Changes In Slope Stability Research Articles

Characterizing hydro‐geotechnical processes of slopes implemented with bioretention cells

AbstractLow impact development (LID) practices are rarely implemented on slopes due to concerns about their poor hydrological performance and the potential impact on slope stability. Implementing LIDs on slopes, involving alterations to surface topography and subsurface hydrology (specifically, the formation of a groundwater mound), can pose challenges in maintaining slope stability. However, sloping areas often require LIDs for sustainable development. It is imperative to supplement the conventional design standard to address these challenges. Before proposing specific solutions, the impact of LIDs on slope stability should be understood first. This includes quantifying the extent of changes in slope stability before and after LID implementation, as well as identifying the key factors that influence stability. To address these, we developed a numerical model in HYDRUS‐2D to simulate the hydrological and geotechnical processes of slopes implemented with a two‐stepped bioretention cell (BC) system. The numerical model was calibrated and validated using monitoring data from a stepped BC in Cincinnati, Ohio, USA. Simulation scenarios encompassed three generic slope angles (15°, 20°, and 25°) with and without BCs, two initial groundwater table positions and two inflow volumes. The hydrological process was characterized by the evolution of the groundwater mound, and the geotechnical process was quantified using the factor of safety (FoS). Our findings indicated slope cutting and filling was likely to enhance stability with an increase in the FoS of 0.1. However, the formation of groundwater mounds, resulting from exfiltration, led to an approximate 0.1–0.2 reduction in the FoS, depending on the inflow volume. The subsequent groundwater mound evolution had no further impact on stability. Ultimately, the FoS was slightly reduced by around 0–0.1 due to the combined effect of cutting and filling operations and groundwater mounds. It was generally safe to implement LIDs on 15° slopes. For steeper slopes, special design considerations are necessary, such as reducing the drainage area to strike a balance between hydrological performance and slope safety.

Changes in Slope Stability over the Growth and Decay of Japanese Cedar Tree Roots

In Japan, repeated driftwood landslide disasters have become a major issue; thus, studies are required to better understand forest function to implement appropriate forest management and prevent such disasters. We investigated the effect of Japanese cedar tree roots on shallow landslide initiation. To incorporate the effect of roots on the two side-flanks of the shallow landslide, we propose a new slope-stability analysis method in which the sliding block is simplified as a three-prism model. The root reinforcement was approximated by the sum of the root pullout forces over a unit area, incorporating changes in the root strength with the growth of the trees after planting and the decay of the stumps after cutting. The reinforced root strength after the stump-cutting decreased linearly with time, with no strength remaining at 9 years. In contrast, the reinforced root strength of the new plants increased according to a logistic curve with time; thus, the root strength increased only slightly up to 9 years after planting, and the minimum total reinforced root strength was observed at this time. The safety factor of the slopes in a forest basin in Ibaraki Prefecture was calculated using the proposed three-prism method at intervals of 5 years on a 1-metre-resolution digital elevation model. The number of unstable grids peaked at 10 years, and a higher risk of slope instability was observed at 5–15 years. Therefore, implementing forest operations for lowering slope instability during this period should be important to prevent landslide disasters.

Numerical Evaluation of Slope Stability based on Temporal Variation of Hydraulic Conductivity

Slope failure is a common phenomenon all over the world on both man-made and natural slopes. Prolonged rainfall is one of the climatic factors which is largely responsible for slope failure. During heavy and prolonged rainfall, a part of the rainwater infiltrates through the soil and seeps into the slope. The infiltrated water lowers the matric suction and increases the porewater pressure. Eventually, the generated porewater pressure decreases the strength of the soil which results in slope failures. To evaluate the effect of rainwater seepage on slope stability, it is necessary to investigate the hydraulic conductivity of the slope soil. The objective of this study is to evaluate the effect of hydraulic conductivity on slope failure mechanisms. A finite element analysis of slope stability was conducted using Geo-Studio software. A numerical model was developed and calibrated with field monitoring data. The field monitoring data included the observation of hydraulic conductivity using a Guelph Permeameter. Afterward, the temporal variation of rainfall and hydraulic conductivity was incorporated into the SEEP/W program and the consequent changes in slope stability were evaluated in SLOPE/W. From the numerical analysis, with the identical strength parameters of the soil, different factors of safety were observed when the slope sections retain different hydraulic properties. Based on the numerical analysis, it was observed that hydraulic conductivity greater than 4×10-6 cm/s leads to slope failure. Periodic monitoring of hydraulic conductivity in the field may provide deep insight into rainfall-induced slope failures.

