scholarly journals A GEOTECHNICAL ASSESSMENT OF USABILITY OF A ROCKSOIL MIXTURE FOR EARTH STRUCTURES

AGROFOR ◽  
2018 ◽  
Vol 2 (3) ◽  
Author(s):  
Eugeniusz ZAWISZA ◽  
Andrzej GRUCHOT

The subject-matter of the work is a mixture of rock and soil from the LafargeDubie mine in Rudawa, southern Poland. The conducted tests aimed at thedetermination of the geotechnical characteristics of this mixture and the evaluationof its suitability for the construction of earth embankments, in particular road ones.The range of the tests comprised determination of parameters characterisingphysical properties, such as granulometric composition, natural moisture content,density of solid particles, optimum moisture content and maximum dry density ofsolid particles, as well as mechanical ones, like shear strength. The obtained resultsshow that the tested mixture is suitable for the construction of road embankments,since as coarse-grained soil, it has a high value of the uniformity coefficient (Cu =1913). Therefore, this is very well graded soil, which provides a good compactionwhen it is built into the embankment. The natural moisture content (on average wn= 9.5%) is close to the optimum one (wopt = 8.5%). The maximum dry density ofsolid particles (ds = 2.16 gcm-3) is much higher than the minimum required (d ≥1.6 gcm-3). The values of the angle of internal friction (on average  = 36) andcohesion (c = 42 kPa) indicate great shear strength, therefore this soil can besubjected to considerable mechanical stresses.

The aim of the present study is to determine the physical and geotechnical characteristics of municipal solid waste (MSW) from an open dump site located in Una town, Himachal Pradesh (India) for the analysis of settlement and structural stability of landfill. Degraded waste was tested for different time intervals ranging from 6 months to 6 years. The physical characterization and the geotechnical tests were performed to determine the composition and the engineering properties of MSW respectively. The presence of moisture content in the fresh waste was 49.5±1.05% but for the degraded (or old) waste it varied between 39.8 to 51.6%. The specific gravity of fresh and old waste varied between 1.83±0.05 and 1.85 for 6 months old waste and 2.28 for 5-6 years old degraded waste respectively. The maximum dry density (MDD) was observed to be 4.28 kN/m2 for fresh waste at the optimum moisture content (OMC) of 78.1% and 4.47 kN/m3 for 6 months old waste and 6.25 kN/m3 for the degraded waste of 5-6 years at 80.2, 85.4% of OMC respectively. The hydraulic conductivity (k) of MSW was found to be decreasing with the degradation of MSW and the overburden pressure whereas the shear strength increased along with the degradation of the waste. The cohesion (c) and angle of internal friction (φ) increased respectively from 31.2 kPa(fresh) to 38 kPa(degraded) and 14° to 22° with the increase in waste degradation. The compression ratio of fresh waste was within the ranges of 0.19-0.29 and for degraded MSW it varied between 0.12 for 6 months old waste and 0.17 for 5-6 years old degraded waste respectively.


Author(s):  
Simeon O Odunfa ◽  
Adebayo O. Owolabi ◽  
Peter O. Aiyedun ◽  
Obanisola M. Sadiq

Pavement failure has contributed immensely to loss of lives, disruption to normal daily activities and increase amount of money being spent on maintenance annually. One of the causes is associated with inadequate investigations on subgrade materials. This study aimed at examining the geotechnical parameters as factors of pavement failure along Lagos–Ibadan Expressway. Samples were collected at the failed and stable portions on some selected road segments and subjected to laboratory tests including Natural Moisture Content (NMC), Linear Shrinkage(LS), particle size distribution and California Bearing Ratio(CBR). The NMC along the failed sections was on the high side (ranged from 13.11% to 26.89%) compared with the stable sections (ranged from 11.11% to 16.40%). Most of the tested soils have percentage passing 0.075mm sieve more than 35% maximum required by the Federal Ministry of Works and Housing for subgrade materials. The maximum dry density(MDD) for the samples at failed and stable sections ranged from 1550 kg/m3 to 1860 kg/m3; 1650 kg/m3 to 1980 kg/m3 respectively while the Optimum Moisture Content(OMC) ranged from 8.30% to 20.30%. The soaked CBR values ranged from 2% to 17% while the unsoaked values ranged from 4% to 25%. The increase in NMC along the failed portions could be as a result of high water table along these sections. Some of the materials at failed locations had values of LS > 8% which suggests high susceptibility to shrinkage and swelling which results in differential settlement and contributed to pavement failure along these sections of the road. Keywords: Geotechnical, Pavement failures, subsurface investigations, Expressway, subgrade materials.


