Effects of Compaction on Internal Stability of Granular Soils PDF Download
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Author: Jahanzaib Israr
Publisher:
ISBN:
Category : Granular materials
Languages : en
Pages : 24
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Book Description
Internal instability occurs when the filtrate under the influence of strong seepage forces accompanies the finer fraction from broadly graded granular soils and induces marked changes in its original particle distributions. The changes in particle size distribution may occasionally render the granular filters ineffective in retaining the protected base soils. A prior assessment of internal instability potential is emphasized through some of the well-accepted constriction and particle size-based criteria. The former criteria are too computationally complex to apply in practice, while the latter require only the particle distribution of a soil and are thus preferred by the practitioners for prompt assessments of internal stability. In this study, gradient-controlled hydraulic tests conducted over a range of variably compacted soils were used to analyze some of the existing criteria, which showed partial success in assessing the current test specimens. Further analysis facilitated a useful revision of a well-accepted criterion, which could then reliably interpret the current test results with enhanced accuracy. Additional experimental data from 15 published filtration studies could further validate the current revision, which incorporates both the particle size distribution and relative density of soils, thus making it more appealing for practitioners. Furthermore, a couple of real-life design examples presented to demonstrate the advantages and implications of the current proposition for practical purposes.
Author: Jahanzaib Israr
Publisher:
ISBN:
Category : Granular materials
Languages : en
Pages : 24
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Book Description
Internal instability occurs when the filtrate under the influence of strong seepage forces accompanies the finer fraction from broadly graded granular soils and induces marked changes in its original particle distributions. The changes in particle size distribution may occasionally render the granular filters ineffective in retaining the protected base soils. A prior assessment of internal instability potential is emphasized through some of the well-accepted constriction and particle size-based criteria. The former criteria are too computationally complex to apply in practice, while the latter require only the particle distribution of a soil and are thus preferred by the practitioners for prompt assessments of internal stability. In this study, gradient-controlled hydraulic tests conducted over a range of variably compacted soils were used to analyze some of the existing criteria, which showed partial success in assessing the current test specimens. Further analysis facilitated a useful revision of a well-accepted criterion, which could then reliably interpret the current test results with enhanced accuracy. Additional experimental data from 15 published filtration studies could further validate the current revision, which incorporates both the particle size distribution and relative density of soils, thus making it more appealing for practitioners. Furthermore, a couple of real-life design examples presented to demonstrate the advantages and implications of the current proposition for practical purposes.
Author: Keow-Pin Khoo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Vincent P. Drnevich
Publisher: Purdue University Press
ISBN: 9781622601202
Category : Transportation
Languages : en
Pages : 194
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Book Description
Although it is known that impact compaction tests are not appropriate for granular soils, these tests continue to be widely used. Excessive settlements frequently occur in granular soils where specified field compaction is based on Standard Proctor (ASTM D 698; AASHTO T 99) maximum dry unit weights. A laboratory test program evaluated alternative test methods for granular soil compaction control and showed that a Vibrating Hammer method (similar to British Standard BS 1377:1975, Test 14) has great promise for laboratory compaction of these soils.
Author:
Publisher: ASTM International
ISBN:
Category :
Languages : en
Pages : 144
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Book Description
Author: W. Fellin
Publisher: CRC Press
ISBN: 9789058093189
Category : Technology & Engineering
Languages : en
Pages : 348
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Book Description
This interdisciplinary volume comprises papers from several fields related to compaction. Topics include: soil compaction for pavements and roads; deep soil compaction by vibration, impact and underground explosion; compaction control; and compaction processes in engineering.
Author: Howard William Lull
Publisher:
ISBN:
Category : Soil stabilization
Languages : en
Pages : 36
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Book Description
The purpose of this report is to review available information on soil compaction as related to soil and water conservation on forest and range lands.
Author: JA. Yamamuro
Publisher:
ISBN:
Category : Granular materials
Languages : en
Pages : 10
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Book Description
An experimental study of the effect of strain rate on the stability of granular soils at high pressures has shown that there is no apparent effect on the location of the instability line. However, during undrained triaxial compression tests the deviator stress, effective stress path, effective stress friction angle, and pore pressures are significantly affected by changes in strain rate. Strain rate effects during drained triaxial compression tests are also presented, but do not appear to be as significant as in undrained tests.
