Ground Settlement Research Articles

Analysis of Uneven Settlement of Long-Span Bridge Foundations Based on SBAS-InSAR

Bridge foundation settlement monitoring is crucial for infrastructure safety management, as uneven settlement can lead to stress redistribution, structural damage, and potentially catastrophic collapse. While traditional contact sensors provide reliable measurements, their deployment is labor-intensive and costly, especially for long-span bridges. Current remote sensing methods have not been thoroughly evaluated for their capability to detect and analyze complex foundation settlement patterns in challenging environments with multiple influencing factors. Here, we applied Small Baseline Subsets Synthetic Aperture Radar Interferometry (SBAS-InSAR) technology to monitor foundation settlement of a long-span bridge. Our analysis revealed distinct deformation patterns: uplift in the north bank approach bridge foundation and the left-side main bridge foundation (maximum rate: 36.97 mm/year), concurrent with subsidence in the right-side main bridge foundation and south bank approach bridge foundation (maximum rate: 35.59 mm/year). We then investigated the relationship between these settlement patterns and various environmental factors, including geological conditions, Sediment Transport Index (STI), Topographic Wetness Index (TWI), precipitation, and temperature. The observed settlement patterns were attributed to the combined effects of stratigraphic heterogeneity, dynamic hydrological conditions, and seasonal climate variations. These findings demonstrate that SBAS-InSAR technology can effectively capture complex bridge foundation deformation processes, offering a cost-effective alternative to traditional monitoring methods. This advancement in bridge monitoring technology could enable more widespread and frequent assessment of bridge foundation stability, ultimately improving infrastructure safety management.

Settlement of piles with negative skin friction: design approaches according to part 3 of Eurocode 7

Piles offer an effective solution for supporting structures in challenging ground conditions. However, ground settlement around deep foundations can induce negative skin friction, adding complexity to the geotechnical analysis and requiring careful consideration in both the pile settlement evaluation and structural integrity design. The article discusses the general recommendations provided by the informative annex of the revised Eurocode 7 version for designing piles subjected to negative skin friction. Using the Fellenius unified pile design concept, we provide a practical design framework for piles subjected to negative skin friction that extends the load-settlement curve methods proposed by Masopust, representing the standard pile design approaches in the Czech Republic. For examples presented, the introduced practical approach, also suitable for manual calculations, is in very good agreement with a refined calculation providing a nonlinear load-settlement curve.

Seismic Resilience of Geogrid Reinforced Concrete Earth-Retaining Wall of Various Incremental Panels Based on Physical and Numerical Modelling

The dynamic response for different earth-retaining walls having geogrid as a reinforcement, combined with cohesionless granular material for backfill to mitigate earth pressure, has been examined through scale-down shaking table experiments and full-scale 3D FE analysis, utilizing ABAQUS as the finite element software. The scale factor is 1/4th for scaled-down. This study included various physical modelling experiments using different geogrid-reinforced earth retaining (GRER) walls (1m height, 7.5cm, thickness, and length 1m). Additionally, comprehensive 3D finite element analysis were conducted with the configurations measuring (4m, height 0.3m, thickness, and length 4m). This study examines hollow prefabricated concrete panels with shear key (PC-W), stone masonry walls of gravity type (GM-W), and traditional reinforced concrete (RC-W) walls. It also presents comparative investigations, such as lateral horizontal displacement of the wall, lateral pressure to the backfill, backfill soil settlement, and settlement of the wall foundation of various (GRER) walls. The accuracy of the Finite Element simulation framework has also been assessed in the shaking table experiment, as well as the FE analyses. According to the results, a PC-W wall with a shear key is the most effective type because it shows more resistance toward displacement. As per the comparison of the test models, GRER walls’ seismic response was more affected by the earthquake waves from the far field having long-term high acceleration values. In contrast, seismic waves from the close field had a smaller impact on the walls’ seismic response. However, the geogrid could improve the GRER seismic resilience deformation. Geogrid layers may reduce backfill pressures and backfill settlements. The geogrids located in the central portion within the reinforced soil and the geogrid roots connected to the walls were essential to the seismic design of the geogrid-reinforced earth retaining wall. To evaluate the reliability of the findings, the models have a predicted R2 variance below 0.1, indicating a consistent relationship between these two variables.

