Effect of Nano-Carbon on Geotechnics Features of Gypseous Soils

2021 ◽  
Vol 895 ◽  
pp. 20-30
Author(s):  
Asaad M.B. Al-Gharrawi ◽  
Assad Layth Hayal ◽  
Mohammed Y. Fattah
Keyword(s):  
Friction Angle ◽  
Collapse Potential ◽  
Soil Cohesion ◽  
Before And After ◽  
Soil Settlement ◽  
Nano Carbon ◽  
Gypseous Soil

A Collapsing soil usually causes problems, this kind of soil has a substantial strength while it is dry, but it loses its strength while inundating and be subjected to extreme settlement. It is impossible to predict in advance the reactions of soils subjected to inundating (i.e. landslide otherwise an important soil settlement). The reduction in irreversible volumes of collapsing soil happens quickly as well as suddenly, once the reduction starts there will be no measurement to be executed which could halt such difficulty. As a result of the soak and leach that are resulting from the dissolute and clean out of gypsum, the collapsing potentials increase during the time. There are many studies in this field that indicated the possibility of modifying this soil by using nanomaterials. In this study, the nanomaterial used is nanocarbon and the soil is gypseous soil taken from Al-Najaf city in Iraq. This work studies the effect of adding nanomaterials on the gypseous soil and investigates its behavior before and after adding nanomaterial. The results showed that adding the nanocarbon affects the collapse potential which decreases by a percent meanwhile the soil cohesion decreased partly when the nanocarbon is added with 0.8% but the friction angle increased about 19%. The best proportion of using of the nanocarbon ranges between 0.8-1.2%.

Collapsibility and Shear Strength of Gypseous Soil Improved by Nano Silica Fume (NSF)

2020 ◽  
Vol 857 ◽  
pp. 292-301
Author(s):  
Alaa D. Al-Murshedi ◽  
Mahdi O. Karkush ◽  
Hussein H. Karim
Keyword(s):  
Shear Strength ◽  
Silica Fume ◽  
Dry Mass ◽  
Soil Samples ◽  
Nano Silica ◽  
Collapse Potential ◽  
Geotechnical Characteristics ◽  
Before And After ◽  
Problematic Soils ◽  
Gypseous Soil

The problematic soils have complex and irregular behavior such as gypseous soils, which concentrated mainly in the dry and semi-dry regions in the world. In Iraq, the gypseous soils cover about 30 to 35% of its total area in the west desert and extended to the southern parts of Iraq. The gypseous soils experience sudden collapse upon wetting. The present paper focuses on studying the effects of nano silica fume (NSF) on the collapsibility and shear strength of gypseous soil before and after soaking. Also, this study, the influence of NSF on the chemical and physical characteristics of gypseous soil have been investigated. A gypseous soil sample obtained from Al-Najaf Sea has gypsum content of 42%. The gypseous soil samples are mixed with three percentages of nano silica fume (1, 2, and 4) % calculated as ratio of the dry mass of soil to measure their influence on the geotechnical characteristics of soil samples. The collapse potential of gypseous soil is reduced with increasing the content of nano silica fume. Also, increasing the content of NSF and curing time resulted in increasing the shear strength of soil samples.

scholarly journals Geotechnical characteristics of some Iraqi gypseous soils

2018 ◽  
Vol 162 ◽  
pp. 01005 ◽  
Author(s):  
Tom Schanz ◽  
Hussein H. Karim
Keyword(s):  
Stress Level ◽  
Friction Angle ◽  
Liquid Limit ◽  
Test Results ◽  
Collapse Potential ◽  
Northern Iraq ◽  
Geotechnical Characteristics ◽  
Gypsum Content ◽  
Gypseous Soil

In Iraq, especially in the last three decades, extensive developments have been evidenced in the regions of gypseous soils due to the need of construction of many numbers of strategic projects. Failure of different structures constructed on gypseous soil in various regions in Iraq have been noticed. For this purpose, three areas in northern Iraq were selected (Samarra, Tikrit and Baiji) to study their geotechnical characteristics due to their high gypsum contents as well as many engineering problems are faced due to dissolution of gypsum. The experimental work involves testing of many properties such as: scanning electron microscopy (SEM), XRD, chemical, physical, compressibility, collapsibility, shear strength and suction. At low stress level, the test results revealed that, higher collapse potential (CP) is recorded for Tikrit soil. While at low stress level, higher CP is obtained for Baiji soil indicating the increase in CP with decreasing gypsum content. Furthermore, the CP significantly increases with increasing stress level and soaking period at a particular stress level. According to severity classification of the collapse potential, Baiji soil is considered as moderate trouble to slight, while Tikrit soil is considered as trouble to moderate. After soaking, both soils become trouble. As well as, the results showed a reduction in Tikrit soil shear parameters ( φ and c ) after soaking period of 6 and 24 hrs as 12.2 to 9.2% in the internal friction angle and 91.5 to 94.2% in cohesion, respectively with respect to dry condition. Maximum total suction is measured for low consistency soils (liquid limit < 30%) represented by Tikrit soil.