2021 ◽  
Vol 9 (1) ◽  
pp. 16-20
Author(s):  
Iyad Alkroosh ◽  
Ali Al-Robay ◽  
Prabir Sarker ◽  
Saif Alzabeebee

This paper investigates the influence of sand content on the mechanical behavior of a low plasticity clay that collected from south of Iraq (Sumer town). Samples have been prepared with sand contents of 0%, 10%, 20%, 30%, and 40% of the clay weight. Standard Proctor and unconfined compression tests have been carried out and the optimum moisture content, maximum dry density, and undrained shear strength have been determined. The results show a gradual increasing trend of the maximum dry density with the increase of the sand content up to 30%. The highest dry density reaches 1.90 g/cm3 corresponding to an optimum moisture content of 12%. In addition, this paper shows that the undrained shear strength is inversely proportional to the increase of the percentage of sand. The results of this work provide a useful addition to the literature regarding the behaviour or low plasticity clay-sand mixture.


2021 ◽  
Author(s):  
Iyad Alkroosh ◽  
◽  
Ali Al-Robay ◽  
Prabir Sarker ◽  
Saif Alzabeebee ◽  
...  

This study investigated the influence of sand content on the mechanical behaviour of a low plasticity clay found in Iraq. Samples were prepared with sand contents of 0%, 10%, 20%, 30%, and 40% of the weight of the clay. Standard Proctor and unconfined compression tests were carried out and the optimum moisture content, maximum dry density, and undrained shear strength were determined. The results showed a gradual increasing trend of the maximum dry density with the increase of the sand content up to 30%. The highest dry density reached was 1.90 gm/cm3 corresponding to an optimum moisture content of 12%. In addition, it was also found that the undrained shear strength was inversely proportional to the increase of the percentage of sand. Thus, the dry density of the clay could be increased well above 1.70 g/cm3, which is the minimum dry density accepted as a compacted subgrade according to the Iraqi General Specifications for Roads and Bridges (2003); hence, the rejected low plasticity clay could be utilised by mixing with sand. The reasons for the increase of the dry density and the decrease of the undrained shear strength has been extensively discussed in the paper.


2020 ◽  
Vol 3 ◽  
pp. 12-25
Author(s):  
Olaoluwa Oluwaniyi ◽  
Imoleayo Fatoyinbo ◽  
Akinola Bello ◽  
Joshua Owoseni

Failure of highway pavement and collapse of building in basement complex of Nigeria is often related to the instability of the residual. This study evaluated the strength characteristics of gneiss-derived residual Soils as materials usable for road pavement structures. A total of eleven soil samples derived from granite gneiss were subjected to laboratory geotechnical analyses based on standard practices. The geotechnical analyses reveal the soils’ natural moisture content, specific gravity, grain sizes, consistency limits, shearing strengths, maximum dry density, and optimum moisture content. Based on AASHTO classification, the soil samples are classified as A-7-6, A-6, and A-7-5. The results of the laboratory analyses revealed that the natural moisture content and specific gravity ranged from 8.30 to 22.70% and 2.6 to 2.8 respectively. Particle size analysis reveals that the coarse contents of the soils ranged from 28.8% to 59.8% and amount of fines ranged from 40.2 to 71.2%. The liquid limit ranged from 31.3% to 68.3%, plastic limit ranged from 20% to 28.0%, plasticity index ranged from 4.8% to 38.90% and linear shrinkage ranged from 5.7 to 13.6%. The maximum dry density ranged from 1481 kg/m3 to 1921 kg/m3 and optimum moisture content ranged from 15.2% to 27.6%. Undrained triaxial shear strength (Cu) ranged from 43.0 Kpa to 250.3Kpa, angle of friction ranges from 11.7 to 29.30, and unconfined compressive strength ranged from 153 to 356.5Kpa. The results indicate that the residual soils are poor sub-grade and foundation materials due to their high amount of fines, linear shrinkage values, plasticity, and swelling potential, as well as low maximum dry density.


