GeoStudio Software Research Articles

The influence of rainfall patterns on factor of safety for clayey soil slopes

The persistent trend of rising temperatures and shifting weather patterns caused by climate change has prompted significant concern around the world. This research aims to evaluate the instability of slopes in Almaty, Kazakhstan, under various rainfall patterns, groundwater tables, and slope geometries by incorporating the principles of unsaturated soil mechanics. However, there have been a limited number of studies incorporating the principle of unsaturated soil mechanics with constant rainfall patterns in Central Asia, particularly in Kazakhstan, on the impact of rainfall-causing landslides. Hence, in this research, GeoStudio software (SEEP/W and SLOPE/W) was used to simulate the factor of safety (FoS) and pore water pressure for the investigated slopes under different rainfall patterns. Results from Hyprop and statistical method show that the saturated volumetric water content is 0.502, whereas the residual one is 0.147 and for the permeability function the conductivity coefficient started to sharply decrease at the suction value of 2 kPa when the air-entry value was 24 kPa. Findings from numerical analysis show the change in FoS for the slope of 10 m height and 27-degree slope angle was 6%, 7%, 7%, and 8% for cyclic, delayed, advanced, and normal distributions, respectively. For the slope with 20 m height and the same 27-degree angle, the change in FoS was 8%, 10%, 8%, and 11% for the cyclic, delayed, advanced, and normal distributions, respectively. These same patterns were shown in slopes with 35-degree and 45-degree angles, having the same 10 m and 20 m heights. Comparatively, this shows that slopes under cyclic rainfall patterns (240 mm of rain within 12 days) are less prone to failure compared to slopes under continuous, delayed, or regularly distributed rainfall patterns. Moreover, an increase in slope height and angle also affect the FoS negatively. It should be noted that the results obtained are only applicable to clayey-loam soil.

Sensitivity analysis of slope stability based on eXtreme gradient boosting and SHapley Additive exPlanations: An exploratory study

Slope instability through can cause catastrophic consequences, so slope stability analysis has been a key topic in the field of geotechnical engineering. Traditional analysis methods have shortcomings such as high operational difficulty and time-consuming, for this reason many researchers have carried out slope stability analysis based on AI. However, the current relevant studies only judged the importance of each factor and did not specifically quantify the correlation between factors and slope stability. For this purpose, this paper carried out a sensitivity analysis based on the XGBoost and SHAP. The sensitivity analysis results of SHAP were also validated using GeoStudio software. The selected influence factors included slope height (H), slope angle (β), unit weight (γ), cohesion (c), angle of internal friction (φ) and pore water pressure coefficient (ru). The results showed that c and γ were the most and least important influential parameters, respectively. GeoStudio simulation results showed a negative correlation between γ, β, H, ru and slope stability, while a positive correlation between c, φ and slope stability. However, for real data, SHAP misjudged the correlation between γ and slope stability. Because current AI lacked common sense knowledge and, leading SHAP unable to effectively explain the real mechanism of slope instability. For this reason, this paper overcame this challenge based on the priori data-driven approach. The method provided more reliable and accurate interpretation of the results than a real sample, especially with limited or low-quality data. In addition, the results of this method showed that the critical values of c, φ, β, H, and ru in slope destabilization are 18 Kpa, 28°, 32°, 30 m, and 0.28, respectively. These results were closer to GeoStudio simulations than real samples.

Quick Estimation of Seepage Discharge and Water Level Height Out Of the Central Core in the Zoned Earth-fill Dam

This paper relates to the investigation of the amount of seepage discharge and the water level height out of the central core in the zoned earth-fill dam using the finite element procedure by Geo Studio-SEEP/W software. The investigation models were carried out in two shapes of the central core, the rectangular and the wedge shapes, by 200 miscellaneous models. For each model, seepage discharge and height of water level out were determined. Investigation results were examined using the artificial neural network technique (ANN) to demonstrate the influence weight of each independent variable (geometry and characteristics) on the output-dependent variables results using the statistical software SPSS. Core material hydraulic conductivity had the highest impact on seepage discharge and water level height while dam upstream slope had the least impact on them. Two statistical empirical equations were developed using multiple nonlinear regression for both the seepage discharge and the height of water level out using the SPSS software. The recommended equations were also verified by comparing their results with the results of 25% of the models analyzed by Geo Studio software. They showed great agreement that the correlation coefficient (r2) was 97.3% for the seepage discharge equation and 96.6% for the height of the water level-out equation.

