scholarly journals Characteristics of Rainfall-Induced Slope Instability in Cisokan Region, Indonesia

2021 ◽  
Vol 53 (5) ◽  
pp. 210504
Author(s):  
Sugeng Krisnanto ◽  
Harianto Rahardjo
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Matric Suction ◽  
Slope Instability ◽  
Access Road ◽  
Level Increase ◽  
Long Access

A 25.5 km long access road has been constructed in a hilly area in Cisokan region. Several slope instabilities occurred during the rainy season, particularly at the end of heavy rainfall. A comprehensive study was performed to understand the characteristics of rainfall-induced slope instability. The study consisted of field observation, analyses of field and laboratory test data, and numerical analyses. The study revealed that in general there were two categories of slopes with instability characteristics: (i) slopes with a significant groundwater level increase during rainfall; (ii) slopes with an insignificant groundwater level increase during rainfall. In the first category, the slope instability was caused by a loss of matric suction and eventually the pore-water pressure, uw became positive as indicated by an increase of the groundwater level. In the second category, the slope instability was caused by a loss of matric suction without a rise in pore-water pressure, uw, to a positive magnitude. Two empirical curves of slope stability were developed as a preliminary guidance to assess slope stability during rainfall in the region.

scholarly journals Behavior analysis by model slope experiment of artificial rainfall

2015 ◽  
Vol 3 (6) ◽  
pp. 4159-4187
Author(s):  
M. C. Park
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Pore Water ◽  
Slope Failure ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Matric Suction ◽  
Slope Stability Analysis ◽  
Model Slope ◽  
Rainfall Seepage

Abstract. In this study, we performed a model slope experiment with rainfall seepage, and the results were compared and verified with the unsaturated slope stability analysis method. In the model slope experiment, we measured the changes in water content and matric suction due to rainfall seepage, and determined the time at which the slope failure occurred and the shape of the failure. In addition, we compared and verified the changes in the factor of safety and the shape of the failure surface, which was calculated from the unsaturated slope stability analysis with the model experiment. From the results of experiment and analysis, it is concluded that the unsaturated slope stability analysis can be used to accurately analyze and predict rainfall-induced slope failure. It is also concluded that in seepage analysis, setting the initial conditions and boundary conditions is very important. If engineers will use the measured pore water pressure or matric suction, the accuracy of analysis can be enhanced. The real-time monitoring system of pore water pressure or matric suction can be used as a warning of rainfall-induced slope failure.

scholarly journals STUDI GEOTEKNIK PENGARUH MUKA AIR TANAH TERHADAP KESTABILAN LERENG TAMBANG BATUBARA

2020 ◽  
Vol 1 (1) ◽  
pp. 475-488
Author(s):  
Jioni Santo Frans ◽  
Muhammad Hafizh Nurfalaq
Keyword(s):  
Rock Mass ◽  
Slope Stability ◽  
Ground Water ◽  
Water Level ◽  
Pore Water ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slope Angle ◽  
Ground Water Level

