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The article presents the results of assessing the compressed thickness criterion for various hypotheses regarding the development of soil creep deformations. Using a simple example, it is shown that the calculations of the settlements development in time, based on the hypothesis that the creep phenomenon is observed only after the end of the filtration consolidation processes (hypothesis A), underestimate the active power of the compressed thickness of soft soils. It is concluded that it is advisable to calculate deformations in accordance with hypothesis B, when the process of creep of the soil skeleton is considered independently, regardless of the filtration consolidation process and its end time.

Despite the prevalence of peat in northern areas of Europe and elsewhere, there are comparatively few case histories of carefully monitored embankments constructed directly on peat. In addition the...

This paper presents a case history of the settlement performance of a railway embankment built on a Prefabricated Vertical Drain (PVD) improved soft alluvial soil of Karakore area, Wollo province, north-east of Ethiopia. The embankment was constructed on Awash - Kombolcha - Haragebaya (AKH) railway project for the purpose of preloading so as to facilitate the consolidation settlement in a short period of time; and it was monitored for more than 750 days. Numerical predictions of Class A and Class C (based on back-calculation procedure) were performed using Plaxis 2D. The soft soil creep (SSC) model was employed for the soft soil layers, while the Mohr-Coulomb (MC) model was used for the drainage and fill layers. The predictions were compared with the field monitoring settlement data. Quite a reasonable agreement was achieved from the finite element modelling of Class C prediction when the prediction was compared with the actual field settlement values. Parametric sensitivity studies were carried out to examine the influence of parameters on the rate and magnitude of settlements. The results of the numerical predictions and parametric studies have been discussed in detail. The soil on the flood plain area of Karakore is found to be very soft to soft alluvial deposit and formed over Tertiary Eocene stiff clay. The variable conditions of the soil formation and deposition highly dictated the deformation and excess pore water pressure behaviour of the soft subsoil sediment. The parametric sensitivity study showed that, following the compression index, the initial void ratio, the hydraulic conductivity, and the OCR highly influenced the settlement responses of PVD-improved soft alluvium soil respectively.

This paper presents a mechanical model for the prediction of short-term and long-term settlement of municipal solid waste in landfills. The load-induced volumetric compression, shear behavior, tensile behavior, and the time-dependent creep compression behavior of the waste are modeled using the soft soil creep model. The compression induced by decomposition of waste is modeled based on the phenomenon of wetting-induced strains observed in compacted fills with expansive soils. The proposed model is validated using benchmark datasets obtained from two long-term laboratory experiments performed on waste samples obtained from a landfill in UK. Two additional numerical simulation cases (CONV—without leachate injection and BIOR—with leachate injection) were examined by application of the proposed mechanical model on a typical full-scale landfill cell geometry to determine the spatial and temporal variation in the short-term and long-term settlement characteristics of waste in the simulated landfill cell. The settlement of waste predicted by the model could capture the key mechanisms of short- and long-term waste settlement in landfills. The leachate injection in BIOR simulation enhanced the rate of depletion of the degradable solids resulting in a significant increase in the waste settlement. For the simulated landfill and waste conditions, the biodegradation-induced settlement contributed to more than 90% of the settlement of the waste in both CONV and BIOR simulations. The distribution of the injected leachate had a considerable influence on the settlement profiles observed within the waste.

A large-scale test bed (LWH=6 m×3 m×2.8 m) instrumented with various sensors is used to examine the effects of rainfall infiltration and evaporation on the deformation and failure of cracked soil slopes, taking the Anhui area along the Yangtze River as a field example. The results indicate that (1) during rainfall, the soil around the shallow shrinkage fissures attains transient saturation, and the attendant decrease of matric suction is the primary cause of the shallow slope failure; (2) slope deformation continues during post-rainfall evaporation; (3) if a period of evaporation is followed by heavy rainfall, soil creep is concentrated near the deepest cracks, and two zones of steep gradients in pore pressure form at the crest and toe of the slope. Finally, a saturated zone forms near each crack base and gradually enlarges, eventually forming a continuous saturated layer that induces the slope instability or failure.

This study summarizes the evaluation of the pile static load test as a tool for the prediction of pile behavior in clayey soils. The pile and soil cases were modeled by three different constitutive models; Mohr-Columb (M-C), Hardening Soil (HS), and Soft Soil Creep (SSC). The static loading test scenarios were also numerically modeled to study the pile behavior. The models were analyzed by using numerical finite elements software (PLAXIS 3D Foundation). A construction site located in Mansoura, Dakahleya Governorate, EGYPT, was selected to perform the field tests. In order to simulate the soil in the numerical models, two borings with depth of 25 m were carried out to investigate the soil properties in the same site where field static pile load tests are performed later. The pile capacity and settlement were calculated theoretically for each case by using both Egyptian Code formula and numerical constitutive models. The load test was simulated twice for each pile. The first simulates the standard static load test while the second simulates the real-life loading. The results showed that the pile behavior obtained by standard static load test was extremely exaggerated. A modified quick static load test method was proposed and verified. Also it has been proved that, the Modified Quick Load Test (MQLT) method can be used as an alternative method to the classical static load test method.

Long-term stability and safety of red mud disposal field is very important for the local residents’ life, which necessitates the knowledge of its creep behavior. Through the improved triaxial creep apparatus, a series of triaxial drained creep tests were conducted. The results indicate that the creep behavior of BRM is significant with confining and deviatoric stresses being critical factors. The soil creep occurs in two stages of transient creep and the steady creep, and a larger deviator stress will lead to a larger creep strain. The main failure mechanism of BRM is plastic shear, accompanied by a significant compression and ductile dilatancy. The Burgers model and the Singh–Mitchell model are used to describe the creep behavior of BRM, and four parameters of these two models are estimated by the nonlinear regression. The deformations predicted by this model are in reasonable agreement with experimental data.