Landslide Mitigation at The Bagong Dam Abutment, Trenggalek District

Landslides occurred continuously from July 2022 until July 2023, disrupting the construction of the Bagong Dam abutment. Geologically, the foundation of the Bagong Dam consists of a fairly thick colluvial layer, which is prone to landslides. So, the analysis of landslide mitigation at the Bagong Dam abutment is needed. The slope stability analysis carried out by Fellenius and Bishop method, then the slope modeling was carried out using Geostudio software. The analysis results on the existing slopes produced a safety factor of 0.987 (1.07) for the Fellenius method and 1.042 (1.07) for the Bishop method. These safety factors indicate that the existing slope is unstable and slope failure is likely to occur. In the first alternative countermeasure analysis, the slope safety factors for the cross-section of the dam at STA 0+625 were 1.715 for upstream and 1.338 for downstream; at STA 0+641, 1.321 upstream and 1.306 downstream; and for the longitudinal section of the dam, 1.525. All these safety factors greater than 1.25, indicating that the slope is stable. In the second alternative countermeasure, the slope safety factors obtained for the cross-section of STA 0+641 were 1.362 for upstream and 1.386 for downstream, and 1.657 for the longitudinal section. These safety factors are also greater than 1.25, which indicates the slope is in stable condition. The additional cost for implementing the first alternative countermeasure is 73.9 million, while for the second alternative is 35.7 million. So that, the second alternative countermeasure is the best choice by the multi-criteria decision-making analysis results.

Advancing landslide early warning systems through saturation monitoring and prediction

Landslides most commonly occur in the rainy season, resulting in damage to infrastructure and human lives. An early prediction framework for landslides would clearly help to mitigate damage. In this work, a prediction framework for shallow landslide initiation was developed and validated with a real case study. To assess the reliability of the prediction framework, back-analysis of a landslide that occurred in Malin village, Maharashtra, India on July 2014 was performed. Relations of landslide stability with soil saturation were established through a physically based approach using GeoStudio software. A leaky barrel algorithm was developed for the study location to monitor the effect of rainfall' on soil saturation. Simulation results of landslide stability were compared with the rainfall–soil saturation algorithm based on the leaky barrel. The presented framework was found to have good predictability of shallow landslide occurrence and is therefore recommended for real-time monitoring of landslide-prone locations.

Study on the Stability of Cut Slopes Caused by Rural Housing Construction in Red Bed Areas: A Case Study of Wanyuan City, China

The red beds that are widely distributed in hilly areas in eastern Sichuan Province are inevitable rock and soil masses in engineering construction. In order to obtain a larger building area, engineering slope cutting is quite common in red bed hilly areas. Engineering slope cutting destroys the inherent stability of a slope and causes geological disasters. In order to practice the concept of sustainable development and explore ways to develop and utilize land resources reasonably and reduce the possibility of geological disasters caused by engineering slope cutting, this paper took the slope cutting sites caused by rural housing construction in the red bed area of Wanyuan City as research objects. The internal and external factors affecting the stability of the cut slopes were summarized through a field investigation, and two typical slopes were selected for analysis. Sampling and indoor tests were conducted to obtain the geotechnical parameters. Geo Studio software (2018 R2) was employed to establish numerical models, simulate the stress and strain distributions, and compute stability coefficients under different slope cutting conditions at the same time. Based on field investigations and numerical simulations, the three main failure modes of shallow landslides caused by slope cutting were summarized, and the evolution process of slope landform accelerated by slope cutting activities was deduced. In an engineering application, the functional relationship between the cutting height and the stability coefficient was fitted. It was found that the critical cut height values of soil slope were 6.3 m, 6.2 m, 5.2 m, and 2.6 m at slope of 10°, 20°, 30° and 40°, respectively; the critical cut height values of rock–soil mixed slope were 9.3 m, 6.5 m, 5.9 m, and 2.2 m at slope of 10°, 20°, 30° and 40°, respectively. The research findings can be used to prevent and manage the hazards caused by slope cutting in this study area.

