Mechanical Behavior Of Soil Research Articles

Stress-Strain Behavior of Soft Soil Stabilized with Nickel Slag, Limestone, and Aluminum Hydroxide

Soil stabilization by combining several minerals is a form of material engineering aimed at increasing the bearing capacity of the soil to a higher level. The development of waste-based materials and the utilization of local potential are part of environmentally conscious construction. This study aims to analyses the mechanical behaviour of soil stabilized with several pozzolanic materials derived from nickel processing waste and limestone, which are local materials with very large deposits. ASTM standards were used in this study for both physical and mechanical testing. Unconfined compressive strength (UCS) tests were conducted to compare the mechanical behaviour of stabilized soil with that of natural soil. The test samples used were cylindrical with a diameter of 35 mm and a height of 70 mm. The binding materials consisted of nickel slag, aluminium hydroxide, and limestone, with the amount of each material based on the dry soil weight (γdry). The addition of lime in this study was varied at 2%, 4%, and 6%. The test results generally show that lime variations and curing time affect the increase in unconfined compressive strength (qu), with the highest value of 30.91 kg/cm² observed at 6% lime content after 28 days of curing.

Use of Advanced Constitutive Models for the Mechanical Behavior of Soft Soils With Diatoms From Bogotá (Colombia)

ABSTRACTMost constitutive models did not initially consider special behaviors in some soils with singular characteristics (e.g., soft soils with diatom content). For example, at first, these models did not consider the effect of soil structure and viscosity. However, in the last decades, these variables have been incorporated into several constitutive models to describe the mechanical behavior of the soil in its natural state. Structure and viscosity laws that adequately reproduce the soil behavior had to be developed to include these variables. This paper compares the mechanical behavior of soft soils in Bogotá with different constitutive models. Bogotá’s soft soils are lacustrine deposits with a high content of diatoms in their structure. Natural soil samples with intact structures show a high‐water content, which can be higher than 300%, liquid limits of up to 400%, void ratios higher than five, and friction angles of almost 40°. In addition, the model validations were made through the simulations of triaxial tests in compression and shear paths. Modified Cam Clay (MCC), hypoplastic (HP), and subloading Cam Clay (SCC) were the constitutive models used. Two models are based on an elastoplastic framework, and the third uses a HP framework. Several lessons were learned from the simulations regarding the strengths and weaknesses of the models compared to the tests carried out. Finally, the extensive discussion revolves around determining the most suitable model for simulating the mechanical behavior of soft soils containing diatoms in Bogotá.

Computed Tomography-Driven Analysis of Particle Breakage Using a Coupled FDM-DEM Approach

This study proposes a refined approach for simulating the mechanical behavior of soils under high stress by integrating the Finite Difference Method-Discrete Element Method (FDM-DEM) with in-situ experiment. This novel framework incorporates advanced technologies such as flexible membrane and X-ray computed tomography (CT) to enhance the predictive capabilities of the simulation with physical insight. The FDM-DEM model adeptly simulates irregular particle shapes, capturing their interactions and the dynamics of particle breakage. The use of flexible membrane within the model further enriches this approach by enabling the capture of deformation responses in granular materials during shearing. Moreover, the adoption of CT technology facilitates continuous optimization of the simulation process. Validation through in-situ experiments has confirmed the model's effectiveness. The ability of the model to predict areas of high stress concentration—and their correlation with observed particle breakage patterns—underscores the utility of the enhanced FDM-DEM framework as a robust predictive tool for understanding the behavior of granular materials under shearing.