Numerical Investigation on the Pull-Out Behaviour of Suction Caissons in Clay

2006 ◽  
Author(s):  
Mostafa Zeinoddini ◽  
Mahmood Nabipour
Keyword(s):  
Aspect Ratio ◽  
Numerical Investigation ◽  
Production Systems ◽  
Friction Angle ◽  
Critical Issue ◽  
Order Effect ◽  
Offshore Structures ◽  
Pull Out ◽  
Soil Cohesion ◽  
Suction Caissons

Since their inception suction caisson foundations have presented themselves as proven means of anchoring floating production systems and fixed offshore structures. The pull-out capacity of suction caissons remains a critical issue in their applications, and in order to produce effective designs, reliable methods of predicting the capacity are required. In this paper results from a numerical investigation on the behaviour of the suction caissons in clays against pull-out loading have been presented. Soil nonlinearities, soil/caisson interactions and the effects from the suction on the behaviour have been taken into account. A linear relationship has been observed between the soil cohesion values and the pull-out capacity. Under drained conditions, beyond specific limits of soil cohesion values, the increase in the cohesion value have found to demonstrate no further influence on the pull-out capacity. The soil internal friction angle has been noticed to have an exponential increasing effect on the pull-out capacity. With constant values of the caisson diameter, an increase in the aspect ratio noticed to have a second order effect of the friction originated part and a linear influence on the cohesion originated part of the resistance. With constant values of the caisson length, an increase in the aspect ratio values has found to result in an exponential decrease of the pull-out capacity. Based on the obtained numerical results simple formulations and approximations have been proposed in order to estimate the effects of the studied parameters on the pull-out capacities.

scholarly journals Inverse distance weighting interpolated soil properties and their related landslide occurrences

2018 ◽  
Vol 195 ◽  
pp. 03013 ◽  
Author(s):  
Purwanto B. Santoso ◽  
Yanto ◽  
Arwan Apriyono ◽  
Rani Suryani
Keyword(s):  
Internal Friction ◽  
Slope Stability ◽  
Soil Properties ◽  
Hard Rock ◽  
Friction Angle ◽  
Inverse Distance Weighting ◽  
Central Java ◽  
Soil Cohesion ◽  
Distance Weighting ◽  
Inverse Distance

The causes of landslides can be categorized into three factors: climate, topographic, and soil properties. In many cases, thematic maps of landslide hazards do not involve slope stability analyses to predict the region of potential landslide risks. Slope stability calculation is required to determine the safety factor of a slope. The calculation of slope stability requires the soil properties, such as soil cohesion, the internal friction angle and the depth of hard-rock. The soil properties obtained from the field and laboratory investigation from the western part of Central Java were interpolated using Inverse Distance Weighting (IDW) to estimate the unknown soil properties in the gridded area. In this research, the IDW optimum parameter was determined by validation toward the percent bias. It was found that the IDW interpolation using higher weighting factor corresponds with a higher percent bias in case of the depth of hard-rock and soil cohesion, while the opposite was found for the internal friction angle. Validation to landslide incidents in western parts of Central Java shows that the majority of landslide incidents occur at depths of hard rock of 6 m-8 m, at soil cohesions of 0.0 kg/cm2-0.2 kg/cm2, and at internal friction angles of 30°-40°.

Study of Correlation on Unconfined Compressive Strength between Different Soil

2013 ◽  
Vol 838-841 ◽  
pp. 926-929
Author(s):  
Xia Zhao
Keyword(s):  
Compressive Strength ◽  
Soil Moisture ◽  
Moisture Content ◽  
Unconfined Compressive Strength ◽  
Laboratory Tests ◽  
Soil Moisture Content ◽  
Correlation Coefficients ◽  
Friction Angle ◽  
Silty Clay ◽  
Soil Cohesion

Take the silty clay and clay as the research object, the correlation between bulk density, moisture content, cohesion, friction angle and unconfined compressive strength was analyzed using laboratory tests, and the results showed that soil cohesion, friction angle and unconfined compressive strength with good correlation, the correlation coefficients were all above 0.9, while severe and soil moisture content and unconfined compressive strength of correlation is weak, followed by the correlation formulas of the index and unconfined compressive strength were established, these formulas can used to predict the unconfined compressive strength of soil.

