation than on the later constructed excavation.

Heating method shows considerable potential for mitigating frost heave of subgrade in cold regions. However, the water-heat-deformation characteristics of subgrade under the coupling effect of freezing-thawing and heating effect remain unclear, which hampers the optimization and widespread application of heating method. Therefore, this paper proposes a numerical model of subgrade water-heat-deformation considering heating effect. The influence and mechanism of heating effect on water-heat-deformation of subgrade is systematically analyzed. The results show that the heating effect changes the water-heat-deformation state of subgrade. Furthermore, the combined influence of shady-sunny slope effect and ballast layer ensures that ground temperature near the subgrade center remains above 0 degrees C, thereby preventing the formation of ice lenses and frost heave. However, the shoulders on both sides enter a freezing state, and freezing rate, freezing depth and frost heave are reduced by more than 45 %, 60 % and 60 % respectively compared with the comparison subgrade. The freezing depth, driving force and rate of water migration are significantly affected by heating effect, which increases the pathways of water upward migration and greatly weakens the segregated frost heave of subgrade. This is the primary mechanism through which the heating method effectively mitigates frost heave in subgrades.

Silty clay is a common compressible soil found in many engineering projects, where its deformation behavior is particularly complex under cyclic loading. This study uses the GDS dynamic triaxial testing system to examine how silty clay deforms under different moisture contents, confining pressures, and cyclic stress ratios (CSR). The results show that the cumulative strain of silty clay follows a three-phase pattern: an initial rapid increase (N = 0-300), followed by a slower rise (N = 300-1000), and finally reaching a stable state (N > 1000). Among the factors tested, CSR has the most significant impact on cumulative strain, with moisture content coming second, while confining pressure has a relatively minor effect. After 1000 cycles, cumulative strain shows a clear linear growth trend. Linear fitting analysis indicates that the uncertainty in the fitted curve is influenced by moisture content, confining pressure, and CSR. Uncertainty is greater at both low and high moisture content levels, while it is lower under moderate moisture conditions. These findings provide valuable insights into predicting soil deformation in engineering applications, helping to improve our understanding of silty clay behavior under cyclic loading.

The deformation characteristics of river embankments on soft ground, improved by circular deep mixed columns and a combination of circular and grid-form columns, were investigated via two centrifugal model tests. The results indicate that the slope stability of the river embankment was effectively sustained in both cases. The combined reinforcement method exhibited superior overall performance, significantly reducing settlement. The greatest settlement was observed at the top of the river embankment, and although the settlement had not fully stabilized one year after construction, the settlement rate had slowed. Compared with the circular reinforcement alone, the river embankment maximum settlement was reduced by 25.3% in the combined reinforcement. Additionally, the grid-form columns effectively reduced the horizontal displacements in the middle and lower parts of the foundation. The deep-mixed columns performed effectively in providing support and reinforcement, and none of the piles reached the bending capacity during the test process. Given the stiffness difference between the columns and the surrounding soil, the stress distribution exhibited a stress concentration effect in the model. The measured column soil stress ratio ranged between 2 and 3, which is considered reasonable. The pronounced stress concentration effect of the mixing columns contributed to a faster consolidation rate of the foundation. On the basis of the measured settlement and excess pore water pressure, the degree of consolidation of the circular column-reinforced foundation one year after construction reached over 90% and 80%, respectively. For the foundations reinforced with combined circular and grid-form deep mixed columns, the degree of consolidation reached over 80% and 75%, respectively.

In marine environments, cyclic loads induced by earthquakes can lead to complex soil responses in marine coral sand. Waves and storms, often at different frequencies, can also contribute to these responses. These factors can finally contribute to instability or failure of offshore structures. To better understand the effect of loading frequency on the dynamic properties of marine coral sand, a series of cyclic triaxial tests on saturated coral sands were carried out. These tests were performed with different gradations at different loading frequencies and loading modes. A GDS dynamic triaxial instrument was used for the tests. The experimental results demonstrate that loading frequency has a significant effect on the cyclic response of coral sand. The maximum shear modulus of saturated coral sand rises with increasing loading frequency. The cyclic strength of saturated coral sand also increases with loading frequency. A strong linear relationship exists between the maximum shear modulus and cyclic strength. This suggests the existence of a cyclic yield strain that is relatively insensitive to loading frequency. Loading frequency significantly affects the axial strain development of saturated coral sand under diverse loading modes. Three stages of axial strain development were identified employing incremental strain analysis. Based on these findings, a new model for axial strain development is proposed, the accuracy of this model is verified by fitting it to the data from this study and existing literature.

Coarse-grained soils are fundamental to major infrastructures like embankments, roads, and bridges. Understanding their deformation characteristics is essential for ensuring structural stability. Traditional methods, such as triaxial compression tests and numerical simulations, face challenges like high costs, time consumption, and limited generalizability across different soils and conditions. To address these limitations, this study employs deep learning to predict the volumetric strain of coarse-grained soils as axial strain changes, aiming to obtain the axial strain (epsilon(a))-volumetric strain (epsilon(v)) curve, which helps derive key mechanical parameters like cohesion (c), and elastic modulus (E). However, the limited data from triaxial tests poses challenges for training deep learning models. We propose using a Time-series Generative Adversarial Network (TimeGAN) for data augmentation. Additionally, we apply feature importance analysis to assess the quality of the numerical augmented data, providing feedback for improving the TimeGAN model. To further enhance model performance, we introduce the pre-training strategy to reduce bias between augmented and real data. Experimental results demonstrate that our approach effectively predicts epsilon(a)-epsilon(v) curve, with the mean absolute error (MAE) of 0.2219 and the R-2 of 0.9155. The analysis aligns with established findings in soil mechanics, underscoring the potential of our method in engineering applications.