Geotechnical Study of The Impact of Groundwater Level For Slope Stability in Coal Mine

Rock mass has force equilibrium which can be disturbed due to changes in rock mass conditions, both by naturally as well as human activities. In response, rock masses could have instability to reach new equilibrium and trigger landslides. Unstable slopes will affect the safety, economic and social factors. Groundwater has its own problems in mining management. Pore water pressure can cause uplift force and reduce the strength of the rock mass forming slopes and affect the slope stability. The study area has groundwater level relatively close to surface and causes the slope to be in nearly saturated condition. This research aims to study of the effect of groundwater levels on the stability of coal mine slopes in the study area. The research method includes collecting primary data through field observations to collect related technical data and secondary data collection through literature studies. Slope stability analysis was carried out to obtain recommendations with a minimum Safety Factor of 1.30. The results showed the ground water level has an inverse relationship to Safety Factor value. The recommendation is depressurisation using drain holes. The target of groundwater level reduction in the mine wall is RL+40 in the sidewall area and RL+65 in the highwall area. Another alternative is is by resloping the overall slope angle of the mine wall in the study area. The mine slope is recommended for layback with an overall slope angle of around 24 °.

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STUDI GEOTEKNIK PENGARUH MUKA AIR TANAH TERHADAP KESTABILAN LERENG TAMBANG BATUBARA

Prosiding Temu Profesi Tahunan PERHAPI ◽

10.36986/ptptp.v1i1.90 ◽

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

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Analysis of plant root–induced preferential flow and pore-water pressure variation by a dual-permeability model

Canadian Geotechnical Journal ◽

10.1139/cgj-2016-0629 ◽

2017 ◽

Vol 54 (11) ◽

pp. 1537-1552 ◽

Cited By ~ 18

Author(s):

Wei Shao ◽

Junjun Ni ◽

Anthony Kwan Leung ◽

Ye Su ◽

Charles Wang Wai Ng

Keyword(s):

Slope Stability ◽

Pore Water ◽

Factor Of Safety ◽

Preferential Flow ◽

Pore Water Pressure ◽

Plant Root ◽

Water Pressure ◽

Planting Density ◽

Permeability Model ◽

The Impact

Vegetation can affect slope hydrology and stability via plant transpiration and induced matric suction. Previous work suggested that the presence of plant roots would induce preferential flow, and its effects may be more significant when the planting density is high. However, there is a lack of numerical studies on how planting density affects soil pore-water pressure and shear strength during heavy rainfall. This study aims to investigate the impact of plant root–induced preferential flow on hydromechanical processes of vegetated soils under different planting densities. Two modelling approaches, namely single- and dual-permeability models, were integrated with an infinite slope stability approach to simulate pore-water pressure dynamics and slope stability. Laboratory tests on soils with two different planting densities for a plant species, Schefflera heptaphylla, were conducted for numerical simulations. The single-permeability model overestimated the pore-water pressure in shallow soil and underestimated the infiltration depth. The dual-permeability model, which is able to model the effects of preferential flow, can better capture the observations of rapid increase of pore-water pressure and deeper pressure response in the vegetated soil. However, caution should be taken on the choice of pore-water pressure when using the dual-permeability model to assess the factor of safety. The dual-permeability model using the pore-water pressure in the preferential flow domain and that in the matrix domain would result in a lower and higher factor of safety, respectively.

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Unsaturated seepage and stability of double-layer slope under rainfall infiltration

E3S Web of Conferences ◽

10.1051/e3sconf/202124803024 ◽

2021 ◽

Vol 248 ◽

pp. 03024

Author(s):

Yuan Zhang ◽

Haifeng Lu

Keyword(s):