The excessive load from the high embankments of high-filled cut-and-cover tunnels (HFCCTs) threatens the safety and stability of HFCCTs. Relatively low-compacted (RLC) soil can reduce such...

Landslide deformations have predictable rheological properties, but, when using finite element analysis, only the elastoplastic constitutive equation of soil is considered. Soil creep properties are not considered, often rendering inaccurate results. In this paper, the three-dimensional state equation of the extended Burgers model is derived based on the creep test results of slip-surface soil and the Mohr–Coulomb elastoplastic model. This paper uses FLAC3D, a finite-element software platform, for secondary development and to verify the accuracy of the model and program. A strength reduction method that considers rheological properties is proposed. A numerical simulation of rheological properties is conducted on a landslide and compared with conventional viscoelastic constitutive results. It can be found that the landslide displacement calculation is significantly smaller when the rheological properties are not considered. The stability coefficient of the landslide calculated by the strength reduction method, considering the rheological properties, is smaller than the coefficient calculated without considering rheological properties.

Geological records indicate that the hyper-aridity in the Atacama Desert has prevailed since at least the mid-Miocene, with shorter periods of increased humidity punctuating long-term aridity. The 7-m-high accumulation of colluvial sediments at the Salar Grande (21°S/70°W) studied here provides a key palaeoclimate record to understand hillslope dynamics and its relation to humid periods. While 10Be surface exposure ages point to long-term surface stability of the flat upslope surface, a combination of humidity-driven soil creep, overland flow and soil creep related to seismic shaking, caused denudation of the hillslope and accumulation of several metres of colluvium over much shorter timescales during the last 130 ka. A robust chronology for the hillslope sediments has been established by using Infrared Stimulated luminescence (pIR-IR225 protocol) on K-feldspar extracts from nine samples collected within the accumulation. A series of tests has been carried out to confirm the suitability of the method. The estimated ages indicate accelerated sedimentation at 35–80 ka, and 100–130 ka, which are interpreted as periods with more humid climate conditions than present. These findings agree with climate variations in the hyper-arid Atacama indicated by the activity of coastal alluvial fans and river catchments.

Patterns of soil consolidation with significant filtration and viscous resistance to volumetric deformation are considered. Joint models were characterized, issues identified and practical calculations of the consolidation of water-saturated boggy soils were presented. The conceptual contradictions for the viscous-elastic-plastic model were analyzed using the Bingham nonlinear water-saturated body model of the KONSO program and the Plaxis Soft soil creep model. The method of the correct determination of creep and nonlinear viscosity parameters during the compression-consolidation testing was presented.

The paper describes the problem of consolidation of clay soil with spherical tensor and stress deviator, taking into account compressibility of pore fluid and the soil creep. In solving the problem, the differential equation is suggested for compacting cohesive soil filled with linearly compressible groundwater. It is considered that the gas volume in the groundwater does not exceed 10 %. The solution of the differential equation is based on the Fourier transform.For the numerical calculation of creep during compaction of consolidated soil an easy-touse method was used, i.e. testing of soil samples of the same monolith in the compression device, but different height. Knowing the relative vertical deformation of these samples, approximation and extrapolation methods allow to find the relative deformation at the sample height tending to zero. At almost zero sample thickness, deformation depends only on the soil creep, while the pore pressure will no longer play a role.The obtained values of the relative strain are used to select the function of the creep nucleus. It is found that the exponential function optimally describes the process of soil compaction over the entire area: from the beginning of compaction to its termination.Knowing the pressure, the stress in soil and the amount of sediment are found with a triaxial compression, taking into account its instantaneous deformation.

Muddy banks of marsh channels experience soil creep – a viscous-like slow deformation resulting in a net downslope transport. Here we present the first field evidence of soil creep in a mesotidal salt marsh using both pole displacement and high precision measurements of soil deformation taken with a vibrating-wire extensometer over two years. Soil extended 2–4 mm/m/year in the high marsh platform and 20–40 mm/m/year in the low marsh bank. This was equivalent to a soil diffusivity of about 0.2 m2/year, which is much higher than the diffusivity on hillslopes and also matches the high value predicted by long-term marsh evolution models. High precision (±0.03 mm) soil deformation measurements shed light on the dynamics of the creep process. First, the low bank compressed and extended by ~5 mm/m every tidal cycle, suggesting that the diurnal changes in water level play a role in the bank movements. Second, net soil extension took place mostly during fall. Net soil extension preceded the period of ice formation, suggesting that freezing and ice rafting are not a leading cause of soil creep. Net soil extension was likely triggered by an increase in water table during fall, which decreased the effective stress and thus destabilized the bank. This high water table was caused by a combination of an abiotic factor – the increase in atmospheric precipitation – and a biotic factor – the decrease in evapotranspiration triggered by vegetation senescence. This study confirms that creep is a significant process in marsh morphodynamics and that vegetation can reduce mass wasting in marsh channels.

The objective of this study is to examine the mechanism of the long-term settlement induced in shield tunneling. A series of finite element analysis were conducted using PLAXIS 3D on a well document shield tunneling case in Taipei Mass Rapid Transit System. Various simulation were executed assessing the impact of consolidation on long-term settlement using Soft Soil and Hardening Soil with Small-strain models. Simulation to assess the impact of the creep behavior of the soil on the long-term settlement was also executed using the Soft Soil Creep model. The computed surface settlements were compared to the field measurements. It was found from this study that the computed settlement matched the field measurement when creep behavior of the soft soil was considered but if creep was not accounted for, the computed settlement undervalued the field measurements. Finally, a series of parametric study was executed to examine the influence of various parameters on the long-term settlement. The results obtained from the parametric study of shield tunneling in thick clay clearly distinguished that mechanism of long-term settlement in shield tunneling is predominantly due to creep behavior of the soft soil since consolidation constitutes 5% of the total settlement while creep accounts for 80% of the total settlement.