Study on Creep and Fracturing of High Antidip Sandwich Rock Slope in High In Situ Stress

2013 ◽  
Vol 405-408 ◽  
pp. 527-534
Author(s):  
Qi Wu ◽  
Xu Biao Deng
Keyword(s):  
Rock Slope ◽  
Stereographic Projection ◽  
Friction Angle ◽  
Depression Angle ◽  
In Situ Stresses ◽  
Slope Excavation ◽  
Before And After ◽  
Projection Analysis ◽  
Intersection Line

The paper set an example of high antidip sandwich rock slope to study its creep and fracturing deformation in high in-situ stresses at Jinping First Stage Hydropower Station in China. The slope creep deformation before and after excavation could be found on slope face and in exploration adits. Displacements at 4 monitoring points on the slope were abnormal for influences of fault f42-9, zone SL44-1 and lamprophyre dike, which indicate creep and fracturing of the big block separated by them. Through stereographic projection analysis, intersection of controlling structural planes of the big block direct outside the slope. Its bottom slide face, fault f42-9, has internal friction angle smaller than depression angle of the intersection line. Barricade in front of the big block removed by slope excavation decreased resistance to slope slide. It is concluded that creep and fracturing deformation of the big block is controlling stability of the slope.

scholarly journals Analytical Instrumentation Techniques of FT-IR, XRD, SEM, and EDX for Adsorption Methods of Ni2+ Ions onto Low Cost Adsorbent

2021 ◽  
Vol 37 (6) ◽  
pp. 1324-1328
Author(s):  
Ajithkumar M ◽  
Arivoli S
Keyword(s):  
Low Cost ◽  
Thermal Action ◽  
Raw Material ◽  
Batch Experiments ◽  
Sem Images ◽  
Before And After ◽  
Ft Ir ◽  
Nano Carbon ◽  
Percentage Removal ◽  
Treated Carbon

The present study investigates the possible removal of Ni2+ ions from aqueous solution by using low-cost Hygrophila auriculata activated nano carbon (HA-ANC) as an adsorbent. The activated nano carbon had been prepared from Hygrophila auriculata stem waste as well; the raw material was carbonized with con. H2SO4 and activated by thermal action. Batch experiments were performed in order to calculate the percentage removal of Ni2+ ions for 90.737% at 60 oC. The properties of treated carbon and untreated carbon are compared using instrumental techniques such as FT-IR, XRD, SEM and EDX, which confirms Ni2+ ions adsorption onto HA-ANC. FT-IR showed that the surface of HA-ANC had more oxygen containing functional groups which enhanced the adsorption of Ni2+. XRD showed the nature of adsorbent, SEM images implies morphological deviance of before and after adsorption of Ni2+ onto HA-ANC and EDX showed that the C content of HA-ANC were higher than that of Ni2+/ HA-ANC.

scholarly journals Comparative Study between Silica Fume and Nano Silica Fume in Improving the Shear Strength and Collapsibility of Highly Gypseous Soil

2020 ◽  
Vol 27 (1) ◽  
pp. 72-78
Author(s):  
Ahmed Al-Obaidi ◽  
Marwa Al-Mukhtar ◽  
Omar Al-Dikhil ◽  
Saeed Hannona
Keyword(s):  
Shear Strength ◽  
Silica Fume ◽  
Friction Angle ◽  
Engineering Properties ◽  
Nano Silica ◽  
Direct Shear Tests ◽  
Apparent Cohesion ◽  
Gypsum Content ◽  
Wet Condition ◽  
Gypseous Soil