ABSTRAK Dalam keadaan normal, suatu massa batuan memiliki kesetimbangan gaya yang bekerja. Kesetimbangan gaya yang bekerja tersebut bisa terganggu akibat terjadinya perubahan kondisi massa batuan, baik secara alamiah (erosi, patah, peningkatan muka air tanah) maupun aktivitas manusia (pengupasan, pengangkutan, penggalian, penimbunan). Respon dari perubahan tersebut, massa batuan dapat mengalami ketidakstabilan sebagai usaha untuk mencapai kondisi kesetimbangan baru. Hal ini akan memicu gerakan massa batuan akibat lereng yang tidak stabil dan terjadinya longsor. Lereng yang tidak stabil akan berdampak terhadap faktor keselamatan, ekonomi, dan sosial. Air tanah memiliki permasalahan tersendiri dalam pengelolaan tambang. Tekanan air pori (pore water pressure) dari air tanah dapat menimbulkan gaya angkat (uplift force) dan menurunkan kekuatan suatu massa batuan penyusun lereng, yang mana akan mempengaruhi kestabilan suatu lereng. Karakteristik daerah penelitian yang memiliki muka air tanah relatif dekat dengan permukaan, menyebabkan lereng berada dalam kondisi hampir jenuh. Penelitian ini bertujuan untuk melakukan studi pengaruh muka air tanah terhadap kestabilan lereng tambang batubara di daerah penelitian. Metode penelitian yang digunakan meliputi pengumpulan data primer melalui observasi lapangan untuk mengumpulkan data-data teknis terkait dan pengumpulan data sekunder melalui studi literatur. Analisa kestabilan lereng dilakukan untuk mendapatkan rekomendasi dengan nilai Faktor Keamanan minimum 1,30. Hasil penelitian menunjukkan muka air tanah memiliki hubungan berbanding terbalik terhadap nilai Faktor Keamanan. Rekomendasi yang dihasilkan yaitu melakukan dewatering dengan menggunakan drain hole. Target penurunan muka air tanah pada dinding tambang daerah penelitian adalah RL+40 pada area sidewall dan RL+65 pada area highwall. Altenatif lain yang diajukan oleh penulis adalah dengan melandaikan sudut lereng keseluruhan (overall slope angle) pada dinding tambang di daerah penelitian. Dinding tambang daerah penelitian direkomendasikan untuk dilakukan pelandaian dengan sudut lereng keseluruhan berkisar 24°. Kata kunci: kestabilan lereng, muka air tanah, longsor, dewatering, sudut lereng keseluruhan  ABSTRACT Under normal circumstances, a rock mass has an equilibrium of working forces. The equilibrium of these working forces can be disrupted due to changes in rock mass conditions, both naturally (erosion, broken, increased ground water level) and human activities (stripping, loading, excavation, backfill). In response to these changes, rock mass can have instability issue as an effort to reach new equilibrium conditions. This  condition will trigger rock mass movements and slope failure due to unstable slopes. Unstable slopes will affect the safety, economic and social factors. Groundwater has its own problems in mining activities. Pore water pressure from ground water can cause uplift force and decrease the strength of a rock mass forming a slope, which will affect the slope stability. Characteristics of the study area which has groundwater level relatively close to surface, causes the slope to be in nearly saturated condition. This research aims to study the effect of groundwater level on the stability of coal mine slopes in the study area. The research method used includes collecting primary data through field observations to collect related technical data and secondary data collection through literature studies. Slope stability analysis is carried out to obtain recommendations with a minimum Safety Factor value of 1.30. The results showed the ground water level has an inverse relationship to the value of the Safety Factor. The recommendations are dewatering using drain holes. The target of groundwater level reduction in the mine wall of the study area is RL+40 in the sidewall area and RL+65 in the highwall area. Another alternative proposed by the author is by resloping the overall slope angle of the mine wall in the study area. The mining wall of the study area is recommended for alignment with an overall slope angle of around 24 °. Keywords: slope stability, ground water level, landslides, dewatering, overall slope angle

scholarly journals Investigation and Monitoring of Groundwater Level: Building Crack Near to IIUM Kuantan

2018 ◽  
Vol 5 (3) ◽  
pp. 51-56
Author(s):  
M.F. Ishak ◽  
Koay B.K ◽  
M.S.I. Zaini ◽  
M.F. Zolkepli
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Groundwater Level ◽  
Rainfall Intensity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
High Concentration ◽  
Monitoring Equipment ◽  
Bottom Part ◽  
Level Building

The objective of this study is to analyze groundwater level on slope that effect the slope stability. In this research, the instrumentation monitoring equipment were applied to investigate the groundwater due to the rainfalls that effected to slope stability. Groundwater level were related to rainfall intensity and pore water pressure as the simulation of behavior of the groundwater pattern through slope model were produced. The result indicates that the pore water pressure and groundwater level are facilitated to be fluctuated by heavy rainfall. Moreover, the different part of slopes need to be compared and it was found that the bottom part of the slope has high concentration of groundwater and pore water pressure due to the rainfall cumulative effects. The result also indicates that the bottom slope is worse when it is subjected to a high groundwater level. Thus, the rising of groundwater level due to rainfall was the main reason for the slope resulted in unstable condition.

