A method to predict desiccation crack depth in a compacted clayey soil

2021 ◽  
Author(s):  
Arash Hassanikhah ◽  
Gerald A. Miller ◽  
Amy B. Cerato
Keyword(s):  
Tensile Strength ◽  
Clayey Soil ◽  
Crack Depth ◽  
Matric Suction ◽  
Moisture Loss ◽  
State Variables ◽  
Near Surface ◽  
Desiccation Cracking ◽  
Incremental Strain ◽  
Desiccation Crack

Estimation of crack depths due to desiccation of clayey soils is needed to predict changes in mechanical or hydraulic properties in the cracked layer. Desiccation cracks are associated with increasing suction due to moisture loss accompanied by restrained shrinkage, which results in tensile stresses in near surface soil layers. A simple analytical method is presented to predict crack depths in compacted clayey soil due to changes in matric suction with depth. The model equation is based on the Hookean elastic equation relating incremental strain to incremental stress and incorporates two stress state variables including net normal stress and matric suction. Input to the model includes the tensile strength and elastic parameters, and to complete the prediction of crack depth, the suction change profile of interest is needed. The method validity was investigated by comparing predicted crack depths to those observed in soil compacted in a bench scale apparatus for studying desiccation cracking. Tensile strength and elastic properties were determined from tests conducted on soil during desiccation under approximate uniaxial conditions. Predicted crack depths were obtained based on changes in suction interpreted from water content sensors at various depths in the soil bed and compared favorably to observed desiccation crack depths.

scholarly journals The, K.M. A Study on the Relationship Between Matric Suction and the Void Ratio and Moisture Content of a Compacted Unsaturated Soil

2018 ◽  
Author(s):  
Minh The Kieu ◽  
András Mahler
Keyword(s):  
Moisture Content ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Void Ratio ◽  
Clayey Soil ◽  
Matric Suction ◽  
Moisture Ratio ◽  
Distinct Advantage ◽  
State Variables ◽  
Test Procedures

The volumetric behaviour of compacted unsaturated soils is particularly complex due to the co-existence of three different phases: solid, liquid and air. Matric suction has been perceived as a significant influence on the volumetric behaviour of unsaturated soils and has been used as one of the constitutive variables for most the constitutive models of unsaturated soils in the literature. However, suction-controlled works are complex in practice since they generally require special test procedures and advanced equipment, and usually are very time-consuming. Thus, some researchers have tried to seek alternative frameworks that use the traditional choice of state variables to simulate the behaviour of unsaturated soils. Recently, Kodikara [1] proposed the MPK framework to interpret the behaviour of compacted unsaturated soil in the void ratio (e) – net stress (p) – moisture ratio (ew ) space. The distinct advantage of the model is that it is based on traditional constant moisture content compaction testing which is more common and simple than constant suction loading. The MPK framework has been shown to be capable of presenting the volumetric behaviour of compacted unsaturated soils. However, this framework is expected to use not only for compacted soil but for the behaviour of unsaturated soil in general. The incorporation of soil suction within the MPK framework can be helpful for creating a correlation with previous models which used matric suction as a constitutive variable. This paper presents the development of LWSBS for one clayey soil in Hungary within the MPK framework and then suction is incorporated, which is related to void ratio and moisture ratio through SWCC.

Tensile strength of clayey soil and the strain analysis based on image processing techniques

2019 ◽  
Vol 253 ◽  
pp. 137-148 ◽  
Author(s):  
Hao-Da Li ◽  
Chao-Sheng Tang ◽  
Qing Cheng ◽  
Sheng-Jie Li ◽  
Xue-Peng Gong ◽  
...  
Keyword(s):  
Image Processing ◽  
Tensile Strength ◽  
Clayey Soil ◽  
Strain Analysis ◽  
Image Processing Techniques ◽  
Processing Techniques

Desiccation cracking of heterogeneous clayey soil: Experiments, modelling and simulations

2021 ◽  
pp. 108065
Author(s):  
Darith-Anthony Hun ◽  
Julien Yvonnet ◽  
Johann Guilleminot ◽  
Abdelali Dadda ◽  
Anh-Minh Tang ◽  
...  
Keyword(s):  
Clayey Soil ◽  
Desiccation Cracking ◽  
Modelling And Simulations

scholarly journals Climatological Features of the Weakly and Very Stably Stratified Nocturnal Boundary Layers. Part III: The Structure of Meteorological State Variables in Persistent Regime Nights and across Regime Transitions

2019 ◽  
Vol 76 (11) ◽  
pp. 3505-3527 ◽  
Author(s):  
Carsten Abraham ◽  
Adam H. Monahan
Keyword(s):  
State Variables ◽  
Surface Cooling ◽  
Atmospheric Flow ◽  
Near Surface ◽  
Vertical Coupling ◽  
Adjustment Time ◽  
Inversion Strength ◽  
Wind Profiles ◽  
Transition Times ◽  
Regime Transitions