Determining Dhap Pokhari lake surface dynamics for restoration strategies through geoelectrical mapping

ABSTRACT Lakes in the hilly regions of the Sikkim Himalayas in India are crucial for water supply and tourism. However, this area experiences frequent earthquakes and microtremors, increasing the risk of seismic hazards and contributing to a higher density of subsurface fractures and discontinuities. This has led to water seepage in lakes across Sikkim, turning some from perennial to seasonal. To investigate these issues, geoelectrical mapping techniques, specifically Vertical Electrical Sounding (VES) and profiling, were used to study Dhap Pokhari Lake in Sikkim’s Pakyong district. The findings revealed a subsurface fracture zone beginning at a depth of 20 m and extending down to 50 m. The VES data showed significant variations in sediment thickness and subsurface lithology between two measurement points only 10 m apart, with a noticeable ground settlement of about 2 m at one location. The profiling results indicated a major fracture and two minor ones, which are likely causing water seepage and ground saturation, particularly during rainy seasons, leading to compaction and ground settlement. This poses a risk to the structural stability of the surrounding areas, highlighting the need for effective lake restoration strategies. Geoelectrical mapping is a valuable tool for identifying such subsurface fractures and making evidence-based strategies to revive lakes in this seismically active region.

Estimation of the wetting induced settlement of loess soils from the wetting soil-water characteristic curve

Collapsible loess soils, known for their significant volume reduction upon the wetting, pose critical challenges in the geotechnical engineering. The estimation of the wetting-induced settlement is crucial for the foundation design and the determination of the negative skin friction on the pile. In this paper, a new method is proposed to estimate the wetting induced collapse from the wetting soil-water characteristic curve (SWCC) and the index properties of the loess soils. In the proposed model, both the water-entry value (WEV) and constant water content suction (ψwc) were adopted for the quantification of the volume change with respect to the reduction in soil suction. The proposed method is verified against the experimental data from published literature. Subsequently, the ground settlement of the loess soil in the inundated condition was calculated by adopting the proposed method and comparing the results with the field measurement data. The results of study indicated that the performance of the proposed method is better than the conventional method in predicting the ground settlement by using the local code in China.

Mechanism-Driven Intelligent Settlement Prediction for Shield Tunneling Through Areas Without Ground Monitoring

Ground settlement is a crucial indicator for assessing the safety of shield tunneling and its impact on the surrounding environment. However, most existing settlement prediction methods are based on historical data, which can only be applied with effective monitoring conditions. To overcome this limitation, this paper proposes the mechanism-driven intelligent settlement prediction method (MISPM), which considers the mechanisms of settlement and attitude movements during construction to design new features that can indirectly reflect settlement. Simulation experiments were used to compare the impact of different candidate features and algorithms on prediction performance, verifying the validity and accuracy of the model. The efficacy of MISPM in predicting settlement changes in advance was substantiated by practical engineering applications. Results showed that MISPM could accurately predict settlement changes even without ground monitoring, thereby corroborating its reliability and applicability in supporting safe tunneling in complex geological environments. In the construction of urban infrastructure, this method has the potential to enhance the efficiency of tunnel construction and ensure environmental safety, which is of great significance for the development of smart cities.

Characteristics and Control of Subway Train-Induced Environmental Vibration: A Case Study