This paper describes the performance of the Moroccan high-speed railway embankment over alluvial soft ground treated with prefabricated vertical drains. For analyzing soil behavior, numerical analyses were performed under 2D finite element Plaxis code. The authors undertook Class-B prediction at first, using two different constitutive models, soft soil and soft soil creep (SSC) models. Class-C prediction was then performed using only SSC. By comparing the predictions with field measurement, it was concluded that the time-dependent model (SSC) produced acceptable results . However, reasonable modification for the SSC model input parameters in Class-C prediction led to obtain accurate matches with field measurements.

Colombo–Katunayake Expressway (CKE) is the second major highway in Sri Lanka connecting the International Airport at Katunayake to Colombo, and this expressway is constructed over soft soils, predominantly peat. A research study was conducted to analyse the stability of two critical sections of the CKE project using finite element method (FEM), limit equilibrium method (LEM) and Matsuo chart. In the FEM, PLAXIS 2D package was used to simulate the behaviour by using four different types of analyses: (1) Mohr–Coulomb (MC) analysis: MC model for all soil layers; (2) MC-SS 1 analysis: soft soil (SS) model for peat and MC model for remaining soil layers; (3) MC-SS 2 analysis: SS model for peat and soft clay layers and MC model for remaining soil layers; and (4) MC-SS-SSC analysis: soft soil creep (SSC) model for peat, SS model for soft clay and MC model for remaining soil layers. Further, LEM analysis was carried out using SLOPE/W and obtained factor of safety (FOS) values were compared with the FEM analysis. In addition, effect of geotextile on the long-term stability was analysed in FEM. Based on the outcome of the FEM analysis, it was noticed that MC-SS 2 model is the best model to predict the actual field condition for soft soil with high overconsolidation ratio values. In addition, FOS values obtained from PLAXIS were in very good agreement with those obtained from SLOPE/W. Incorporation of geotextile improves the stability of the embankment, and the optimum stiffness of the geotextile should be selected for practical applications.

Frost heaving and boiling are the most common road disorders due to the special climatic conditions in a seasonal frozen area. From the perspective of controlling road disorders in seasonally frozen areas and making effective use of industrial waste residue, two kinds of subgrade modified soil—crumb rubber modified fly ash soil (CRFS) and oil shale waste residue modified fly ash soil (OSFS)—were proposed by the research group. The research results proved that the two new subgrade fillers both have excellent engineering characteristics in cold areas, such as high strength and low thermal conductivity, and both have the function of waste utilization, giving them broad application prospects. In road engineering, the instability of slopes and retaining walls and the uneven settlement of the subgrade are closely related to soil creep, which are problems that cannot be ignored in road design and use. As a new material to treat road disorders in seasonally frozen areas, more attention should be paid to the continuous deformation property of modified soil under long-term load. The study on the creep characteristics of the modified soil can provide reliable parameters for the design of the modified soil subgrade and predict the settlement of the subgrade after construction, which is of great significance to the stability of the subgrade. In this paper, an experimental study on the consolidation–creep characteristics of two kinds of subgrade modified soil in a seasonal frozen region was carried out, the relationship between modified soil deformation and time is discussed, and the effects of different moisture contents and compaction degrees on the creep characteristics of modified soil were analyzed. The test results provide parameters for the engineering design of modified soil subgrade and provide data support for the popularization and application of modified soil in seasonally frozen subgrade.

This paper investigates performance of pressed-in piles in saturated clay ground under isolated (SP) condition and pile group (PG) condition via both experimental and numerical methods. In the experiments, static load test (SLT) was conducted on one SP immediately and on another SP and PGs 24 hrs after the installation to investigate the consolidation effect on the pile capacity. The numerical analyses were conducted following the procedure of the model tests using PLAXIS 3D. The constitutive soil model called “soft soil creep model” was employed to describe the soil behaviors with parameters mainly obtained from laboratory element tests. The effect of the pile installation process on the ground stresses is simulated by cylindrical expansion. Both the measured and calculated results indicate that the ground consolidation significantly increases pile capacity, and the simulations results show a good agreement with the experimental results in terms of initial stiffness and pile shaft resistance.

The shape of soil‐mantled hillslopes is typically attributed to erosion rate and the transport efficiency of the various processes that contribute to soil creep. While climate is generally hypothesized to have an important influence on soil creep rates, a lack of uniformity in the measurement of transport efficiency has been an obstacle to evaluating the controls on this important landscape parameter. We addressed this problem by compiling a data set in which the transport efficiency has been calculated using a single method, the analysis of hilltop curvatures using 1‐m LiDAR data, and the erosion rates have also been determined via a single method, in‐situ cosmogenic 10Be concentrations. Moreover, to control for lithology, we chose sites that are only underlain by resistant bedrock. The sites span a range of erosion rates (6 – 922 mm/kyr), mean annual precipitation (39 – 320 cm/yr), and aridity index (0.08 – 1.38). Surprisingly, we find that hilltop curvature varies with the square root of erosion rate, whereas previous studies predict a linear relationship. In addition, we find that the inferred transport coefficient also varies with the square root of erosion rate but is insensitive to climate. We explore various mechanisms that might link the transport coefficient to the erosion rate and conclude that present theory regarding soil‐mantled hillslopes is unable to explain our results and is, therefore, incomplete. Finally, we tentatively suggest that processes occurding in the bedrock (e.g., fracture generation) may play a role in the shape of hillslope profiles at our sites.

