scholarly journals The variation characteristics in the groundwater level, pore water pressure and underground temperature during snow-melting season in landslide areas.

Landslides ◽  
1986 ◽  
Vol 23 (3) ◽  
pp. 21-27 ◽  
Author(s):  
Shoji OGAWA ◽  
Takeshi KAMEI ◽  
Tadashi WADA ◽  
Masaki HASHIMOTO
Keyword(s):  
Pore Water ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Snow Melting ◽  
Variation Characteristics ◽  
Melting Season

Influences on Liquefaction-Induced Damage of Pore Water Seepage into an Unsaturated Surface Layer

2020 ◽  
Vol 15 (6) ◽  
pp. 754-764
Author(s):  
Yohsuke Kawamata ◽  
Hiroshi Nakazawa ◽  
◽  
Keyword(s):  
Surface Layer ◽  
Pore Water ◽  
Groundwater Level ◽  
Water Movement ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Lateral Spreading ◽  
Soil Liquefaction ◽  
Water Seepage ◽  
Long Duration

Various studies have examined soil liquefaction and the resultant structure damage. The 1995 Southern Hyogo Prefecture Earthquake, a near-field earthquake, caused significant damage when the ground was liquified due to the rapidly increased pore water pressure in several cycles of major motions. Therefore, the effect of pore water movement during earthquakes has been assumed to be limited, and liquefaction has mainly been evaluated in undrained conditions. Additionally, the ground and building settlement or inclination caused by liquefaction are deemed to result from pore water drainage after earthquakes. Meanwhile, in the 2011 Tohoku Earthquake, off the Pacific Coast, a subduction-zone earthquake, long-duration motions were observed for over 300 s with frequent aftershocks. Long-duration motions with frequent aftershocks are also anticipated in a future Nankai Trough Earthquake. The effect of pore water movement not only after but during an earthquake should be considered in cases where pore water pressure gradually increases in long-duration motion. The movement of pore water during and after an earthquake typically results in simultaneous dissipation and buildup of water pressure, as well as volumetric changes associated with settlement and lateral spreading. Such effects must reasonably be considered in liquefaction evaluation and building damage prediction. This research focuses on pore water seepage into the unsaturated surface layer caused by the movement of pore water. Seepage experiments were performed based on parameters such as height of test ground, ground surface permeability, and liquefaction duration. In the tests, water pressure when the saturated ground below the groundwater level is fully liquified was applied to the bottom of the specimen representing an unsaturated surface layer. Seepage behaviors into the unsaturated surface layer were then evaluated based on the experiment data. The results show that the water level rises due to pore water seepage from the liquefied ground into the unsaturated surface layer right above the liquefied ground. For this reason, a ground shallower than the original groundwater level can be liquified.

Field Test on the New Method of Vacuum Dewatering with Lower-energy Dynamic Consolidation for Silty Soil Ground

2011 ◽  
Vol 243-249 ◽  
pp. 3306-3310 ◽  
Author(s):  
Hong Bo Zhang ◽  
Xiu Guang Song ◽  
Hong Hong Wang ◽  
Zheng Ma
Keyword(s):  
Pore Water ◽  
Field Test ◽  
Groundwater Level ◽  
Lower Energy ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Excess Pore Water Pressure ◽  
Dynamic Consolidation ◽  
Vacuum Dewatering ◽  
Excess Pore

The dynamic consolidation method has been used widely in various engineering domain. With this method, the velocity of reconsolidation settlement was enhanced, the consolidation result was good, and the cost was lower than other methods. However, in the flooded area of Yellow River, the groundwater level is higher, and the shallow saturated silty soil liquefaction will be happened with this single method of dynamic consolidation. It goes against the roadbed stability. According to engineering practice, the vacuum dewatering with lower energy dynamic consolidation method was proposed in this paper. In order to monitor the effect of this consolidation method, the water-level observation hole, pore water pressure gauge, standard guide pile, level gauge have been set up. They could be used to get the groundwater level, the excess pore water pressure, horizontal displacement and land subsidence, respectively. These monitors would last the whole period of the consolidation experiment. Field test results shows that the excess pore water pressure was reduced by 80%-90% during one to three days.

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 Reduction of Groundwater Buoyancy on the Basement in Weak-Permeable/Impervious Foundations

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Jikai Zhou ◽  
Chenghuan Lin ◽  
Chen Chen ◽  
Xiyao Zhao
Keyword(s):  
Pore Water ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Laboratory Model ◽  
Test Results ◽  
Underground Structures ◽  
Significant Difference ◽  
Reduction Coefficient

At present, groundwater buoyancy is directly calculated by Archimedes’ principle for the antifloating design of underground structures. However, this method may not be applicable to weak-permeable/impervious soils, e.g., clayey foundations, because there is a significant difference between the groundwater buoyancy obtained from field measurements and that calculated by Archimedes’ principle. In order to determine whether the method of calculating groundwater buoyancy in weak-permeable/impervious soil layers by Archimedes’ principle is reasonable, this paper investigated the groundwater buoyancy on the basement in such foundations through laboratory model tests. The following factors that may influence the magnitude of groundwater buoyancy were investigated: change of groundwater level, duration of pore water pressure, and buried depth of the basement. In this study, model test results show that the groundwater buoyancy obtained from measurements is evidently lower than that calculated by Archimedes’ principle. Reduction extent can be expressed by a “reduction coefficient,” which can be calculated by a fitting formula. Moreover, experimental groundwater buoyancy increases with the increase in the groundwater level, and it almost does not change with the growth of duration of pore water pressure. Reduction coefficient ranges between 0.25 and 0.52 depending on different buried depths of the basement. In general, experimental groundwater buoyancy decreases with the increase in the buried depth of the basement.

Two Dimensional Parametric Analysis of Time Variation Characteristics of Raft Foundation on Saturated Subsoil

2011 ◽  
Vol 90-93 ◽  
pp. 2167-2172
Author(s):  
Chun Yi Cui ◽  
Zhong Tao Wang ◽  
Xiao Fei Li
Keyword(s):  
Pore Water ◽  
Time Variation ◽  
Pore Water Pressure ◽  
Yield Criterion ◽  
Water Pressure ◽  
Fe Model ◽  
Excess Pore Water Pressure ◽  
Raft Foundation ◽  
Variation Characteristics ◽  
Excess Pore

For further discussing time variation characteristics of raft foundation on saturated subsoil due to consolidation, parameterized numerical analyses are completed based on Biot consolidation equations by developing elasto-plastic coupled FE model in plane strain state, together with adopting Mohr-Coulomb yield criterion. Computational results show that internal force and deformation of raft foundation display obvious non-monotonic features, which is associated with dissipation of excess pore water pressure. The disequilibrium of dissipation of excess pore water pressure displays more intensive between subsoil areas near raft center and the border due to less Poission’s ratio of subsoil, which leads to more dissipation time and regulation magnitude of distribution of stress and deformation in subsoil. When subsoil is of low permeability coefficients and Poission’s ratios, the non-monotonic features become more clearly and sustain with longer term variation characteristics.

Pore Water Pressure Variation Characteristics Analysis of Soft Soil Foundation Disposed by Dynamic Drainage Consolidation Method

2011 ◽  
Vol 243-249 ◽  
pp. 2880-2884
Author(s):  
Gui Hua Yang ◽  
Jin Liang Han
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Simulation Method ◽  
Pressure Variation ◽  
Transient Vibration ◽  
Characteristics Analysis ◽  
Variation Characteristics ◽  
Soil Foundation

The pore water pressure variation during the process of dynamic drainage consolidation is calculated and analyzed with numerical simulation method, using constitutive model of Finn. The pore water pressure in mud presents transient vibration process, and decreases with depth. The pressure in mud is always higher than in sang bag well, which reveals that sang bag well is an effective vertical drainage channel in process of dynamic drainage consolidation. In addition, seen from the characteristics of pore water pressure variation, effective consolidation depth can be accurately forecasted.

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