The Coefficient of Earth Pressure at Rest K0 of Sands up to Very High Stresses

The mechanical behaviour of soils subjected to any stress path in which deviatoric stresses are present is heavily characterised by non-linearity, irreversibility and is strongly dependent on the initial state of stress. The latter, for the majority of geotechnical applications, is normally determined by the at-rest earth pressure coefficient K0, even though this state is valid, strictly speaking, for axisymmetric conditions and for zero-lateral deformations only. Many expressions are available in the literature for the determination of this coefficient for cohesive and granular materials both for normal consolidated and over-consolidated conditions. These relations are available for low to medium stress levels. Results of an extensive experimental investigation on two sands of different mineralogy up to very high stress (120 MPa) are reported in the paper. For reach very high vertical stresses, a special oedometer has been realised. In the loading phase (normal consolidated sands), the coefficient K0n depends on the stress level. It passes from values of about 0.8 to values of about 0.45 in the range of effective vertical stress σ′v = 0.5–4 MPa. Subsequently, K0n is about constant and varies between 0.45 to 0.55 up to very high vertical effective stresses (120 MPa). For the sands employed in the tests, Jaki’s relation did not lead to reliable results at relatively low pressures, while at high pressures, the same relationship seems to lead to reliable predictions if it refers to the constant volume angle of shear strength. For the over-consolidated sands, K0C strongly depends on the OCR, and for very high values of OCR, K0C could be greater than Rankine’s passive coefficient of earth pressure, Kp. This result is due to the very locked structure of the sands caused by the grain crushing, with intergranular contact of sutured and sigmoidal, concavo-convex and inter-penetrating type, that confer to the sand a sort of apparent cohesion and make it similar to weak sandstone.

Undrained shear mechanical behaviors of dense gassy sand

Shallow gas can cause many disasters, and it is reported in many marine engineering constructions. For this, it is imperative to understand the impact of gas on the mechanical behaviors of soil. This study investigated the influence of undrained triaxial compression tests on dense gassy sand commonly encountered in coastal areas. Triaxial tests were performed on specimens with saturations of 100%, 99.8%, 95.9%, and 92.7% under confining pressures of 50 kPa and 200 kPa by a self-developed multi-purpose integrated triaxial apparatus (MITA) for gassy soil. The results are presented in terms of monotonic stress‒strain behavior, volumetric behavior, shear strength, and excess pore water pressure (EPWP). The occurrence of gas bubbles has different effects on loose and dense sands, augmenting the undrained shear strength of loose sand while concurrently diminishing that of dense sand. The deviatoric stress of dense sand increases during shear shrinkage, which is similar to the characteristics of loose sand under the influence of gas bubbles. However, following sand dilation, the effect of gas bubbles on deviatoric stress manifests in an antithetical manner. With elevated gas content, the shear strength of dense sand decreases, accompanied by a deceleration in the development of EPWP and a notable increase in volumetric changes. To this end, a microscopic explanation concerning the deformation and evolution of gas bubbles within sand during the shear process was presented to reveal the macroscopic laws governing the undrained shear attributes of dense gassy sand.

Application of Gum Arabic on the Geotechnical Properties of Subgrade Materials

This study investigates the impact of Gum Arabic on the geotechnical properties of subgrade soil materials, a non-traditional soil stabilization technique. Given the need for sustainable and locally available alternatives in road construction, the study aims to assess how different percentages of Gum Arabic affect the physical and mechanical behavior of soil. The research aims to provide sustainable and locally available alternatives in road construction. Three soil samples were treated with varying percentages of Gum Arabic, (1.5%, 3%, 6% and 12%), and standard geotechnical tests were conducted under both soaked and unsoaked conditions. The results showed that the average natural moisture content of the soils was 7.9%, 2.2%, and 4.6%. The addition of Gum Arabic increased the peak maximum dry density of the soil samples by 8.02%, 1.88, and 7.88%. The maximum unsoaked California Bearing Ratio (CBR) values of soil samples were 32.1%, 81.7%, and 48.7%, respectively. Whereas, maximum soaked CBR values of soils S1, S2 and S3 obtained at 1.5%, 6% and 1.5% additions of gum Arabic were 8.4%, 28.7% and 16.9% respectively. The study recommends using 3% Gum Arabic to improve the CBR property of soil samples. The application of Gum Arabic showed significant improvements in soil behavior under both soaked and unsoaked conditions.

Mechanical Behavior of Soils Polluted by Olive Mill Wastewater – Case Bouladhieb Evaporation Pond Site, Sfax, Tunisia

Mechanical Behavior of Soils Polluted by Olive Mill Wastewater – Case Bouladhieb Evaporation Pond Site, Sfax, Tunisia

The improved cyclic resistance of bio-treated sands with various gradations for liquefaction mitigation: Density increase and/or cementation?