This paper presents an interesting case study for a very large ground improvement project in north Egypt using prefabricated vertical drains (PVD) and surcharge. The first 15m of soil at this site is soft silty clay to silty sand over 35m layer of very soft clay. To build a trustable numerical model that can predict the behaviour of the complex situation, a trial area was built, including several types of instrumentations for intensive monitoring of deformations and excess pore water pressures over time. Undisturbed samples were collected all over the soil profile and tested in the lab to determine the soil parameters to be used in the numerical model. An axisymmetric numerical model was built and calibrated using the collected data to predict the soil behaviour and the development of settlements due to the construction works. The analyses were performed using the soft soil model and the soft soil creep model; thus, the numerical investigations allow an evaluation of the long-term effects. The comparisons of the finite element analysis with the measured deformations presented in this paper show a very good match. Moreover, pre and post in situ measurements of standard cone penetration tests with sensors for the measurement of the pore water pressures (CPTu) have been used to calibrate the numerical model. These CPTu tests were used additionally to verify the improvement of the soil shear parameters over the preloading duration. It is shown that a combination of surcharge and vertical drains can be successfully used to improve the soft soil conditions present at the discussed project.

To mitigate the risk of structural failure in coastal engineering caused by soft marine soil creep, this study presents a coupled macroscopic and mesoscopic creep model of soft marine soil to predict long-term deformation behavior of the soil. First, the mesoscopic characteristics of soft marine soil (e.g., pore, particle, and morphological characteristics) under different external pressures were obtained using a scanning electron microscope. Then, both the mesoscopic and macroscopic characteristics of soil were quantified using directional probability entropy and then used as inputs to develop the model. The model predictions agree with the experimental data. In addition, the experimental results indicate linear negative correlations between porosity and pore ratio with stress—the relationships between the fractal dimension of pore distribution and probability entropy of particle orientation under stress are generally nonlinear. Further, results of sensitivity analysis indicate that the probability entropy of particle orientation is one of the most critical parameters governing long-term creep deformation behavior of soft marine soil.

The postconstruction settlement of the bridge approach is usually uneven, which could create a bump in the roadway. Indeed, this is a typical situation at the end of the bridge approach and requires a solution. One of the main causes of postconstruction settlement is the creep of soil. This paper is aimed at generalizing a new design method for controlling highway postconstruction settlement by replacing subgrade with expanded polystyrene (EPS). In the new method, the creep coefficient can be calculated based on the Yin-Graham EVP model. Thus, the relationship between the overloading ratio (OLR) and overconsolidation ratio (OCR) is obtained. The new method involves five steps: (a) determine the creep coefficient based on the relationship between the creep coefficient and over consolidation ratio, (b) divide the ground into a suitable number of sublayers, (c) select groups of different overloading ratios and then calculate the average values of the additional stress and overconsolidation ratio for each sublayer under different OLRs, (d) calculate the postconstruction settlement under different OLRs, and (e) determine the replacement capacity for different sections. This method can be used for quantitative design according to different requirements of postconstruction settlement of foundation. Taking Huzhou Avenue as an example, the case study illustrates the calculation process of the new method in detail.

This chapter first describes the spatial distributions of mass movements, gullies, and tunnels within the Wangjiagou (WJG) watershed; then, the spatial relations between gully development and mass movement, tunnel formation and gully development, and mass movement and tunnel formation are analyzed. Furthermore, the effect of runoff generation from the intergully area on sediment production in the gully area is evaluated. The upper intergully area is dominated by sheet and rill erosions, and the lower gully area is active in mass movement, tunnel erosion, and gully erosion. Runoff generated from the intergully areas not only causes erosion there but also causes significant erosion in the gully area. In the gully area, tunnel formation is closely associated with gully development in the headwater and hillside gullies but is largely absent in the valleyside gullies and ephemeral stream channels. Mass movement is also active in gully development and is dominated by earth falls in headwater gullies, slides and falls in hillside gullies, and soil creeps in ephemeral stream channels. The spatial interactions of erosion processes should be taken into consideration in erosion control and planning in the watershed.

The development of a sports hall in the Unika Soegijapranata Campus in Central Java is constrained by geological conditions. At the time of land preparation, a crack appears on the fence of the sports hall foundation that was predicted as a sign that they have a soil creep. This condition has threatened the implementation of such development. Therefore, it is necessary to know the subsurface conditions, especially the sliding surface location and pattern of the existing cracks in the ground. This information is beneficial to avoid soil creep risk. In order to support the information, both the geological survey and seismic refraction were conducted in this location. According to the survey, it is found that the sliding surface was identified as volcanic breccia with the depth from 5 m up to 20 m. There are many faults found based on the seismic data, and many cracks appear on the surface, which suspected as the creep crown. Some areas of the sports hall are located in the soil creep crown. According to the drilling data and geo-electrical survey, the sliding surface location of the soil creep was identified within volcanic breccia layers. It is recommended to shift the planned location of the sports hall in order to avoid or minimize the soil creep risk.

