Article
Engineering, Geological
Zhiqiang Lin, Jiangu Qian, Zhenhao Shi, Qian Zhai
Summary: This study examines the uniqueness of strength parameters for coarse- and fine-grained unsaturated soils with bimodal soil-water retention curves (SWRCs) using the suction stress concept. The results show that both types of soils exhibit a bilinear strength envelope in the suction stress-shear strength plane, which differs from unsaturated soils with unimodal SWRC.
ENGINEERING GEOLOGY
(2022)
Article
Computer Science, Interdisciplinary Applications
Zhiqiang Lin, Jiangu Qian, Zhenhao Shi
Summary: This study introduces a novel model to estimate the shear strength of expansive soils. Experimental results show a linear relationship between capillary suction stress and shear strength, but the friction angle contributed to shear strength is different from the internal friction angle of saturated soils.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Ke Chen, Xuzhen He, Fayun Liang, Daichao Sheng
Summary: Estimating capillary pressure's contribution to effective stress is essential for studying mechanical and hydraulic behavior of unsaturated soils. Based on experiments, we find that degree of saturation (Sr) is a better variable than matric suction (s) for modeling Bishop's effective stress parameter (chi). We introduce wet area fraction as an alternative to chi, considering the influence of hydraulic hysteresis and pore size distribution on shear strength through the soil water retention curve (SWRC). This model requires soil material parameters in the reference state and can predict strength characteristics in different mechanical or hydraulic states.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Engineering, Geological
Houman Soleimani-Fard, Diethard Koenig, Meisam Goudarzy
Summary: This research evaluated the shear strength parameters of fine-grained soils, finding that ductile behavior was more noticeable in samples with lower suctions and higher straw contents. The shear strength significantly increased with an increase in suction, and the shear band inclination was influenced by both suction and straw content.
Article
Engineering, Geological
Tuan A. Pham
Summary: This paper presents a new generalized equation for estimating the shear strength of unsaturated soils. The equation takes into account the interaction of air, water, and solid phases, as well as the effect of particle contact area, which is often neglected in existing equations. Compared to existing equations, the proposed equation can capture the nonlinear influence of saturation degree and matric suction on unsaturated shear strength. Experimental data and comparison with other equations demonstrate the validity and superiority of the proposed equation.
INTERNATIONAL JOURNAL OF GEOMECHANICS
(2022)
Article
Engineering, Environmental
Tuan A. Pham, Melis Sutman
Summary: This study presents a new shear strength equation for unsaturated soils based on the micromechanical model and disturbed state concept. The model considers the solid contact area ratio, which is often neglected in existing equations. The results show that the proposed model accurately predicts the shear strength of unsaturated soils and performs better than other existing models. Additionally, the model takes into account the effect of temperature on unsaturated shear strength.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2022)
Article
Engineering, Geological
Kwestan Salimi, Amy B. Cerato, Farshid Vahedifard, Gerald A. Miller
Summary: The paper presents a general model for the tensile strength characteristic curve (TSCC) which establishes a relationship between the tensile strength versus water content in unsaturated soils. The model considers the differences in the characteristics of capillary and adsorptive mechanisms and interparticle forces, which cause dissimilarities in the resultant tensile strength characteristic curve in different soil types. The proposed model was validated against laboratory-measured tensile strength reported in the literature for 10 soils, showing greater predictive accuracy than several alternative models, particularly for clayey soils at low water contents.
JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING
(2021)
Article
Engineering, Geological
Omar Al Hattamleh, Samer Rababah, Ahmad Alawneh, Ahmad Alqawab'ah
Summary: The study experimentally verified the unified effective stress theory based on suction stress through unconfined compressive strength test and indirect tensile test. The theory was found applicable and valid within a certain range of water content, with the addition of fiber causing fluctuations but improving the soil's mechanical properties.
