scholarly journals Numerical study on bearing capacity of a pile group next to a slope in unsaturated soils

2020 ◽  
Vol 195 ◽  
pp. 01006
Author(s):  
Amirreza Pourfatollah ◽  
Ali Pirjalili ◽  
Aliakbar Golshani
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Numerical Study ◽  
Pile Group ◽  
Soil Strength ◽  
Strength Parameters ◽  
Water Characteristics ◽  
Soil Shear Strength

The bearing capacity of a pile group mostly depends on parameters of the soil shear strength affected by the soil-water characteristics, especially in unsaturated soils. The soil shear strength is entirely affected by hydraulic stresses in unsaturated soil, such as precipitation and evaporation. Further, the bearing capacity of the pile installed on unsaturated soil depends on hydraulic stresses applied to the soil. Furthermore, slope vicinity may cause a severe decline in the pile bearing capacity. The present study aimed to investigate a pile group in unsaturated soil adjacent to a slope and analyzed the effect of the rainfall on the soil strength parameters. Thus, a numerical study has been performed using a finite difference software,i.e., FLAC2D. Besides, to investigate the model in a real situation, the intensity and duration of rainfall are considered to evaluate changes in hydraulic stresses. Finally, the results show that the rainfall causes a considerable decrease in soil strength parameters in unsaturated soil, leading to the reduction of the pile group bearing capacity and slope stability.

scholarly journals Effect of Urease Enzyme on Shear Strength of Clay Shale

2018 ◽  
Vol 7 (4.36) ◽  
pp. 424 ◽  
Author(s):  
Maxwel Joseph Henri Nainggolan ◽  
Wiwik Rahayu ◽  
Puspita Lisdiyanti
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Triaxial Test ◽  
Clay Soil ◽  
Soil Strength ◽  
Clay Shale ◽  
Strength Performance ◽  
Enzyme Mixture ◽  
Urease Enzyme

In recent years, utilization of biotechnology in geotechnical field has rapidly grown. One of the biotechnologies being utilized is urease enzyme, a stabilization material by bio-cementation method studied in this research.  Urease enzyme is manually mixed with additional 10% of clay soil to clay shale. The objective of mixing it is to increase the bearing capacity of the clay shale. Consolidated undrained triaxial test was performed for testing the soil strength performance for samples that had undergone curing for 2, 4, and 6 weeks. The results indicated that the sample stiffens, proved by the increase of shear strength from consolidated undrained triaxial test. The shear strength value produced by the variation of the urease enzyme mixture + 10% the clay is higher than that of without the original clay shale.  

Capillary-based effective stress formulation for predicting shear strength of unsaturated soils

2015 ◽  
Vol 52 (12) ◽  
pp. 2067-2076 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Marc Lebeau
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Unsaturated Soils ◽  
Water Retention ◽  
Adsorbed Water ◽  
Soil Strength ◽  
Liquid Films ◽  
Degree Of Saturation ◽  
Stress Parameter ◽  
Effective Stress Parameter

A number of investigations have shown that the shear strength of unsaturated soils can be defined in terms of effective stress. The difficulty in this approach lies in quantifying the effective stress parameter, or Bishop’s parameter. Although often set equal to the degree of saturation, it has recently been suggested that the effective stress parameter should be related to an effective degree of saturation, which defines the fraction of water that contributes to soil strength. A problematic element in this approach resides in differentiating the water that contributes to soil strength from that which does not contribute to soil strength. To address this difficulty, the paper uses theoretical considerations and experimental observations to partition the water retention function into capillary and adsorptive components. Given that the thin liquid films of adsorbed water should not contribute to effective stress, the effective stress parameter is solely related to the capillary component of water retention. In sample calculations, this alternative effective stress parameter provided very good agreement with experimental data of shear strength for a variety of soil types.

scholarly journals Experimental and Numerical Study on Ultimate Shear Load Carrying Capacity of Corroded RC Beams

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhanzhan Tang ◽  
Zhixiang He ◽  
Zheng Chen ◽  
Lingkun Chen ◽  
Hanyang Xue ◽  
...  
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Cross Section ◽  
Loss Rate ◽  
Numerical Study ◽  
Rc Beams ◽  
Load Carrying ◽  
Shear Bearing Capacity ◽  
The Cross ◽  
The Impact

For an RC beam, the strength of steel rebar, the bonding strength between the concrete and reinforcement, and the bite action between the aggregates will deteriorate significantly due to corrosion. In the present study, 10 RC beams were designed to study the impact of corrosion on the shear bearing capacity. The mechanism of corrosion for stirrups and longitudinal bars and their effects were analyzed. Based on the existing experimental data, the correlation between the stirrup corrosion factor and the cross section loss rate was obtained. An effective prediction formula on the shear bearing capacity of the corroded RC beams was proposed and validated by the experimental results. Moreover, a numerical analysis approach based on the FE technique was proposed for the prediction of the shear strength. The results show that corrosion of the reinforcements could reduce the shear strength of the RC beams. The corrosion of stirrups can be numerically simulated by the reduction of the cross section. The formulae in the literature are conservative and the predictions are very dispersed, while the predictions by the proposed formula agree very well with the experiment results.

scholarly journals Role of hydromechanical properties of plant roots in unsaturated soil shear strength

2019 ◽  
Vol 7 (2) ◽  
pp. 133-138
Author(s):  
Anthony K. Leung ◽  
David Boldrin ◽  
Ali A. Karimzadeh ◽  
Anthony G. Bengough
Keyword(s):  
Shear Strength ◽  
Unsaturated Soil ◽  
Plant Roots ◽  
Soil Shear Strength

scholarly journals Measuring the Strength of Root-Reinforced Soil on Steep Natural Slopes Using the Corkscrew Extraction Method

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1135 ◽  
Author(s):  
Gerrit Meijer ◽  
Glyn Bengough ◽  
Jonathan Knappett ◽  
Kenneth Loades ◽  
Bruce Nicoll
Keyword(s):  
Shear Strength ◽  
Soil Analysis ◽  
Soil Strength ◽  
Effective Field ◽  
Reinforced Soil ◽  
Wind Loading ◽  
Rapid Estimation ◽  
Soil Shear Strength ◽  
Soil Component ◽  
Natural Slopes

Roots can help to stabilise slopes against landslides and anchor trees against wind loading, but their mechanical contribution to the strength of soil is difficult to rapidly quantify under field conditions. A new field measurement method, quantifying the shear strength of rooted soil by measuring the resistance against extraction of soil cores using a large corkscrew device, was tested across three heterogeneous slopes (unforested, forested and clearfelled) in Scotland. The presence of roots significantly increased the measured shear strength in the surface layer of the Sitka spruce forested slope. Differences in strength between the three areas were however not significant. This could be attributed to the large variation in the soil component of the combined root–soil shear strength, which was strongly affected by variations in both soil density and gravel content. Measured strength on these natural slopes were much more variable compared to previously investigated sites. These results highlight the importance of investigating the variation in soil strength during root-reinforcement measurements, and furthermore demonstrate the need for a sufficiently large number of tests to address this variation. The corkscrew provides rapid estimation of root-reinforced soil shear strength on sites with difficult accessibility. Compared to the more conventional shear vane method, which yielded comparable soil strength results, the corkscrew proved more suitable in stony soil layers and has the additional benefit of simultaneously extracting small (rooted) soil samples that could be used for further root and soil analysis. It therefore proved a useful and effective field tool for use when a rapid estimation of root-reinforced soil shear strength is required.

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