scholarly journals Numerical Analysis of the Geotechnical Problems of Seepage Effects underneath Chafta Weir, North East of Amara City

2020 ◽  
Vol 55 (2) ◽  
Author(s):  
Riaed S. Jassim Alsiede
Keyword(s):  
Safety Factor ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Harvesting ◽  
Foundation Soil ◽  
North East ◽  
Common Problems ◽  
Piping Erosion ◽  
Southern Iraq ◽  
Geotechnical Problems

Seepage is a very important issue in the design and construction stages of hydraulic structures and represents one of the most common problems in dams. This study aims to estimate seepage and piping erosion in the foundation soil, especially downstream (toe), of Chafta weir, north east of Amara city, Southern Iraq. Chafta weir is part of the water harvesting project in the area. This project will play an important economic and environmental role in the future development of the eastern Maysan area and is also significant as it is the first water harvesting project in the province. A simulation model was created by SEEP/W software to calculate the amount of seepage, the distribution of pore-water pressure under the weir foundation, seepage velocity and hydraulic gradient. Then, the actual safety factor of the weir was calculated. Seepage depends mainly on the head differences between upstream and downstream weir sides. Seepage causes piping erosion and increasing the uplift pressure below weir body, so factor of safety must include all these factors. The safety factor showed that the suggested weir body is relatively stable.

The Research of Pore Water Pressure Effect on the Slope Safety Factor Based on Flac

2012 ◽  
Vol 166-169 ◽  
pp. 1433-1436 ◽  
Author(s):  
Hai Bo Liu ◽  
Li Hua Zhang ◽  
Da Hao Lin
Keyword(s):  
Pore Water ◽  
Safety Factor ◽  
Pressure Effect ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slope Safety

On the basis of the Australian Computer Society(ACADS)`s typical questions1(a),first, regardless of the slope in the case of pore water pressure, used FLAC procedure calculate the safety factor, the result was very close to the reference answer given by ACADS, we can see the accuracy of FLAC. Then, applied to the slope of different pore water pressure, obtained safety factor under corresponding conditions, then, we found that the pore water pressure had effect on the slope safety factor, but the influence are not same, when the pore water pressure less than a certain value, the influence are very small, but, when the pore water pressure exceeded this value, the influence became very large.

Security Control Method of Loading for Surcharge Preloading Based on the Stress Path

2011 ◽  
Vol 368-373 ◽  
pp. 2795-2803
Author(s):  
Heng Hu ◽  
Yan Li ◽  
Zhi Liang Dong ◽  
Yan Luo ◽  
Gong Xin Zhang
Keyword(s):  
Pore Water ◽  
Safety Factor ◽  
Control Method ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Stress Path ◽  
Excess Pore Water Pressure ◽  
Surcharge Preloading ◽  
Security Control ◽  
Excess Pore

All the time, security control method of loading is an important research part in the surcharge preloading, which is directly related to safety of the construction process. Starting from the stress path, discussing the variation of excess pore water pressure and relationship between stress path and security, and bringing forward the control method with a safety factor Fs based on the stress path. By measuring the change of excess pore water pressure, the control method with a safety factor Fs can reflect quantitatively the security status of soil and achieve the purpose of the process control, finally the security control method including the safety factor of loading and speed control is put forward to monitor construction safety. The safety factor of loading Fs is verified and back analyzed with the finite-element software, getting the correction factor from 0.90 to 1.20.

Predicting the long-term performance of a wide embankment on soft soil using an elastic–viscoplastic model

2010 ◽  
Vol 47 (2) ◽  
pp. 244-257 ◽  
Author(s):  
M. R. Karim ◽  
C. T. Gnanendran ◽  
S.-C. R. Lo ◽  
J. Mak
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Element Analysis ◽  
Foundation Soil ◽  
Vertical Permeability ◽  
Input Material ◽  
Modified Cam Clay ◽  
Long Term Performance ◽  
Term Performance

