Friction Angle Research Articles

Pullout behaviour of strip plate anchors in clay overlying sand

Plate anchors are being increasingly employed to establish mooring systems for offshore floating facilities owing to their notable efficiency and cost-effectiveness. The majority of prior studies have concentrated on plate anchors, examining the vertical to horizontal orientations, particularly when embedded in single layer clay or sand. However, it is common to encounter multiple layers of soil with varying characteristics in practical engineering, leading to inaccurate estimation of pullout capacity when based solely on the properties of a single soil layer. This paper reports pullout behaviours of strip plate anchors in clay overlying sand by adopting two dimensional finite element analysis. To simulate the hardening and subsequent softening behaviour of medium to dense sand, a modified Mohr-Coulomb model is considered. The current Finite Element (FE) results are in good agreement when compared with both previous FE simulations and physical model test data. Then, the soil flow mechanisms (e.g. the accumulated plastic shear strain, the friction angle) surrounding the anchor during pullout out are revealed. Based on a series of FE results, a calculation framework considering the effect of thickness of clay layer is designed to predict the pullout behaviour of plate anchors in clay overlying sand.

Influence of Xanthan Gum-Based Soil Conditioners on the Geotechnical Properties of Soils

The impact of climate change has become increasingly severe in forests, where droughts and strong winds on the one hand and extreme rainfall events on the other hand can damage forest ecosystems. To mitigate the effects of drought and enhance soil water retention capacity, three types of soil conditioners (SCs), labeled SC_R, SC_CG, and SC_ZZC, were developed as part of the European project ONEforest. All the conditioners are based on Xanthan gum and have different types and amounts of fillers with diverse cellulose fiber lengths. These can offer the potential to optimize the SC characteristics, e.g., water absorption, water retention, and mechanical stability. This paper focuses on the influence of fillers in the SCs on the geotechnical properties of forest soils from Ljubelj in the Alpine part of Slovenia (S1), Catalonia, northeastern Spain (S2), and Heldburg, Germany (S3). The results show an increase of 53% to 100% in the water absorption of treated soil. A less favorable impact of the SCs was found on the drained shear strength and the compressibility. The drained shear strength of untreated forest soils in a saturated state was S1 c′ = 4.4 kPa, φ′ = 33.5°; S2 c′ = 1.4 kPa, φ′ = 30.0°; and S3 c′ = 12 kPa, φ′ = 28.0°. The addition of SCs results in a reduction in the drained shear strength of saturated mixtures. The reduction depends on the dosage of added SC—whether it is a low (L) or a high (H) dosage. For instance, when the soil S1 was treated with a low dosage of the soil conditioner SC_R, it demonstrated a cohesion (c′) of 11 kPa and a friction angle (φ′) of 27.0°. However, increasing the dosage of the SC_R led to a decrease in both the cohesion and the friction angle for the same soil (c′ = 7.7 kPa, φ′ = 25.0°). Additionally, the type of soil conditioner also impacts the drained shear strength. Among the mixtures with a high dosage of the SC_R, SC_CG, or SC_ZZC, those containing the SC_CG with the longest fibers stand out, demonstrating the highest friction angle. Therefore, longer fibers can be a promising component of the SCs to reduce the negative influence of XG on the mechanical properties of treated soils.

Optimizing properties of clayey soil using lime and waste marble powder: a sustainable approach for engineering applications

Several studies have explored the potential of waste marble powder (WMP) and lime (LM) as solutions for issues associated with clayey soils. While WMP enhances mechanical properties and addresses environmental concerns, LM effectively improves soil characteristics. This research investigates the efficacy of LM and WMP, both individually and in combination, in addressing challenges specific to clayey soils in Bouzaroura El Bouni, Algeria. These soils typically exhibit low load-bearing capacity, poor permeability, and erosion susceptibility. LM demonstrates promise in enhancing soil properties, while WMP not only addresses environmental concerns but also enhances mechanical characteristics, providing a dual benefit. The study utilizes a three-variable experiment employing Response Surface Methodology (RSM) Box-Behnken Design, with variations in clay content (88%–100%), LM treatment (1.5%–9%), and WMP inclusion (1.5%–9%). Statistical analysis, including ANOVA, reveals significant patterns with p-values <5%. Functional relationships between input variables (clay, LM, and WMP) and output variables (cohesion, friction angle, and unconfined compressive strength) are expressed through high determination coefficients (R2 = 99.84%, 77.83%, and 96.78%, respectively). Numerical optimization identifies optimal mixtures with desirability close to one (0.899–0.908), indicating successful achievement of the objective with 88% clay content, 3% LM, and 6% WMP. This study provides valuable insights into optimizing clay soil behavior for environmental sustainability and engineering applications, emphasizing the potential of LM and WMP as strategic additives.