Optimasi Geometri Lereng dengan Evaluasi Nilai Faktor Keamanan Menggunakan Software Geostudio

The slopes of the Widas watershed in Kutorejo Village, Bagor District, Nganjuk Regency were hit by a landslide, damaging a 50-meter-long road. This damage has an impact on the activities and mobility of residents. The impact of landslides caused enormous losses, both infrastructure damage and loss of life. Several studies have been carried out, in determining slope stability it is necessary to observe at the research location and determine the type of soil, soil consistency, and soil shear strength parameters. This research aims to determine the value of the safety factor (FK) on the slopes of the Widas River. This research began by conducting a case study, including interviews, collecting field survey data, taking soil samples, and laboratory testing. Slope stability analysis was carried out using Geostudio software. The research results show that the soil type is classified as Poorly Graded Sand (SP), and the soil consistency is classified as Non-Plastic soil with a liquid limit of 26.093 and a shear angle of 20° - 30°. Slope improvements were carried out by changing the slope geometry until a slope ratio of 1V:2H was obtained by creating two slope core models. The FK value increased from 1.007 to 1.107 and 1.437 to 1.585 under pore water pressure conditions. Thus, the slope modeling obtained can be used to overcome landslide problems.

SEEPAGE ANALYSIS ON THE EMBANKMENT BODY ZONAL TYPE DAM IN BAGONG EAST JAVA INDONESIA

Dam construction is one form of water resource utilization in Indonesia. In addition to its potential functions and benefits, dams in Indonesia also pose significant risks. Therefore, detailed planning for dam construction is essential. The Bagong Dam has a zonal embankment type with a vertical core. This type of dam has larger pores or voids compared to concrete/asphalt dams. Consequently, a detailed seepage calculation is necessary to avoid adverse events. Water seepage can be addressed by analyzing it using the Geo-Studio software, which can identify the depression line, as well as the velocity and discharge of seepage through the dam body. The analysis includes conditions such as Normal Water Surface (NWS), Flood Water Surface (FWS), Rapid Drawdown, and Dead Storage. The analysis will produce seepage patterns (depression lines), seepage discharge, and seepage velocity. The calculated seepage discharge in Geo-Studio is 5.82 x 10-3 m3/s, compared to the manually calculated seepage discharge of 5.98 x 10-3 m3/s, resulting in a negligible difference of 2.672%, with a discharge difference of 0.00016 m3/s. The highest critical velocity occurs in rip-rap material and embankments at a height of 4.04 x 10-1 in the NWS modelling. The critical diameter limit for the most critical (smallest) material to be carried away is found in clay material with a critical diameter of 5.61.10-14 cm. The safety factor for suffusion symptoms indicates the most critical value in NWS modelling, with a value of 4.51. The seepage discharge is still within safe limits since the calculated discharge through the dam body is 0.062 m3/s less than the permitted discharge.

The influence of drain pipe location and diameter on seepage through an earth dam

Earth dams are built for various reasons these including storage of water, regulation of water flow, prevention of flooding, and the generation of hydroelectric power. The drain pipes within an earth dam, are considered one of the more important control devices used to reduce the effects of problems caused by seepage. As such, the role of drain pipes against seepage problems in an earth dam, has been studied numerically in this investigation. The effects of drain pipe location and their diameters (50, 75, 100, and 150 mm), were examined using different hydraulic heads. The analysis focuses on the characteristics of relative seepage flow, exit gradient, and factor of safety regarding sliding. A range of models of typical earth dams, with and without drain pipes, have been simulated using Geo-Studio software in SEEP/W and SLOPE/W applications, examining more than 200 different cases. By using the data computed from numerical models, new formulas for predicting the seepage parameters and factors of safety were developed in this study by using the multiple non-linear regression (NLR) approaches. The findings show that the presence of a drain pipe reduces seepage flow and the exit gradient, at the same time increasing the factor of safety. Regarding pipe diameter, the rate of seepage and exit gradient decreased while the factor of safety increased as the diameter of the pipe increased. The factor of safety increased by between 11 and 25% when the drain pipe was placed in an optimal position, allowing for a reduction in seepage flow and exit gradient.