Factors affecting thickness and frequency of turbidites triggered by earthquakes in Kumburgaz Basin, Sea of Marmara

Submerged fault ruptures generate earthquake-triggered mass flow deposits, which are extensively used as a tool in subaqueous paleoseismology. In tectonically active deep sedimentary basins, such as the Sea of Marmara (SoM), these mass flow deposits are defined as turbidite-homogenite units (THUs), consisting essentially of a coarse basal part and an overlying homogeneous mud (homogenite). Detailed characterization of THUs is crucial in order to establish meaningful criteria to link these units with earthquakes events and to identify their transport routes and depositional mechanisms. Here, we combine μ-X-ray Fluorescence (μ-XRF), Anisotropy of Magnetic Susceptibility (AMS) and additional rock magnetism analyses of a 21-m long piston core from the Kumburgaz Basin of SoM to define the upper stratigraphic boundary of THUs with hemipelagic sediments and investigate the controls of hydrological changes on turbidite frequency and thickness over the last 15 kyrs BP. The sedimentary succession of this period includes a lower lacustrine and an upper marine unit with two Holocene sapropel intervals. The sequence is interrupted by a total of 70 THUs, characterized by a significant magnetic foliation related to the depositional setting rather than the magnetic signature. Magnetic mineralogy of the coarse basal parts of THUs have more ferromagnetic particles than the overlying homogenites and background sediments. While the homogenite parts have a more constant mineralogy than the basal parts, they do not differ the background sediments.Based on an event-free chronostratigraphic model derived from radiocarbon ages and the published age of lacustrine-marine (L-M) transition, the average THU occurrence intervals in the lacustrine (14.8–12.6 kyrs BP), lower sapropel (11.2–5.7 kyrs BP), upper sapropel (5.4–2.7 kyrs BP) and non-sapropelic part of the marine unit (2.7 kyrs BP-present) are 235 yrs., 287 yrs., 114 yrs. and 160 yrs. respectively. The average thickness of the THUs in the same units are 20.8 cm, 15.7 cm, 6.1 cm and 6.1 cm. The variability of average THU occurrence intervals and THU thicknesses are controlled by the sea level rise and salinity increase following the full marine connection of the SoM at 12.6 kyrs BP, which caused changes in slope stability, sediment composition and sediment deposition in different parts of the basin. Geomechanical properties of the lower sapropel appears to have been important in resulting long THU recurrence intervals and relatively high THU thicknesses.

Coupling action of rainfall and vehicle loads impact on the stability of loess slopes based on the iso-water content layer

To clarify the changes in slope stability of loess slopes under the coupling action of rainfall and vehicle loads. Experiments with different water contents under different environmental conditions were carried out indoors, and the relationship function between water content and shear strength parameters was obtained; Secondly, based on Geostudio, an equivalent layered calculation model of water content-strength parameters of loess slope was established, the variation law of soil sample matrix suction with volumetric water content was measured by volumetric pressure plate tester. Finally, by using a combination of finite element analysis of saturated/unsaturated seepage and limit equilibrium analysis of slope stability, the SLOPE/W module in the modeling software GeoStudio is used to calculate and analyze the effects of vehicle loads, rainfall intensity, rainfall duration, and other working conditions on the stability of loess slopes, respectively. The results show that when the lane is in the middle of the slope, the vehicle load parameters have little effect on the uphill stability, but have a greater impact on the downhill; With the increase in rainfall, the change curves of the slope safety coefficient gradually overlap when the vehicle loads are four-axis,five-axis, and six-axis. This shows that when studying the change of slope safety factor under the dual influence of vehicle loads and rainfall, rainfall is the main cause of slope stability; The change rate of slope safety factor increases gradually with the increase of rainfall, and the change trends of the upper, lower and overall parts of the slope are similar.