A comparison between geomembrane-sand tests and machine learning predictions

The interaction between soils and geosynthetics plays an important role in the applications of these materials for reinforcement in geotechnical engineering. The complexities of soil-geosynthetic interactions vary depending on the type and properties of both the geosynthetic and the soil. This paper introduces a machine learning approach, specifically a random forest algorithm, for predicting interface friction angles. The dataset comprises 495 interfaces involving geomembranes and sand, with fourteen influencing parameters recorded for each interface, influencing the shear strength outcome. In the analysis, Pearson's correlation coefficient is employed to measure the linear interdependence between each pair of input-input and input-output variables. Following the linear regression analysis, an optimized random forest is utilized to project the interface friction angle. The random forest algorithm divides the selected data into training and testing sets, and only 3% of the training set and 6% of the testing set exceed ±5° from the actual records. The coefficient of determination (R2) indicates strong agreement between the predicted and laboratory study friction angles, with R2 = 0.93 for the training set and R2 = 0.92 for the testing set. Consequently, the random forest algorithm demonstrates effectiveness in predicting interface friction angles.

A Calculation Method for Reliability Index of a Deep–Bedded Karst Tunnel Construction with Cavity Located Ahead of Tunnel Working Face

For the purpose of reliability quantitative assessment of the surrounding rock of the deeply embedded karst tunnel and the geological body around the cavern in the case of the cavern in the forepart of the tunnel face, on the basis of the upper bound limit analysis method, the energy dissipation theory, as well as the reliability theory, the dimensionless performance function of each damage area of the deeply buried karst tunnels could be established in the case of the cavern in the front of the tunnel face. Subsequently, the probability of failure and the reliability index of each damage region of the deep–bedded karst tunnel in the case of the cavern in the front of this tunnel face should be calculated through the Monte Carlo simulation sampling approach. The investigation has demonstrated that the larger the cohesion of the geotechnical body and the larger the internal friction angle within the geotechnical body, the larger the reliability indexes of the geotechnical bodies around the tunnel. The larger the diameter of the cavern and the larger the tunnel burial depth, the greater the probability of failure in the left part of the geotechnical body around this cavern, and the smaller the reliability indexes of these damage areas.

A numerical investigation into the equivalent parameters of a compressible soil treated by stone columns

A series of triaxial test simulations are adopted to estimate the equivalent strength parameters for compressible soil samples reinforced with stone columns. The simulations utilize the finite difference code, Fast Lagrangian Analysis of Continua in three dimensions FLAC3D. An elasto-plastic model is applied to utilize a Mohr-Coulomb yield criterion. The equivalent strength parameters are estimated using newly proposed formulas for geo-composite materials. The researchers compare the obtained results to the analytical formulas proposed in the literature. Additionally, the equivalent parameters are used in equivalent area models. This study investigates the effect of the replacement area ratio. This study offers two applications. Firstly, it evaluates the safety factor of embankments constructed on compressible soil improved with stone columns. Secondly, it estimates the bearing capacity of strip footings on compressible soil treated with stone columns. In all applications, both individual column and equivalent area models are considered. The proposed equations for the equivalent elastic parameters (E, ν) and the mechanical properties, equivalent cohesion, and internal frictional angle (c and φ) give results that agree with the solutions reported in the existing literature.

