Ground Water Pore-Pressure Influences on Stream Restoration

2013 ◽  
Author(s):  
J.A. Magner ◽  
O. Baird. K.J. Kuehner
Keyword(s):  
Ground Water ◽  
Pore Pressure ◽  
Stream Restoration ◽  
Water Pore ◽  
Water Pore Pressure

scholarly journals Till Fabric and Deformational Structures in Drumlins Near Waukesha, Wisconsin, U.S.A.

1985 ◽  
Vol 31 (109) ◽  
pp. 220-228 ◽  
Author(s):  
Scott D. Stanford ◽  
David M. Mickelson
Keyword(s):  
Ground Water ◽  
Pore Pressure ◽  
Effective Stress ◽  
Ice Flow ◽  
The Core ◽  
Minimum Drag ◽  
Melt Water ◽  
Sediment Flow ◽  
Till Fabric ◽  
Sand And Gravel

AbstractDeep gravel-pit exposures reveal the distribution and structure of till and underlying sand and gravel in drumlins near Waukesha, Wisconsin. The subglacial sediment is interpreted to have moved laterally into the drumlin sites because the till thickens from the margin to the core of the drumlins, the stone orientation in the till is perpendicular and oblique to ice flow on the drumlin margins, and recumbent isoclinal folds occur in sand on the drumlin margins with axes parallel to the drumlin axes. The resulting accumulations of sediment presented obstacles to ice flow and were streamlined into the minimum-drag drumlin shape by erosion on the margins and by remolding of material in the core of the drumlins. These drumlin nuclei may have formed at spots where there was low effective stress on the bed. The subglacial sediment became mobile as a result of high pore pressure that may have developed as ground water and subglacial melt water were trapped behind a frozen bed at the ice margin. Under certain conditions, however, lateral sediment flow might also have occurred when the sediment was frozen.

Correlation of seismicity and water level in the Açu reservoir—an example from Northeast Brazil

1995 ◽  
Vol 85 (5) ◽  
pp. 1483-1489 ◽  
Author(s):  
Joaquim M. Ferreira ◽  
Ronaldo T. De Oliveira ◽  
Marcelo Assumpção ◽  
José A. M. Moreira ◽  
Robert G. Pearce ◽  
...  
Keyword(s):  
Water Level ◽  
Pore Pressure ◽  
Horizontal Stress ◽  
Northeastern Brazil ◽  
Clear Correlation ◽  
Pressure Diffusion ◽  
Field Campaigns ◽  
Maximum Horizontal Stress ◽  
Regional Stresses ◽  
Water Pore Pressure

Abstract Seismic monitoring of the Açu reservoir (31-m depth, 2.4 × 109 m3 in volume), in Rio Grande do Norte State, Northeastern Brazil, started in 1987 about 2 years after impoundment. The largest earthquake so far (magnitude 2.8) occurred in August 1994. From 1987 to 1989, the monthly number of induced events had a clear correlation with the water level, with a 3-month delay, and the activity occurred mainly inside the reservoir. Although no preimpoundment monitoring had been carried out, the correlation of the water level and the seismicity strongly suggests the activity was induced by pore pressure diffusion. Since 1990, the activity migrated toward the border of the reservoir, and the number of events no longer correlated with the water level. A seismographic network was deployed around the reservoir during two field campaigns (1989 and 1990/91), showing that the activity occurred preferentially with strike-slip mechanisms on NE oriented faults. The E-W orientation of the P axes, parallel to the regional maximum horizontal stress, and the presence of many NE trending faults and fractures in the Precambrian basement near the reservoir, suggest that the probably induced seismicity was a typical case of water pore pressure facilitating earthquake occurrence in pre-existing zones of weakness under high regional stresses.

scholarly journals Till Fabric and Deformational Structures in Drumlins Near Waukesha, Wisconsin, U.S.A.

