Download or read book A Constitutive Model for Fiber reinforced Soils written by Cheng-Wei Chen and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fiber inclusion to improve the properties of compacted soil is becoming increasingly common in geotechnical engineering projects. However, the technique requires extensive testing on soil and fiber samples before it can be implemented. Although research performed over the last few decades has evaluated certain fiber-reinforced soil properties and formations, the development of constitutive models for fiber-reinforced soil has lagged. This dissertation aims to minimize testing requirements for fiber-reinforced specimens and thereby to encourage the implementation of fiber-reinforced soils in engineering. Extensive testing on unreinforced and reinforced silty and Ottawa sand specimens was performed to develop and to validate a constitutive model for predicting the stress strain-volume-pore pressure response of fiber-reinforced soils. Results showed that the effective friction angle and cohesion intercept increased significantly in consolidated undrained CU) and consolidated-drained (CD) triaxial compression tests for both fiber-reinforced silty sand and Ottawa sand. The shear strength parameters of fiber-reinforced silty sand and Ottawa sand are strain dependent so more shear strain was needed to mobilize fiber resistance for specimens consolidated at higher effective stresses. Moreover, the laboratory results suggested that fiber-reinforcement provides both a deviatoric (q[function]) and a hydrostatic (p[function]) contribution to the stresses in the specimens. However, the hydrostatic contribution of fibers varied according to different soil types and loading conditions. The proposed constitutive model to predict the mechanical properties of fiber-reinforced soils is based on superposition of the response of unreinforced soil and the response due to fibers. Key assumptions in the model include: (1) fibers are uniformly distributed in the specimens. (2) [integral] mob accounts for the reductions in fiber strain due to relative slip between the fibers and the soil, and varies with effective consolidation stress, soil types, and loading conditions, (3) yielding is considered, (4) shear distortion ([for all] is equal to triaxial shear strain ([for all]q), (5) the total axial strain in the fibers ([for all] t) is equal to 0.25 times axial strain plus 1.68 times volumetric strain from tests on unreinforced specimens, and (6) the initial p[function] 0 and q[function] 0 are used to account for the compaction, extrusion, and consolidation process. The model was found to be capable of reproducing the deviatoric stress well for all reinforced silty sand and Ottawa sand. The predicted pore pressure and volumetric strain were all in a close agreement with the observed behavior up to large strains for both soils. However, the predicted volumetric strain behavior shows some tendency to over-predict the dilatancy of the reinforced silty sand specimens consolidated less than 20-psi (140-[kappa]Pa). The predictions in fiber deviatoric and hydrostatic stresses in CU tests matched reasonably well and followed the same trends as the measured behavior, except for specimens consolidated at higher effective stresses. In CD tests, the deviatoric and hydrostatic stresses matched reasonably well and mimicked the measured behavior, but tended to deviate slightly from the observed response at large strains.

Download or read book Development of a Constitutive Model for Fiber reinforced Soils written by Ricardo J. Romero and published by . This book was released on 2003 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the research was to develop a model to predict the effective stress-strain-pore pressure-volume change behavior of fiber-reinforced soils from the superposition of the response of unreinforced soil and the response attributed to fibers. Consolidated-undrained triaxial compression tests (CU tests) and consolidated-drained triaxial compression tests (CD tests) were performed on comparable fiber-reinforced and unreinforced soil specimens. The results of these tests indicate that the inclusion of fibers significantly improves the strength of soils, and increases the peak strength as well as the strain to failure. Fiber-reinforcement increased both the cohesion intercept ( c ' ) and the effective stress friction angle ([straight phi] ' ). It was found that c ' and [straight phi] ' are strain dependent. Reinforced specimens sheared under undrained conditions exhibited higher pore pressure than unreinforced specimens. Under drained conditions, reinforced specimens showed significantly less dilation than unreinforced specimens, which is in agreement with the response observed in undrained tests. It was postulated that these responses are caused by an "internal confining stress" provided by the fibers. Based on the results of laboratory tests, a model is proposed to predict the stress-strain-pore pressure-volume change behavior of fiber-reinforced soils. The key components of the model include mechanism to account for initial stresses in the fibers induced during compaction, saturation, and consolidation; stresses induced during shearing of the specimens; stresses due to volume changes in the specimen; and, finally, pullout or yielding of the fibers. The proposed model is capable of reproducing very well the stress-strain behavior. Pore pressures and volume changes are well predicted at shear strains less than 10 percent and under consolidation pressures less than 550 kPa. However, pore pressures and volume changes are not well predicted at larger strains.

