Soil Deformation Research Articles

New Methodology for Assessing Seismic Ground Vulnerability Based on Microtremor and Taiwan Seismic Intensity Scale

ABSTRACT The Taiwan Ground Deformation Index (TGDI) is proposed to quantify site vulnerability using a non-linear soil deformation model, PGA parameters from the Taiwan seismic intensity scale, and microtremor analysis. Site vulnerability is graded into four levels: low (TGDI < 2.4), moderate (2.4 ≤ TGDI < 4.2), high (4.2 ≤ TGDI < 7.4), and very high (TGDI ≥ 7.4), based on susceptibility to seismic damage. Validating TGDI with 13 disaster events in Tainan during the 2016 Meinong earthquake showed 12 cases of moderate-to-high vulnerability. Since weak ground and strong amplification properties favor TGDI increases, this index serves as an early warning parameter for disasters.

Characterising the permanent deformation of subgrade soils under seasonal variation

Rutting, a prevalent failure mode in flexible pavements, largely stems from subgrade issues. Despite this, there is a lack of standard protocols to evaluate subgrade rutting or permanent deformation (PD). This study attempted to characterise PD in subgrades, focusing on a poorly graded sand and two silty sands. Moisture contents above and below optimum levels were considered to account for seasonal variations. The research involved adapting a test to assess the PD by determining typical stresses on the subgrade. Moreover, given these soils' unsaturated state and medium- to fine-grained nature, suction is an important factor. Suction-controlled multi-stage Repeated Load Triaxial tests were conducted, and the results were fitted by a PD model modified to account for suction. The characterisation was compared with the subgrade strain criterion used in pavement design solutions. Results indicated discrepancies between the PD characterisation and strain criteria predictions, with the silty sands performing better than the poorly graded sand, consistent with the shakedown theory.

Coupling effects on class C predictions of soft soil settlements

AbstractIn uncoupled consolidation analysis, settlement and pore water pressure are solved independently, whereas in coupled analysis, they are solved simultaneously to ensure continuity (i.e., the volume change in soil due to compression must equal the water volume change caused by dissipation). This study investigates the coupling effects of soil deformation and pore water pressure dissipation in the back analysis of soft soil settlements. It further evaluates the suitability of both coupled and uncoupled constitutive models with different types of monitoring data, providing practical guidance for selecting consolidation models and achieving reliable long-term predictions. The one-dimensional governing equations for soft soil consolidation, incorporating prefabricated vertical drains and creep deformation, are first reviewed. A case study of a trial embankment in Ballina, New South Wales, Australia, is then used to demonstrate the impact of coupling effects and monitoring data on settlement predictions. The results show that considering coupling effects not only improves long-term settlement predictions but also reduces uncertainties in the updated soil parameters, especially when both settlement and pore water pressure data are used.

Study on the Settlement and Deformation Characteristics of Surrounding Rock of Loess Tunnel

There is a water culvert with masonry structure in the mountain of Hanguguan Tunnel. Soil deformation caused by tunnel excavation leads to channel cracking. On the one hand, channel water infiltration leads to loess tunnel collapse, which can easily cause engineering accidents and delay the construction period. On the other hand, it will affect the channel water supply and cause social problems. In this paper, the spatial deformation of the tunnel excavation process in the loess layer is revealed through the settlement of the vault in the tunnel, the monitoring of the convergence of the perimeter, and the force monitoring of the lining support structure of the Hanguguan tunnel, and the influence of the tunnel excavation deformation on the culvert is revealed through numerical calculation. The results show that the arch at the tunnel exit has the largest settlement deformation, the larger cumulative settlement, and the faster settlement rate, and the deformation of the culvert is small, only a millimeter. Compared with the monitoring data, the numerical simulation of tunnel excavation and the vertical settlement are basically consistent with the actual situation.