scholarly journals Effect of groundwater fluctuation, construction, and retaining system on slope stability of Avas Hill in Hungary

2021 ◽  
Vol 13 (1) ◽  
pp. 1139-1157
Author(s):  
Eslam M. Hemid ◽  
Tamás Kántor ◽  
Ahmed A. Tamma ◽  
Mostafa A. Masoud
Keyword(s):  
Slope Stability ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slope Instability ◽  
Negative Effects ◽  
Destructive Effect ◽  
Groundwater Levels ◽  
Groundwater Level Fluctuations ◽  
The Church

Abstract Landslides are one of the natural hazards, which have significant negative effects on both humans and the environment. Thus, slope stability analyses and stabilization processes are necessary to obviate or mitigate landslides. In this study, the effect of groundwater level fluctuations and the construction of a building (i.e., a recently built church) on slope stability was investigated on the eastern slope of the Avas Hill, at Miskolc, in Northeast Hungary. Soil movements and groundwater levels were monitored and geological and slope stability models were constructed. Furthermore, the possibility of constructing a retaining system was evaluated to minimize the detrimental effects of both groundwater level fluctuations and the construction of the church. The findings showed that the fluctuation in groundwater levels had a destructive effect on slope stability due to pore-water pressure, which decreased the soil strength of the slope and slope stability. On the other hand, the church added an external load onto the underlying soil leading to an increase in slope instability. Hence, we suggested constructing retaining structures such as gravity retaining walls to increase the soil shear strength and enhance slope stability in the long term.

scholarly journals Infiltration, seepage and slope instability mechanisms during the 20–21 November 2000 rainstorm in Tuscany, central Italy

2006 ◽  
Vol 6 (6) ◽  
pp. 1025-1033 ◽  
Author(s):  
V. Tofani ◽  
S. Dapporto ◽  
P. Vannocci ◽  
N. Casagli
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Factor Of Safety ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Critical Time ◽  
Infiltration Rate ◽  
Slope Instability ◽  
Storm Event ◽  
Surface Boundary

Abstract. On 20–21 November 2000, a storm of high intensity, with a estimated return period of more than 100 years, triggered over 50 landslides within the province of Pistoia in Tuscany (Italy). These failures can be defined as complex earth slides- earth flows. One of the documented landslides has been investigated by modelling the ground water infiltration process, the positive and negative pore water pressure variations and the effects of these variations on slope stability during the rainfall event. Morphometric and geotechnical analyses were carried out through a series of in-situ and laboratory tests, the results of which were used as input for the modelling process. The surface infiltration rate was initially simulated using the rainfall recorded at the nearest raingauge station. Finite element seepage analysis for transient conditions were then employed to model the changes in pore water pressure during the storm event, using the computed infiltration rate as the ground surface boundary condition. Finally, the limit equilibrium slope stability method was applied to calculate the variations in the factor of safety during the event and thereby determine the critical time of instability. For the investigated site the trend of the factor of safety indicates that the critical time for failure occurs about 18 h after the storm commences, and highlights the key role played by the soil permeability and thickness in controlling the response in terms of slope instability.

Effect of rainfall on matric suctions in a residual soil slope

1996 ◽  
Vol 33 (4) ◽  
pp. 618-628 ◽  
Author(s):  
T T Lim ◽  
H Rahardjo ◽  
M F Chang ◽  
D G Fredlund
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Matric Suction ◽  
Residual Soil ◽  
Soil Slope ◽  
Field Instrumentation ◽  
Pore Water Pressures ◽  
Residual Soil Slope