Soils with highly gypsum content signify known as soils that exhibit collapsibility and sudden failure when being submerged to wetting. Many of the constructions built on this soil showed cracked and/or collapsed at some parts as these soils immersed or leached with water. The utilization of extremely fine materials, for example, Microscale or Nanoscale, is generally utilized these days. This research compared the use of Silica fume (SF) (micro material) and Nano Silica fume (NSF) (Nanomaterial) to explore the capability of these very fine materials to mend the shear strength and collapsibility properties of highly gypseous soils. The soil as Poorly Graded Sand (SP) was used, with a gypsum amount equal to 62%. A succession of direct shear tests and double odometer tests were carried on dry and submarined specimens of soil at various percentages of SF and NSF. The obtained results indicate that mixing the highly gypseous soils with SF or NSF improved the engineering properties of these soils, especially for the wet condition. The average increment in apparent cohesion when adding SF (5-20) percentage varies between (140-310) % in dry soil and (20-40) % in soaked soil. Same results obtained when mixing the gypseous soils with (1-5) % of NSF. Also, the Nanomaterial provided an improvement of the friction angle in dry and submerged cases respectively. Considering that, the SF gives adverse results upon the friction angle of the soil. The SF and the NSF both condensed the dangers of gypseous soil collapsibility. Consequently, the use of NSF can be assertively suggested to improve the engineering characteristics of highly gypseous soils when compared with SF, where only mixing of 3% of NSF gives the best results.

scholarly journals Study on Application Effect of Sand Consolidating Agent for the Slope of Highway Subgrade in Season Frozen Zone

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Dongliang Zhang ◽  
Guangqing Yang ◽  
Xiaodi Niu ◽  
Lu Zhang ◽  
Zhijie Wang
Keyword(s):  
Compressive Strength ◽  
Friction Angle ◽  
Freeze Thaw ◽  
Direct Shear Tests ◽  
Thaw Cycle ◽  
Sand Body ◽  
Before And After ◽  
Freeze Thaw Cycle ◽  
Sandy Slope ◽  
Sand Particles

In deep season frozen areas, the solidified layer is easy to be destroyed due to the influence of freeze-thaw cycles after the surface layer of the sandy slope is solidified by chemical methods. In order to study the application effect of the new sand consolidating agent after solidifying sand body, the mechanism of strength formation was analyzed by scanning electron microscopy (SEM). The freeze-thaw cycle tests were carried out on sand consolidating samples. The direct shear tests and unconfined compressive strength tests were carried out before and after freeze-thaw cycles to analyze the freeze-thaw resistance of sand consolidating samples. The sand consolidation agent was tested on-site, and its strength was tested to observe its effect. The results showed that the adhesive membranes on the surface of sand particles were formed by the sand consolidating agent, which increased the cohesion and strength of sand particles. After freeze-thaw cycle tests, the cohesion, internal friction angle, and compressive strength of the solidified sand gradually decreased with increasing freeze-thaw cycles. The decreasing rate reduced from fast to slow and then tends to be stable. The failure mode of samples changed from brittle failure to plastic failure. The sand consolidating layer can effectively prevent collapse of the sandy slope. Combining with the external-soil spray seeding, the sand consolidation layer is beneficial to the growth of plants.

scholarly journals Impact of Plant Root Morphology on Rooted-Soil Shear Resistance Using Triaxial Testing

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Suyun Meng ◽  
Guoqing Zhao ◽  
Yuyou Yang
Keyword(s):  
Internal Friction ◽  
Root System ◽  
Root Morphology ◽  
Root Length ◽  
Friction Angle ◽  
Plant Roots ◽  
Distribution Characteristics ◽  
Soil Cohesion ◽  
Shearing Strength ◽  
Individual Root

Mechanical reinforcement by plant roots increases the soil shearing strength. The geometric and distribution characteristics of plant roots affect the soil shearing strength. Current research on the shear strength of rooted-soil is mostly based on direct shear tests with a fixed shear surface and thus cannot reflect the actual failure state of the rooted-soil. In this study, Golden Vicary Privet was used to create a rooted-soil, and a triaxial test method was used for soil mechanical property analysis. The influence of the root geometry (root diameter and individual root length) and distribution characteristics (root density and root distribution angle) on the rooted-soil shearing strength was studied by controlling the root morphology in the specimens. According to the results, both the root geometry and distribution characteristics affect the rooted-soil shearing strength. For a fixed total length of the roots, the longer the individual root length is, the better the soil shearing strength is. In addition, the reinforcement effect of the root system increases as the angle between the root and the potential failure surface increases. The results also show that the root system significantly enhances the soil cohesion while only minimally affecting the internal friction angle. The maximum rooted-soil cohesion is 2.39 times that of the plain soil cohesion, and the maximum internal friction angle of rooted-soil is 1.24 times that of plain soil. This paper provides an approach for the determination of the rooted-soil strength and a rationale for vegetation selection in ecological slope reinforcement applications.

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