Effects of shield construction on dynamic characteristics and deformation of interlayer soil: A case study in Changchun, China

Effects of shield construction on dynamic characteristics and deformation of interlayer soil: A case study in Changchun, China

Effects of changing adjacent building conditions on ground settlement profiles around deep excavation construction

ABSTRACT This study investigates the impact of deep excavation on ground settlement under various adjacent building conditions using the finite element method. It simulates diaphragm wall earth retention systems with plate elements and uses H-beam assemblies with preloaded anchors to represent temporary earth retention and ensure safety measures. Adjacent structures are also modeled with plate elements. Unlike traditional methods that often overestimate settlement by simulating only ground loads, this research includes the effects of neighboring basements and validates the model using field data. The study employs the HSS model, which provides a more accurate representation of soil deformation compared to the Mohr-Coulomb model. Findings indicate that ground settlement significantly increases when the adjacent building’s basement depth is about half the excavation depth, stabilizing as it approaches 1.6 times the excavation depth. Settlement is more pronounced for buildings closer to the diaphragm wall and decreases with distance. The relationships are described by normalized curves, and y = 1.9x−0.4 and 2.5/√x, representing the behavior of ground settlement in response to varying building conditions.

Modeling pore fluid pressure and deformation in unsaturated soils under gravitational compaction and cyclic loading

Cyclic loading of fluid-bearing soils often induces excess pore water pressure, leading to accumulation of strain in the solid matrix. Additionally, variations in material density and volumetric fraction due to gravitational effects generate momentum forces, which subsequently cause deformation in the soil. In this paper, we present a mathematical framework of poroelasticity that generalizes the simultaneous action of gravitational body forces and cyclic loading to analyze solid deformation and fluid pressure dissipation in partially-saturated porous media. To account for the effect of gravity, the gradient of the vertical displacement needs to be treated as an additional dependent variable alongside pore air and water pressures.We numerically solve a mixed strain-controlled and pressure-prescribed boundary-value problem using a finite difference scheme as a representative example to quantify the impact of gravitational forces. Our results show that gravitational compaction affects both total settlement and excess pore water pressure, with its influence being particularly significant at lower water saturations, regardless of excitation frequency, soil depth, or type. The effect of gravity is more pronounced in soils with higher compressibility but appears insensitive to excitation frequency. Notably, the gravitational effect correlates linearly with the depth of the soil deposit and, therefore, should be well integrated into the consolidation theory of poroelasticity.

Prediction of permanent deformation of subgrade soils under F-T cycles using SABO-optimized CNN-BiLSTM network

Accurately predicting the permanent deformation of subgrade soils under combined loading and seasonal freeze-thaw (F-T) effects is crucial for optimizing pavement design and maintenance planning in cold regions. However, existing empirical models have limitations in capturing the non-linear deformation behavior influenced by interacting factors. This study developed a deep learning framework, specifically a convolutional neural network-bidirectional long short-term memory (CNN-BiLSTM), for time-series prediction of subgrade strains. Laboratory tests established a comprehensive database to examine soil response across various conditions. Regression analysis revealed the constraints of traditional models. The optimized hybrid architecture directly learned patterns from experimental data, outperforming regression by 29−71 % based on error metrics. Sensitivity analysis confirmed that the model identified primary governing inputs consistent with theory. Hyperparameter tuning with the Subtraction-Average-Based Optimizer further enhanced performance. This data-driven methodology demonstrated the potential of advanced machine learning in simulating complex subsurface deformation behavior under compounding factors in seasonal frozen environments.

Interaction between underwater explosion bubbles and soil–water interface: A numerical and experimental study

To explore the interaction between underwater explosion bubbles and soil–water interface, a near soil–water interface underwater explosion model based on the arbitrary Lagrangian–Eulerian method was established in this work. The peak pressure of the shock wave, maximum bubble radius, and bubble evolution in free-field and bottom-charge underwater explosions determined from the proposed simulation were highly consistent with the experimental results, thereby validating the proposed numerical model. The effects of the explosion distance and amount of explosive charge on the bubble–soil surface interaction were evaluated. The results showed that the reflection coefficient of the soil–water interface was in the range of 1.204–1.250, suggesting that it was hardly affected by the explosion distance and amount of explosive charge. The attenuation coefficient of the saturated soil was found to be 1.058. With the decrease in the explosion distance, the period and maximum radius of the bubbles slightly increased, and soil deformation increased as the lower surface of the bubbles was closer to the soil surface. For explosion distances of 0.3 and 0.4 m, only an overall movement of the soil surface was observed. When the explosion distance was 0.2 m or lower, a powerful downward jet was generated upon the pulsation of the first bubble, resulting in craters and slender depressions in the soil. With the increase in the amount of explosive charge, the period and maximum radius of the bubbles increased, and soil deformation also increased. These findings are expected to help advance our understanding of underwater explosion dynamics.