This paper presents modelling of the consolidation of foundation soil under a wide embankment constructed over soft soil. An elastic–viscoplastic (EVP) constitutive model is used to represent the foundation soil for the coupled finite element analysis (FEA). A unit-cell analysis is carried out to capture the maximum settlement and the development of excess pore-water pressure with time below the centreline of the embankment for a long period (9 years). A new function for capturing the varying nature of the creep or secondary compression coefficient is proposed and used in association with the EVP model. The input material parameters for this study were determined from extensive laboratory experiments except for the equivalent horizontal permeability, which was systematically estimated by using vertical permeability data obtained from one-dimensional consolidation tests and by back-analysing the first 12 months of field settlement data. Comparisons are made among the predictions obtained adopting an elastoplastic modified Cam clay model and the EVP model with constant and varying creep coefficients for the foundation soil and the corresponding field data. The predictions with the EVP model are found to be better than those with the elastoplastic model and the use of a varying creep coefficient for the EVP model seems to further improve its predicting ability.

scholarly journals PENURUNAN OPRIT JEMBATAN SEMARANG LINGKAR UTARA DAN JEMBATAN KALI JAJAR DEMAK JAWA TENGAH DENGAN PRE-FABRICATED VERTICAL DRAIN

2021 ◽  
Vol 4 (1) ◽  
pp. 27
Author(s):  
M Zaki ◽  
Wardani SPR ◽  
Muhrozi Muhrozi
Keyword(s):  
Bearing Capacity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soil Improvement ◽  
Unit Weight ◽  
Fast Time ◽  
Foundation Soil ◽  
Vertical Drain ◽  
Long Time

<p><em>Construction on soft soil, often creates problems. The Semarang North Ring Bridge and Kali Jajar Bridge are the Recent soft Marine Alluvium zones located in the Pantura area which have very soft soil characteristics with a depth of more than -30.0 meters this has resulted in a very large settlement due to very small grains, flood, rob, pore water pressure increases so that the shear strength of the soil will be small, the compression is large and the permeability coefficient is small so that if the construction load exceeds the critical bearing capacity, the damage to the foundation soil will occur. To get the increase in soil bearing capacity, it can be achieved by changing the properties of the soil from the shear angle (</em>f<em>), cohesion (c) and unit weight (</em>g<em>). The settlement can be reduced by increasing the cavity density from the compression of the soil particles (Wesley, 1977). Soil improvement takes a long time, aiming to increase shear resistance so that it requires a fast time in this case is to use Pre-Fabricated Vertical Drain (Bowles 1981). The results of the analysis of the pattern of decline and the effectiveness of the use of PVD (pre-fabricated vertical drain) at the Oprit Bridge in the two research locations have the same decrease in the range of the same heap height at (H = 4 meters) there is a decrease of 117.53 cm at 64 months on the bridge. Kali Jajar (STA. 3 + 200) and there was a decrease of 268.94 cm at 37 months at the Semarang North Ring Bridge</em></p>

scholarly journals Genesis of the glaciotectonic thrust-fault complex at Halk Hoved, southern Denmark.

2012 ◽  
Vol 60 ◽  
pp. 61-80
Author(s):  
Tillie M. Madsen
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Ice Sheet ◽  
Thrust Fault ◽  
Complex Deformation ◽  
North East ◽  
Macro Scale ◽  
Scandinavian Ice Sheet ◽  
Late Weichselian ◽  
Southern Fringe

The coastal cliff of Halk Hoved, southern Jutland, Denmark, is a major glaciotectonic complex formed by proglacial deformation of the North-East (NE) advance from the Scandinavian Ice Sheet in Late Weichselian. We describe and interpret the pre-, syn- and post-tectonic sedimentary successions and macro-scale architecture of this complex. Initially, the Lillebælt Till Formation (unit 1) and the overlying glaciofluvial sediments (unit 2) were deposited during the Warthe glaciation in Late Saalian. During the NE advance towards the Main Stationary Line (MSL) in Late Weichselian, these sediments were pushed along a décollement surface whereby a thrust-fault complex was formed. In a cross section the complex extends for more than 900 m and consists of eighteen c. 15–20 m thick thrust sheets stacked by piggyback thrusting. Accumulated displacement amounts to at least 235 m along thrust faults dipping at 30–40° towards N-NE, resulting in at least 24% glaciotectonic shortening of the complex. Deformation was presumably facilitated by elevated pore-water pressure in the Lillebælt Till Formation. As the compressive stress exceeded the shear strength of the weakened till, failure occurred, and a décollement horizon formed along the lithological boundary between the Lillebælt Till Formation and the underlying aquifer. During deformation, piggyback basins formed wherein sediments of hyperconcentrated flow (unit 3) and glaciolacustrine diamicton (unit 4) were deposited. The whole thrust-fault complex and the intervening sediments were truncated subglacially as the NE advance finally overrode the complex. Following the retreat of the NE advance, a succession of glaciofluvial sediments (unit 5) and finally the East Jylland Till Formation (unit 6) were deposited during the advance of the Young Baltic Ice Sheet. The Halk Hoved thrust-fault complex is a prominent example of glaciotectonism at the southern fringe of the Scandinavian Ice Sheet.