MICP (microbial induced calcium carbonate precipitation) method shows a huge potential in solving geological and geo-environmental engineering problems, such as liquefaction mitigation, soil remediation, erosion control, slope stabilization and dust control., due to its low-carbon, sustainable and undisturbing character. For the liquefaction mitigation, previous studies showed the remarkable enhancement in cyclic behavior of bio-cemented soils. Little attention has been paid to how soil gradation affects the effectiveness of MICP method in enhancing soil properties, which is one of the key factors of soil mechanical behavior. MICP method has been mainly used in fine sands (mostly <1 mm) with narrow gradation and a certain number of particles smaller than 75 μm. As a result, few papers discussed the application of bio-cementation to soils with larger grains. In addition, the respective contributions of density increase and cementation on cyclic resistance enhancement is still not clear. In this study, a fine sand (0.1–1 mm), a coarser sand (1–5 mm), and a mixture of both, were used, featuring a larger mean size (d50 mm) and uniformity coefficient (Cu) than in most previous studies. In this study, cyclic undrained triaxial tests were performed to analyze the liquefaction potential of loose and dense untreated specimens, and initially loose treated specimens. Results show that sand gradation has a great influence on the cyclic behavior and MICP effectiveness. For all the sands, the MICP treatment gives rise to a significant increase in cyclic resistance and mitigates liquefaction. This enhancement is due to the formation of cementitious precipitates in the pores or on the surface of particles, which creates (1) bridges between particles and/or change in grain characteristics (i.e., size, roughness, angularity), and (2) an increase in density. For sands with various gradations, these two effects differ in magnitude: in the coarsest sand, the effect of density increase appears to be predominant whereas, in the finest and medium sands, the formation of bonds seems to play the major part. These results are important to evaluate the possibility of using this method to improve cyclic resistance in various sands, and to compare the treatment effect with other techniques.

Mechanical Behaviour of Soil Treated with Chitosan and Calcium Metasilicate Considering the Fungal Growth

Biopolymers have been widely experimented with as organic stabilizers in the last decade for improving soil properties. However, the high nutritional value of some biopolymers like chitin, carrageenan, casein, and chitosan can also promote microbial growth which can affect the improvement in the strength of biopolymer-stabilized soil. This study investigates the mechanical behaviour of clay treated with chitosan at dosages of 0.5, 1.0, 1.5, and 2.0% at various curing periods of 7 d, 28 d, 56 d, and 90 d and also observes the fungal growth, the conditions favourable to fungal growth, and the effect of an inorganic secondary additive on the mechanical behaviour of treated soil. The study shows that fungal growth is higher with the time and dosage of chitosan. The strength of chitosan-treated samples increased with both dosage and age despite the fungal growth observed on the treated soil, as did the fungal growth. On treating the soil with 2% chitosan, the percentage increase in strength was nearly 14.39%, and on the 56th day, it was phenomenally increased to 1534.39%. In an attempt to control the fungal growth, a secondary additive, calcium metasilicate (calsil), was added to various dosages of chitosan-treated soil (CTS). The secondary additive did not completely stop the fungal growth but certainly controlled fungal growth. Chitosan and calsil are hydrophilic, increasing OMC by 67% and 150% for the high CTS and calsil–chitosan-treated soil (CCTS) doses. Calsil coated the soil particles and prevented closer packing under compaction, reducing MDUW by 7.8% and 18% for CTS and CCTS at maximal dosage. The development of hydrated cementitious products made the soil brittle, causing the post-peak strength of CCTS samples to diminish significantly with age. FTIR spectroscopy showed hydrogen bonding strengthening CTS, while XRD revealed cementitious compounds in CCTS. The strength of the soil treated with chitosan and calsil showed a higher strength than soil treated with only chitosan.

Modelling internal erosion using 2D smoothed particle hydrodynamics (SPH)

This paper presents a stabilised multi-phase smoothed particle hydrodynamics (SPH) model applicable to seepage-induced internal erosion and the resulting deformation in soils. Based on the continuum mixture theory, a new single-layer SPH model in the u-w-p formulation is derived for the mathematical description of the erodible porous material. A new modified constitutive model is formulated to account for the influence of erosion on the mechanical behaviour of soils. Extensions of a first-order consistent boundary condition as well as the diffusion algorithm for hydro-mechanical coupling in SPH are also proposed to accommodate the analysis of erosion-transport process. A novel viscous dissipation term is designed to mitigate the numerical instability commonly encountered in coupled problems. In contrast to existing stabilisation terms in the SPH literature, which operate on both the bulk component and shear component, this new stabilisation term offers the possibility to increase the dissipation of unphysical oscillation due to the shear deformation. The proposed method is validated through a series of benchmark tests. The results demonstrate the effectiveness of the proposed approach in addressing the coupled problem in porous materials involving multi-phase flow, phase interaction/transfer, and large deformation with enhanced accuracy, stability, and robustness.