A slope stability study involving shallow slip surfaces should include the effect of negative pore-water pressures in a slope. A field instrumentation program was carried out to monitor negative pore-water pressure (i.e., in situ matric suction) in a residual soil slope in Singapore. Variations in matric suction and the matric suction profiles under (1) a canvas-convered grassed surface, (2) a grassed surface, and (3) a bare ground surface, in response to rainfalls were investigated. Changes in matric suction due to changes in climatic conditions decrease rapidly with depth. The change was found to be most significant in the bare slope and least significant under the canvas-covered slope. The amount of decrease in matric suction after a rainstorm was observed to be a function of the initial matric suction just prior to the rainstorm. Positive pore-water pressures were observed above the groundwater table, suggesting the development of a perched water table within the slope. These observations are also typical of other regions experiencing high seasonal rainfalls. The field monitoring program presented can be adopted for investigating rainfall-induced landslides in other parts of the world. Key words: matric suction, negative pore-water pressure, field instrumentation, rainfall, residual soil, slope stability.

scholarly journals Analysis of infiltration, seepage processes and slope instability mechanisms during the November 2000 storm event in Tuscany

2005 ◽  
Vol 2 ◽  
pp. 301-304
Author(s):  
V. Tofani ◽  
S. Dapporto ◽  
P. Vannocci ◽  
N. Casagli
Keyword(s):  
Slope Stability ◽  
Pore Water ◽  
Factor Of Safety ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Critical Time ◽  
Infiltration Rate ◽  
Slope Instability ◽  
Storm Event ◽  
Surface Boundary

Abstract. On the days 20-21 November 2000, a storm of exceptional intensity triggered over 50 landslides within the province of Pistoia in Tuscany (Italy). These failures are mostly of complex type, originating as rotational or translational landslides, and transforming into flows. Two of these landslides were investigated in this paper by modelling the ground water infiltration process, the pore water pressure variations, both positive and negative, and the effects of these variations on slope stability during the rainfall event. Morphometric and geotechnical analyses were carried out for both sites through a series of in-situ and laboratory tests, the results of which were used as input for the modelling process. In a first step the surface infiltration rate was simulated using a modified Chu (1978) approach for the Green and Ampt (1911) equations in case of unsteady rainfall together with a surficial water balance. A finite element seepage analysis for transient conditions was then employed to model the changes in pore water pressure during the event, using the computed infiltration rate as the ground surface boundary condition. Finally, once again using the data from the previous step as input, the limit equilibrium Morgenstern-Price (1965) slope stability method was applied to calculate the variations in the factor of safety during the event and thereby determine the most critical time of instability. In both sites this method produced a curve for the factor of safety that indicated that the most critical time for failure occurred a few hours after the peak of rainfall.

Study on Slope Instability Disciplinarian on the Condition of Rainfall

2013 ◽  
Vol 353-356 ◽  
pp. 654-658
Author(s):  
Nan Tong Zhang ◽  
Xiao Chun Zhang ◽  
Hua Rong Wang ◽  
Chen Yan
Keyword(s):  
Slope Stability ◽  
Tensile Stress ◽  
Rainfall Intensity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Road Construction ◽  
Slope Instability ◽  
Slope Surface ◽  
Large Area ◽  
Break Zone

Slope stability is one of the problems of road construction which should be faced with and solve. Rainfall can reduce the shear strength of slope soil and raise the underground water level which can lead to increase slope soil pore water pressure. The influence of rainfall infiltration on slop is mainly to change the slope seepage field, increase dynamic and hydrostatic water load on the slope soil and decrease of soil shear parameters. More abundant rainfall of typhoon area could make the road slope stability more fragile. Based on Matoushan Mountain along 104 state roads in Taizhou city, Zhejiang province, slope instability disciplinarian on the condition of rainfall is studied using the method of numerical simulation in this paper. As the results, when the rainfall intensity was 0.006 m/h and continuous rain was in 24 hours, the slope surface compressive stress tends to zero which began to appear tensile stress area on the condition of self-weight. And when the rainfall intensity was 0.01 m/h and continuous rain was in 24 hours, the large area of the slope surface was tensile stress area which means to appear break zone in slope surface and likely to landslide at the same time.

Sign in / Sign up

Export Citation Format

Share Document