2021 ◽  
Vol 3 (2) ◽  
pp. 1-5
Author(s):  
O. E Agbasi

A good road network consists of a constant stretch of asphalt laid down for a smooth ride. The spot in the smooth ride on the pavement is commonly referred to as "pavement failure." Soil type, load bearing capacity of materials, zone of vulnerability, resistance to permeation, compressibility, shrinkage limit, and other details are frequently required in order to construct a very good and solid foundation for the planned bridge site. In Nigeria, numerous factors contribute to the failure of road construction projects. They are primarily insufficient research on subgrade and other pavement materials (sub-base and base courses) prior to the start of road projects; flawed engineering, including a poor drainage system and supervision throughout road construction; and shoddy workmanship that was superimposed with asphaltic concrete to improve strength. Within the Niger Delta basin, the study area is located between latitude 5.485°N and longitude 7.035°E. The Benin Formation underpins the study area. It is composed primarily of friable sands, conglomerates, very coarse sandstone, and isolated gravel units, as well as intercalation of Pliocene to Miocene shale/clay lenses. Natural Moisture Content (NMC), Linear Shrinkage (LS), Particle Size Distribution, and California Bearing Ratio were among the laboratory tests performed on samples collected at failed and stable sections of some selected road segments (CBR). When compared to the stable sections, the NMC along the failed sections was on the high side (ranging from 13.11 percent to 26.89 percent) (ranging from 11.11 percent to 16.40 percent). The majority of the tested soils passed the 0.075mm sieve with a percentage greater than the Federal Ministry of Works and Housing's maximum of 35% for subgrade materials. The maximum dry density (MDD) for the samples at failed and stable sections was 1550 kg/m3 to 1860 kg/m3; 1650 kg/m3 to 1980 kg/m3; and the Optimum Moisture Content (OMC) was 8.30% to 20.30%. The soaked CBR values ranged from 2 to 17 percent, while the unsoaked values ranged from 4 to 25 percent.


2020 ◽  
Vol 5 (12) ◽  
pp. 67-75
Author(s):  
Stella Nwaife Chibuzor ◽  
Elizabeth lfeyinwa Okoyeh ◽  
Boniface Chukwukadibia Ezeanyaoha Egboka

Regolith derived from Nanka Formation; Southeast Nigeria was evaluated for their geotechnical characteristics. The methods of investigations include Fieldwork experiment and laboratory analysis of water and soil samples. The result of hydraulic parameters of the soil at 1meter, 2 meters depth and drilled cuttings from boreholes revealed permeability average values of 1.29E-05(cm/s) and 9.15E-6(cm/s), hydraulic conductivity average value of 1.27E-04(cm/s) and 8.93E-05(cm/s). Drilled cuttings from three boreholes revealed permeability average value of 8.15E-06(m/s), 2.68E-06(m/s) and 6.20E-06, hydraulic conductivity average values of 8.90E-03(m/s), 2.92E-03(m/s) and 6.75E-3(m/s).These values indicate permeable soil with high hydraulic conductivity typical of silty-clay and sand. The permeability/hydraulic conductivity accounts for the high infiltration/percolation of water into the soil. Infiltration of water through the soil initiates geochemical reactions and dissolution mineral which leaves the soil loose and unconsolidated. Geotechnical characteristics show low to medium plasticity and a liquid limit average of 42.36 and 35.45, indicating the capacity of the soil to absorb moisture and expand, bulk density average value of 1.90 mg/m3and compaction test of maximum dry density average value of 1.80 g/cm3 at an optimum water content average of 12.89% indicate low density. Shear strength components of cohesion values range from 0 to 55KN/m2 with average value of 25 KN/m2 and friction angle values range from 7° to 25° suggesting low cohesion and angle of internal friction. This is attributed to the low clay content and the cohesive force is not enough to sustain the soil. Field experiments of cone penetration test of in-situ results indicate a weak and incompetent soil material that is unstable and vulnerable to erosion. The finding would be relevant in soil mechanics problems.