Mae Moh lignite mine is the largest open-pit mine in Thailand. The current mine operation is with over 250 m depth. The mine has been operated for over 50 years and would have a plan for the further operation of the next 20 years approximately. With a much deeper mine operation, this open-pit mine would be unavoidably to deal with more stress condition complexity of slope stability analysis, in particular for the long-term(time-dependent) stability. The long-term slope stability generally relates to the material “creep behavior” of which the time-dependent effect of a small deformation scale continually takes place under the constant stress condition. The main component of the Mae Moh open-cut slope is “claystone” which can be classified as the soft rock. It has properties in between soil and rock, causing difficulties in setting an appropriate test facility and determining a constitutive model to investigate its creep behavior. This study aimed to investigate the use of the soft soil creep (SSC) model to describe the creep behavior of the Mae Moh claystone based on a series of test results obtained creep tests from an own customized triaxial creep test facility designed to suit with the soft rock-like material. Plaxis 3D, the powerful commercial finite element program, was also used to simulate such creep behavior using the SSC model, one of its build-in constitutive material models. The Mohr-Coulomb (MC) model was also used as a benchmark in the finite element simulation. Results showed the SSC model could better simulate the time-dependent deformation of the Mae Moh claystone than using the MC model. It could be noticed that the SSC model would be an option to describe the creep behavior of the soft rock, using derived inputs based on the soft rock properties as it can be seen from a good agreement between test results and simulation of the slope of this study.

Channel networks increase in complexity as the importance of erosion grows compared to diffusion by soil creep, giving rise to a channelization cascade. In this cascade, smaller channels join to fo...

Processes contributing to soil creep dominate the downslope movement of soil particles in many regions, and climate is generally hypothesized to have an important influence on the efficiency of the...

Agroforestry, as the dominant land use at the volcanic foot slope in Java Island, is prone to landslide due to a combination of rough relief and thick soil layer. However, evaluations of specific vegetation patterns against landslide reactivation due to soil erosion, which relays on the existing slope units and geomorphological processes, are still limited. The research data were collected through aerial photo interpretation by delineating morphological units of old landslides, slope units, and the existing land use. This was followed by field surveys for two consecutive purposes, i.e., (1) verification of aerial photo interpretation and (2) identification and intensity assessment of existing geomorphological processes. The data were tabulated according to slope units, as a basis for tree and crop arrangement in controlling erosion and landslide, by considering economic, social, and ecological functions. The agroforestry would control the landslides reactivation if the tree and crop arrangement was based on the morphological units formed by the previous landslide. The slope units are classified into residual zones at the highest elevations with flat slopes, erosion zones with the steepest slope, and sedimentation zones at the lowest elevations with gentle slopes. Trees and crops at those three units of the former landslide have different functions in controlling processes of rill erosion, gully erosion, and soil creep.

A simple analytical relations are commonly used in engineering practice to calculate ice wall thickness. One of them is Vyalov’s relation that takes into account the features of a real technological process of tubing lining and the inelastic deformation associated with frozen soil creep. An estimation of applicability and margin of safety of this equation is an issue of engineering mechanics. In this paper, we propose a mathematical model for description of ice wall deformation under natural external loading and present the results of the computational experiments in which an optimal thickness for the ice wall is determined. Based on this simulation, we modify the existing analytical relation, which makes it possible to calculate the thickness of an ice wall of unlimited height.

Slope‐stability models predict that steeper hillslopes require smaller hydrological triggers for shallow landslides to occur due to the added downslope pull of gravity, which should result in more frequent landslides and faster erosion. However, field observations indicate that landslide frequency does not consistently increase on steeper hillslopes. Here, we use measurements of 1,096 soil landslides in California and Switzerland, and a compilation of landslide geometries, to show that steeper hillslopes typically have thinner soils and that thin soils inhibit landslides due to enhanced roles of cohesion and boundary stresses. We find that the landscape‐averaged landslide erosion depth peaks near the threshold slope for instability, and it drops to half that value on hillslopes that are just 5° to 10° steeper. We propose that faster rates of soil creep on steeper slopes cause thin and more stable soils, which in turn reduces landslide erosion, despite the added pull of gravity.

The ubiquitous nature of iron oxides in soils makes their study significant from a number of viewpoints. The factors controlling soil magnetic mineral assemblages are essentially the same as for other soil properties, with parent material, climate, organisms, relief and drainage, and time all playing a role. The formation of ferrimagnetic minerals within the upper layers of a soil, even in lithologies devoid of primary ferrimagnetic minerals, is a widely observed phenomenon in temperate zones. Soil creep and soil wash will alter the spatial pattern of topsoil depth and particle size distributions. On a slope where magnetic enhancement is widespread, surface-scanning sensors can be used to produce magnetic toposequences and maps to show zones of erosion and deposition. Sediments derived from soils for which the concentration of secondary minerals is low relative to that of primary minerals, are likely to possess mineral magnetic properties controlled by particle-size variations.

If the bearing capacity of the soil is not sufficient an improvement method has to be considered. In case of soft and cohesive soils the vibroreplacement technique can be used. This paper describes the numerical simulation of a group of encased granular columns under an embankment based on a real life project situated to the north of Hamburg, Germany. The soft soil creep model and the hardening soil model were used to model the behaviour of the soft clay and granular material respectively. The material parameters were determined based on laboratory tests conducted on test samples from the field. The installation effect of columns in numerically modelled based on the cavity expansion method in a 2D axis symmetric model. The results of the installation effect in terms of stress state changes in the soft soil after complete consolidation are then imported to the 3D model involving group of columns. The results of the numerical simulations are validated against field measurement data in form of vertical settlement of the ground at various locations with respect to time and horizontal deformations in the encased columns with depth.