Download or read book Constitutive Modeling of Soils and Rocks written by Pierre-Yves Hicher and published by John Wiley & Sons. This book was released on 2013-03-01 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: This title provides a comprehensive overview of elastoplasticity relating to soil and rocks. Following a general outline of the models of behavior and their internal structure, each chapter develops a different area of this subject relating to the author's particular expertise. The first half of the book concentrates on the elastoplasticity of soft soils and rocks, while the second half examines that of hard soils and rocks.

Download or read book Fiber reinforcement of Soils and Stability Analysis of Reinforced Foundation Soils written by Chardphoom Viratjandr and published by . This book was released on 2006 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Incremental Constitutive Model for Geofiber Reinforced Soil written by Kexin Ma and published by . This book was released on 2004 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geofiber reinforced soil (GFRS) is highly inhomogeneous with its two constituents: geofiber and soil. The overall behaviors of GFRS are determined by its characteristics such as the properties of constituents, geometry of geofiber, content and distribution of geofibers in the reinforced soil, and their interactions. Because the macroscopic approach alone is unable to respond to the effect of local characteristics, a micromechanical approach is desirable for the analysis of GFRS. In this dissertation, an incremental constitutive model considering microscopic damage was developed in which applied mean-field theory is used in each steps of the analysis. The roles of soil and geofiber in the reinforced soil, the interface between the geofiber and the soil, and the fiber-matrix interaction were analyzed for both local and global responses. An interface evolutionary law was introduced into the model and was used with each step to obtain the total stiffness of GFRS, which is a function of micro-structural parameters and the applied macro strain. A series of torsional shear tests were conducted to provide data on the properties of the soil and to verify the validity and accuracy of the proposed model. Three types of samples, classified in terms of the weight of their geofiber contents of 0.0%, 0.2% and 0.5%, were investigated in these tests. They were also subjected to a variety of loading frequencies ranging from 0.01 Hz to 5.0Hz. The shear modulus of soil as a function of shear strain amplitude and loading frequency was obtained by using curve-fitting techniques in the analysis of test results. Results from the torsional shear tests indicate that the presence of geofiber leads to higher stiffnesses of the reinforced soil and the higher geofiber content is more effective than the lower fiber content. It also indicates that the shear stress increases in a nonlinear manner with an increase in shear strain. Nonlinear behavior is more pronounced in reinforced soil than that in unreinforced soil. The shear modulus always increases with an increase in loading frequency in this test range. When comparing the results determined by the experiments and those determined by theoretical predictions, good agreement was found regarding the torsional shear behaviors of GFRS. -- Abstract.

Download or read book Mechanical Response of Fiber reinforced Soil written by Chunling Li and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constitutive Behavior of Fabric Reinforced Encapsulated Soil written by Donald H. Gray and published by . This book was released on 1986 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: The stress-strain-time response of sand reinforced with continuous, orientated fabrics (geotextiles) was measured experimentally in triaxial compression tests. Similar tests were run on sand samples reinforced with discrete, randomly distributed fibers. Both striking similarities and interesting differences were observed in the mechanaical response and failure modes for these two types of reinforced soil. Quasi-uniaxial compression tests were run on sand samples that were both internally reinforced and externally encapsulated in fabric as well. A finite element model was developed to predict the behavior of a soil-fabric composite under either plane strain or axysymetric loading. A special apparatus was constructed to measure experimentally the load-deformation behavior of fabrics under in-isolation vs. in-soil conditions. The dynamic response of sand reinforced with both discrete, randomly distributed fibers and parallel arrays of oriented fibers is under investigation. The influence of critical inclusion properties (e.g., concentration, aspect ratio, stiffness) and test parameters (e.g., mean confining stress, strain amplitude) on the dynamic shear modulus and damping ratio of fiber reinforced sand are being studied.

Download or read book Design oriented Constitutive Model for Steel Fiber Reinforced Concrete written by Felipe Laranjeira de Oliveira and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Inelastic Constitutive Model for Soils written by Yii-Wen Pan and published by . This book was released on 1986 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constitutive Relations for Soils written by G. Gudehus and published by . This book was released on 1984 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constitutive Modeling and Flexural Analysis of Steel Fiber Reinforced Concrete for Structural Applications written by Cha-Don Lee and published by . This book was released on 1990 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constitutive Modeling of Soils an Overview written by Atef Fatthy Saleeb and published by . This book was released on 1982 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constitutive Modelling of Soils and Fibre reinforced Soils written by Thomas Bower and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constitutive Modeling of Fiber Reinforced Concrete written by Dajin Liu and published by . This book was released on 1992 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constitutive Models for Flexural Toughness of Fiber Reinforced Concrete written by Sverre Monrad Amundsen and published by . This book was released on 1990 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Constitutive Model for Agricultural Clay Soil written by R.L. Kushwaha and published by . This book was released on 1994 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Time dependent Constitutive Model for Cohesive Soils written by Rudolph Bonaparte and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: