scholarly journals Vertical Electrical Sounding (VES) investigation for road failure along Mekelle – Abi-Adi road segment, northern Ethiopia

2021 ◽  
Vol 13 (1) ◽  
pp. 134-146
Author(s):  
Gebreslassie Mebrahtu ◽  
Solomun Atsbaha ◽  
Berihu Abadi Berhe
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Mass ◽  
Vertical Electrical Sounding ◽  
Road Segment ◽  
Northern Ethiopia ◽  
The Road ◽  
Subsurface Geology ◽  
Asphalt Road ◽  
Electrical Sounding

Roads constructed along the mountainous terrains of Ethiopia are susceptible to landslides mostly during rainy season. Mekelle – Abi Adi road is one of the economically important road corridors that connects many towns with Mekelle city. However, the asphalt road segment is heavily affected by quasi-translational type of landslide which hinders traffic flow of the area. Vertical electrical sounding (VES) method was applied to investigate subsurface geology of the road failure along Mekelle – Abi-Adi asphalt road, northern Ethiopia. The geo-electric section result revealed that the shallow subsurface geology of the site is characterized by four distinct geological formations, from top to bottom are: shale, shale-limestone intercalation, limestone and shale-gypsum units. The subgrade of the failed road section is shale unit which is overlain by jointed sandstone unit. The sandstone unit serves as a recharge zone to the bottom shale layer by percolating water via sub-base fill materials which in turn blocks vertical percolation and promote seepage force to the overlying soil mass. Hence, the road failure in the study area seems to be caused due to the development of pore water pressure in the shale layer which soaked water during heavy rainfall. The recommended remedial method for the road failure is re-designing of the affected route from chainage 48 km+850 m to 49 km+250 m towards the northwest of the study area and excavates the top 6 m shale unit.

Downslope movements at shallow depths related to cyclic pore-pressure changes

1993 ◽  
Vol 30 (3) ◽  
pp. 464-475 ◽  
Author(s):  
K.D. Eigenbrod
Keyword(s):  
Pore Water ◽  
Slip Surface ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Ground Surface ◽  
Soil Mass ◽  
Passive Resistance ◽  
Pressure Changes ◽  
Timber Piles

Slow, shallow ground movements in a slope near Yellowknife caused excessive tilting of timber piles that supported an engineering structure. To avoid damage to the structure, the pile foundations had to be replaced by rigid concrete piers that were designed to resist the forces of the moving soil mass. Downhill movements were rather slow and, during an initial inspection, were indicated only by soil that was pushed up against a series of piles on their uphill sides, while gaps had formed on their downhill sides. No open cracks or bulging was observed on the slope. A stability analysis indicated that the slope was not in a state of limit equilibrium. To obtain a better understanding of the creep movements in the slope and their effect on the rigid concrete piers, extensive instrumentation was carried out after the construction of the piers. This included slope indicators, piezometers, thermistors, and total-pressure cells against one of the concrete piers. In addition, a triaxial testing program was undertaken in which the effect of cyclic pore-water pressure changes on the long-term deformations of the shallow clay layer was investigated. From the data collected in the field and laboratory, it could be concluded that (i) tilting of the original timber piles was caused by downslope movements related to cyclic pore-water increases; (ii) the lateral soil movements increased almost linearly with depth from 2 m below the ground surface, with no indication of a slip surface; and (iii) the pressures exerted by the moving soil mass against the rigid concrete piers within the soil mass were equal to the passive resistance activated within the moving soil mass. Key words : soil creep, slope movements, soil pressures, pore-water pressures, freezing pressures, permafrost, cyclic loading.

ANISOTROPIC CONSOLIDATION OF LEDA CLAY

1969 ◽  
Vol 6 (3) ◽  
pp. 271-286 ◽  
Author(s):  
L. K. Walker ◽  
G. P. Raymond
Keyword(s):  
Stress Ratio ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Volumetric Strain ◽  
Soil Mass ◽  
Plastic Strain Increment ◽  
Anisotropic Consolidation ◽  
Leda Clay ◽  
Stress Ratios ◽  
Effective Principal

Under field loading conditions, the consolidation of a clay layer is likely to take place under effective principal stress ratios (σ1′/σ3′), which vary from point to point throughout the soil mass. From a consideration of idealized stress paths, an estimate is made of the effect of stress ratio on rates of volumetric strain and excess pore water pressure dissipation. These predictions are partly supported by data obtained from anisotropic consolidation tests on Leda clay, the major disagreements being due to the significant influence of structural cementation on the rate process.The experimentally observed rates of shear strain have been analyzed in terms of stress-dilatancy concepts. The plastic strain-increment ratio was shown to be a unique function of effective stress ratio, thus confirming the validity of previous work on remoulded clays. A theoretical prediction of this relationship postulated by Burland (1965) did not approximate to the experimental data, due probably to the influence of secondary deformations. The data did, however, show a relationship similar in form to that derived by Walker (1969) for the secondary deformation of remoulded kaolin.

Research on Influencing Factors of Drainage Performance in Engineering

2012 ◽  
Vol 212-213 ◽  
pp. 671-678
Author(s):  
Xu Shu Sun ◽  
Jian Lin Li ◽  
Xiao Liang Xu ◽  
Jian Rrong Li ◽  
Fei Liu
Keyword(s):  
Influencing Factors ◽  
Small Angle ◽  
Permeability Coefficient ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Mass ◽  
Vertical Permeability ◽  
Horizontal Drainage ◽  
Drainage Hole ◽  
Better Than

In order to control the seepage and eliminate the adverse effects, influencing factors of drainage in engineering are discussed in this paper. The drainage holes are simulated by rod element to study the influence of drainage performance on angle and length. Compared the drainage performance of drainage galleries in different location, the optimal assembly is obtained. Meanwhile, drainage performance is analyzed by different permeability coefficient and anisotropy of rock and soil mass. The results show that: (1) Drainage flow of small angle and short drainage hole is close to big angle and long one, the small angle flows more than the big angle when increasing the same length. (2) Shallow drainage galleries can significantly drop the free surface and the deep one can greatly decrease the pore water pressure. Drainage galleries built at the upstream side and bottom, as the optimum assembly, can enormously change the seepage field. (3) For anisotropy materials, the horizontal drainage performance is better than vertical when Ky/Kx decreases. On the contrary, vertical is superior to the horizontal. Increasing vertical permeability coefficient is benefit to drainage.

Simplified Computation of 1D Consolidation for Unsaturated Soil when Air Phase Neglected

2010 ◽  
Vol 168-170 ◽  
pp. 298-302
Author(s):  
Hao Feng Xu ◽  
Kang he Xie
Keyword(s):  
Unsaturated Soils ◽  
Laboratory Tests ◽  
Continuity Equation ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Mass ◽  
Excess Pore Water Pressure ◽  
One Dimensional ◽  
Consolidation Model ◽  
Consolidation Analysis

It is a complicated problem for consolidation analysis of unsaturated soils. Nowadays’ theories are very theoretical, and the parameters in them are so many that it is difficult to solve the equations, i.e., they are not excellently fit for application in engineering. So it is significant to get a simplified theory for consolidation analysis of unsaturated soils. In this paper, according to the phenomena observed in consolidation’s experiments for unsaturated soils, it is assumed that pore-air pressure undergoes an instantaneous dissipation and the consolidation of unsaturated soils can be described as the process of dissipation of excess pore-water pressure. Then a simplified consolidation model is put forward. And based on the principle of the whole soil mass conversation, the continuity equation is founded. Subsequently one- dimensional consolidation equation is derived, which is similar to Terzaghi’s equation for consolidation of saturated soils. Finally, the numerical results from the derived equation are compared with the experimental results from laboratory tests reported in the literature, and the agreement is good. It can be concluded that the hypothesis is rational and the simplified computation is practical in engineering.

Monitoring of Inland Tide Embankment of Binzhou Port

2014 ◽  
Vol 1065-1069 ◽  
pp. 499-502 ◽  
Author(s):  
Jian Shan Gao
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Mass ◽  
Monitoring Data ◽  
Structure Stability ◽  
Integrated Monitoring ◽  
Initial Stage ◽  
Hyperbolic Curve ◽  
Settlement Monitoring

For the purpose of foundation and structure stability during the construction of tide embankment, three monitoring projects including embankment settlement monitoring, berm platform settlement monitoring and pore water pressure monitoring are installed. Integrated monitoring data shows that foundation appears oversize instantaneous settlement on account of high construction speed, short loading interval at initial stage. Following with the shaping of embankment, stable monitoring data range, slow change rate and high dissipation speed of pore water pressure come along. Based on actual embankment settlement data, consolidation degree of soil mass is high and foundation stability becomes strong by means of hyperbolic curve.

scholarly journals A Study on Correlation between Pore Water Pressure, Rainfall and Landslide Occurrence

2013 ◽  
Vol 4 (2) ◽  
pp. 24-27
Author(s):  
Suhaimi D.N.A.A ◽  
Selaman O. S.
Keyword(s):  
Pore Water ◽  
Heavy Rainfall ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Microsoft Excel ◽  
Exponential Relationship ◽  
Saturation Condition ◽  
Landslide Occurrence ◽  
The Road ◽  
Landslide Event

Landslides not only include loss of human lives and properties, but also effect the transportation direct and indirectly. This study focus on the correlation between rainfalls and pore water pressure which lead to landslide event. For this study, the scope of study focuses at Bau, Sarawak whereby lot of landslide event occurs along the road in 2009. Triaxial test is conduct in lab to measure pore water pressure which modeling landslide occurs on 11th January 2009 at KM 72.00 Bau-Lundu Road. From the laboratory test, it can be seen that continuous and heavy rainfall will increase the pore water pressure in soil. When the pore water pressure increase from 809.94 kPa to 829.25 kPa, the strength of the soil will be decrease due to the water content inside the soil. Other than that, correlation between pore water pressure and rainfall can be seen as an exponential relationship by plotting agraph using Microsoft Excel. It indicates that continuous rainfall within 11 days will increase the changes in pore water pressure and causes the soil to be in fully saturation condition. After 27 hours, the soil will be in failure which leads to landslide.

scholarly journals Identification of liquefaction disaster in Jondul Rawang, Padang City West Sumatra

2020 ◽  
Vol 156 ◽  
pp. 01004
Author(s):  
Utami Dewi Arman ◽  
Rafki Imani ◽  
Afrilda Sari ◽  
Widiawati Purba
Keyword(s):  
Rainfall Intensity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Peat Soil ◽  
Drainage System ◽  
Secondary Data ◽  
Soil Mass ◽  
Primary Data ◽  
Intensity Increase ◽  
West Sumatra

Liquefaction is a condition of continuous soil mass deformation at residual stress due to increasing pore water pressure that results in effective stress reduced. This study was conducted to identify the potential hazards of liquefaction in the Jondul Rawang area in Padang City. This study is to observe the soil contour and characteristics. Primary data obtained by observing the soil contour, soil characteristics, and the form of buildings, etc. Whilst, secondary data obtained from the related documents as supporting data. The results concluded that the Jondul Rawang area is potentially liquefaction area where the soil contours and characteristics could be classified as peat soil and lied in the swamps. Furthermore, if the rainfall intensity increase then flooding occurred. Then as consequences, there were many residential houses and other buildings around the area turning into tilted and drowned due to the degradation of soil bearing capacity. Therefore, requiring disaster management efforts against the threat of liquefaction in that area, both in terms of the drainage system due to flooding and overall repairs for the sewerage could work well.

Evolution of the factor of safety following excavation in clay

2009 ◽  
Vol 46 (5) ◽  
pp. 487-493 ◽  
Author(s):  
J. S. L’Heureux ◽  
S. Leroueil ◽  
J. F. Laflamme
Keyword(s):  
Pore Pressure ◽  
Factor Of Safety ◽  
Clayey Soil ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Mass ◽  
Eastern Canada ◽  
Soft Clays ◽  
Clay Deposits ◽  
The Difference

Numerical analyses have been performed to study the evolution of the factor of safety following the excavation of a cut in clay. The analyses consider variable thickness of the clayey soil deposit under the excavation. The results show that, for a given clayey soil, there is a relation between the time for full dissipation of excess pore-water pressure from the soil mass following the excavation and the geometry of the cut (Htot/Hexc). The analytical results agree reasonably well with pore pressure measurements made in excavations in clay deposits from eastern Canada. This suggests that time to reach full pore pressure equilibration following the excavation of a cut in homogenous clayey soil deposits can be predicted when knowledge of the coefficient of swelling–consolidation is available. Lastly, results obtained in the present study show that 50% of the difference between the short- and long-term factors of safety may be lost at values as low as about 8% of the time to reach equilibration of pore pressures. This means that the time during which one can rely on the short-term strength of the clayey soil following the excavation may be relatively short, especially for soft clays.

scholarly journals Pengaruh Beban Kendaraan sebagai Beban Terbagi Rata terhadap Deformasi Geogrid sebagai Perkuatan Embankment

2012 ◽  
Vol 8 (1) ◽  
pp. 31
Author(s):  
Adhe Noor Patria
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Vertical Displacement ◽  
Soil Mass ◽  
Vehicle Load ◽  
Surcharge Load ◽  
The Difference ◽  
High Level

<p>Soft soil such as clay was sensitive soil. Public contructions built in this kind of soil would face some problemssuch as long period consolidation time, unstable embankment slope, not easily compacted and high level settlement. Some solution that could be suggested were the usage of vertical drain, or the usage of geosynthetics material such as geogrid combined with floating  piles.Analysis was carried out by using plaxis version 7.2. soil for embankment and embankment foundation was modelled in plane strain. Also geogrid andfloating piles were modelled in palne strain too. Surcharge load on top of embanknet were variated, they were 20, 35 and 50 kPa. The simulation was carried out in staged contruction mode.Final vertical displacement in geogrid due to 50  kPa vehicle load as surcharge load and long term load period (in this case excess pore water pressure was small) was -0,9062 m for  rigid embankment and -1,4206 for interface embankment. The difference occured due to slip at the interface of geogrid and soil. It  leaded to adding soil mass supportd by geogrid, furthermore the deflection of geogrid became bigger.</p>

Sign in / Sign up

Export Citation Format

Share Document