2019 ◽  
Vol 26 (1) ◽  
pp. 20-25
Author(s):  
Adnan Jayed zedan ◽  
Rizgar Ali Hummadi ◽  
Sarah Abdullah Hussein

Gypseous soil which is used is taken from Tikrit city in Salah Aldeen government and specially from Tikrit University from a depth (1.5-2)m, It’s type is sandy gravely with a small percentage of silt and clay while the percentage of gypsum is (34-36)%, The tests on soil is standard proctor compaction, direct shear, collapsibility and California bearing ratio. The number of samples is (70). The effect of adding concrete waste (2, 4, 6 and 8%) and waste of Asphalt mixture (2, 4, 6 and 8) % on dry soil, as well as the effect of mixture of the optimum percentages of both additions on the properties of gypseous soil, is the aim of the study. Adding concrete waste at optimum percentage (6)% causes an increase maximum dry density at (16)% and a decrease in optimum moisture content at (5)%. Whereas adding concrete mixture waste in its optimum percentage (2)% caused a decrease in maximum dry density values with an increase of optimum moisture content, and when adding mixture of optimum percentage of waste, an increase happened in the M.D.D.(14)% with a decrease in O.M.C. at (4)%. Adding the optimum percentage (8) % for both. Value of cohesion increases (100)% when adding concrete waste with an increase in the angle of internal friction (14)% and a decrease in collapsibility in a percentage of (90)%, while adding waste of asphalt mixture shows an increase in cohesion value (112)% with a decrease in the angle of internal friction (2)%and a decrease in collapsibility in a percentage of (90)%, when adding mixture of optimum percentages the value of cohesion increase (108)% with an increase in angle of internal friction (14)%and a decrease in collapsibility in a percentage of (91)%. Values of California Bearing Ratio in dry and soaked condition increases (49)% when adding (8)% of concrete wastes which is the optimum percentage, while adding waste of asphalt mixture causes a decrease in the value of C.B.R. and the optimum percentage is (2)% , but adding optimum percentages mixture of them causes an increase in values of (52)% in dry condition and (53)% in soaked condition.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Foad Buazar

Abstract This study reports the synthesis and potential application of biocompatible silica nanoparticles for subgrade soil stabilization. Nanosilica preparation as a major component from wheat husk ash is systematically studied and confirmed by FTIR, ICP, XRD, and TEM analyses. The produced biogenic nanosilica showed an amorphous structure with an average size of 20 nm. Upon loading various green nanosilica contents, our results show an improvement in the key parameters including Atterberg’s limits, maximum dry density, optimum water content, and shear strength of treated soil. Under optimal loading condition, the nanosilica-mediated soil analyses reveal a significant increase in the plastic and liquid limits by factors of 1.60 and 1.24 whereas plasticity index is declined by a factor of 0.78 rather than untreated soil specimen. The treated soil demonstrates a superior increase in the angle of internal friction, cohesion, shear strength, and maximum dry unit weight by factors of 2.17, 3.07, 2.21 and 1.5, respectively. The California Bearing Ratio (CBR) strength of nanosilica-cured soil presents a substantial increase by a factor of 5.83 higher than the corresponding original subgrade soil. We obtained the maximum increase in strength parameters of modified soil at the optimum biogenic nanosilica content of 1.5%.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yonglong Qu ◽  
Wankui Ni ◽  
Fujun Niu ◽  
Yanhu Mu ◽  
Jing Luo ◽  
...  

Freeze-thaw interface in unsaturated coarse-grained soil (CGS) is a weak plane which can cause slope failures in cold regions. This study presents a series of large-scale direct shear tests on freeze-thaw interface in CGS through a temperature control system. The tested soil was taken from a high slope in the Qinghai-Tibet Plateau. It was remolded with three dry densities (1.9, 2.0, and 2.15 g/cm3) and three moisture contents (9.0%, 11.5%, and 14.0%). With testing results, direct shear curves mainly performed as hardening deformation, and they were affected considerably by specimen conditions. The shear strength increased with both the increasing dry density and normal stress, but it was opposite with moisture content changed. The cohesion and internal friction angle increased with the increase in dry density but decreased with the moisture content. The particle movement and water migration of freeze-thaw interface in CGS during the test were significant, and they had close relations with the shear properties of specimens. And, an empirical model was produced to express the effect of pore ice on the shear strength of interface during the shear test. The tests and analysis in this study may provide useful references for CGS slope stability analysis in high cold regions.


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