File Name: soil behaviour and critical state soil mechanics sand.zip
Soil mechanics is a branch of soil physics and applied mechanics that describes the behavior of soils. It differs from fluid mechanics and solid mechanics in the sense that soils consist of a heterogeneous mixture of fluids usually air and water and particles usually clay , silt , sand , and gravel but soil may also contain organic solids and other matter. Soil mechanics is used to analyze the deformations of and flow of fluids within natural and man-made structures that are supported on or made of soil, or structures that are buried in soils.
PhD thesis, University of Nottingham. One of the greatest breakthroughs in soil mechanics was the development of Critical State Soil Mechanics CSSM in the s and s and the derivation of a continuum elasto-plastic constitutive model, namely Cam clay, which was the foundation for other continuum models for clays, and much later for sands. However, as yet there has been no micro mechanical analysis which explains the existence of such continuum models; such a micro perspective must take into account the discontinuous nature of soil.
The application of critical state framework depends on the presence of either a unique critical state line CSL. However, many authors have observed that a transitional behaviour occurs in certain granular intermediate soils in which the fines content and the initial void ratio have a significant effect on the location of this line. This work investigates these effects in poorly graded granular soils as previous studies reported that this type of soil does not exhibit transitional behaviour. A unique state boundary surface is identified by determining the critical state parameters from each group and using these parameters to normalise the stress paths; this shows that the critical state framework can be successfully applied to this type of soil. This is a preview of subscription content, access via your institution. Rent this article via DeepDyve.
Instability of liquefaction is one of the major reasons which results in the failure of earth structure such as dam. The present study focuses on the simulation of static liquefaction behavior for granular materials such as sand and sand-silt mixtures. Based on micromechanical analysis of inter-particle behavior, a simple one-scale model is proposed to simulate the stress-strain response of sand; then the proposed model is extended to simulate the sand-silt mixtures using the mixture theory combining the properties of sand and silt according to their proportions. Empirical expressions are introduced to fit the critical state strength and the location of the critical state line for each mixture. Parameters of the model can be divided into two categories: the first seven parameters have the same values either with pure sand or pure silt for silt-sand with any given fines content; the other three parameters are the function of fines content and three more parameters are required to estimate their values. The predicted results of triaxial test of sand and sand-silt mixtures with different fine content, which has a good agreement with the results of laboratory tests, suggest that the proposed model can simulate static liquefaction behavior of sand and sand-silt mixtures.
Nevertheless, the development of the critical state of sand matrix soils is lacking. This paper discusses the development of critical state lines and corresponding critical state parameters for the investigated material, sand matrix soils using sand-kaolin mixtures. The output of this paper can be used as an interpretation framework for the research on liquefaction susceptibility of sand matrix soils in the future. The strain controlled triaxial test apparatus was used to provide the monotonic loading onto the reconstituted soil specimens. All tested soils were subjected to isotropic consolidation and sheared under undrained condition until critical state was ascertain. Based on the results of 32 test specimens, the critical state lines for eight different sand matrix soils were developed together with the corresponding values of critical state parameters, , , and. The range of the value of , , and is 0.
Critical State of Sand Matrix Soils
The particulate implementation of the discrete element method DEM can replicate many of the complex mechanical characteristics associated with sand. This research firstly shows that the CSSM framework is useful to assess whether a DEM simulation gives a response that is representative of a real soil. The influence of sample size on the critical-state response observed in DEM simulations that use rigid-wall boundaries was examined. The observed sensitivity was shown to be caused by higher void ratios and lower contact densities adjacent to the boundaries. True-triaxial simulations with different intermediate stress ratios b were performed.
The soil water content at the stage where the plant dies, is called permanent wilting point. The soil still contains some water, but it is too difficult for the roots to suck it from the soil see Fig. Some soil moisture characteristics.
Refworks Account Login. UBC Theses and Dissertations. Featured Collection. Mahdi Taiebat, Professor, Civil Engineering, UBC Additional Examiner iii Abstract A newly designed and developed triaxial permeameter is presented, along with results from a series of commissioning tests for drained and undrained compression on uniformly graded Fraser River sand.
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