The effect of preparation of biocemented sand sample on its strength measured using direct shear tests

Urea, calcium, and urease are the primary components of enzyme-induced calcium carbonate precipitation (EICP) method. The composition of these ingredients significantly effects the content and strength of the precipitate. The objective of this study is to investigate the optimum dosage of urea-calcium chloride and urease enzyme from test tube experiments, on the calcium carbonate precipitate when used with sand. The results of samples prepared using two different methods are compared using direct shear tests to note the effect of biocementation on the strength of the cemented sand. Bench-scale conductivity tests show that large urea-calcium chloride concentrations in combination with adequate urease activity improves the precipitate efficiency. The method of treatment also affects the strength of the treated sand, with the injection method being more efficient in cementing the sand particles compared to the mix-and-compact approach. While both the sample preparation methods resulted in the increase in peak friction angle and cohesion intercept, concentration of urea-calcium chloride higher than 0.75 mol/L and urease activity more than 30 kU/L reduced the overall shear strength. The shear behaviour of the precipitate seemed to be influenced by its morphology, which was different for different chemical concentrations and urease activities. Stress dilatancy relations were determined for EICP treated sands and appear to follow Taylor's work-hypothesis relationship.

Improvement of Geotechnical Properties of Clayey Soil Using Biopolymer and Ferrochromium Slag Additives

The geotechnical properties of clay soil and its mixtures with different proportions (0.75%, 0.85%, 1%, and 1.15%) of Agar Gum biopolymer and Ferrochromium Slag (0.25%, 0.50%, 0.75%, and 1%), having various curing times and freeze-thaw cycles, were studied through a series of soil mechanical tests to investigate possibilities to improve its undesired/problematic plasticity, compaction, and shear strength characteristics. The results revealed that treatment with an optimal ratio of 1% Agar Gum and 1% Ferrochromium Slag alone, as well as together with, improved the geotechnical properties of the clay soil considerably. Both the unconfined and shear strength properties, along with the cohesion and internal friction angle, increased as much as 47 to 173%, depending on the curing time. The higher the curing time, the higher the shear strength, cohesion, and internal friction angle are up to 21 days. Deteriorating the soil structure and/or fabric, freeze-thaw cycles, however, seem to have an adverse effect on the strength. The higher the freeze-thaw cycle, the lower the shear strength, cohesion, and internal friction angle. Also, some improvements in the plasticity and compaction properties were determined, and environmental concerns regarding Ferrochromium Slag usage have been addressed.

Analytical Method for the Deformation-Based Design of Retaining Walls in Asymmetric Excavation

Conventional methods for designing retaining structures are not applicable to asymmetric excavation or deformation-based designs. This study proposes a quadruple-line displacement-dependent earth pressure coefficient model. Based on the proposed model, an analytical solution was developed to facilitate the deformation-based design of the asymmetric length of retaining walls propped at the crest. Furthermore, the effects of the soil internal friction angle, strut stiffness, excavation asymmetry level, and deformation control value on the embedment ratio (Re) of retaining walls were investigated. The results showed that Re determined by the classical equivalent-beam method is unsafe due to its basis on the ultimate-state earth pressure theory. The Re value of the shallower side exhibited greater sensitivity to asymmetric excavation than that of the deeper side. The retaining structure’s required Re decreased with an increase in the excavation asymmetry level. The required Re on either side of the retaining structure decreased as the deformation control values increased. The controlled deformation had a more obvious effect on the Re value of the retaining structure on the deeper side. The proposed method can be used for the deformation-based design of asymmetric wall lengths of retaining structures propped at the crest, considering the different excavation depths on both sides.

EFFECT OF MOISTURE CONTENT ON SOME SELECTED MECHANICAL PROPERTIES OF FARO 44 AND 57 VARIETY OF RICE (PADDY AND DEHUSKED)

The mechanical properties of rice are among the most important parameters for designing and development of a rice milling machine, destoning machine as well as materials handling. The objective of the study was to determine the mechanical (angle of sliding and internal frictions) properties of (FARO 44 and FARO 57) paddy and dehusked at three different moisture content (5, 10 and 15%) moisture content dry basis. These properties were determined using Funnel and Baker technique and shear box apparatus respectively. The results showed that, angles of internal friction were at least 15.2°, on the average within the moisture ranges tested however, 35° angles were also obtained. Angles of sliding friction ranged between 40° - 50°. This study concludes that moisture content and variety affect the engineering property; angle of internal friction is useful in the determination of lateral and horizontal stress in the silo for grain storage.