With the widespread construction of the subway in the Chinese mainland, the environmental vibration caused by subway operation has attracted increasing attention. Train-induced environmental vibrations can cause structural deformation, uneven settlement of line foundations, and tunnel leakage, affecting the structural safety of lines and foundations. This research focuses on a segment of the Nanchang Metro Line 3, which has been chosen as the subject of investigation. A numerical model was developed to analyze the subway train-induced environmental vibration, employing the finite element method (FEM). Utilizing a numerical model, an investigation was conducted to examine the impact of train speed on the subway train-induced environmental vibration, the train-induced environmental vibration transmission characteristics were analyzed, and the control effects of vibration reduction tracks on train-induced environmental vibration were discussed. Train-induced vibration tests were also conducted on Nanchang Metro Line 3 to verify the control effects of various vibration reduction tracks. The results indicate that the subway train-induced environmental vibration rises as the train speed goes up, and the vibration peaks always appear around 63 Hz. When the train speed doubles, the Z-vibration level increases from about 5.1 dB to 5.9 dB. Subway train-induced environmental vibration shows a fluctuating decreasing trend with increasing distance from the centerline of the tunnel. The Z-vibration level reaches its maximum 4 m away from the centerline of the tunnel. Compared with the embedded sleeper, the vibration-damping fastener exhibits a vibration reduction effect of about 9 dB to 18 dB, the rubber vibration-damping pad exhibits a better vibration reduction effect of about 16 dB to 24 dB, and the steel spring floating plate exhibits the best vibration-damping effect of about 18 dB to 28 dB. The calculated Z-vibration levels are basically consistent with the measured values, indicating the accuracy of the calculated results of the control effects of the vibration reduction tracks.

AI-powered simulation models for estimating the consolidation settlement of shallow foundations

AI-powered simulation models for estimating the consolidation settlement of shallow foundations

Finite Element Analysis and Improved Evaluation of Mechanical Response in Large Oil Storage Tanks Subjected to Non-Uniform Foundation Settlement

This study developed a finite element model to address the issue of non-uniform settlement in large crude oil storage tanks. The model consisted of four key components: the tank foundation, bottom plate, wall plate, and large fillet welds. The Ramberg-Osgood model was used to describe the material’s nonlinearity. Key factors such as the radius-to-thickness ratio, height-to-diameter ratio, harmonic number, and amplitude were evaluated for their impact on the radial deformation of the tank’s top wall. Two numerical models were developed—one accounting for the coupling effect between the foundation and the tank bottom, and the other without it. The differences in radial deformation between these models were analyzed, revealing that deformation was minimally influenced by the radius-to-thickness ratio, but increased with higher height-to-diameter ratios and harmonic amplitudes. At low liquid levels, radial deformation increased with harmonic number, but at high levels, it decreased once the harmonic number exceeded four due to the decoupling of the tank bottom from the foundation. The model considering foundation coupling exhibited less radial deformation compared to the one neglecting it, particularly as the harmonic number and amplitude increased. An improved evaluation method identified a critical range of harmonic amplitudes for a 100,000 m3 tank, within which the coupling effect can be reasonably neglected, allowing deformation to be calculated using the simpler model.

Design and Monitoring Application of an Adjustable Intelligent Bearing Based on Pressure Sensing.

Single-pier, dual-bearing bridges are susceptible to effects such as concrete creep, thermal expansion, and uneven foundation settlement. When combined with eccentric loading from heavy vehicles, these factors collectively can significantly increase the risk of bridge overturning. To address this risk, a comprehensive analysis of the bridge overturning mechanism was conducted. Considering the current limitations of health monitoring in bearing reaction force (BRF) measurement and risk mitigation, an adjustable intelligent bearing based on pressure sensing and self-locking principles was developed. Its mechanical performance was analyzed under the most unfavorable load conditions. To further validate the approach, a specific experimental bridge was used as a case study. The effectiveness of the force measurement and height adjustment functions was evaluated through moving load experiments. The results showed that the force measurement function accurately captured dynamic BRF changes within a precision range of ±0.1% FS and demonstrated high sensitivity to instantaneous impact effects. The height adjustment function achieved a reaction force change of up to 40 kN within the maximum adjustment range of 1.2 mm, significantly improving the load distribution of the bridge. These findings validated the reliability of the proposed intelligent bearing in real-time monitoring and proactive risk adjustment. This effectively overcomes the limitations of existing bearings, which only perform passive monitoring. Overall, it achieves the real-time monitoring of BRF and proactive control of bridge overturning risks.