A simple testing-analysis method to evaluate the mechanical characteristics of soils under cyclic loading

ABSTRACT This study presents a simple, yet robust testing methodology employed for investigating the mechanical behaviour of soils under cyclic loading conditions. Small cylindrical specimens of soil (10.5 mm diameter and 35.0 mm high) were subjected to oscillatory torsional loading in either strain sweep or stress sweep mode using the dynamic shear rheometer. Key mechanical properties, including dynamic shear modulus, phase angle, and energy dissipation capacity, were obtained and used to effectively identify threshold strain levels which differentiated the linear, nonlinear, and damage response of the soil. This study further applied the proposed method to stabilized soils to evaluate the effects of stabilizers on improving soil stiffness, while also considering their potential effects on increasing soil brittleness, which could ultimately lead to reduced resistance to fatigue cracking. The successful development of this testing protocol has the potential to evolve into a specification-type method due to its efficiency, repeatability, sensitivity, and fundamental robustness.

Numerical modeling of LEAP-2022 dynamic centrifuge tests adopting a multi-surface plasticity model

This study presents the numerical results of a series of laboratory and dynamic centrifuge tests conducted by the team at Universidad del Norte, as part of the LEAP-2022 project. The soil's mechanical behavior was simulated using a pressure-dependent multi-surface plasticity constitutive model, which was carefully calibrated based on cyclic soil tests performed on Ottawa F-65 sand. These tests covered a wide range of initial densities, initial effective stresses, and cyclic stress ratios. The comparison between laboratory and numerical element tests revealed that the adopted constitutive model reasonably replicated most features of the material's undrained cyclic response, including liquefaction occurrence and the progressive development of double-amplitude permanent shear strains. The calibrated constitutive model was then used to blindly predict the dynamic behavior of centrifuge experiments composed of a sheet pile-soil system using the OpenSees finite elements software framework; these simulations are referred to as Type-B predictions. The numerical simulation showed that the model provided reasonable representation of soil responses in terms of accelerations and pore water pressure build-up; however, the simulations consistently overpredicted the displacements of the sheet piles. Therefore, based on the centrifuge experimental results, minor adjustments of the material parameters were performed, and the centrifuge tests were re-simulated; these simulations are referred to as Type-C predictions. The comprehensive evaluation exposed both the strengths and weaknesses of the modeling approach for the simulation of liquefiable deposits. Despite the discrepancies in sheet pile displacement, the study instills confidence in the model's applicability to liquefaction-related projects with similar conditions.

Microscopic origins of shape effects on migration and clogging of fines in porous media using coupled CFD-iDEM

The unstable mechanical behavior of soil particles during suffusion, including migration and clogging of fine particles in porous media, is prone to induce seepage catastrophes. Mechanical behavior of migratory fines and porous soils during suffusion is significantly influenced by the particle shape, which remains unclear. In this study, a coupled computational fluid dynamics and the irregular discrete element method (CFD-iDEM) framework is developed to investigate the migration and clogging mechanisms. A series of numerical simulations that consider spheres and irregular particles with different levels of aspect ratio are carried out to elucidate the microscopic origins of shape effects on clogging. Migratory fine particles are discharged from the grain inlet and enter the coarse particle skeleton by imposing a downward seepage flow. The subsequent migration and clogging phenomena and microscopic mechanisms are investigated. The results reveal that irregular particles present varying degrees of ability to develop clogging clusters, and spheres are more prone to traverse deeper into soil skeleton. The proposed CFD-iDEM method is able to reproduce macroscopic phenomena of saturated porous medium as well as to analyze microscopic origins of fluid–particle interactions, which contributes to practical guidance for engineering applications.