Penilaian Tingkat Kestabilan Lereng De ngan Metode Slope Mass Rating (SMR) pada Bench S dan J PT Tanjung Bukit Nunggal Kabupaten Bangka Tengah

Excavation activities on mining activities cause tension changes on the ground that trigger the occurrence of deformation then followed by changes in slope stability. If slope stability is impaired then it will lead to the possibility of an avalanche, this will certainly result in the disruption of mining activities that endanger workers who are on the slope area with potential for avalanches. This study aims to find out parameters of basic RMR and deflection values of basic RMR at bench S and J, find out the values of slope stability using SMR at bench S and J, and cope with slope instability based on SMR values. The methods used in this study are quantitative and qualitative methods namely scanline sampling and rock physical test that is Uniaxial Compressive Strenght (UCS) tests, and Rock Quality Designation (RQD) measurements. The results of this study show that the rock conditions at the bench S and J are still good with RMR values of approximately 71 ± 73, the probability of avalanche occurrence is very low as SMR values range 71 ± 73, but still it needs to be carried out cutting on blocks indicated to ruins.

“Green” operation of a building - an object of cultural heritage

The aim of the study is to determine the further «green» operation of a building - an object of cultural heritage in technogenic conditions that formed in the 20-21 centuries, based on monitoring the actual engineering and geological conditions of the urban historical territory of Voronezh. The study of the engineering-geological conditions of the territory and the structures of the building was carried out in three stages. At the first stage, a reconnaissance survey was carried out to identify surface forms of manifestation of modern engineering and geological processes; at the second stage - examination and monitoring of soil properties of the foundations and the building structures; at the third stage - calculation of slope stability in the Midas GTS NX software package and selection of the optimal slope reinforcement with a retaining wall. Changes in the physical properties of soils and the violation of soil conditions on the slope of the historical territory of Voronezh during technogenic soaking of soils were revealed. Calculation of slope stability in the Midas GTS NX PC revealed the influence of the surrounding modern buildings on the deformation of the building structures -object of cultural heritage. The influence of technogenic changes in slope stability in the process of modern development on the urban historical territory on the «green» ecology, i.e. safe operation of the building - a cultural heritage site.

Evaluation of the stability of vegetated slopes according to layout and temporal changes

Vegetation in slopes can effectively improve slope stability. However, it is difficult to estimate the effects of vegetation on slope stability because of variations in plant species and environmental conditions. Moreover, influences of plant growth on slope stability change with time, resulting in changes in the safety factor. This study was conducted to evaluate the stability of vegetated slopes with time and investigate the effects of different layouts of plant species on slope stability. Here, we used a plant growth model and slope stability analysis to build an evaluation model. To accomplish this, one species of tree, shrub and grass was chosen to set six layout patterns. A slope with no vegetation served as a control. The safety factors of the seven slopes were then calculated using the developed evaluation model and differences in the safety factors of slopes were compared and discussed. The slope vegetated with Platycladus orientalis reached the most stable state at the age of 60 years. Shrub slope (Vitex negundo) had the maximum safety factor after 20 years. Overall, the safety factor of vegetated slopes increased from 12.1% to 49.6% compared to the slope with no vegetation. When wind force was considered, the safety factor value of the slope changed from 3.5% to 43.5%. Vegetation mixtures of trees and grasses resulted in the best slope stability. Planting grasses on slopes can improve slope stability of trees to a greater degree than that of slopes with shrubs in the early stage of growth.

Large‐scale land acquisition as a potential driver of slope instability

AbstractRecently, vast tracts of land have been acquired by foreign and domestic–foreign partnerships to satisfy an increasing demand for agricultural products, often resulting in the conversion of forested landscapes into agricultural fields. Those conversions often occur in areas characterized by high slope angles with the potential to cause mass wasting and shallow landslides. An interesting case‐study is the Licungo basin in Mozambique, where from 2000 nearly 160,000 ha of forest were converted, 17% of which occurred in areas acquired through large‐scale land acquisitions (LSLAs). This study analyses the relationship between deforestation occurring within LSLA areas and the likelihood of landslide occurrence. To this end, we use a spatially distributed physically based model that couples the assessment of slope stability with hillslope‐scale hydrological processes and evaluates the change in slope stability associated with remotely sensed forest loss. Relative to conditions where no human modification of land cover has occurred, we find that LSLAs have the potential to increase the extent of areas susceptible to slope failure by as much as 15,000 ha. We also quantified potential direct and indirect implications of such events for the food supply of local populations, estimating that 4,000 people could lose approximately 700 kcal cap−1 d−1 if all LSLAs are put under production. This study demonstrates the linkages between LSLAs, slope instability, and knock‐on environmental and societal impacts. Governments should therefore take such impacts into account (in addition to those related to habitat destruction and carbon emissions) when issuing permits and concessions within forested lands.