Abstract The evolution of profiles of meteorological state variables during nights with and without transitions in the nocturnal stably stratified boundary layer (SBL) between weakly stable (wSBL) and very stable (vSBL) regimes, as classified by a hidden Markov model, is examined at nine different tower sites. During wSBL-to-vSBL transitions, inversion strengths increase, near-surface winds decelerate, and atmospheric layers vertically decouple. Turbulence kinetic energy (TKE) steadily decreases before wSBL-to-vSBL transitions and fluctuations of the vertical velocity become weak. In contrast to land-based sites where wSBL-to-vSBL transitions are normally caused by surface cooling, at sea-based stations the transitions generally are initiated by advection of warm air aloft. The vSBL-to-wSBL transition is characterized by a fast breakdown of the inversion strength, acceleration of wind profiles, and a restored vertical coupling of the atmospheric flow. TKE recovers on time scales of minutes first in atmospheric levels between 50 and 100 m. Profiles of state variables for the two different regimes during very persistent nights (nights without SBL regime transitions) are clearly separated and similar to structures during nights with transitions away from transition times. During very persistent nights the wind conditions stay relatively steady. Similarly, the temperature is steady after an initial adjustment time at sunset (wSBL) or shortly after sunset (vSBL). Even though nights with and without transitions are a common feature of the SBL, there is no clear indicator in Reynolds-averaged mean variables that distinguishes very persistent nights from nights with transitions.

Suction Measurements on a Saskatchewan Soil Using a Direct-Measurement, High-Range Suction Sensor

1997 ◽  
Vol 1596 (1) ◽  
pp. 84-92
Author(s):  
Delwyn G. Fredlund ◽  
Julian K-M. Gan ◽  
Yun Guan ◽  
Neil Richardson
Keyword(s):  
Tensile Strength ◽  
Direct Measurement ◽  
Negative Pressure ◽  
Laboratory Data ◽  
Matric Suction ◽  
Bridge Site ◽  
Cavitation Nuclei ◽  
The Town ◽  
High Range

A tensiometric-type suction sensor capable of direct measurement of matric suctions greater than 100 kPa has recently been developed. The sensor has been used to measure matric suctions up to 1250 kPa. The sensor makes use of the tensile strength of water for the measurement of matric suction. The cavitation of water in conventional tensiometers occurs at a negative pressure approaching 1 atmosphere because of the presence of cavitation nuclei. In the absence of cavitation nuclei, the tensile strength of water can be on the order of several atmospheres. The direct-measurement, high-range suction sensor has been used for the measurement of matric suction on borehole samples obtained during a soils investigation at a bridge site near the town of Outlook, Saskatchewan, Canada. The method has proven to be fast and simple to use. Matric suction measurements of the samples from the Outlook bridge site are presented, along with an interpretation of the laboratory data.

Modeling and Simulating Methods for the Desiccation Cracking

2019 ◽  
Vol 16 (05) ◽  
pp. 1840011
Author(s):  
Sayako Hirobe ◽  
Kenji Oguni
Keyword(s):  
Finite Element ◽  
Cell Size ◽  
Cell Formation ◽  
Coupling Model ◽  
Element Analysis ◽  
Weakly Coupled ◽  
Desiccation Cracking ◽  
Cell Topology ◽  
Dry Out ◽  
Desiccation Crack

The desiccation cracks can be observed on dry-out soil fields or other various materials under desiccation. These cracks have a net-like structure and tessellate the surface of the materials into polygonal cells. The averaged cell size changes systematically depending on the size of the specimen. In spite of the varieties of the materials, these fundamental features of the cell topology are conserved. This implies the existence of the governing mechanism behind the desiccation crack phenomenon regardless of the materials. In this paper, the desiccation crack phenomenon is modeled by the coupling of desiccation, deformation, and fracture. We perform simulations for the reproduction of the desiccation cracking based on this coupling model. In the simulations, the finite element analysis for the desiccation problem and the analysis of particle discretization scheme finite element method for the deformation and the fracture problems are weakly coupled. The results of the simulations show the satisfactory agreements with the experimental observations in terms of the geometry of the crack pattern, the increase tendency of the averaged cell size depending on the size of the specimen, and the hierarchical sequence of the cell formation. These agreements indicate that the proposed model and method capture the fundamental features and the mechanism of the desiccation cracking.

scholarly journals FLEXURAL REINFORCED CONCRETE ELEMENTS NORMAL SECTION BEARING CAPACITY EVALUATION IN FRACTURE STAGE

2017 ◽  
Vol 9 (2) ◽  
pp. 70-78 ◽  
Author(s):  
Justas SLAITAS ◽  
Zbynek HLAVAC ◽  
Arnoldas ŠNEIDERIS
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Crack Depth ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Assessment Process ◽  
Reinforced Concrete Structures ◽  
Compression Zone ◽  
Normal Section

This article examines flexural reinforced concrete structures condition assessment process in existing buildings on the stage where the reinforcement stress is between the yield and the tensile strength. The research is made on V. Jokūbaitis proposed methodology directly measuring the compression zone height, allowing us to evaluate the behavior of reinforced concrete beam fracture sufficiently precisely. This paper confirms the hypothesis that, when reinforcement reaches yielding stress, elastic strain dominates in concrete‘s compression zone and it is reasonable to use triangular concrete compression zone diagram, without tensile concrete above crack evaluation. The methodology of reinforced concrete structures bearing capacity assessment according to limit normal section crack depth is proposed. There is established connection between bending moments, when reinforcement achieve yielding stress and tensile strength, which allows us to decide about structures bearing capacity reserve. The results are confirmed with experimental studies and calculated values obtained by methodologies based on different reduced stress diagrams of concrete‘s compressive zone.

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