Effect of Strain Hardening on Burr Control in Drilling of Austenitic Stainless Steel

Austenitic stainless steel has been widely used in various industries, such as aerospace, medical, and hydrogen energy, due to its high strength over a wide range of temperatures, corrosion resistance, and biocompatibility. However, stainless steel is a difficult-to-cut metal because its ductility and low thermal conductivity induce a strain hardening with significant plastic deformation at high temperatures. Burr formed at the back side of a plate is a critical issue which deteriorates the surface quality, especially in drilling. Burr removal operation, therefore, should be done in the machine shop. This study discusses the effect of strain hardening of austenitic stainless steel, SUS 316L, on burr formation. Hardness and cutting tests were conducted to compare the strain hardening effect for three types of workpieces: as-received, pre-machined, and tensile treated specimens. In the employed specimens, the tensile treated specimen is harder than the as-received specimen. Those specimens have uniform hardness in the depth direction from surfaces. Pre-machined specimen, in which the back side of the plate was finished by face milling, has a distribution of hardness in the depth direction from a surface. The highest hardness appears in the subsurface of the pre-machined specimen. The cutting forces in the steady processes, in which the entire edges remove material, were nearly the same as the tested specimens each other. However, remarkable differences were confirmed in the chip thickness and burr formation. The higher strain hardening of the tensile treated specimen is effective to suppress burr formation. The cutting characteristics are then identified to associate burr control with the shear plane model of orthogonal cutting using an energy-based force model. The shear stresses, shear angles, and friction angles of the tensile treated and as-received specimens are compared to discuss the effect of strain hardening on reduction of burr formation.

Ground Tire Rubber as a Sustainable Additive: Transforming Desert Sand Behavior

AbstractManaging waste tires presents a significant challenge globally, particularly in regions experiencing high temperatures and shortage of landfill sites. This issue is affecting countries like Kuwait, where the abundance of waste tires is a major source of environmental and safety risks, particularly during the intensely hot summer months. This extreme heat has sparked numerous fires, leading to substantial air pollution due to thick black smoke. Given the limited disposal options, recycling waste tires and finding practical applications for ground tire rubber (GTR) is essential. To address the challenge, a comprehensive laboratory testing program was conducted, using locally produced rubber aggregates as an additive to Kuwait's local surface sands. Two new variables were examined namely the size and gradation of the GTR, and the density of the compacted mixes. For this purpose, two different sizes of rubber aggregates, fine and coarse produced locally, were utilized, and the impact of relative compaction on the strength and compressibility of the mixtures was investigated by testing samples compacted to the maximum density and to 95% of the maximum density. The results suggest that combining local surface sands with rubber tire additives results in a lighter, more permeable, and compressible material, contributing significantly to sustainable waste management. With 20% rubber additive the maximum dry density decreased by nearly 20%, and the permeability increased by 1.74–3.11 times and the compression index increased by 6.15 and 3.8 times with fine and coarse rubber respectively. The angle of friction remained unchanged at 36° with the addition of coarse rubber and decreased by 3°–4° with fine rubber. The change in behavior although not an increase in the strength and stiffness, offers a range of suitable practical applications in civil engineering and environmental management, including use as a drainage layer, embankment construction on soft ground, earth fill around retaining walls, an additive in asphalt mixes, and in manufacturing compressible tiles for sports facilities.

An alternative method for predicting internal friction angle of rock materials

The shear strength properties of rock materials, cohesion and internal friction angle, are determined by carrying out tri-axial strength test on cylindrical core specimens in laboratory. But determination of these parameters by triaxial tests in accordance with standards and suggested methods, particularly for weak, fractured and weathered rocks is exteremely difficult and/or impossible due to difficulties related to preparation of test specimens suitable for this test. In addition, the tri-axial test requires high cost equipment and too much time for sample preparation and testing. In such cases, there is a need to precisely estimate the friction angle and estimation of rock shear strength properties using some indirect methods, as they are economical and easy to carry out. In this study, the traditional method, which is recommended to be used for the prediction of internal friction angle (ϕ) when triaxial test data is not available, was briefly assessed with its some limitations and an alternative method using theoretical tensile strength and uniaxial compressive strength to predict ϕ was proposed. Then the prediction performances of traditional and proposed methods were compared using a very large data set collected from published literature. The statistical reliability of the derived equations was assessed using F- and t-tests and according to the test results the prediction equations were found to be statistically reliable. The results indicated that the method proposed in this study using the theoretical tensile strength yields best predictions of ϕ when compared to those estimated from the traditional methods based on direct and Brazilian tensile strength values.