Slope Stability ◽

Pore Water ◽

Safety Factor ◽

Pore Water Pressure ◽

Water Pressure ◽

Soil Parameters ◽

Lag Period ◽

Rainfall Patterns ◽

Continuous Rainfall ◽

Slope Safety

Taking a homogeneous double-layer soil slope as an example, the SEEP/W module and SLOPE/W module in the finite element analysis software GeoStudio were used in this paper. Then, the changes of pore water pressure and stability under different rainfall patterns and soil parameters were studied. Finally, the variation curves of pore water pressure and slope safety factor with rainfall time were obtained. The results show that: Soil parameters a and m are directly proportional to the slope safety factor, while n is inversely proportional to the slope safety factor. Under the condition of continuous rainfall, the decreasing rate of slope safety factor is directly proportional to the rainfall intensity.Under different rainfall patterns, the continuous rainfall in the advanced and normal rainfall patterns will cause the slope stability to decline and then gradually recover, while delayed and averaged rainfall patterns rainfall will cause the slope stability to decline continuously.In addition, there is a lag period in the change of slope safety factor, and the whole lag period lasts about 6 hours. During the lag period, the pore water pressure inside the soil began to decrease, while the slope safety factor continued to decrease. The safety factor starts to recover after the lag period ends.

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Slope Stability Analysis Under Pore-Water Pressure: A Case Study in Zarm-Rood Earthfill Dam, Iran

10.21203/rs.3.rs-498150/v1 ◽

2021 ◽

Author(s):

Mojtaba Gholamzade ◽

Ahad Bagherzadeh Khalkhali

Keyword(s):

Stability Analysis ◽

Slope Stability ◽

Pore Water ◽

Safety Factor ◽

Pore Water Pressure ◽

Water Pressure ◽

Slope Stability Analysis ◽

Operating Conditions ◽

Successful Implementation ◽

The Stability

Abstract It is well known that construction of dams or reservoirs have geomorphological impacts on the environment and could potentially accelerate the occurrence of landslides. One of the most common impact is the occurrence of new landslides and activation of the old one, which may turn into a natural disaster. Thus, controlling the stability of landslides become challenging issue specifically in the presence of f pore-water pressure. In general, the presence of water or pore-water pressure reduces the soil resistance and also leads to increase in stimulus loads, resulting in reduction of stability coefficients. In the present study, using GeoStudio SLOPE/W software, the effect of the proximity of the dam reservoir in terms of different operating conditions on the stability analysis of the landslide area of Zarm-Rood Dam is investigated. In the first step, the evaluation of internal stability of landslides and the effect of the presence of water on stability coefficients were evaluated and then the sustainable design of landslides was proposed. It was found that when extra pore-water pressure ranges from 0.2 to 0.4, safety factor is decreased by about 10%. Accordingly, safety factor is decreased by about 17% when extra pore-water pressure range from 0.4 to 0.6. This research demonstrates successful implementation of GeoStudio SLOPE/W for slope stability analysis in dam construction projects.

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Landslide Susceptibility in Relation to Correlation of Groundwater Development and Ground Condition

Advances in Civil Engineering ◽

10.1155/2017/4320340 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

S. N. L. Taib ◽

O. S. Selaman ◽

C. L. Chen ◽

R. Lim ◽

D. S. Awang Ismail

Keyword(s):

Pore Water Pressure ◽

Water Pressure ◽

Slope Angle ◽

Slip Surfaces ◽

Slope Modeling ◽

Pressure Development ◽

Groundwater Rise ◽

Ground Condition ◽

Constant Slope ◽

The Impact

Rainfall is inevitably one of the main factors that trigger landslides. However, not much study has been conducted on the impact of groundwater rise on slope stability. Thus, this study is intended to focus on the rise of the groundwater level from the bottom of the slope which would lead to landslides due to pore pressure development by eliminating other landslide-triggering factors (i.e., infiltration and surface runoff). Saturated sand was used for slope modeling, and sand densities of 1523 kg/m3, 1562 kg/m3, and 1592 kg/m3 were tested with a constant slope angle of 45°. Another set of experiments was also performed on slopes having angles of 25°, 45°, and 60° and with a maintained density of sand at 1562 kg/m3. Through observation, failure was initiated first at the toe of the slope before minor and major slips or total collapse occurs. Dimensions of slip surfaces were measured and included in SLOPE/W for the computation of the safety factor. In conclusion, safety factors are found to be higher in denser soil and in the lowest slope angle. However, faster occurrence of collapse in denser soil was identified and could be contributed by the faster pore water pressure development.