Stability analysis and design charts for over-dip rock slope against bi-planar sliding

Bi-planar sliding is one of the main instabilities in over dip rock slope. The geometry and strength of the bi-planar sliding surface comprised of two sets of cross-discontinuities play an important role in slope stability assessment. However, few studies had been conducted to systematically investigate the influences of them. In this study, three categories of failure modes related to the failure region, namely, the shallow, intermediate and deep, are proposed. Corrected Implicit Transfer Coefficient Method (CITCM) with the modified sliding surface is proposed as an alternative to the Limited Equilibrium Method (LEM) for calculating the slope factor of safety (Fos). The change patterns of slope stability are derived from the Fos values calculated via CITCM considering different scenarios of geometrical and mechanical parameters of the critical bi-planar sliding surface. The equivalent slope model for the overlap rock slope under bi-planar sliding is proposed to explain slope stability change patterns reasonably. The design charts for preliminary slope stability assessment are presented in the over-dip rock against bi-planar sliding. Finally, compared with other traditional Limited Equilibrium (LE) approaches, case history engineering applications validate the proposed design charts in calculating Fos, determining the critical sliding surface, and recognizing the failure mode is more effectively.

Application of Grid-Work Girders of Grouted Oblique Steel Pipe Piles for Reinforcement of Embankments with Slope Deformation Failure

In special situations, the treatment plan for embankment failure is hindered by cracking and sliding failure in highway embankment slopes. For example, the prestressed anchor cable or bolt frame beam is not suitable as the absence of a hard anchorage ground layer, or slip deformation embankment cannot be removed and rebuilt to protect the existing sub-grade. An ideal solution in this situation is to use grid-work girders of oblique steel pipe piles. The grouting of oblique steel pipe piles is a method that uses a composite foundation of steel pipe piles to reinforce slopes. Specifically, grout is embedded into steel pipe piles and passes through the sliding surface. Grouting can change deformable soil into composite soil and protect steel pipes from corrosion. Steel pipe piles serve as reinforcement by applying anti-slide force directly onto the soil. By means of a successful example of slope deformation treatment, this work discusses the scope of the application, the stress characteristics, the changes in slope stability, and the reinforcement effects after slope strengthening. The results would benefit engineering projects involving similar slope failure treatments.

Combining in situ monitoring using seabed instruments and numerical modelling to assess the transient stability of underwater slopes

Abstract The stability of submarine slopes is often characterized using campaign-based geophysical and geotechnical measurements in combination with numerical modelling. However, such one-off measurements do not reflect transient changes in slope stability. In situ monitoring of physical parameters critical for slope stability over periods of months to years can provide crucial information on slope stability and can also be used in an early-warning system for submarine landslides and the possibly resulting tsunamis. We review existing techniques that are capable of monitoring seafloor deformation over long periods of time. Based on numerical models we can identify the magnitude of parameters related to landslide-induced seafloor deformation. Simulations of three different failure scenarios up to the point of failure show that the development of the stress state of a slope and hence stability over time can be captured by measurements of tilt, pressure and strain at the seafloor. We also find that different failure mechanisms induce different deformation signals at the seafloor, in particular tilt. Hence, with a site- and target-specific survey design (or a large pool of instruments), seafloor deformation measurements in combination with numerical modelling can be used to determine the temporal evolution of slope stability as well as to identify underlying failure mechanisms.

Increasing rock-avalanche size and mobility in Glacier Bay National Park and Preserve, Alaska detected from 1984 to 2016 Landsat imagery

In the USA, climate change is expected to have an adverse impact on slope stability in Alaska. However, to date, there has been limited work done in Alaska to assess if changes in slope stability are occurring. To address this issue, we used 30-m Landsat imagery acquired from 1984 to 2016 to establish an inventory of 24 rock avalanches in a 5000-km2 area of Glacier Bay National Park and Preserve in southeast Alaska. A search of available earthquake catalogs revealed that none of the avalanches were triggered by earthquakes. Analyses of rock-avalanche magnitude, mobility, and frequency reveal a cluster of large (areas ranging from 5.5 to 22.2 km2), highly mobile (height/length < 0.3) rock avalanches that occurred from June 2012 through June 2016 (near the end of the 33-year period of record). These rock avalanches began about 2 years after the long-term trend in mean annual maximum air temperature may have exceeded 0 °C. Possibly more important, most of these rock avalanches occurred during a multiple-year period of record-breaking warm winter and spring air temperatures. These observations suggested to us that rock avalanches in the study area may be becoming larger because of rock-permafrost degradation. However, other factors, such as accumulating elastic strain, glacial thinning, and increased precipitation, may also play an important role in preconditioning slopes for failure during periods of warm temperatures.