Study on rainfall infiltration characteristic parameters of unsaturated soil

The study of the rainfall infiltration mechanism of unsaturated soil has always been a hot issue in the field of geotechnical engineering. It is worth studying which parameters should be introduced to characterize the infiltration characteristics of unsaturated soil in the calculation and analysis of rainfall infiltration. In this paper, the Fredlund–Xing model was quoted in the SEEP/W module of the Geostudio software, and the transient numerical calculation of rainfall infiltration under the same rainfall duration T and different rainfall intensity I was carried out for a soil column. Three infiltration characteristic parameters were introduced: rainfall infiltration front depth WF, suction reduction depth MRn, and section infiltration rate IR. The variation of these three parameters and rainfall intensity I during rainfall were sorted out and analyzed; it is indicated that WF increases with the extension of rainfall duration. MRn decreases with the increase of suction reduction rate n%, and when the rainfall duration is 24 h, the maximum depth of the soil column affected by rainfall is approximately 35% of the total depth. IR is mainly affected by the rainfall intensity I and the saturation permeability coefficient ks. There is a limit value for the influence of I on WF, MRn, and IR, and the limit rainfall intensity under the calculation conditions in this paper is I = 2.5ks.

Deformation triggers and stability evolution of landslide from multiple observations

External causes like changes in reservoir level and intense rainfall can cause reservoir landslides. Exploring the factors that govern landslide deformation and analyzing its stability evolution is essential in mitigating the associated risks. The Sanzhouxi landslide, which has experienced ongoing movements and has been implemented a professional monitoring system, is chosen for analysis in this paper. A combination of geological survey and analysis of monitoring data is utilized to explore landslide deformation characteristics. A data mining method, grey relation analysis (GRA), is subsequently performed to determine the causes of landslide deformation. Furthermore, the stability of the Sanzhouxi landslide in response to reservoir level fluctuation and rainfall for each day over an entire year is assessed using the Morgenstern-Price (MP) approach in 2D GeoStudio software. Such a process illustrates clearly how the landslide stability alters with external triggers changing. The findings reveal that the landslide deforms variably in spatial and temporal. The reservoir level rising contributes to landslide deformation primarily, while rainfall has a secondary impact. The factor of safety (FS) of the Sanzhouxi landslide drops from 1.17 to 1.07 during high reservoir water level periods and remain the same or increase in other periods except for some transitory moments while decreasing only by about 2% under the effect of rainfall. The daily FS results validate the dominant influence of reservoir level fluctuation on the stability of the landslide. The comprehensive understanding of landslide movement based on deformation characteristics, triggering factor identification, and daily stability validation, contributes to realizing nearly real-time prediction and evaluating the risk due to slope movements in similar geological settings worldwide.

Seepage Quantity Analysis Beneath Concrete Dams with Various Sheet Piles using Different Numerical Models

Seepage is a dangerous phenomenon under hydraulic structures and the main cause of failure and damage to dams when neglected and not processed. This study evaluates the numerical effects of the sheet piles' quantity, depth, and spacing beneath a concrete dam with isotropic and homogenous foundations on the seepage rate, pressure head, and exit gradient. The solutions were obtained using SEEP/W code in GeoStudio software 2018 for three configurations using single, double, and triple sheet piles. In addition, SLIDE software 6.02 was examined using single and double sheet piles. Dimensional analysis was applied to draw the dimensionless variables that affect the seepage rate and exit gradient, and all tests were repeated for three different sheet pile depths and distances from the heel of the dam. The findings showed that the seepage rate in all studied configurations reduced when sheet pile depth increased. The position of the sheet pile from the dam's toe significantly decreased the seepage rate in cases using single and double sheet piles, while in cases using three-sheet piles, the position of the middle sheet pile insignificant decreased seepage. It was recognized that when using a single sheet pile, the drop in pressure head increased with depths when the sheet pile was located at the heel and middle of the dam. In addition, in the case of a single sheet pile at the toe or using two and three-sheet piles, the pressure drop decreased as the depths increased. Also, the results showed that the middle sheet pile location in the case of three sheet piles slightly affected pressure reduction. Furthermore, the results showed that using two and three-sheet piles was more effective than using a single one in reducing the exit gradient, while the position of the middle one in the case of using three-sheet piles was insignificant. A nonlinear empirical equation was developed using SPSS 22 program, and the comparison of the seepage rate measured by SEEP/W and SLIDE software versus its quantity calculated from empirical equations showed a good agreement as the determinations (R2) coefficients were equal to 0.9779 and 0.9928, respectively.

