Mechanical Behavior and Testing Methods of Unsaturated Soils

2009 ◽  
pp. 114-114-16 ◽  
Author(s):  
TB Edil ◽  
SE Motan ◽  
FX Toha
Keyword(s):  
Mechanical Behavior ◽  
Unsaturated Soils ◽  
Testing Methods

Modified State Surface Approach to Study Unsaturated Soil Hysteresis Behavior

2020 ◽  
Vol 2674 (10) ◽  
pp. 484-498
Author(s):  
Beshoy Riad ◽  
Xiong Zhang
Keyword(s):  
Mechanical Behavior ◽  
Unsaturated Soils ◽  
Construction Material ◽  
Constitutive Models ◽  
Experimental Results ◽  
Special Focus ◽  
Surface Approach ◽  
Hysteresis Behavior ◽  
Mechanical Hysteresis ◽  
Hydraulic Hysteresis

Unsaturated soils are often used as a construction material in transportation infrastructures. In this situation, unsaturated soils are subjected to cyclic mechanical loading from traffic loads or wetting-drying cycles in seasonal climatic conditions. While mechanical hysteresis is a common feature of soils in general, hydraulic hysteresis is associated with unsaturated soils. Although several constitutive models for unsaturated soils have been proposed, the mechanical and hydraulic hysteresis behavior of unsaturated soils has been little studied. A modified state surface approach (MSSA) was first proposed for investigating the mechanical behavior of unsaturated soils. It was then extended to study the coupled hydro-mechanical behavior of unsaturated soils with a special focus on the consistency between different soil phases. However, hydraulic and mechanical hysteresis were neglected in MSSA formulations. In this paper, based on evidence from experimental results, the MSSA is extended further to study the coupled hydro-mechanical hysteresis behavior of unsaturated soils. The extended MSSA can reproduce several forms of mechanical and hydraulic behavior observed in experimental results that cannot be represented by existing constitutive models. To demonstrate the capabilities of the extended MSSA, typical behaviors are simulated and compared, qualitatively, with the characteristic trends of the behavior of unsaturated soils. Experimental results from the literature are then used to evaluate the model to predict, quantitatively, the observed behaviors. The agreement between measured and predicted results is considered satisfactory and confirms the possibility of the proposed approach to reproduce the hysteresis behavior of unsaturated soils.

Theoretical Evaluation of the Mechanical Behavior of Unsaturated Soils

2010 ◽  
Vol 29 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Michinori Honda ◽  
Shintaro Ohno ◽  
Atsushi Iizuka ◽  
Katsuyuki Kawai ◽  
Hideki Ohta
Keyword(s):  
Mechanical Behavior ◽  
Unsaturated Soils ◽  
Theoretical Evaluation

A neural network framework for mechanical behavior of unsaturated soils

2003 ◽  
Vol 40 (3) ◽  
pp. 684-693 ◽  
Author(s):  
Ghassem Habibagahi ◽  
Alireza Bamdad
Keyword(s):  
Neural Network ◽  
Mechanical Behavior ◽  
Unsaturated Soils ◽  
Axial Strain ◽  
Volumetric Strain ◽  
Constitutive Law ◽  
Soil Conditions ◽  
Neural Network Approach ◽  
Network Simulations ◽  
Multilayer Perceptron Network

In this paper, a neural network approach is used to describe the mechanical behavior of unsaturated soils. A sequential architecture was chosen for the network, that is, a multilayer perceptron network with feedback capability. The input layer consisted of nine neurons, where six of them represented the initial soil conditions and the remaining three neurons were continuously updated for each increment of axial strain based on outputs from the previous increment. The output layer consisted of three neurons representing values of deviatoric stress, volumetric strain, and change in suction at the end of each increment. Next, a database was developed from triaxial test results available in the literature. The database was used to train and test the network. Neural network simulations were compared with experimental results. The comparison indicates the good performance of the proposed network for predicting the mechanical behavior of unsaturated soils. Moreover, the trained network was employed to simulate other stress paths not present in the database to model the so-called "collapse phenomena." The results were promising.Key words: unsaturated soil, neural network, stress–strain, collapse, modeling, constitutive law.

The mechanical behavior of unsaturated soils

1985 ◽  
Vol 22 (3) ◽  
pp. 173 ◽  
Author(s):  
D.R.P. Hettiaratchi ◽  
J.R. O'Callaghan
Keyword(s):  
Mechanical Behavior ◽  
Unsaturated Soils

Prediction of Coupled Hydro-Mechanical Behavior of Unsaturated Soils Based on Seasonal Variations in Hydrologic Conditions

2020 ◽  
Author(s):  
Majid Mahmoodabadi ◽  
Lindsey Sebastian Bryson
Keyword(s):  
Mechanical Behavior ◽  
Unsaturated Soil ◽  
Seasonal Variations ◽  
Unsaturated Soils ◽  
Wetting And Drying ◽  
Water Characteristics ◽  
Hydrologic Data ◽  
Prediction Approach ◽  
Hydrologic Conditions

Seasonal variations in hydrologic conditions greatly influence the hydro-mechanical properties of unsaturated soils. There are several models available to estimate shear strength of unsaturated soil under various hydrologic conditions. However, many of these existing models provide little to no data regarding the deformations associated with wetting and drying of unsaturated soils. The incremental hydro-mechanical behavior for an unsaturated soil is generally described by a constitutive framework. In this study, a modified-Sheng, Fredlund and Gens (SFG) soil constitutive model was utilized with in-situ hydrologic data to simulate fully coupled mechanical behavior for an unsaturated slope over different hydrologic events. This paper also presents a hydrological prediction approach to estimate hydrologic characteristics of unsaturated soils over several wetting and drying events using only the soil-water characteristics parameters of the main drying curve. The proposed approach provides a possibility of describing long-term hydrologic behavior of unsaturated soils by means of limited amount of in-situ hydrologic data. The outcome of this study provides geotechnical engineers with a capability of estimating deformational behavior of unsaturated soils under various real-time rainfall/evapotranspiration conditions and implementing more effective emergency planning.

An elastoplatic framework for coupling hydraulic and mechanical behavior of unsaturated soils

2009 ◽  
Vol 25 (3) ◽  
pp. 473-490 ◽  
Author(s):  
Kanthasamy K. Muraleetharan ◽  
Chunyang Liu ◽  
Changfu Wei ◽  
Tohren C.G. Kibbey ◽  
Lixia Chen
Keyword(s):  
Mechanical Behavior ◽  
Unsaturated Soils
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