Expanded polystyrene geofoam (EPS) is used as a lightweight fill material in a wide range of geotechnical engineering applications, including, embankments, retaining walls, and buried structures. Under high compressive loads, EPS may experience long-term compression that needs to be taken into consideration during design. This study presents the results of an experimental investigation that has been conducted to evaluate the creep response of two different EPS geofoam materials (EPS15 and EPS22) under uniaxial compression loading. Four identical setups have been designed and built to allow for multiple geofoam samples to be simultaneously tested under different applied pressures. The effect of stress level on the creep strain is investigated. Results showed that, for the two investigated EPS materials, creep strains started to develop when the applied pressure exceeded 50% of the uniaxial compressive strength of the material and became significant at applied pressure of about 70% of the material strength. A three-dimensional numerical model that is capable of capturing the creep response of soft soils is adapted and calibrated using the available experimental data. The suitability of the model to investigate the effect of lateral confinement on the creep deformation of the geofoam samples is also examined. It is concluded that, although soft soil creep models are able to capture the uniaxial creep response of geofoam, it is not suitable to model the effect of lateral confinement, particularly for low density EPS material.

A nonlinear visco-elastic–plastic creep constitutive model is established combined with a Bingham creep model and a Kelvin creep model. Additionally, the soil creep parameters of an undisturbed soil specimen from the Wuxi subway engineering investigation site are determined according to triaxial creep testing using the ordinary least square algorithm. The ground characteristic curves considering the time effect are proposed by combing the creep equation and cavity expansion theory. Finally, the change laws of segment support force and segment deformation as a function of time were investigated through a case study of a section of the Wuxi Subway Line No. 1, and the proposed analytical solution and numerical modeling provide consistent results for tunnel lining pressure.

The Aznalcollar tailings dam failure moved the Spanish authorities to pay attention to tailings deposits. The Almagrera tailings dam holds one of the largest mining waste deposits in Andalucia. The dry closure of this dam has been detailed in this manuscript. Some serious difficulties had to be solved. Firstly, the dam had undergone up to five raisings before the closure operations started, and this process had not been properly documented. Secondly, the reservoir water was contaminated by the toxic tailings placed several metres below and, due to the high acidity of this water, the geotechnical characterization of the tailings deposit has been really challenging. Thirdly, the definition of the model itself has been a complex task due to the consideration of many phases and different hypotheses. In the finite element calculation, a constitutive model of perfect non-associated plasticity has been used for the dam and a soft soil creep model for the tailings. Next, it has been decided to decontaminate a closed mine by placing its abandoned material—Las Vinas fill—on top of the tailings deposit inside the reservoir. This operation generated important settlements on the tailings deposit. These settlements had to be accelerated by placing drainage wells to avoid the cracking of the final cap. The safety factor during the dry closure operations under dynamic loading was insufficient and a compacted rockfill reinforcement had to be laid on the downstream slope of the dam. Very few papers describe a successful dry closure of a tailings dam as is done here.

Significance Soil is apparently solid as it moves downhill at glacial speeds, but can also liquefy from rain or earthquakes. This behavior is actually similar to that of glass, which creeps very slowly at low temperatures but becomes a liquid at higher temperatures. We develop a discrete granular-physics hillslope model, which shows that the similarities between soil and glass are more than skin deep. Despite the geologic and climatic complexity of natural environments, the shapes and erosion rates of hillsides over geologic timescales appear to be governed by generic dynamics characteristic of disordered and amorphous materials., Soil creeps imperceptibly downhill, but also fails catastrophically to create landslides. Despite the importance of these processes as hazards and in sculpting landscapes, there is no agreed-upon model that captures the full range of behavior. Here we examine the granular origins of hillslope soil transport by discrete element method simulations and reanalysis of measurements in natural landscapes. We find creep for slopes below a critical gradient, where average particle velocity (sediment flux) increases exponentially with friction coefficient (gradient). At critical gradient there is a continuous transition to a dense-granular flow rheology. Slow earthflows and landslides thus exhibit glassy dynamics characteristic of a wide range of disordered materials; they are described by a two-phase flux equation that emerges from grain-scale friction alone. This glassy model reproduces topographic profiles of natural hillslopes, showing its promise for predicting hillslope evolution over geologic timescales.

Soil and regolith creep have been analyzed for at least the last 140 years, using many methodological configurations and temporal and spatial scales. The general concept of creeping soil and its mechanism, first proposed by W.M. Davis and G.K. Gilbert at the end of the 19th century, evolved since the 1940s towards theoretical models and precise short- and long-term field measurements. This fruitful epoch continued with results enhanced at the turn of the 20th century by the application of new research methods (e.g. radiometry) and a redefinition of the term soil creep to encompass the sum of stochastic shallow subsurface and near-surface processes causing net downslope movement of soil or regolith. Simultaneously, another possibility of creep detection was noticed in dendrochronology, and since the 1970s, in the formally defined discipline of dendrogeomorphology, indirect evaluations of creep activity were performed based on tree-ring analyses of bent trees. This method found many followers, but was also heavily criticized as imprecise and lacking in evidence of which kind of tree trunk curvature (e.g. “pistol-butt”- like deformation, S-shape curvature) could be ascribed to creep movement. From the beginning, soil creep was associated with the activity of living organisms on hillslopes. However, this aspect of creep studies has never been fully developed, in spite of the solid foundations and directions of potential studies pointed out by Charles Darwin at the end of the 19th century. In this paper we focus on the historical context of soil creep studies, and highlight forest ecosystems as probably the most active environment of biogenic creep, mainly due to tree uprooting and other biomechanical effects of living and dead trees (root channel infilling, tree root mounding etc.) that are a factors in biotransport. In the final sections the position of biogenic creep in the structure of biogeomorphic systems is discussed in relation to such important conceptual frameworks as the biogeomorphic ecosystem, biogeomorphic feedback window and ecosystem engineering. We also describe several hypotheses that should be carefully tested in the future, and propose several research methods that have the ability to further our knowledge about soil creep: radiometry, laser scanning and soil micromorphology.