Challenges in the Measurement of Cross-shore Geotechnical Characteristics of Sandy Beach Surface Sediments

Geotechnical properties of surficial beach sediments affect beach erosion and shoreline changes. This study sets out to measure relative density, moisture content, friction angle, and shear strength of sandy beach surface sediments from dune to swash zone towards the goal of assessing their importance in sandy beach morphodynamics. Methods of sediment sampling, a conductivity based moisture probe, field penetrometers, and a field vane shear were deployed to collect data at the sandy Atlantic-side beach in Duck, North Carolina. The tools used were assessed based on their operability in the beach environment and data quality, and results are discussed in the context of beach morphodynamics. A digital field vane shear provided an efficient and direct method of measuring shear strength, but the difficulty of computing stresses on the failure plane, which is necessary to validate the results, ultimately reduced the usability of this instrument. The results from three penetrometers were compared to a partially-saturated bearing capacity model, where a portable free-fall penetrometer yielded the best fit. However, a modified velocity-dependent strain rate correction factor () was required to convert dynamic sediment resistance to a quasi-static resistance for the partially saturated sands. A small-scale digital push in penetrometer also achieved a positive correlation when compared to moisture content, but the small tip diameter (5 mm) coupled with the grain size at the beach (0.35 mm) raised concerns about the ability to derive an accurate measure of strength. It was determined that estimating strength parameter using a partially saturated bearing capacity model was appropriate for water contents less than 25% by volume, or anywhere in the crosshore above the swash to the dune. Relative density and moisture content were found to be closely linked, with partial saturation resulting in samples that featured negative relative densities up to .

Clothing Comfort Sensing System based on Triboelectric and Tribological Behavior of Fabrics

Static electricity accumulated on fabrics often causes discharged discomfort, fire, explosion, and cardiovascular diseases. Meanwhile, the electricity can be harvested and used for self-powered wearable devices. Therefore, it is essential to regulate fabric triboelectricity through studying the relationship between friction coefficients and triboelectric charges. In this paper, a reciprocating tribometer coupled with triboelectric testing instruments is designed to collect in-situ tribological and triboelectric properties for laterally sliding fabric based triboelectric nanogenerators (F-TENGs). In this case, the regulation factors involve motion conditions (including load, frequency, friction angle, etc.), surface components and environments. The results show that faster sliding speed and lower humidity produce higher triboelectric outputs of F-TENGs. Especially, amino groups modified silk shows an extremely strong electron-donating ability and achieves a high triboelectric current of 382.2nA when paired with polyimide, which is enhanced by 1.67 times compared with silk. Most importantly, the friction coefficient values of F-TENGs show almost the same trend as the triboelectric outputs. Based on this, a sensing system for monitoring comfort level of fabrics is successfully designed through rubbing tested fabrics and observing indicator lamps. This work proposes a tribological approach with valuable insights of the underlying mechanism of triboelectric charging and extended applications.

Evaluating the sensitivity of direct shear testing of soils for rheological characterization of masonry mortars

The present work evaluated the applicability of the direct shear test of soils (ASTM D 3080) as an alternative for the rheological characterization of masonry mortars. The sensitivity analysis of the method for mortars was carried out by varying the particle size distribution of the sand and the water/dry material ratio, generating twelve different mixtures. In addition to a basic characterization, the shear test results were compared with those of the squeeze-flow test (ABNT NBR15839). For squeeze-flow, 24 tests were carried out with two speeds (0.1 and 3mm/s), and for direct shear, 48 tests were carried out with 4 normal stresses (13.5, 25, 50, and 100 KPa). It is concluded that the direct shear test, using cohesion and friction angle parameters, demonstrated the ability to adequately characterize the complex behavior of plastic mortars and the sensitivity to variations in the mixture. A linear correlation was found between the friction angle (shear test) and the consistency index (flow table), with R2 = 0,87. Furthermore, for high plasticity mortars, was found a non-linear correlation between compression flow (squeeze flow) and cohesion (direct shear test), with R2 = 0,67.