scholarly journals ANALISIS PENGARUH TEKANAN AIR PORI PADA LERENG YANG DIPERKUAT DENGAN GEOTEKSTIL

2021 ◽  
Vol 4 (1) ◽  
pp. 139
Author(s):  
Satria Seprianto ◽  
Andryan Suhendra
Keyword(s):  
Tensile Strength ◽  
Pore Water ◽  
Safety Factor ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slope Reinforcement ◽  
Slope Safety

ABSTRACTInfrastructure development in Indonesia is growing  rapidly. With the large number of infrastructure developments in various slope topographies, it is one of the locations that is part of this development. The slope area is prone to landslides so that strengthening is necessary. One of the reinforcement that can be done is with geotextiles. In its installation, it is necessary to calculate the correct length and strength of the geotextile for reinforcement. The tensile strength and length of the geotextile as well as the parameters of the embankment affect the safety factor of slope construction. One of the factors being considered is the pore water pressure which reduces the slope strength. So that the results of this study will show how much the influence of pore water pressure on slope reinforcement with geotextiles. After analysis, it was found that the increase of pore water pressure resulted in decreasing of slope safety factor.ABSTRAKPembangunan infarstruktur di Indonesia berkembang sangat pesat. Dengan banyaknya pembangunan imfrastruktur di berbagai topografi lereng menjadi salah satu lokasi yang menjadi bagian dalam pembangunan tersebut. Daerah lereng rawan akan terjadinya longsor sehingga perlu dilakukan perkuatan. Salah perkuatan yang dapat dilakukan adalah dengan geotekstil. Dalam pemasangannya dibutuhkan perhitungan panjang dan kuat geotekstil yang tepat untuk perkuatan. Kuat tarik dan panjang geotekstil serta parameter tanah timbunan mempengaruhi faktor keamanan konstruksi lereng. Salah satu faktor yang dipertimbangkan adalah tekanan air pori yang menjadi penurunan kekuatan lereng. Sehingga hasil studi ini akan menunjukkan seberapa besar pengaruh tekanan air pori pada perkuatan lereng dengang geotekstil. Setelah dilakukannya analisis didapatkan bahwa kenaikan tekanan air pori mengakibatkan penurunan nilai faktor keamanan lereng.

Numerical analysis and monitoring of Pappadai dam

2005 ◽  
Vol 42 (6) ◽  
pp. 1631-1643 ◽  
Author(s):  
Piernicola Lollino ◽  
Federica Cotecchia ◽  
Lidija Zdravkovic ◽  
David M Potts
Keyword(s):  
Numerical Analysis ◽  
Soil Structure ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Constitutive Models ◽  
Foundation Soil ◽  
Reservoir Impoundment ◽  
Stiff Clay ◽  
Pressure Changes ◽  
Deformation Patterns

This paper presents a case history for the construction of the Pappadai dam in Italy. The dam is constructed from rockfill, with an upstream bituminous membrane, and is built on stiff clay foundations. The instrumentation of the dam and of the foundation soil provides detailed insight into the deformation patterns and pore-water pressure changes during dam construction and for the subsequent 7 years. Two-dimensional plane-strain finite element analyses, using fairly simple constitutive models for soil and rockfill behaviour, were performed to reproduce the soil–structure interaction so that the effects of reservoir impoundment, which has yet to be carried out, could be investigated. The paper shows that a careful choice of parameters and an understanding of the mechanical behaviour of the in situ soils can result in satisfactory predictions of the overall soil–structure interaction.Key words: rockfill, stiff clay, dam, field data, numerical analysis.

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

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.

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

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.

Sign in / Sign up

Export Citation Format

Share Document