Creep behavior of loess-like soil is closely related to microstructural changes. The microstructure of loess-like soil collected from the Xi'an area, China, was investigated using triaxial creep tests. Qualitative microstructural observations were made by examining vertical and transverse sections from the undisturbed and tested samples with a polarizing microscope. Quantitative data were acquired by image analysis of SEM images of those sections. The image analysis documented changes in particles and pore structure under different axial stress and confining pressures. The results show that: (1) Undisturbed samples have plank-macrospore cline-cementation structure with the particles distributed randomly. The number and area of four kinds of pores decrease in the decay creep stage. The orientation of particle long-axis gradually aligns (weakly) in the steady creep stage. The samples have a lightly cemented mosaic microporous structure and plastic minerals like illite significantly aligned in a preferred orientation, and rigid quartz and feldspar grains become slightly arranged along the illite preferred direction in accelerated creep stage. The orientation of particles and pores interconnections eventually result in the creep failure of sample. (2) The prefer orientations of pores are most significant in accelerated creep stage, and the pores have insignificant preferred orientation in creep failure stage. (3) Mesopores cover the largest area, and they are the most important factors leading to loess-like soil creep. Undisturbed samples contain the largest number of pores which cover the largest area among all of the samples. As creep progresses, both number and area decrease gradually before accelerated creep stage, and finally the pore area has its largest in creep failure stage. (4) The pores in these samples are relatively oblate in shape with rough outlines in undisturbed samples, and the greater the deviatory stress is, the slender the pores with smoother outlines will be.

Soil creep is characterised by slow displacement, with depths of a few meters and loosely defined limits. Buildings and infrastructure located on slopes affected by such landslides may suffer significant damages if their foundations are poorly dimensioned. The presence of soil creep in urban areas makes it necessary to develop landslide activity maps, derive hazard maps, and implement risk management plans. Even though both geological and geomorphological analyses can provide basic information, it is often necessary to use additional techniques to obtain information about ground displacements. This paper proposes a method to derive a soil creep activity map using a multi-approach analysis based on geological, geomorphological, and persistent scatterer interferometry (PSI) data. PSI is a satellite-based technique to estimate land displacement velocity. The work described in this paper was carried out in the town of El Papiol, in the metropolitan area of Barcelona (Spain). This is an urban area that has been heavily affected by soil creep over the past decades. The results achieved show that PSI data substantially improve the information provided by the geological and geomorphological analyses and make it possible to accurately define the landslide area and estimate its activity.

In order to investigate the mechanism of the long-term settlement of road on the soft soil, an in situ measurement of a highway in southeast China was conducted during both the construction and post-construction stage. In the theoretical analysis, the long-term settlement of the pavement on thick soft soils was divided into three main components: the consolidation settlement, the creep deformation and the traffic load-induced deformation. The equivalent time line model based on the viscous–elastic–plastic theory was adopted to simulate the road settlement caused by the consolidation and creep of the subsoil. A cyclic strain accumulation model, which was obtained from laboratory tests of soil elements, was adopted to consider the road settlement induced by cyclic traffic loadings. A pavement dynamic response model was used to calculate the dynamic stresses in the subsoil generated by moving traffic loads when the road was open to service. It was found that the equivalent time line model combined with the cyclic strain accumulation model could predict the road settlement accurately at both the construction and post-construction stage. Numerical results showed that the traffic speed had limited effect on the post-construction road settlements for the speed range considered. The post-construction settlement of the road, mainly composed of the traffic-induced settlement and soil creep deformation, could be reduced significantly by increasing the embankment surcharge during the construction stage. The creep component accounted for over 10% of the total post-construction settlement, while the percentage of the creep deformation in total post-construction settlement decreased rapidly as the embankment surcharge increased.

A 3 m high embankment with prefabricated vertical drains was constructed over Ballina clay. It has been thoroughly instrumented for monitoring over three years after construction. Based on the data available at the site, the authors undertook Class A predictions of embankment performance using two approaches: a simple 1D consolidation analysis and a sophisticated large strain finite element analysis (FEA) using Soft Soil Creep (SSC) model. Class C predictions were then conducted using the SSC model in FEA, with and without large strain. It is demonstrated that the SSC model can give satisfactory results when large strain FEA was used.

The performance of a trial embankment on soft ground treated with wick drains has been predicted, in terms of total surface settlement, lateral movement, and dissipation of excess pore pressure. The settlement performance was predicted on the basis of hand calculations, carried out in a spreadsheet, using the classical radial consolidation equations of Barron and Hansbo. This was followed up with numerical analysis using 2-D finite element code in PLAXIS 2D2016, employing their soft soil creep model. Analyses were carried out on a single cell, for comparison with the hand calculations, using both axisymmetric and plane strain models. An analysis was also carried out in plane strain for a section through the whole embankment. This was used to predict the lateral movements and also the dissipation of excess pore pressures at selected points, for comparison with measured data from instruments. After the results of monitoring the trial embankment were published, the numerical model has been modified and shows excellent agreement with the measured data. A description of the modelling is provided, as well as details showing the limited way in which the model has been modified.

The paper describes the Class A prediction and Class C back-calculations of the Ballina test embankment using the finite element program Plaxis and the Soft Soil Creep Model (SSCM). The prediction underestimated the measured settlement 3 years after construction by about 20%. This was mainly due to too high stiffness in the transition zone beneath the clay and that SSCM underestimated the shear deformation of the clay. Furthermore, the horizontal permeability of the clay was overestimated. In the back-calculation, it was possible to obtain a excellent match with the measured settlements by reasonable modifications of the input parameters.

