Determination of the consolidation coefficient of low compressibility materials. Department of construction engineering advanced soil mechanics chaoyang university of technology secondary effects 102 where the soil structure undergoes maximum breakdown under the applied stresses, i. It is the consolidated nature of soil or the maximum effective stress experienced by the soil prior to consolidation test. Compressibility and consolidation 5 coefficient of compressibility a v e 1 void ratio at effective stress e 2 void ratio at effective stress.
Tagalog, ce the design of foundations of structures such as buildings, bridges, and dams generally requires a knowledge of such factors as. Skemptons pore pressure coefficient effective cohesion. The assumption of elastic behaviour may be reasonable for some soils but this is not so in general. Uniformity coefficient represents the shape of the particle size distribution curve. Soil mechanics mcq civil engineering questions answers. Introduction compressibility characteristic of a soil is one of the basic requirements for foundation design. Relationships betwa basic soilsengineering equations basic. Pdf determination of the consolidation coefficient of low.
Read more soil mechanics mcq civil engineering questions answers. As for the bottom ash, it would mean that their compressibility is similar to that of a natural soil with the same uscs classification and. Coefficient of consolidation of a soil is affected by a compressibility b permeability c both compressibility and permeability d none of the above ans. These characteris tics are used to estimate the amount of settlement of a structure which would result from the consolidation of its earth foundation because of the structure load.
Compressibility characteristics of remoulded residual. From the changes in thickness at the end of each load stage the compressibilityof the soil may be observed, and parameters measured such as compression index c c and coefficient of volume compressibility m v. This means that a greater volume of water must be expelled from the soil. The compressibility and strength characteristics of. Moreover, this theory is the most widely used in national standards and in soil mechanics engineering applications therefore, the terzaghi theory is used in the present work and is applied to. Consolidation settlement soil mechanics eurocode standards. Discussion of chapter 10 compressibility of soil 1 types of. This means that a more rapid rate of consolidation occurs. Specific yield, also known as the drainable porosity, is a ratio, less than or equal to the effective porosity, indicating the volumetric fraction of the bulk aquifer volume that a given aquifer will yield when all the water is allowed to drain out of it under the forces of gravity.
In this page you can learn various important soil mechanics multiple choice questions and answers, sloved soil mechanics lab viva questions with answers, important soil mechanics interview question papers,foundation engineering questions and answers etc. The coefficient of volume change m v is defined as the volume change per unit increase in effective stress for unit volume of soil craig, 2004. Soil mechanics and foundation engineering questions and. A coefficient of compressibility is the decrease in void ratio per unit increase of pressure. They are obtained from consolidation tests on representative undisturbed samples of the compressible soil stratum. Literature for the course soil mechanics iliterature for the course soil mechanics i. Clay the branches bc and fg are nc state of a soil. The settlement in such soils involve time parameters and it is possible to calculate and evaluate the parameters using the common tests in geotechnical.
Variable permeability, compressibility, soil consolidation. Strength and compressibility behaviors of expansive soil. The velocity of water flowing through a soil mass between any two points depends directly on the hydraulic gradient or the head loss per unit length between the two points. Compressibility and consolidation 2 lecture outline. Ahmed soil mechanics note chapter seven compaction. After a table from determination of coefficient of consolidation from early stage of.
This would mean a very low compressibility high stiffness for a fine soil like fly ashes, and would be in the lower part of the usual range for fly ash 2. The behavior of the soil is an important element which always concerned in the civil engineering. On the storage coefficient and the equations of groundwater flow. Discussion of chapter 10 compressibility of soil 1 types. Influence of structure and liquid limit on the secondary. A reduction in height h of the soil layer occurs as a functionof time, eventually reaching an equilibrium value. Soil mechanics compressibility of soil, consolidation. The solutions of many soil mechanics problems would be greatly simplified if soils behaved like elastic solids. The r ate at which it escape s depends on the coefficient of permeability, thickness, and compressibilit y of the soil. Lecture 8 consolidation and compressibility slideshare. Jan 21, 2014 the relevant parameters of the soil, including initial void ratio, coefficient of compressibility, coefficient of volume compressibility, compression index, and coefficient of consolidation. It occurs when is stress applied to a soil that causes the soil particles to pack together more tightly, therefore reducing its bulk volume. When this occurs in a soil that is saturated with water, water. The coefficient of volume compressibility mv is assumed to be constant.