Prediction of the Unconfined Compressive Strength of Salinized Frozen Soil Based on Machine Learning

Unconfined compressive strength (UCS) is an important parameter of rock and soil mechanical behavior in foundation engineering design and construction. In this study, salinized frozen soil is selected as the research object, and soil GDS tests, ultrasonic tests, and scanning electron microscopy (SEM) tests are conducted. Based on the classification method of the model parameters, 2 macroscopic parameters, 38 mesoscopic parameters, and 19 microscopic parameters are selected. A machine learning model is used to predict the strength of soil considering the three-level characteristic parameters. Four accuracy evaluation indicators are used to evaluate six machine learning models. The results show that the radial basis function (RBF) has the best UCS predictive performance for both the training and testing stages. In terms of acceptable accuracy and stability loss, through the analysis of the gray correlation and rough set of the three-level parameters, the total amount and proportion of parameters are optimized so that there are 2, 16, and 16 macro, meso, and micro parameters in a sequence, respectively. In the simulation of the aforementioned six machine learning models with the optimized parameters, the RBF still performs optimally. In addition, after parameter optimization, the sensitivity proportion of the third-level parameters is more reasonable. The RBF model with optimized parameters proved to be a more effective method for predicting soil UCS. This study improves the prediction ability of the UCS by classifying and optimizing the model parameters and provides a useful reference for future research on salty soil strength parameters in seasonally frozen regions.

Evaluation of the Mechanical Behavior of Soil Stabilized with Asphalt Emulsion Using Multi-Stage Loading

The objective of this research was to assess the mechanical response (resilient and plastic) of soil stabilized with petroleum asphalt concrete using asphalt emulsion under multi-stage loading. To enhance the adhesion of the asphalt film to the soil grains, the stabilized soil underwent air-drying curing for seven days. Dosage was conducted through the indirect tensile strength test using diametral compression. With the optimum content determined in the dosage (2% emulsion), additions and removals of 0.5% asphalt emulsion from this content were performed. Consequently, three specimens were molded with concentrations of 1.5%, 2%, and 2.5% of slow-setting cationic asphalt emulsion. These specimens were then subjected to drained triaxial tests under multi-stage loading, using 5 different stress pairs, totaling 50,000 cycles. Analyzing the regions defined by the total and permanent deformation curves allowed studying the plastic and elastic response, the proportionality between these regions, and the increase in elastic and plastic regions of the soil and stabilized soil in a single test, providing a more accurate interpretation. Regarding the measured deformations, as the deviator stress was increased with each loading cycle, the stabilized samples exhibited an increase in plastic deformations compared to the natural soil (control). It was also observed a proportional increase in the resilient region, indicating that the addition of asphalt made the soil less rigid but provided cohesion that was absent before stabilization. Doi: 10.28991/CEJ-2024-010-01-02 Full Text: PDF

Numerical sensitivity analysis for stress-strain simulation and flow liquefaction assessment of tailings storage facilities using the NorSand constitutive model

With the advent of critical state Soil Mechanics (CSSM), the void ratio began to be recognized as a key parameter, along with the stress state, which defines the mechanical behavior of soils and other particulate geomaterials by using the state parameter. The state parameter is the difference between the current and critical void ratio so that its definition requires the critical state line (CSL) identification. This work presents numerical calibration results, using the NorSand constitutive model, from three sets of triaxial compression tests selected from the literature. The SIGMA/W module of the Geostudio® System was adopted to perform the simulations of the triaxial compression tests, and the results showed adequate fit between real tests and numerical simulations. The parameters necessary for the modeling with NorSand model, defined from the numerical calibration, were used in a stress-strain evaluation of a hypothetical upstream tailings dam. These simulations allowed the evaluation of the differences in the tailings storage facility (TSF) responses in terms of both deformation behavior and flow liquefaction instability. Flow liquefaction instability is described in the literature as a complete loss in shear strength and the development of excessive strains due to the contractive response of tailings when subjected to low confining stress. The results suggest that the use of the NorSand model is, in general, a good option to reproduce the typical strain-softening behavior of such structures. Furthermore, it was clear the high sensitivity of the constitutive model parameters, drawing attention to the importance of best laboratory practices for carrying out triaxial tests to obtain reliable parameters for NorSand modeling.