The effects of the Phlaegrean Bradyseism on building systems: Field research applied in Pozzuoli

The contribution presents the results of field research aimed at assessing the effects of the Phlaegrean Bradyseism phenomena on a building system located in the historic centre of Pozzuoli (Italy). The study falls within the scope of building façade vulnerability analyses conducted by the authors to support the Public Administration in managing bradyseismic emergencies.Considering that the seismic-deformation phenomena connected to Bradyseism affect the performance and integrity of façade components, the research focused on studying its impact on the technical elements within the Technological Unit Classes of “Load-bearing Structure”, “Enclosure”, and “External Partition”, which directly project onto the external environment and collectively constitute the Building Envelope. The methodology for impact assessment was developed by correlating data acquired from a monitoring system installed on the façade of a surveyed building with characteristic parameters related to seismic events and soil deformations in a specific reference period. The analyses conducted excluded any significant impact of these seismic-deformation forcings on the building's Load-bearing Structure, both in terms of displacements and damage. On the other hand, significant impacts were found on the technical elements of the building envelope, which, due to their lower resistance and ductility, represent a constant hazard for the exposed urban system's safety, configuring a Building Risk scenario.

Stochastic analysis of the interaction between excess fluid flow and soil deformation in heterogeneous deformable porous media

Stochastic analysis of the interaction between excess fluid flow and soil deformation in heterogeneous deformable porous media

Utilization of calcium carbide residue based soil stabilizer in road construction: Strength, environmental impact, and field application

This research paper delves into the utilization of calcium carbide residue (CCR)based stabilizer (designated as CSC) in road subgrade soil stabilization, with a comprehensive evaluation of its mechanical strength, environmental safety, and efficacy in field applications. Amid growing environmental concerns and the push for sustainable construction materials, this study presents an innovative approach by repurposing CCR, a by-product of the acetylene production process, in enhancing the structural integrity of road foundations. Through a series of laboratory tests, the investigation reveals significant improvements in the unconfined compressive strength (UCS) and California bearing ratio (CBR) of CSC-stabilized soils, compared to traditional lime stabilization methods. The field test DCPI results indicate that the CBR value of the field test CSC stabilised soil is 50.19% after three days, whereas the CBR value of the field test lime stabilised soil is only 29.51% after the same period. The CBR value of the CSC stabilised soil is significantly higher than that of the lime stabilised soil. This study also tested the leachate of the stabilised soil, analysing the concentration of heavy metals. The results indicated that the leachate from the stabilised soil complies with heavy metal leaching standards, demonstrating the ecological benefits of CSC utilisation. Furthermore, field experiments conducted on the G312 National Highway in Jiangsu Province, China, further validated the laboratory test results. The findings from the field trials indicated that sections stabilised with CSC exhibited superior performance in terms of reduced soil deformation and enhanced load-bearing capacity. Additionally, a life cycle carbon emission analysis was conducted for the field trial section, comparing the carbon emissions of the CSC binder with those of the lime binder throughout the entire life cycle of road construction. The results from the trial section demonstrated that the use of the CSC binder significantly reduced carbon emissions. The study underscores the potential of CSC as a cost-effective, environmentally friendly stabilizing agent, offering a pragmatic solution to the dual challenges of industrial waste management and soil stabilization in road construction.

Cumulative effects of cyclic train loading on strains in reinforced soils around tunnels

Metro tunnels often experience uneven settlement of the soil beneath them during operation, a problem that is especially pronounced in soft soil layers such as silt. This uneven settlement negatively affects the operational safety of subways, prompting engineers to use soil reinforcement techniques to mitigate ground deformation. However, there is a lack of research on the cumulative deformation of reinforced soils under cyclic train loading. In this study, dynamic triaxial tests were conducted to obtain the deformation parameters of silty reinforced soils under cyclic loading. The principal dynamic relationship was summarized, and the effect of loading frequency on soil deformation was analyzed. The results indicated that as the loading frequency increased, the cumulative deformation of the soil decreased. Using the dynamic constitutive relationship derived from the tests, the finite element method was employed to model the interaction system between the load, tunnel, and strata, as well as the dynamic modulus attenuation behavior of the reinforced soil layer. This approach was used to investigate the cumulative deformation characteristics of reinforced soils under cyclic loading. The findings indicated that the dynamic modulus of the reinforced soil decayed rapidly at the beginning of the loading period, leading to an accelerated increase in the cumulative deformation. Additionally, the cumulative deformation was measured at different train speeds, revealing that when the speeds exceeded 80 km/h, the cumulative strain of the soil increased gradually with speed.

STUDIES OF THE EFFECT OF REINFORCEMENT WITH GEOSYNTHETIC MATERIALS ON THE STRENGTH OF SOILS UNDER CONDITIONS OF TRIAXIAL COMPRESSION AND SINGLE-PLANE SECTION

The study is a comprehensive analysis of the effect of geosynthetic materials on the strength characteristics of soils under triaxial compression and single plane shear conditions. The triaxial compression method is used to investigate the complex effects on soil specimens, which reflects real conditions and ensures the reliability of the results.The aim of the study is to evaluate the effectiveness of geosynthetic materials as a means of soil reinforcement. Particular attention is paid to analysing changes in the mechanical properties of soils reinforced with different types of geosynthetics compared to unreinforced samples. The study includes laboratory tests, during which the parameters of strength, deformability and stability of soils under different loads and variations of test conditions are evaluated.The results of the study provide important information for specialists in geotechnical design and construction. They help to evaluate the effectiveness of geosynthetic materials in strengthening soil structures under high loads and complex conditions.Additionally, the study includes an analysis of the effect of geogrid on the strength of weak soils, which allows to identify optimal strengthening options and compare their effectiveness.Thus, the study is a relevant contribution to the development of knowledge on the interaction between geosynthetic materials and soil structures, contributes to the optimisation of design and increases the durability of soil structures

A pore network modeling approach to bridge void ratio‐dependent soil water retention and unsaturated hydraulic conductivity curves

AbstractIn geotechnical engineering, understanding the relationship between soil permeability and deformation is essential, particularly for applications like earth dams, where compaction‐induced permeability reduction is crucial for performance optimization. In unsaturated soils, soil moisture content significantly impacts hydraulic conductivity. Traditionally, changes in unsaturated hydraulic conductivity have been linked to soil void ratios. However, a pore network modeling perspective reveals the significance of structural parameters, such as pore and throat size distribution and pore coordination number. This study introduces a pore network model to estimate unsaturated hydraulic conductivity based on void ratio‐dependent soil‐water retention curves. It examines how soil deformation at varying stress levels affects structural parameters and the water phase continuity. The model shows strong potential in predicting unsaturated hydraulic conductivity across different stress levels, aligning well with experimental data and established equations. Notably, the aspect ratio and coordination number parameters are most affected by stress levels. The study also presents relationships to describe changes in pore network structural parameters with soil void ratio, which can be used to predict soil‐water retention curves and unsaturated hydraulic conductivity at various stress levels.

Experimental study on deformation and failure mechanism of geogrid-reinforced soil above voids

Geosynthetic materials are crucial for reinforcing soil above subterranean voids. However, the complexities of load transfer mechanisms in reinforced structures remain elusive. This study investigates the deformation and failure mechanisms in geogrid-reinforced soil using trapdoor experiments. The particle image velocimetry (PIV) technique was utilized for detailed observation of soil deformation, while fiber optic strain sensing cables were used to monitor tensile strains within geogrids. Results indicate that soil arching redistributes loads across the trapdoor area, effectively transferring loads from subsiding to adjacent stable regions. As trapdoor displacement increases, the initial soil arch collapses, prompting the formation of another stable arch. This cycle of development and failure of soil arch continues until shear bands reach the ground surface. Soil arches are more prone to failure over shallower voids. Strain data reveal that the geogrid's tension varies with the tensile strain and is highest near the void's edges. For shallow voids, the tensioned membrane effect of the geogrid bears more of the overlying soil weight, whereas for deeper voids, soil arching plays a more significant role in load transfer. This study provides important insights into the interaction between soil arching and tensioned membrane effects, offering potential implications for optimizing geosynthetic design.

Isotropic compression behavior of salinized unsaturated agricultural soil: An experimental and constitutive investigation

Salinity-induced soil degradation is a significant challenge in coastal reclamation areas, impacting agricultural productivity and infrastructure development. Variations in soil compression and deformation caused by changes in salinity warrant further investigation, particularly for agricultural applications. This study explores the relationship between soil pore water salinity and compressibility by conducting isotropic compression tests on salinized unsaturated agricultural soils treated with distilled water, 0.5 mol/L and 1 mol/L sodium chloride (NaCl) and calcium chloride (CaCl2) solutions. The results demonstrate that the type and concentration of salts significantly affect the compression behavior of these soils. The constitutive parameters were calibrated based on the experimental data. To account for osmotic suction, Barcelona Basic Model (BBM) was adjusted. The findings indicate that as pore water salinity increases, soil compressibility decreases, reflected by a compression index (Cc), and higher pre-consolidation stress (py). This modification aimed to quantify the impact of pore water salinity on soil compression. To validate the constitutive model, a numerical analysis of an isotropic compression test was carried out. This study contributes to our understanding of the isotropic compression behavior of coastal saline soil, proposes a constitutive framework for predicting soil responses under different salt conditions, and provides theoretical support for engineering construction in coastal reclamation areas.

Mechanical response analysis of primary support for shallow buried loess tunnel under surface surcharge

At present, the research on the influence of surrounding soil deformation induced by tunnel construction under the action of surcharge is generally based on the situation after the tunnel has been built, and less consideration is given to the existence of surface surcharge near the planned route of the tunnel when the tunnel is not built. Therefore, based on the Luochuan tunnel under construction, this study monitors the deformation of shallowly buried loess tunnels under different surcharge conditions and analyzes the influence of varying surcharge conditions on the deformation and stress of the tunnel through numerical simulation to determine the effective range of surface surcharge. The results show that the influence of surcharge load on tunnel stability is the most significant when located at the tunnel axis, and the influence degree increases with the increase of load. The adverse effects of surcharge load mainly occur in the range of 2 times the tunnel diameter. Once the range is exceeded, the internal force of the tunnel support structure is not sensitive to the surcharge load. In engineering, the surface surcharge can be controlled within the safety displacement limit by referring to the displacement calculation results.

Insights into the shallow landslide mechanism of expansive soil slope induced by freeze-thaw cycles and snowmelt infiltration

For rigorous understanding the shallow landslide mechanisms and deformation characteristics of expansive soil slopes, a comprehensive in-situ monitoring platform is established. Triaxial creep tests and microstructure analysis with scanning electron microscopy (SEM) are also conducted on expansive soil samples obtained from Binxi station. Field monitoring data indicates that freeze-thaw (F-T) cycle and snowmelt infiltration significantly increase the creep deformation of expansive soil slope during spring melting period. Due to the influence of F-T cycle and snowmelt infiltration, more soil grains are involved in the shear deformation contributing to a large, localized shearing. Additionally, the microstructural analysis shows that F-T cycle influence the relationship between expansive soil grains that gradually change from face-face contact to point-face contact or edge-edge contact form. The shallow landslide mechanisms of expansive soil slope are revealed from creep deformation and microstructure characteristics of soils after the F-T cycle and snowmelt infiltration, which can be summarized into two stages, namely, the snowfall accumulation state and snow melt-shallow infiltration stage. These results can serve as a good reference for the prevention of expansive soil slopes in seasonally frozen regions.

Progressive development of soil arching and deformations in two and three-dimensional trapdoor tests

This study conducted Two- and three-dimensional (3D) trapdoor tests using a newly developed trapdoor test device, to investigate the evolution of soil arching and fill deformation with different relative fill densities and fill heights. The test results show that the trapdoor settlements normalized by trapdoor width required for the soil arching ratios to reach minimum and ultimate values increased with fill height. In tests with dense fill, both the minimum and ultimate soil arching ratios were smaller compared to tests with loose fill at the same fill height. Two symmetrical slip surfaces developed from the trapdoor edges, with their inclination angles depended on the dilatation angle of the sand. The proposed Gaussian distribution function with fitting parameters well matched the measured fill settlement profile. In the dense fill tests, the settlement trough width and volume loss induced by trapdoor settlement gradually decreased with fill elevation due to its strong shear dilation behavior. Conversely, the loose fill exhibited weaker shear dilation behavior, resulting in a larger settlement region. The settlement trough width and volume loss ratio, derived from the measured fill deformation, can be used to predict the fill deformation, including the surface settlement.