GEOTEXTILES AND GEOMEMBRANES
(2021)
Review
Polymer Science
Junran Zhang, Jiahao Liu
Summary: This study summarizes the effects of biopolymers on soil's engineering properties and the main directions of current research. It discusses the advantages and disadvantages of different biopolymer materials and their effects on specific engineering characteristics of soil, as well as factors such as source, viscosity, pH, and cost. The study also highlights the importance of understanding the variation laws of biopolymer-treated soil in different environmental conditions to promote safer and more scientific application in geotechnical engineering practice.
Article
Energy & Fuels
Kwestan Salimi, Amy B. Cerato, Farshid Vahedifard, Gerald A. Miller
Summary: This study presents a temperature-dependent model for the tensile strength characteristic curve (TSCC) of unsaturated soils. The model incorporates the effects of temperature into adsorptive and capillary suction stress components, showing good agreement with laboratory-measured data. This model can improve the accuracy of desiccation cracking analysis in unsaturated soils.
GEOMECHANICS FOR ENERGY AND THE ENVIRONMENT
(2021)
Article
Computer Science, Interdisciplinary Applications
Leonardo Maria Lalicata, Agostino Walter Bruno, Domenico Gallipoli
Summary: This paper presents an analytical method that predicts the horizontal capacity of piles in unsaturated soils. The method extends the Broms approach to account for the combined effect of the groundwater table and the apparent cohesion of the unsaturated soil. It calculates the maximum horizontal force and bending moment sustained by the pile for different head fixities, considering non-dimensional parameters related to the pile's geometry, flexural resistance, soil resistance, and failure mechanism. The proposed method accurately predicts the lateral capacity of piles, emphasizing the importance of considering the partially saturated state of the soil.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Engineering, Geological
Suman Roy, Sathiyamoorthy Rajesh
Summary: In this study, a novel tensile strength framework is proposed to determine the tensile strength characteristic curve (TSCC) of both coarse- and fine-grained soils over the entire saturation range. The variation of the parameters for the TSCC model for different types of soils, testing methods, and sample preparation methodologies is critically assessed. The proposed framework is validated with experimental data sets for both coarse- and fine-grained soils, showing good agreement in most cases.
INTERNATIONAL JOURNAL OF GEOMECHANICS
(2023)
Article
Geochemistry & Geophysics
Lifeng Zeng, Longtan Shao
Summary: The effective stress equation for unsaturated soil is the most important equation in unsaturated soil mechanics. In this study, a new three-phase physical model is proposed to consider the gradient of the pore water content in the balance equations of different constituent phases. By comparing the result with the total balance equation, a generalized Terzaghi's effective stress equation is derived, which ensures a smooth and continuous transition from unsaturated to saturated conditions. This equation can provide a better choice for estimating the effective stress in unsaturated soils by considering the different pressure effects and transformations between capillary water and adsorbed water.
Article
Chemistry, Multidisciplinary
Mehmet Ugur Yilmazoglu, Askin Ozocak
Summary: This study conducted experiments on model footings of different types and sizes on saturated silty soil layers with different saturation degrees and void ratio values, and proposed a new equation for characterizing the ultimate bearing capacity (UBC) of shallow foundations on unsaturated silty soils. The UBC of unsaturated soils can be determined based on the results of unconfined compressive strength tests (UC) measured on unsaturated soil samples and based on the degree of saturation and the fitting parameter.
APPLIED SCIENCES-BASEL
(2023)
Article
Soil Science
Xinjun Huang, Tusheng Ren, Rainer Horn
Summary: Wheeling induces compression and shearing forces on soils, leading to changes in hydraulic, gaseous, and thermal properties. This study investigates the effects of compaction and shearing on soil mechanical properties, specifically the pore water pressure and effective stress. The results suggest that compaction and shearing increase pore water pressure, ultimately reducing soil strength. Therefore, it is crucial to consider field water content, traffic loading, and wheeling speed to minimize soil structure and stability destruction caused by wheeling.
EUROPEAN JOURNAL OF SOIL SCIENCE
(2023)