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

International Journal of Engineering Technology and Sciences ◽

10.15282/ijets.v5i3.1129 ◽

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.

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

Open Geosciences ◽

10.1515/geo-2020-0294 ◽

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.

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Slope Cracks in the Safety Assessment of the Rainfall Period

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.405-408.2364 ◽

2013 ◽

Vol 405-408 ◽

pp. 2364-2369 ◽

Cited By ~ 3

Author(s):

Te Hsing Chang ◽

Chi Li Lin ◽

Fu Kuo Huang

Keyword(s):

Shear Strength ◽

Numerical Model ◽

Moisture Content ◽

Slope Stability ◽

Groundwater Level ◽

Safety Assessment ◽

Pore Water Pressure ◽

Water Cycle ◽

Water Pressure ◽

Cycle System

Unsaturated cracked slopes are easily to be affected by rainfall in the soil. Actually, some of the rainfall becomes the surface runoff and the rest permeates the crack under the ground in water cycle system. The infiltration makes the groundwater level rise. It also increases the pore water pressure and slide stress of the soil and decreases the anti-shear strength of soil. That makes the slope fracture or deform. However, most of the slope stability analyses set the physical properties of the soil as constant values but neglect the influence of the crack and infiltration. Those analyses underestimate the influence of the crack and the change of water content to the anti-shear strength of the soil. Therefore, it was unable to predict the possible damage time point by these evaluation results. The knowledge and methodology of the rainfall combine infiltration and slope stability analysis in this research. Simulations of the moisture content of the soil and the groundwater level are performed by FEMWATER numerical model. The simulating conditions are based on the different cracked positions and rainfall durations. The data of moisture content changes of the soil will be transformed into the parameters of safety factors fitted by STEDWIN numerical model. The influence of the slope stability with different cracked positions was gained from the simulations.

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Effect of pore water pressure on soil crack against safety factor of slope stability

Journal of Physics Conference Series ◽

10.1088/1742-6596/1450/1/012014 ◽

2020 ◽

Vol 1450 ◽

pp. 012014

Author(s):

I W Arya ◽

I W Wiraga ◽

I G A G S Dwipa ◽

I M W Pramana

Keyword(s):

Slope Stability ◽

Pore Water ◽

Safety Factor ◽

Pore Water Pressure ◽

Water Pressure ◽

Soil Crack

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Study on the Influence of Various Rainfall Types on the Stability of High and Steep Slopes

Geofluids ◽

10.1155/2021/7906573 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Jin Qian ◽

Ding Sun ◽

Guodong Li ◽

Yue Wu

Keyword(s):

Slope Stability ◽

Pore Water ◽

Safety Factor ◽

Pore Water Pressure ◽

Interaction Analysis ◽

Coupling Effect ◽

Water Pressure ◽

Late Summer ◽

Simulation Method ◽

Structural Safety

Taking the high and steep slope of a ski resort as the background, in order to ensure the structural safety of the slope in the subsequent complex rainfall environment, the calculation principle of unsaturated soil slope stability is summarized, and the parameter interaction analysis is proposed. The numerical simulation method is used to study the influence of various rainfall types on slope stability; combined with a multiparameter combination, the slope stability is analyzed. The results show that different types of rainfall have a significant impact on the safety factor of the slope, the safety factor of the slope under the front rainfall type is the smallest, the minimum value is 1.38, and the front rainfall mostly occurs in the late summer, so it is necessary to avoid construction in the late summer or do a good job of safety monitoring in the late summer. Through setting monitoring points, it is found that the pore water pressure of the three positions from small to large is in the order of slope toe<slope middle<slope top, and the pore water pressure at the slope toe is basically 0 kPa. At this time, the matric suction at the slope toe is the minimum, so the protection should be strengthened. In the combination analysis of the four parameters, the direct effect and coupling effect of C15 are at a small level, which indicates that when the four parameters fluctuate together, the mutual coupling is not the effect of a single parameter, which provides a theoretical reference for the follow-up related research.

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