Soil samples are tested in the laboratory to determine the settlement characteristics of the soil under load. The coefficient of permeability k for vertical flow is assumed to be constant. Parameters that describe soil s compressibility include. Effective stresses and permeability and well hydraulics. Compressibility and consolidation of soil are crucial parameters required in the. For a given increment of compressive vertical stress on the soil sample, time dependent compression of the soil sample is observed. Consolidation of soil is due to a load which is a static and short term b. Compressibility of soil hcmut project management system. It is found that the compressibility m v of an apparently uniform soil. Compression index an overview sciencedirect topics. The seepage force in a soil, is a perpendicular to the equipotential lines b proportional to the exit gradient c proportional to the head loss d all the above. Knowledge of the rate at which the compression of the soil takes place is essential from design consideration. Pdf modified terzaghi consolidation curves with effective. An equation for predicting settlement of ultrasoft soil in both the slurry and soil stages is elaborated upon.
This study investigates the compressibility of a plastic indiana clay st. Vertical stress below the center of a uniformly loaded circular area. Apr 01, 2019 the coefficient of compressibility a v is represented by the slope of void ratio versus applied pressure curves, an important indicator of the magnitude of soil compressibility. Compressibility of soil second term 2011 problem 4. Multiple choice questions and answers soil mechanics and foundation engineering 01. The compressibility of soil is defined as the capability of soil to decrease its volume under mechanical loads, whereas the consolidation is the compression of saturated soil under steady pressure and it is occurred as a result of water expulsion from the soil voids. Since soil is a compressible material these structures experience downward movement or settlement. Relationships betwa basic soilsengineering equations and basic. Soil mechanicsis the branch of science that deals with the study of the physical properties of soil and the behavior of soil masses subjected to various types of forces. Hence, the compressibility of soils is expressed in the terms of a plot between void ratio on the yaxis and effective stress on the xaxis.
The properties of the soil such as plasticity, compressibility or strength of the soil. C a soil is said to be well graded if it has most of the particles of about the samesize d none of the above answer. Pdf compressibility characteristics of soils researchgate. The solutions of many soil mechanics problems would be greatly simplified if soils. Also, transient groundwater flow is related to coefficient of con solidation, rate of soil compaction, and hydraulic conductivity. This a question of great importance when designing. Pdf determination of the consolidation coefficient of. Pdf one of the assumptions of the standard consolidation theory used in soil mechanics is that the coefficient of consolidation is a material property. Motivation and overview our objective is now to understand how soils compress or consolidate with time after loads are placed on them. Void ratio is used to represent compression because it is a ratio of the volume of voids to the volume of solids, the former being reflective of compression and the latter being constant in soil compression. As for the bottom ash, it would mean that their compressibility is similar to that of a natural soil with the same uscs classification and the same relative density. This value, which is sometimes called the coefficient of volume decrease, represents the compression of a soil, per unit of original thickness, due to a unit increase in pressure, i. These are very soft with low shear strength and high compressibility. Compressibility of clays international society for soil.
What are the compressibility and consolidation of soil. Compressibility of ultrasoft soil world scientific. Pdf compressibility characteristics of soils forms one of the important soil. Consolidation coefficient determinationas previously noted in equation 1 the consolidation coefficient can be expressed as a function of the permeability and compressibility. This study presents a new insight on a possible exponential correlation of cc with q c n 60 and q c. It is the effective stress which controls the volume and the strength of the soil.
Appendix e contains plots of coefficient of consolidation against void ratio. A soil is oc if the present effective pressure to which it is subjected to is less than the maximum pressure to which the soil was subjected to in the past the branches ab, cd, df, are the oc state of a soil. Application of the principles of soil mechanics to an engineering. The property of the soil that permits the flow of water through its voids with ease is known as permeability. Methods to determine the compression indices and coefficients of consolidation at different stress ranges, which are required for the prediction of magnitude of settlement and time rate of settlement, are developed. Pdf evaluation of volume compressibility coefficient variations. The determination of the appropriate compressibility for soil b is illustrated in fig. The big difference of compressibility, coefficient of consolidation, etc.
B for a well graded soil, both uniformity coefficient and coefficient of curvature are near unity. Compressibility of fieldcompacted clay transportation research. The coefficient of volume compressibility m v is assumed to be constant. Summary of hydrologic and physical properties of rock and soil materials as analyzed by the hydrologic laboratory of the u. Degree of consolidation is a directly proportional to time and inversely proportional to drainage path b directly proportional to time and inversely proportional to square of. Compressibility characteristics of remoulded residual soils. Enrol today in our site and get access to our study package comprising of video lectures, stud. Correlation of plasticity index and compression index of soil. Consolidation and permeability behavior of high porosity. The virgin compression curve for a particular soil is shown in the given figure.
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