Microseismic Monitoring and 3D Finite Element Analysis of the Right Bank Slope, Dagangshan Hydropower Station, during Reservoir Impounding

The right bank slope of Dagangshan hydropower station in China has complex geological conditions and is subjected to high in situ stress. Notably, microseismic activities in the right bank slope occurred during reservoir impounding. This paper describes the microseismic monitoring technology, and three-dimensional (3D) finite element analysis is used to explore the microseismic activities and damage mechanisms in the right bank slope during reservoir impounding. Based on data obtained from microseismic monitoring, a progressive microseismic damage model is proposed and implemented for 3D finite element analysis. The safety factor for the right bank slope after reservoir impoundment obtained from the 3D finite element analysis, which included the effects of progressive microseismic damage, was 1.10, indicating that the slope is stable. The microseismic monitoring system is able to capture the slope disturbance during reservoir impounding in real time and is a powerful tool for qualitatively assessing changes in slope stability over time. The proposed progressive microseismic damage model adequately simulates the changes in the slope during the impoundment process and provides a valuable tool for evaluating slope stability.

A method for predicting the factor of safety of an infinite slope based on the depth ratio of the wetting front induced by rainfall infiltration

Abstract. Most landslides in Korea are classified as shallow landslides with an average depth of less than 2 m. These shallow landslides are associated with the advance of a wetting front in the unsaturated soil due to rainfall infiltration, which results in an increase in water content and a reduction in the matric suction in the soil. Therefore, this study presents a modified equation of infinite slope stability analysis based on the concept of the saturation depth ratio to analyze the slope stability change associated with the rainfall on a slope. A rainfall infiltration test in unsaturated soil was performed using a column to develop an understanding of the effect of the saturation depth ratio following rainfall infiltration. The results indicated that the rainfall infiltration velocity due to the increase in rainfall in the soil layer was faster when the rainfall intensity increased. In addition, the rainfall infiltration velocity tends to decrease with increases in the unit weight of soil. The proposed model was applied to assess its feasibility and to develop a regional landslide susceptibility map using a geographic information system (GIS). For that purpose, spatial databases for input parameters were constructed and landslide locations were obtained. In order to validate the proposed approach, the results of the proposed approach were compared with the landslide inventory using a ROC (receiver operating characteristics) graph. In addition, the results of the proposed approach were compared with the previous approach used: a steady-state hydrological model. Consequently, the approach proposed in this study displayed satisfactory performance in classifying landslide susceptibility and showed better performance than the steady-state approach.

Reservoir-landslide hazard assessment based on GIS: A case study in Wanzhou section of the Three Gorges Reservoir

Reservoir-landslide is mainly caused by changes in hydrodynamic conditions of slope interior at the time of water storage or discharge. The current study mainly focuses on the typical reservoirlandslide, but the sudden occurrence of some unknown landslides brought a lot of difficulties for hazards prevention. Therefore, we proposed a method to evaluate the regional scale reservoir-landslide hazard. We took Wanzhou section of Three Gorges Reservoir (China) as the study area and systemically and synthetically carried out the reservoir-landslide hazard evaluation under the condition of water level regulation. Firstly, we made reservoir-landslide susceptibility assessment by using the methods of spatial analysis and statistics based on geological and geomorphological materials and field survey data, and then, analyzed the regional-scale slope stability based on the infinite slope model used to analyze the bank slope stability change under the condition of water fluctuation, finally, developed a reservoir-landslide hazard evaluation model based on the results of susceptibility and stability. The hazard evaluation model was used to predict and evaluate the hazard change under the role of water level regulation. The results showed that the landslide hazard of the whole region decreased during water storage, landslide hazards increased during water discharge. The faster the regulation speed, the greater the slope hazard. The results can provide the basis for hazard management and regional land-use planning.