Monitoring and Data Analyses of Pressure Changes and Ground Settlements Induced by Slurry TBM Tunneling in a Semiconfined Aquifer: Case Study in the Netherlands

Monitoring and Data Analyses of Pressure Changes and Ground Settlements Induced by Slurry TBM Tunneling in a Semiconfined Aquifer: Case Study in the Netherlands

Fully hydro-mechanical coupled analyses of the deep excavation above a multi-aquifer-aquitard system

Deep work shaft excavations have become increasingly common as a preliminary step of tunnel construction. Deep excavation above a multi-aquifer-aquitard system (MAAS) complicates the flow field and stress field surrounding the excavation, inevitably affecting the performance of excavations. However, previous studies with drained or undrained analyses ignored the effects of dewatering-induced groundwater flow on the performance of deep excavations. To better understand this aspect, this study performs fully hydro-mechanical coupled analyses to investigate the performance of a 39.5 m-deep excavation above a multi-aquifer-aquitard system, which considers dewatering in two confined aquifers. A sophisticated three-dimensional (3D) numerical model is developed to simulate the detailed construction processes of drainage, excavation, dewatering, and strut installation. The study presents a comparison of two scenarios (with and without dewatering in a confined aquifer) with respect to wall deflection, stratum deformation, pore pressure, and effective stress path. The analysis results indicate that the effective stress paths are highly dependent on stratum permeability and construction activities. The dewatering behavior significantly reduces the excavation-induced deformation, primarily due to increased effective level and consequently increased resistance on the excavated side. As a result, ground settlements decrease due to less wall deflection.

Influence of large-diameter shield tunneling on deformation of adjacent high-speed railway subgrade in soft soils and effectiveness of protective measures

The excavation of large-diameter shield tunnels in soft soils inevitably impacts adjacent high-speed railway infrastructure. This study investigates the effects of constructing a 14.02 m large-diameter shield tunnel on the deformation of a nearby high-speed railway subgrade in soft soils of Shanghai, and evaluates the effectiveness of various protective measures. A numerical model was developed to simulate the horizontal deformations of railway subgrade piles, as well as the vertical and horizontal deformations of track slab resulting from shield excavation. Comprehensive real-time monitoring of track slab displacements in both vertical and horizontal directions, along with ground surface deformation, was conducted. The accuracy of the computational model and the effectiveness of the implemented protective measures were validated through field measurements. The results demonstrate that isolation piles with coupling beams proved to be the most effective method for protecting the railway subgrade. The maximum observed ground settlement above the tunnel reached −20.3 mm, while the peak heave was recorded at 3.7 mm. Notably, the additional vertical and horizontal deformations of the high-speed railway track were successfully constrained within the 2-mm threshold. These findings provide valuable insights for safety assessments and the implementation of protective measures in similar projects.

Influence of Rocking Shallow Foundation Parameters and Analysis of Seismic Response Characteristics

Rocking shallow foundations interrupt the seismic transmission path from the base of the structure and possess advantages, such as effective seismic isolation, self-resetting capabilities post-earthquake, and low costs. A numerical model of the rocking shallow foundation was developed in OpenSees (version: Opensees 3.5.0) based on field test data using numerical simulation. The effect of different parameters (column height, foundation sizes, top mass, and soil softness and stiffness) on the seismic response characteristics of rocking shallow foundations is investigated, and the seismic response characteristics of rocking shallow foundations are analyzed under the action of sinusoidal waves of different frequencies and various seismic wave types. The results of the study show that, as the height of the column increases, the bending moment decreases and settlement decreases; as the size of the foundation increases, the bending moment increases and settlement increases; as the mass of the top increases, the bending moment increases and settlement increases; and as the soil becomes softer, the bending moment decreases, and settlement increases. Inputting a sine wave that matches the structure’s natural oscillation frequency may induce resonance. This phenomenon can significantly amplify the structure’s vibrations; thus, it is essential to avoid external excitation frequencies that coincide with the foundation’s natural oscillation frequency. Under seismic loading, the rocking shallow foundation can mitigate the bending moment in the superstructure. When the displacement ratio remains within −0.5 to 0.5 percent, the foundation settlement is minimal. However, when the absolute displacement ratio exceeds 0.5 percent, the soil exhibits plastic deformation characteristics, resulting in increased foundation settlement. This study is an important contribution to the improvement of seismic performance of buildings and an important reference for improving seismic design standards and practices for buildings in earthquake-prone areas. In the future, the seismic response characteristics of rocking shallow foundations under bidirectional seismic action will be investigated.