A test embankment was established on the soft Ballina clay and practising engineers and academics were invited to make predictions of the behaviour of the embankment. Comprehensive geotechnical investigations were performed and the testing data were provided to the predictors. This paper presents Class A and Class C predictions made by the authors for the embankment. In Class A prediction, the soft clay was modelled as a single homogeneous layer. The Class A prediction showed good agreement with measurements for settlement, but not for pore pressure and lateral ground movement. Class C prediction divided the soft clay into two layers based on the information of ground investigation, and achieved better predictions for settlement, pore pressure and lateral movement. Finite element analysis using Plaxis 2D was carried out for the prediction, and Soft Soil Creep model was used for the soft clay. Consolidation parameters were assessed by statistical analysis of the oedometer test data. Sensitivity studies were performed to investigate the influence of parameters on the analysis results. Results of the predictions and sensitivity studies are discussed in the paper.

The paper summarises key results of a class A prediction obtained from 2D and 3D finite element analyses performed for the Embankment Prediction Symposium 2016. In addition class C predictions are included and the changes in input parameters for the finite element model are discussed. Although different constitutive models have been employed in the class A prediction where short term displacements, i.e. after embankment construction, have been considered in addition to long term consolidation and creep settlements only long term displacements are dealt with in this paper. Thus, only results obtained with the Soft Soil Creep model implemented in the finite element code Plaxis are presented. Input parameters have been chosen based on laboratory and in situ experiments and verified by back calculation of undrained triaxial tests and CRS tests. 3D FEA have been carried out confirming that a 2D representation is sufficient for this problem.

The long-term consolidation settlement of soft soils under infrastructures is seriously concerned in coastal areas. In practice, soft soil ground is usually composed of multiple layers with different properties, and the effect of soil creep is nonnegligible. However, in conventional consolidation analysis, creep is seldom included during the “primary” consolidation. With conventional creep model, creep strain will reach infinity with time, which is unreasonable in the long-term view. In this study, a new simplified method based on Hypothesis B is presented to calculate both short-term and long-term consolidation settlements of multi-layered soils exhibiting non-linear creep. There are three main characteristics for this new simplified method: (a) the consolidation analysis for multi-layered soil is conducted using spectral method; (b) a nonlinear creep function with creep limit is incorporated to calculate both short-term and long-term creep settlements; (c) the “primary” consolidation and creep are calculated independently and combined with an empirical parameter α together with the consolidation degree U for correcting the creep settlement. Finite element analysis with a self-developed Elastic Visco-Plastic (EVP) constitutive model considering creep limit was also carried out. Verifications by field cases and finite element simulation demonstrate the efficiency and accuracy of the new simplified method in calculating the long-term settlements of soft soil ground under varied engineering conditions. Influences of major parameters selection in the calculation of the new simplified method are also discussed.

Glaciation and deglaciation modify the stress of the slopes affected by these processes and can trigger their instability and landslides. This study describes, characterizes and reconstructs a large rotational landslide of soil and moraine material, which occurred on February 10, 2013 on the western slope of Upsala Channel, North Branch of Argentino Lake, in Southern Patagonia. With this aim a qualitative analysis of the slope condition before and after the date of the landslide occurrence, the possible conditioning and triggering factors, and the destructive consequences of the related tsunami that affected the margins of the lake was carried out. To reconstruct the state of the slope before and after the event, techniques of photo-interpretation of optical satellite imagery, digital elevation models, historical photographs, in situ observations, bathymetric data and stories of the park rangers of Los Glaciares National Park were used. The retreat of the Upsala Glacier has caused the relaxation of the slopes of the channel conditioning its stability. Among the conditioning and triggering factors that favored the process of activation and generation of the landslide event, are the presence of unconsolidated moraine material covering the channel slopes, steep slopes exposed to the east, which increases its exposure to the sun and melting of snow accumulated during the winter, and the existence of soil creep processes. Although the specific triggering factor is unknown, sediment saturation by surface runoff and water infiltration, eventually a severe rain event, foot slope erosion by glacial activity, and local and regional seismic activity can be mentioned as potential triggering factors. The slope showed evidences of instability for more than 20 years prior to the generation of the landslide, and there is currently evidence that the slope may undergo.

The time-dependent soil creep behavior affects the strength and deformation of the shear zone in landslides. Limited studies have been carried out on the undisturbed soil samples from the deep shear zone due to the difficulties in obtaining them. This problem is investigated using a case study of the well-known Huangtupo landslide, which is the largest landslide in the Three Gorges Reservoir area of China. The creep properties of the undisturbed shear zone were studied using triaxial creep testing. Two creep stages (the primary stage and the attenuation secondary creep stage) were observed, which were characterized by a creep rate that approached zero, instantaneous deformation and the development with a constant speed. The long-term shear strength of the shear zone was calculated based on the test results. The creep stages and long-term shear strength are significantly different from those of direct creep tests of reconstituted shear zones due to the influence of the confining pressure and coarse particles. The Computerized Tomography (CT) scanning technique was also applied, and the results showed clear rotation of some coarse particles in the middle parts of the samples, which was reflected by their shapes. The changes in particle position were more significant at the bottom of the sample. Based on these results, an empirical constitutive model was proposed to describe the relations among stress, strain and time, and this model fits the experimental data well. The inhomogeneity of the undisturbed soil samples leads to different creep properties from those in ideal theoretical models; therefore, new stochastic constitutive models should be explored and developed for further studies.