Infiltration-induced seasonally reactivated instability of a highway embankment near the Eisenhower Tunnel, Colorado, USA

Infiltration-induced landslides are major natural hazards. When they occur along highways they can impede traffic, damage infrastructure, and threaten public safety. This paper presents a case study of an active landslide on an embankment of Interstate-70 west of the Eisenhower Tunnel in central Colorado, USA. Records indicate that the hillslope under I-70 has moved episodically over the previous 40years. In the previous two decades the road surface has been displaced vertically by more than 60cm. The objective of this work is to develop a conceptual model capable of quantifying the seasonally reactivated landslide movement at the site. Inclinometer data of subsurface deformation and geologic and hydrologic mapping are used to develop the conceptual model as well as to constrain a numerical model. A two-dimensional hydro-mechanical numerical model is used to test the conceptual model under three different infiltration rates during the period of snowmelt in the spring. The framework used in the numerical model accounts for the major physical processes driving instability of the slope: time-dependent variably saturated flow, the resultant changes in stress, and induced deformation. When the snowmelt water infiltrates into the slope, the soil water content and the water-table level vary accordingly. These time-dependent variations result in changes in soil matric suction, effective stress, and consequently change in slope stability. The model calculates pore-water pressures, suction stress, and the distribution of effective stress in the embankment slope at different times. Global factors of safety as a function of time are calculated along the predetermined sliding surface using effective stresses calculated with finite elements. The slope stability assessment quantitatively confirms the conceptual model and is consistent with the displacements monitored at the site during the years of 2007–2009. It is shown that annual snowmelt infiltration of 60–100cm of water can reduce the factor of safety by 6%, enough to sustain landslide movement for as long as 8months each year.

Thaw‐Consolidation Effects on the Stability of Alpine Talus Slopes in Permafrost

ABSTRACTThe relative contributions of thaw consolidation and slope‐parallel seepage to the generation of overall porewater pressure and resultant potential changes in slope stability are determined in two case studies of thawing soils. The first study concerns experimental slopes of frozen silt inclined at 12° and 24° that thawed during scaled centrifuge modelling reported by Harris et al. (2008). The second study concerns a natural slope near Pontresina, eastern Swiss Alps, of coarse‐grained talus inclined at 37° and overlying fine‐grained soil that contains the permafrost table. In both cases, seepage parallel to the slope was found to contribute much more to the excess porewater pressures in the thawing soils than did thaw consolidation. This suggests that the effects of thaw consolidation on the stability of alpine talus slopes in mountain permafrost may have only minor significance. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Numerical Model of Antecedent Rainfall Effect on Slope Stability at a Hillslope of Weathered Granitic Soil Formation

Abstract Modeling rainwater infiltration in slopes is vital to the analysis of slope failure induced by heavy rainfall. Although the significance of rainwater infiltration in causing landslides is widely recognized, there have been different conclusions as to the relative roles of antecedent rainfall to slope failure. In this study, a numerical model was developed to estimate the effect of antecedent rainfall on an unsaturated slope, the formation of a saturated zone, and the change in slope stability under weak rainfall and rainstorm event. Results showed that under a rainstorm event, slope failure occurred at comparably similar time although the antecedent rainfall drainage periods prior to the major rainfall were different (i.e., 24-h, 48-h and 96-h). However, under weak rainfall condition, differences of the antecedent rainfall drainage periods have significant effect on development of pore-water pressure. A higher initial soil moisture conditions caused faster increase in pore water pressure and thus decreasing the safety factor of the slope eventually increasing likelihood of slope failure.

Effect of soil water retention model on slope stability analysis

Understanding of the relationship between volumetric water content (q) and soil capillary pressure (ψ), and between unsaturated hydraulic conductivity K and ψ is important in the analysis of rainwater infiltration into soil and its effect to slope stability. These relationships are known as the water retention curve and the hydraulic conductivity function, respectively. Much soil water retention-hydraulic conductivity models have been proposed such as Brooks-Corey (BC), van Genuchten (VG) that were derived based on empirical fitting curve, and Lognormal (LN) distribution model derived based on soil pore radius distribution. In this study, numerical simulations were performed using the three models to estimate the extent of rainwater infiltration into an unsaturated slope; the formation of a saturated zone, and the change in slope stability. Comparisons were made in terms of soil moisture, water movement phenomena in a soil slope, and the slope stability characteristic. The results of the numerical simulation shows that although BC, VG and LN models have different value of initial condition, the outcome of soil moisture content, water movement and slope stability characteristic are very similar during rainstorm event. Key words: Soil hydraulic properties, water retention-hydraulic conductivity mode, slope stability analysis.