Assessment of Slope Stability by the Fellenius Slice Method: Analytical and numerical approach

Slope stability is a topic of great importance in civil engineering, as slope failures can cause considerable damage to infrastructure and downstream properties. In this study, we applied the Fellenius slice method, using both the analytical method, as well as the numerical method, which was performed using the SLOPE/W module of the Geostudio software. The results obtained by both methods showed that the increase in soil cohesion improves the stability of the slope. The safety coefficients obtained by the analytical method vary between 0.534 and 1.086, while those obtained by the numerical method vary between 0.539 and 1.096, for cohesion values ranging from 4 kPa to 20 kPa. The safety coefficients obtained by the analytical and numerical methods follow straight lines of equation y=0.0344x+0.4092 and y=0.0345x+0.4169, respectively. The results of the analytical method show that a safety factor of 1.5 is achieved at a value of 32 kPa for the cohesion, while the numerical method shows a safety factor of 1.5 achieved at a value of 32 kPa for the cohesion. The difference between the two cohesions is explained by the smaller number of slices used in the analytical method. Nevertheless, the equation from the analytical method can be used as a general guide to evaluate the evolution of the safety coefficient of a slope with surcharge under long-term behavior with incremental cohesion, but this does not exclude verification by dedicated software based on the finite element method.

A Genetic Algorithm Optimization Model for Stability of an Inclined Cutoff with Soil-Embedded Depth

A coupled artificial neural network model with a genetic algorithm optimization model is developed for a practical case of a single cutoff. The proposed cutoff is of a soil-embedded vertical part with an inclined extension. The model successfully found the optimum dimensions of the vertical and inclined parts, the optimum angle of inclination, and the optimum length of protection downstream of the cutoff for a factor of safety of 3 against piping. Two thousand one hundred cases are modeled first using Geo-studio software to find the required length of downstream protection against piping for different lengths of the vertical, inclined lengths of the cutoff, its angle of inclination, soil layer depth, and degree of anisotropy. Then the created data set was used to develop an Artificial Neural Network (ANN) model for finding the length of protection required. The ANN model showed high performance with a determination coefficient of (0.922). The genetic algorithm model needs a minimum number of randomly generated populations of 100000 and three crossover iterations to produce a stable optimum solution. Running the model for different practical cases showed that the optimum angle variation was low and fluctuated around 30o. This low angle variation was due to its lower effect on the downstream soil protection length compared to the other decision variables. At the same time, the other dimensions varied with input variables, such as the depth of the soil layer, the seepage driving head, and the degree of isotropy. For a degree of anisotropy (ratio of vertical to horizontal hydraulic gradient) less than 0.5, the results showed no need for protection against piping; hence it is recommended to use minimum dimensions for such a case. The coupled model can easily obtain the optimum dimensions for any given input. Importance analysis showed that the optimum length of the downstream protection was highly affected by the vertical and inclined length of the cutoff, while it was less affected by the angle of inclination. Correlation analysis supported the importance analysis.

The Characteristics and Seepage Stability Analysis of Toppling-Sliding Failure under Rainfall