DETERMINATION OF SUBSIDENCE PROFILES OF THE RAILWAY AND HIGHWAY EMBANKMENTS FOUNDATIONS, DAMS AND LEVEES MADE OF SOIL MATERIALS

Purpose. Determination of foundations subsidence of railways, roads, and other embankments, as well as dams and levees made of soil materials during their design, construction, and operation, is mandatory. At the same time, if the foundation is composed of soils with a small modulus of general deformation (silt, peat, peaty, and similar soils), then not only the average subsidence and its unevenness should be determined, but also determine the profiles of subsidence outside the structures. This is because the subsidence of the foundation has the same order as the height of the embankment (dams, levees); therefore, when determining the additional volume of material required for the construction of an embankment (dams, levees), these deformations must be considered. The purpose of the article was to develop an algorithm for calculating the subsidence profiles of railways, roads, and other embankments, as well as dams and levees made of soil materials. Methodology. Theoretical studies of geomechanical processes using analytical and numerical mathematical methods. Analysis and generalization of theoretical research results. Findings. An algorithm is proposed that allows using simple analytical dependencies to determine those necessary for calculation and design, construction and operation parameters of the system "soil base of dams (levees) and embankments made of soil materials with a trapezoidal cross-section and a rigid core": – the lower limit of the compressed stratum; – subsidence of the foundation within the sole of the base of the dam, levees, or embankment. Originality. It is established that the foundation subsidence on the vertical passing through the center of the dam, levees, or embankment with a symmetrical profile is not less than the subsidence on the calculated verticals passing through any point of the dam, levees, or embankment with an asymmetric profile. Practical value. The main practical result of the work is a more complete (compared to the current regulatory documents) consideration of the features of subsidence of the system "dam, levees (or embankment) made of soil materials – soil base" with a significant reduction in the number of calculations. The results we obtained allow us to determine those necessary for the calculation, design, construction, and operation of dams, levees and embankments made of soil materials characteristics.

Machine Learning–Finite Element Mesh Optimization-Based Modeling and Prediction of Excavation-Induced Shield Tunnel Ground Settlement

Ground settlement prediction for shield construction is highly important and challenging. This study introduces a machine learning algorithm combined with finite element numerical simulation, i.e., machine learning–finite element mesh optimization. For surface subsidence prediction, 16 combination models of ANN, KNN, RF and SVR were optimized by PSO, GA, BT and BO, involving raw data preprocessing, principal component analysis, hyperparameter selection and prediction accuracy evaluation. A subway shield tunneling project was analyzed, in which the meshes of finite element numerical models were discretized into different sizes from 1.0[Formula: see text]m to 2.0[Formula: see text]m. In total, 360 sets of data points were extracted from the simulation results, including stress, strain, shield jacking force, internal friction angle, cohesion force, and settlement, of which 252 data points were used as the input parameters of machine learning model. Analysis of average error rate of finite element–machine learning coupling models showed that the finite element model had the highest accuracy of settlement prediction when the mesh size of the finite element model was 1.4[Formula: see text]m, and the GA-SVR model had the highest accuracy and generalization ability in ground settlement prediction. This study highlights the uniqueness of machine learning–finite element mesh optimization model in application.

Thermo-Mechanically Coupled Settlement and Temperature Response of a Composite Foundation in Complex Geological Conditions for Molten Salt Tank in Tower Solar Plants

The degradation of complex geological structures due to thermo-mechanical cycling results in a reduction in bearing capacity, which can readily induce engineering issues such as uneven settlement, cracking, and even the destabilization of the foundations of molten salt storage tanks. This study establishes a foundational model for a molten salt storage tank through the use of COMSOL Multiphysics and conducts a numerical simulation analysis to evaluate the settlement deformation and temperature distribution of the foundation under the influence of thermo-mechanical coupling. Concurrently, the research proposes two distinct design approaches for the tank’s foundational structure. A comparative analysis of the results indicates that the use of a pile raft foundation in conjunction with a traditional foundation mode results in a reduction of settlement at the center of the foundation’s top surface by 380.1 mm, while also decreasing the maximum effective stress in the steel ring wall by 240.7 MPa. The thermal effects impact a depth of 10 m in the foundation soil and an influence radius of 20 m. Additionally, the foundation soil exhibits optimal thermal insulation properties, resulting in minimal energy loss. These findings indicate that the pile raft foundation in conjunction with a traditional foundation mode displays remarkable adaptability to complex geological conditions, with both settlement and temperature distribution of the foundation maintained within acceptable limits.