Utjecaj tipova tla i geomembrana na ponašanje sučelja i posmičnu čvrstoću

The interface shear behaviour between the geomembranes and soils was studied. Sand/bentonite (80/20), crushed sand, river sand, crushed gravel, and river gravel were used in this study. Polyvinyl chlorides were cured in the 0.5 molar saltwater and high-density polyethylene was cured in municipal solid waste leachate for eight months. Direct shear experiments were performed using cured GMs. This study recommends the use of crushed gravel in projects that use polyvinyl chloride and high-density polyethylene. The interface friction angles, which were exposed to the effects of saltwater and municipal solid waste leachate, decreased even after eight months, and this reduction effect should be considered in future projects. When designing projects involving GMs exposed to MSW leachate, particularly in landfills, potential damage over time should be considered, and appropriate design parameters should be selected. Failure to do so can lead to disasters that cause the loss of life and property.

DEM investigation on sandy soil behaviors under the influence of particle shape

The mechanical properties of sandy soil, a prevalent material in engineering construction, are affected by several factors, including the particle shape. This study utilized a rigid block unit for particle simulation and established specimens reflecting the real particle appearance based on μCT scanning geometry. Four simple particle types with varying roundness were designed according to the roundness definition, and corresponding numerical test models were developed. These models were employed to examine the effect of particle roundness on the macroscopic mechanical properties of sandy soil using triaxial shearing simulation tests, disregarding other shape parameters. The results demonstrate that particle roundness significantly affects the mechanical properties of sandy soil. Within a roundness range of [0,1], samples with varying particle roundness displayed different deviatoric stress–strain curves. As the roundness increases, the peak deviatoric stress decreases, and both the cohesive strength and friction angle of the samples reduce.

Shear rate dependency on flowing granular biomass material

The commercialization of bioenergy has been significantly limited by various material handling issues due to the poor flowability of granular biomass materials. Addressing these issues demands a fundamental understanding of flow physics and robust models to predict the multi-regime flow behavior of biomass particles. In this study, we investigated the multi-regime flow behavior of loblolly pine chips, a widely used bioenergy feedstock, through combined experiments and simulations. A quasi-static hypoplastic model and a cross-regime Drucker–Prager (DP)-μ(I) model were utilized and validated against inclined plane flow experiments to understand the quasi-static and dense flow behavior of milled pine chips. The results show that along the inclined plane, loblolly pine chips mainly present in heap flow (varying thickness along the plane), and in plane flow (iso-thickness along the plane) only when the inclination closes to the material’s critical state internal friction angle. The results also show that the multi-regime DP-μ(I) model predicts a completely different velocity profile from the hypoplastic model. DP-μ(I) model can capture the flow behavior of pine chips in both flow regimes well but at the cost of extra parameter determination, and the shear-rate dependent rheology model can successfully capture the flow of elongated high-frictional particles. These findings advance the scientific understanding of the multi-regime flow behavior of granular biomass materials and shed light on formulating novel constitutive models to assist granular biomass handling in the bioenergy industry.

Influences of strain rate on mechanical behaviors of unsaturated and quasi-saturated loess under varying drainage conditions

Although time-dependent deformation of geomaterials underpins slope-failure prediction models, the influence of strain rate on shearing strength and deformation behavior of loess remains unclear. The consolidated undrained (CU) and drained (CD) triaxial testing elucidated the impact of strain rate (0.005-0.3 mm/min) on strength envelopes, deformation moduli, pore pressures, and dilatancy characteristics of unsaturated and quasi-saturated loess. Under drained conditions with a controlled matric suction of 50 kPa, increasing strain rates from 0.005 mm/min to 0.011 mm/min induced decreases in failure deviatoric stress (qf), initial deformation modulus (Ei), and cohesion (c), while friction angles remained unaffected. Specimens displayed initial contractive volumetric strains transitioning to dilation across varying confining pressures. Higher rates diminished contractive volumetric strains and drainage volumes, indicating reduced densification and strength in the shear zone. Under undrained conditions, both unsaturated and quasi-saturated (pore pressure coefficient B=0.75) loess exhibited deteriorating mechanical properties with increasing rates from 0.03 mm/min to 0.3 mm/min. For unsaturated loess, reduced contractive volumetric strains at higher rates manifested relatively looser structures in the pre-peak stress phase. The strength decrement in quasi-saturated loess arose from elevated excess porewater pressures diminishing effective stresses. Negative porewater pressures emerged in quasi-saturated loess at lower confining pressures and strain rates. Compared to previous studies, the qf and Ei exhibited rate sensitivity below threshold values before attaining minima with marginal subsequent influence. The underlying mechanism mirrors the transition from creep to accelerated deformation phase of landslides.