Toppling-sliding failure is a typical mode of deep-seated toppling failure. In this mode, massive collapsed rock masses form the main sliding body, which is sensitive to rainfall events and prone to instability under rainfall due to its unique slope structure. In the present study, based on the detailed investigation on the geology and deformation characteristics, we studied the deformation and failure mechanism of a large-scale deep-seated toppling in Nandongzi Village, Pingquan City, Hebei Province. We constructed an engineering geology model to describe the toppling-sliding failure under rainfall. In addition, based on the saturated–unsaturated seepage theory and using the SLOPE/W and SEEP/W modules in the GeoStudio software, we explored the seepage law and factors controlling the seepage failure of toppling-sliding under rainfall. From surface to interior, the slope can be divided into topplingalling zone, strong toppling zone, slight toppling zone, and non-deformation zone. The geological structure consisting of an upper strong slab and an underlying weak rock layer, controls the early deformation, and the deformation and failure mode is compressing-bending-toppling. Due to the influence of excavation and rainfall, the sliding movements occur along planar rupture planes in the toppling-falling zone in the later stage, during which the failure mode switches to creeping-cracking. At present, the stability of the slope is highly sensitive to rainfall. When the rainfall intensity exceeds 220 mm/day (50 years return period storm), the factor of safety will fall below 1.05 and subsequently the sliding failure may be triggered. Because of the difference in permeability characteristics between the toppling-falling zone and the strong toppling zone, high pore-water pressure is developed at their boundary, leading to a drastic decrease in the factor of safety. Specifically, the more considerable difference in permeability, the lower the safety factor. Overall, this study is significant in scientific guiding for evaluating and preventing such slope failures.

Slope stability prediction based on a long short-term memory neural network: comparisons with convolutional neural networks, support vector machines and random forest models

The numerical simulation and slope stability prediction are the focus of slope disaster research. Recently, machine learning models are commonly used in the slope stability prediction. However, these machine learning models have some problems, such as poor nonlinear performance, local optimum and incomplete factors feature extraction. These issues can affect the accuracy of slope stability prediction. Therefore, a deep learning algorithm called Long short-term memory (LSTM) has been innovatively proposed to predict slope stability. Taking the Ganzhou City in China as the study area, the landslide inventory and their characteristics of geotechnical parameters, slope height and slope angle are analyzed. Based on these characteristics, typical soil slopes are constructed using the Geo-Studio software. Five control factors affecting slope stability, including slope height, slope angle, internal friction angle, cohesion and volumetric weight, are selected to form different slope and construct model input variables. Then, the limit equilibrium method is used to calculate the stability coefficients of these typical soil slopes under different control factors. Each slope stability coefficient and its corresponding control factors is a slope sample. As a result, a total of 2160 training samples and 450 testing samples are constructed. These sample sets are imported into LSTM for modelling and compared with the support vector machine (SVM), random forest (RF) and convolutional neural network (CNN). The results show that the LSTM overcomes the problem that the commonly used machine learning models have difficulty extracting global features. Furthermore, LSTM has a better prediction performance for slope stability compared to SVM, RF and CNN models.

PENGARUH RENCANA PENINGKATAN VOLUME TAMPUNGAN TERHADAP STABILITAS TUBUH BENDUNGAN KEDUNG OMBO

The strategy to meet the water demands of Semarang and Demak Regencies involves enhancing the storage capacity of the Kedung Ombo Dam. This augmentation will inevitably alter the typical water level, thereby affecting the stability of the dam structure as it bears a greater load. Furthermore, the Kedung Ombo Dam, which is nearly 32 years old, necessitates re-evaluation since it lacks the full benefit of contemporary design methods. This study is confined to examining the slope stability, both static and pseudostatic, at a steady state flow, with the highest normal water level elevation (elevation +92.00) as the focal point. The slope stability analysis was conducted via the finite element method using the Slope/W in Geo-Studio software. The outcome of the static slope stability analysis indicates that the safety factor of the Kedung Ombo Dam body remains above the minimum allowable safety factor. In the pseudostatic analysis, the safety factor during the Operating Basic Earthquake (OBE) remains above the minimum allowable safety factor. However, during the Maximum Design Earthquake (MDE), the safety factor demonstrates a value that is lower than the minimum allowable safety factor. Nevertheless, the analysis of fixed displacement or permanent deformation reveals that the maximum settlement that occurs during the MDE earthquake does not exceed 50% of the available freeboard.