Investigation of the microscopic properties of natural structured clay

Conducting quantitative research on the microstructure of soft clay can reveal the essence of its soil mechanical behavior, which is of important practical significance for geological disaster risk assessment and prevention. To quantitatively investigate the microscopic properties of natural structured clay, soft clay soils from various sedimentary environments in the Hangzhou Estuarine Bay area were chosen as the research subject in this study. Subsequently, a comprehensive investigation into the microstructure of clay was conducted, involving X-ray phase analysis and SEM imaging analysis. The results revealed the following: (1) In comparison to the deep clay deposited in fluvial-lacustrine environments, the shallow mucky clay in marine sediments had a higher clay mineral content, accounting for 48%. Illite makes up the majority of it, with minor levels of kaolinite and montmorillonite being present. (2) The shallow mucky clay in the Hangzhou Estuarine Bay area had a typical agglomerate-flocculated structure. In contrast, the deeper clay showed a flocculated structure with less uniform particle sizes, strong stacking randomness, poor directional alignment of soil pores, and tends to form arrangements where edges are adjacent to faces or edges are adjacent to other edges. (3) Compared to the deep clay deposited in fluvial-lacustrine environments, the marine-deposited shallow mucky clay displayed orderly pore arrangements, strong directional alignment, significant pore shape variability, and minimal pore size changes between adjacent pores. The microstructure of soil plays a crucial role in determining the physical, mechanical, and other engineering properties of the soil. This study provides insightful information about the relationship between clay microstructure and geotechnical characteristics in Hangzhou and the surrounding areas.

Evaluating influences of deposition direction and state-dependence on large deformation processes of granular column collapse

This paper examines the impacts of deposition direction and density of granular soils on their large deformation behavior encapsulated by column collapse processes. We combine a critical state-based, anisotropic constitutive model for sand and material point method (MPM). The constitutive model includes state- and fabric-dependent dilatancy and hardening, thus accounting for the effects of density and deposition direction on the mechanical behavior of soils. The MPM model is first validated against experimental results. We then investigate the fundamental connections between local constitutive properties of soils (e.g., friction and dilation) and global column collapse response. Based on these correlations, this work further studies how material density and deposition direction influence collapse behavior, including run-out distance, residual height, and slope angle of the static region. Results indicate that run-out distance is relatively insensitive to initial soil density but can be significantly altered by the deposition direction of soils. Peak run-out distance is observed as the deposition direction is aligned with sliding band formed within the granular column. Moreover, a higher density or a smaller inclination of deposit direction leads to a greater residual height and a steeper slope of the static region. The mechanisms of above effects from soil properties perspectives are discussed.

Modelling of the elastoplastic behaviour of the bio-cemented soils using an extended Modified Cam Clay model

An elastoplastic constitutive model based on the Modified Cam Clay (MCC) model is developed to describe the mechanical behaviour of soils cemented via microbially induced calcite precipitation (MICP). It considers the increase of the elastic stiffness, the change of the yield surface due to MICP cementation and the degradation of calcium carbonate bonds during shearing. Specifically, to capture the typical contraction-dilation transition in MICP soils, the original volumetric hardening rule in the MCC model is modified to a combined deviatoric and volumetric hardening rule. The model could reproduce a series of drained triaxial tests on MICP-treated soils with different calcium carbonate contents. Further, we carry out a parametric study and observe numerical instability in some cases. In combination with an analytical analysis, our numerical modelling has identified the benefits and limitations of using MCC-based models in the simulation of MICP-cemented soils, leading to suggestions for further model development.

Hydro-geomorphological conditions for the classification of terrain susceptibility to shallow translational landslides: a geo-hydro ecological approach

This work is part of the review of methodological procedures for the analysis and classification of terrain susceptibility to shallow translational landslides, following the geohydro ecological approach. The pilot area is located in Nova Friburgo (RJ), specifically in the D’Antas Creek basin (53 km2). At this stage of the work, geomorphological parameters and indices were evaluated, including slope angle, curvature, drainage efficiency index (DEI) and topography position index (TPI), seen as relevant in regulating the hydrological and mechanical behavior of soils. The results obtained were intersected with an inventory of landslide scars (n = 382) referring to the extreme rainfall event in January 2011, which occurred in the highland region, called Região Serrana, of the state of Rio de Janeiro. This intersection allowed an evaluation between these parameters and the slopes rupture. The concentration of landslide area per class subsidized the establishment of weights for each of the adopted classes, based on the AHP method. A readjustment of the slope angle classes was proposed, as well as the inclusion of the standard curvature in the construction of the Hydro-Geomorphological Conditions Map. The results were promising, with a concentration of 88.74% (0.85 km2) of the landslide areas in the class of high erosive potential.