Author: Harry Bolton Seed
Publisher:
ISBN:
Category : Soil compaction
Languages : en
Pages : 22
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Book Description
Author: J. Michael Duncan
Publisher: John Wiley & Sons
ISBN: 1118651650
Category : Technology & Engineering
Languages : en
Pages : 336
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Book Description
The definitive guide to the critical issue of slope stability and safety Soil Strength and Slope Stability, Second Edition presents the latest thinking and techniques in the assessment of natural and man-made slopes, and the factors that cause them to survive or crumble. Using clear, concise language and practical examples, the book explains the practical aspects of geotechnical engineering as applied to slopes and embankments. The new second edition includes a thorough discussion on the use of analysis software, providing the background to understand what the software is doing, along with several methods of manual analysis that allow readers to verify software results. The book also includes a new case study about Hurricane Katrina failures at 17th Street and London Avenue Canal, plus additional case studies that frame the principles and techniques described. Slope stability is a critical element of geotechnical engineering, involved in virtually every civil engineering project, especially highway development. Soil Strength and Slope Stability fills the gap in industry literature by providing practical information on the subject without including extraneous theory that may distract from the application. This balanced approach provides clear guidance for professionals in the field, while remaining comprehensive enough for use as a graduate-level text. Topics include: Mechanics of soil and limit equilibrium procedures Analyzing slope stability, rapid drawdown, and partial consolidation Safety, reliability, and stability analyses Reinforced slopes, stabilization, and repair The book also describes examples and causes of slope failure and stability conditions for analysis, and includes an appendix of slope stability charts. Given how vital slope stability is to public safety, a comprehensive resource for analysis and practical action is a valuable tool. Soil Strength and Slope Stability is the definitive guide to the subject, proving useful both in the classroom and in the field.
Author: Nurses Kurucuk
Publisher:
ISBN:
Category :
Languages : en
Pages : 217
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Book Description
Soil compaction is widely applied in geotechnical engineering practice. It is used to maximise the dry density of soils to reduce subsequent settlement under working loads or to reduce the permeability of soils. The durability and stability of structures are highly related to the appropriate compaction achievement. The structural failure of roads and airfields, and the damage caused by foundation settlement can often be traced back to the failure in achieving adequate compaction. For that reason, soil compaction is important for engineering activities involving earthworks. Compacted soils are unsaturated by nature, which includes both air and water within their voids. Thus, unsaturated soil mechanics principles are crucial in understanding the compaction behaviour of soils. There are several qualitative studies, which attempt to explain the compaction behaviour of soils and there is a vast body of literature covering the behaviour of compacted soils. Still, fundamental research on the compaction process is limited. In addition, the current constitutive models available for unsaturated soils assume that the soil state after compaction is the initial state of the soil. However, compacted soils undergo a stress history which influences the post compaction behaviour. Considering these facts, it still remains that the compaction of soil is a complex phenomenon, which is not well explained, particularly from a quantitative sense. Further understanding of the compaction behaviour during the compaction process will provide important insights on the behaviour of compacted soils. The main aim of this research project is to extend the current understanding of the compaction process of soils. The research focuses on three different areas: investigating the experimental behaviour of soils during the static compaction process and obtaining data for compaction modelling; developing a compaction model using the existing constitutive models for unsaturated soils; and evaluating the performance of this model in predicting the compaction behaviour of soils. In the experimental part, static compaction tests were conducted on two different granular soils, sand with 2% and 5% bentonite content by weight. The tests were undertaken on samples with different water contents in order to observe the effect of matric suction on the compaction behaviour. The initial matric suction of the specimens was measured using the null type axis translation technique and the matric suction variations were monitored during the compaction process. It was found that the unsaturated samples were always more compressible than the saturated sample. This finding is contrary to the assumption made in most constitutive models, and thus modelling the compaction behaviour using these models may result in some deficiencies. In addition, in granular soils with low water content the axis translation technique was found to be very time consuming for the suction measurements. This was attributed to the discontinuous water phase within the samples. To develop a compaction model, a volume change constitutive relationship for unsaturated soils, defined in terms of two independent stress variables, was incorporated with pore pressure predictions. The model was developed for undrained, semi-drained and drained loading conditions. Initially, compressibility coefficients in the volume change relationship were considered as constant parameters, i.e., the compressibility of a soil element does not change with increasing vertical stress. Using constant compressibility coefficients, the compaction curve can be predicted only for the wet side of the curve, not the dry side. Thus, variable compressibility coefficients were derived from constitutive models proposed in the literature, and using these coefficients, the well-known shape of the compaction curve was predicted on both dry and wet side of the compaction curve. It was found that the shape of the compaction curve can be the theoretically predicted using unsaturated soil mechanics principles. The main insight gained from the model development was that the influence of matric suction on the material compressibility with respect to net stress is the governing factor determining the inverted parabolic shape of the compaction curve. The performance of the compaction models were examined on their ability to predict the compaction behaviour of soils. Data for four different soils, two sand-bentonite mixtures tested in this study, and Boom clay and Speswhite kaolin data from literature, were used for models evaluation. Two different constitutive modelling approaches were analysed, which are the separate stress state variables approach and combined stress state approach. It was concluded that the samples prepared from initially slurry soils and from initially dry soils could not be treated the same and would require the use of different sets of soil parameters. In addition, the compaction behaviour of soils, prepared from initially dry samples, could only be modelled over a narrow range of water contents using a single set of soil parameters. Minimum two sets of soil parameters are required to model the compaction behaviour over a wide range of water contents with the current constitutive models.