1985 ◽  
Vol 31 (109) ◽  
pp. 220-228 ◽  
Author(s):  
Scott D. Stanford ◽  
David M. Mickelson
Keyword(s):  
Ground Water ◽  
Pore Pressure ◽  
Effective Stress ◽  
Ice Flow ◽  
The Core ◽  
Minimum Drag ◽  
Melt Water ◽  
Sediment Flow ◽  
Till Fabric ◽  
Sand And Gravel

AbstractDeep gravel-pit exposures reveal the distribution and structure of till and underlying sand and gravel in drumlins near Waukesha, Wisconsin. The subglacial sediment is interpreted to have moved laterally into the drumlin sites because the till thickens from the margin to the core of the drumlins, the stone orientation in the till is perpendicular and oblique to ice flow on the drumlin margins, and recumbent isoclinal folds occur in sand on the drumlin margins with axes parallel to the drumlin axes. The resulting accumulations of sediment presented obstacles to ice flow and were streamlined into the minimum-drag drumlin shape by erosion on the margins and by remolding of material in the core of the drumlins. These drumlin nuclei may have formed at spots where there was low effective stress on the bed. The subglacial sediment became mobile as a result of high pore pressure that may have developed as ground water and subglacial melt water were trapped behind a frozen bed at the ice margin. Under certain conditions, however, lateral sediment flow might also have occurred when the sediment was frozen.

scholarly journals Groundwater fluctuations during a debris flow event in Western Norway – triggered by rain and snowmelt

2020 ◽  
Author(s):  
Stein Bondevik ◽  
Asgeir Sorteberg
Keyword(s):  
Debris Flow ◽  
Pore Pressure ◽  
Air Temperature ◽  
Groundwater Level ◽  
Trigger Factor ◽  
Groundwater Temperature ◽  
Western Norway ◽  
Storm Rainfall ◽  
Short Time ◽  
Water Pore Pressure

Abstract. Pore pressure is crucial in triggering debris slides and flows. Here we present measurements of ground water pore pressure and temperature recorded by a piezometer 1.6 m below the surface on a slope susceptible to debris flows in Western Norway. One of the largest oscillations in data collected over four years coincided with a debris flow event on the slope that occurred during storm Hilde on 15–16 November 2013. More than 100 landslides were registered during the storm. Rainfall totalled about 80–100 mm in 24 hours, locally up to 129 mm, and an additional trigger factor for the slides was a rapid rise in air temperature that caused snowmelt. On 15 November, the groundwater level in the hillslope rose by 10 cm per hour and reached 44 cm below the surface. At the same time, air temperature rose from 0 °C to over 8 °C, and the groundwater temperature dropped by 1.5 °C. The debris flow probably occurred late in the evening of 15 November, when the groundwater level reached its peak. Measurements of the groundwater in the hillslope in the period 2010–2013 show that the event in 2013 was not exceptional. Storm Dagmar on 25–26 December 2011 caused a similar rise in groundwater level, but did not trigger any failures. The data suggest that during heavy rainstorms the slope is in a critical state for a slide to be triggered for a short time – about 4–5 hours.

Numerical Analysis of the Influences of Water Level on Seepage Stability of Tailing Dam

2014 ◽  
Vol 580-583 ◽  
pp. 1928-1931
Author(s):  
Fang Ding He ◽  
Xue Feng Cao ◽  
Xia Yang ◽  
Zhi Dong Zhou
Keyword(s):  
Numerical Simulation ◽  
Water Level ◽  
Pore Pressure ◽  
Simulation Software ◽  
Saturation Line ◽  
Tailing Dam ◽  
Pressure Changes ◽  
Relationship Of ◽  
The Relationship ◽  
Water Pore Pressure

Understanding the influences of water level on seepage stability of tailing bay is an important topics in hydraulic engineering design. The seepage stability of tailing bay under different water level was calculated with the numerical simulation software FLAC3D and the change laws of water pore pressure and saturation line in the dam was analyzed. The results show that the saturation line in the dam is a parabolic curve and the pore pressure changes in layers. With the increasing of water level, the saturation line in the heaping dam ups rather obviously while it is not obvious in the initial dam. The maximum pore pressure in the bottom of the dam increases with the relationship of water level up, the shallow of the saturation line is in the heaping dam heel.

Dilatancy, pore fluids, and premonitory variations of ts/tp travel times

1972 ◽  
Vol 62 (5) ◽  
pp. 1217-1222 ◽  
Author(s):  
Amos Nur
Keyword(s):  
Ground Water ◽  
Travel Time ◽  
Pore Pressure ◽  
Travel Times ◽  
Pore Fluids ◽  
Subsequent Increase ◽  
Compressional Waves ◽  
Time Ratio ◽  
Laboratory Results ◽  
Focal Zone

Abstract Nerseov et al. (1969) found that the travel-time ratio of shear and compressional waves, ξ = ts/tp varies prior to the occurrence of earthquakes in the Garm region, USSR. Laboratory results indicate that the decrease of ξ can result from dilatancy of rocks around the focal zone. The subsequent increase of ξ, which terminates with an earthquake, can be caused by the flow of ground water into the dilated zone. The increasing pore pressure weakens the rock and leads to the observed failure.

scholarly journals PENGARUH MUKA AIR TANAH TERHADAP TEGANGAN EFEKTIF TANAH DASAR CANDI PRAMBANAN BERDASAR METODE ELEMEN HINGGA

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Tri Wahyu Kuningsih ◽  
Dwi Novi Wulansari
Keyword(s):  
Ground Water ◽  
Water Level ◽  
Pore Pressure ◽  
Effective Stress ◽  
Ground Water Level ◽  
Excess Pore Pressure ◽  
Physical Damage ◽  
World Cultural Heritage ◽  
Excess Pore

ABSTRACTIndonesia which geographically has an area located at 6º LU up to 11º LS and 97º BT up to 141º BT is an area prone to earthquakes. Determination of the temple as a world cultural heritage has implications for the responsibilities and obligations of the Indonesian people in an effort to protect and maintain the building in accordance with the conventions set by UNESCO. The convention, among others, is maintaining the preservation of buildings from the dangers of war, physical damage due to age, and natural disasters. This research was conducted with the aim to determine the effect of groundwater depth and earthquake acceleration on the strength of Prambanan Temple subgrade based on finite element method. Simplification of Siwa Temple as a modeling in software input. The results of the study are the shallower depth of the ground water level, the effective stress of the soil will also be reduced. When effective stress decreases, the strength of the soil will also decrease. The deeper the depth of the water table, the effective stress of the soil increases. The depth of the ground water level affects the amount of excess pore pressure. The more shallow the depth of the ground water level, the amount of excess pore pressure will also increase even the value is positive. The deeper the depth of the ground water level, the greater the amount of excess pore pressure decreases even the value is negative.Key words : Prambanan Temple, effective stresses, excess pore pressureABSTRAKIndonesia yang secara geografis mempunyai wilayah yang terletak pada 6º LU sampai dengan 11 º LS serta 97º BT sampai dengan 141º BT merupakan daerah yang rawan terhadap gempa bumi. Penetapan candi sebagai warisan budaya dunia berimplikasi pada tanggung jawab dan kewajiban bangsa Indonesia dalam upaya melakukan pelindungan dan pemeliharaan bangunan tersebut sesuai dengan konvensi yang telah ditetapkan oleh UNESCO. Konvensi tersebut antara lain menjaga pelestarian bangunan dari bahaya perang, kerusakan fisik karena termakan usia, dan bencana alam. Penelitian ini dilakukan dengan tujuan untuk mengetahui pengaruh kedalaman muka air tanah dan percepatan gempa terhadap kekuatan tanah dasar Candi Prambanan berdasar metode elemen hingga. Ilustrasi penyederhanaan Candi Siwa sebagai pemodelan dalam input perangkat lunak. Hasil penelitian adalah semakin dangkal kedalaman muka air tanah, maka tegangan efektif tanah juga akan berkurang. Pada saat tegangan efektif berkurang maka kekuatan tanah juga akan berkurang. Semakin dalam kedalaman muka air tanah, tegangan efektif tanah semakin meningkat. Kedalaman muka air tanah mempengaruhi besarnya excess pore pressure. Semakin dangkal kedalaman muka air tanah, besarnya excess pore pressure juga akan meningkat bahkan nilainya positif. Semakin dalam kedalaman muka air tanah, besarnya excess pore pressure semakin menurun bahkan nilainya negatif.Kata kunci : candi prambanan, tegangan efektif, excess pore pressure.

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