FINITE ELEMENT METHOD OF SEEPAGE AND STABILITY ANALYSIS OF SAURA-KEFFI EARTH DAM

Finite element method (FEM) based analysis using the SEEP/W and SLOPE/W sub-programme options of a GEOSTUDIO software was used to analyze Saura-Keffi earth dam in Nasarawa State, Nigeria with the view to analyze the dam seepage and its stability. The created dam geometry was assigned material properties and boundary conditions at reservoir water levels of: minimum (3 m), normal (6 m) and maximum (7 m). The analysis was conducted under the cases that the dam was without and with seepage measures (SCM). The results of the analyzed semi-permeable homogenous dam revealed a percentage reduction inseepage flux to 28.3% when the dam was considered with a central core and complete cut-off trench along the dam crest axis. see figure 7. The pore-water (PWP) revealed a decrease in value from (12 to 11.2) kPa at minimum water head with SCM. The PWP further increased by 18.9% as water rises from 6 m to 7m with SCM. The exit gradient showed an insignificant increase in value of 1.2% with the construction of SCM which indicates less flow at the exit end of the dam leading to increase in stability. The horizontal filter drain at the downstream lower and kept the phreatic line within the dam body to allow for adequate embankment and foundation drainage as shown in figure (5&6). The F.S at the maximum water level revealed an increase in value from 1.27 to 1.52 when a horizontal filter was considered. The Morgenstern-priced method of slope stability was used to estimate an acceptable minimum F.S of 1.52 at 0.5 lambda value with the introduction of horizontal filter.

Geoinformatics-based investigation of slope failure and landslide damming of Chenab River, Lahaul-Spiti, Himachal Pradesh, India

A huge landslide blocked the flow of the Chenab River near Nalda village on the morning of 13th August 2021 in the Lahaul-Spiti district of Himachal Pradesh, which led to the flooding of several villages (Nalda, Jasrath, Tarang, etc.) in the Udaipur subdivision. The slope (∼200 ​m height, ∼220 ​m width, and approx. 30 ​m depth) on the left bank of the Chenab River failed, which brought colossal soil and debris. This resulted in the damming of the Chenab River near Leh Baring village, which lies upstream of Nalda Village Bridge and opposite to Junde village, creating a huge water reservoir that later started overflowing, posing a major threat to downstream villages. This caused damage to the houses located downstream, which were submerged, animals were also washed away, and a large part of agricultural land was also inundated. The event was observed and studied using satellite images of high-resolution obtained from Google Earth and Sentinel 2A. The Spatio-temporal satellite images were used to observe the scars developed in the region over the past few years along the river, which evidently show the early signatures of slope failure. To analyze the stability of the hill slope, the factor of safety of the hill was evaluated using SLOPE/W GeoStudio software. Slope map and drainage density map were also generated, showing the vulnerability of the hill slope. The debris flow runout simulation of the event was performed using the RAMMS debris flow model to calculate the volume of the landslide and the water reservoir formed due to damming of the Chenab River. The volume of the landslide (debris) due to slope failure was approx. 2.22 million m3 and the water reservoir volume was approximately 0.3 million m3. The significant factors accountable for the landslide i.e. the slope of the hill, geomorphology of the area, lithology (phyllites), presence of narrow and elongated valleys, the confluences of the river in the area, and continuous rainfall in the region during that period were evaluated. The paper also emphasizes monitoring of such vulnerable areas based on high-resolution time series satellite images, which are available on a regular basis to avoid the loss of human lives in the future.

Case study on soil-reinforced embankment slope stability with natural fibre additives

In this work, an attempt was made to study the influence of jute fibre reinforcement with the help of three case studies. The first case study described laboratory model testing and numerical analysis performed on a modelled slope that simulated an existing embankment that failed on many occasions following overnight heavy rainfall. The second case study discussed how vegetation may minimise the likelihood of soil separation and the velocity of surface run-off by decreasing surficial soil erosion. Jute geotextiles have excellent hydrophilic characteristics that aid plant development; for this reason, they were used in the case study. The third case study developed a multi-fibre approach to traditional geotextiles to create an eco-sustainable product(s) with superior geotechnical qualities for improving the efficiency of earthen structures using soft revetments. The conclusion of these case studies expressed the novel objective of improvement of embankments with stability analysis. This research also involved soil sample testing and numerical modelling using the GeoStudio software suite. The slope model considers reinforcement with different numbers of rows of jute tassels on the embankment for enhanced stability and factor of safety. The presence of jute fibre geotextiles results in better performance in the stabilisation of soil and the minimum value of deformation and maximum value of the factor of safety.