Numerical Analysis of Grouting Reinforcement Effects on Deep Foundation Pits Adjacent to Elevated Railways

To mitigate the impact of foundation pit construction on adjacent existing structures, grouting reinforcement techniques are often employed to enhance the deformation strength of the soil. This study focuses on the expansion project of the Dayun Comprehensive Hub in Shenzhen, conducting full-scale numerical simulations of the excavation of deep foundation pits adjacent to existing elevated railways and examining the effects of different grouting reinforcement schemes. The results indicate that the single-row and double-row grouting schemes increased the bearing capacity of the foundation piles by 23.7% and 31.9%, respectively, significantly enhancing the structural bearing performance. After reinforcement, the maximum deformation position of the elevated bridge foundation piles shifted upward, and the settlement distribution of the cap beam became more concentrated, indicating that grouting reinforcement effectively controlled the ground settlement and the deformation of the foundation piles. Furthermore, compared to controlling the deformation of the retaining structures, grouting reinforcement was more effective in controlling ground settlement and pile deformation, highlighting its advantages in complex environments. Although the double-row grouting scheme demonstrated superior technical performance, the single-row scheme remains the preferred option considering reinforcement efficiency and economic factors.

Effect of Fines Content on the Compression Behavior of Calcareous Sand

Due to the hydraulic sorting effect in the hydraulic filling process, a fine-grained aggregate layer dominated by silty fine sand with uneven distribution is easily formed in reclamation projects, which triggers issues with the bearing capacity and nonuniform settlement of calcareous sand foundations. In this study, a series of one-dimensional compression tests were conducted to investigate the effect of different fines contents (fc) on the compression behavior of calcareous sand. The results show that at the same relative density (medium-density, Dr = 50%), the addition of fine particles leads to a reduction in the initial void ratio (for fc ≤ 40%). Furthermore, while the compressibility of the soil samples increases with the rising of fines content, it begins to decrease with further addition of fine particles beyond a threshold value of fines content (fc-th). Additionally, particle crushing contributes to the compressive deformation of calcareous sand, and the particle relative breakage of calcareous sand increases at the initial stage of adding fine particles. Moreover, a comparison of the compression test results between calcareous silty sand (fc = 10%) and clean sand reveals that the addition of fine particles accentuates the compressibility differences among calcareous sands with different relative densities. These findings provide valuable insights for addressing the challenges posed by fine-grained layers in calcareous sand foundations.

Research on the Geosynthetic-Encased Gravel Pile Composite Highway Foundation in Low-Temperature Stable Permafrost Regions

In low-temperature stable permafrost regions, both active and passive cooling measures are commonly employed to ensure the long-term stability of highway structures. However, despite adopting these measures, various types of structural issues caused by permafrost degradation remain prevalent in high-grade highways. This indicates that in addition to preventing permafrost melting, structural reinforcement of the foundation is still necessary. Based on the analysis of the long-term foundation temperature field and settlement using the finite element method, which was validated through an indoor top-down freeze–thaw cycle test, this paper explores, for the first time, the feasibility of applying geosynthetic-encased gravel pile composite highway foundations—previously commonly used for permafrost destruction—in low-temperature stable permafrost areas where permafrost protection is the primary principle. By analyzing the long-term temperature field, settlement behavior, and pile–soil stress ratios of permafrost foundations influenced by both the highway structure and composite foundation, it was found that when the pile diameter is 0.5 m, pile spacing is 2 m, and pile length is 11 m, the mean monthly ground temperature of the permafrost foundation will not be significantly affected. Therefore, the properly designed geosynthetic-encased gravel pile composite highway foundation can be adopted in low-temperature stable permafrost regions where permafrost protection, rather than destruction, is required.