File Name: soil mechanics and foundation engineering formulas .zip
- Important Formulas for Geotechnical Engineering
- Important Formulas for Geotechnical Engineering
- Soil Mechanics Lecture Notes Pdf
Our planet Earth has an average radius of km and a mean mass density of 5. The mantle consists of two parts, upper mantle and lower mantle. The upper mantle is solid rock while the lower mantle is molten rock.
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.
Principles of soil mechanics are also used in related disciplines such as geophysical engineering , coastal engineering , agricultural engineering , hydrology and soil physics. This article describes the genesis and composition of soil, the distinction between pore water pressure and inter-granular effective stress , capillary action of fluids in the soil pore spaces, soil classification , seepage and permeability , time dependent change of volume due to squeezing water out of tiny pore spaces, also known as consolidation , shear strength and stiffness of soils.
The shear strength of soils is primarily derived from friction between the particles and interlocking, which are very sensitive to the effective stress. The primary mechanism of soil creation is the weathering of rock.
All rock types igneous rock , metamorphic rock and sedimentary rock may be broken down into small particles to create soil. Weathering mechanisms are physical weathering, chemical weathering, and biological weathering    Human activities such as excavation, blasting, and waste disposal, may also create soil.
Over geologic time, deeply buried soils may be altered by pressure and temperature to become metamorphic or sedimentary rock, and if melted and solidified again, they would complete the geologic cycle by becoming igneous rock. Physical weathering includes temperature effects, freeze and thaw of water in cracks, rain, wind, impact and other mechanisms. Chemical weathering includes dissolution of matter composing a rock and precipitation in the form of another mineral. Clay minerals, for example can be formed by weathering of feldspar , which is the most common mineral present in igneous rock.
The most common mineral constituent of silt and sand is quartz , also called silica , which has the chemical name silicon dioxide. The reason that feldspar is most common in rocks but silica is more prevalent in soils is that feldspar is much more soluble than silica.
Silt , Sand , and Gravel are basically little pieces of broken rocks. According to the Unified Soil Classification System , silt particle sizes are in the range of 0. Gravel particles are broken pieces of rock in the size range 4. Particles larger than gravel are called cobbles and boulders. Soil deposits are affected by the mechanism of transport and deposition to their location.
Soils that are not transported are called residual soils —they exist at the same location as the rock from which they were generated. Decomposed granite is a common example of a residual soil. The common mechanisms of transport are the actions of gravity, ice, water, and wind.
Wind blown soils include dune sands and loess. Water carries particles of different size depending on the speed of the water, thus soils transported by water are graded according to their size. Silt and clay may settle out in a lake, and gravel and sand collect at the bottom of a river bed. Wind blown soil deposits aeolian soils also tend to be sorted according to their grain size. Erosion at the base of glaciers is powerful enough to pick up large rocks and boulders as well as soil; soils dropped by melting ice can be a well graded mixture of widely varying particle sizes.
Gravity on its own may also carry particles down from the top of a mountain to make a pile of soil and boulders at the base; soil deposits transported by gravity are called colluvium. The mechanism of transport also has a major effect on the particle shape. For example, low velocity grinding in a river bed will produce rounded particles. Freshly fractured colluvium particles often have a very angular shape.
Silts, sands and gravels are classified by their size, and hence they may consist of a variety of minerals. Owing to the stability of quartz compared to other rock minerals, quartz is the most common constituent of sand and silt.
Mica, and feldspar are other common minerals present in sands and silts. The common clay minerals are montmorillonite or smectite , illite , and kaolinite or kaolin. The specific surface area SSA is defined as the ratio of the surface area of particles to the mass of the particles. Clay minerals typically have specific surface areas in the range of 10 to 1, square meters per gram of solid.
The minerals of soils are predominantly formed by atoms of oxygen, silicon, hydrogen, and aluminum, organized in various crystalline forms. These elements along with calcium, sodium, potassium, magnesium, and carbon constitute over 99 per cent of the solid mass of soils. Soils consist of a mixture of particles of different size, shape and mineralogy.
Because the size of the particles obviously has a significant effect on the soil behavior, the grain size and grain size distribution are used to classify soils. The grain size distribution describes the relative proportions of particles of various sizes.
The grain size is often visualized in a cumulative distribution graph which, for example, plots the percentage of particles finer than a given size as a function of size. Sands and gravels that possess a wide range of particle sizes with a smooth distribution of particle sizes are called well graded soils. If the soil particles in a sample are predominantly in a relatively narrow range of sizes, the sample is uniformly graded.
If a soil sample has distinct gaps in the gradation curve, e. Uniformly graded and gap graded soils are both considered to be poorly graded. There are many methods for measuring particle-size distribution. The two traditional methods are sieve analysis and hydrometer analysis. The size distribution of gravel and sand particles are typically measured using sieve analysis.
A known volume of dried soil, with clods broken down to individual particles, is put into the top of a stack of sieves arranged from coarse to fine. The stack of sieves is shaken for a standard period of time so that the particles are sorted into size bins. This method works reasonably well for particles in the sand and gravel size range.
Fine particles tend to stick to each other, and hence the sieving process is not an effective method. If there are a lot of fines silt and clay present in the soil it may be necessary to run water through the sieves to wash the coarse particles and clods through.
A variety of sieve sizes are available. The boundary between sand and silt is arbitrary. According to the Unified Soil Classification System , a 4 sieve 4 openings per inch having 4. According to the British standard, 0. The classification of fine-grained soils, i.
If it is important to determine the grain size distribution of fine-grained soils, the hydrometer test may be performed. In the hydrometer tests, the soil particles are mixed with water and shaken to produce a dilute suspension in a glass cylinder, and then the cylinder is left to sit. A hydrometer is used to measure the density of the suspension as a function of time.
Clay particles may take several hours to settle past the depth of measurement of the hydrometer. Sand particles may take less than a second. Stoke's law provides the theoretical basis to calculate the relationship between sedimentation velocity and particle size. ASTM provides the detailed procedures for performing the Hydrometer test.
Clay particles can be sufficiently small that they never settle because they are kept in suspension by Brownian motion , in which case they may be classified as colloids. There are a variety of parameters used to describe the relative proportions of air, water and solid in a soil. This section defines these parameters and some of their interrelationships.
Note that the weights, W, can be obtained by multiplying the mass, M, by the acceleration due to gravity, g; e. It is easily measured by weighing a sample of the soil, drying it out in an oven and re-weighing. Standard procedures are described by ASTM. Geotechnical engineers classify the soil particle types by performing tests on disturbed dried, passed through sieves, and remolded samples of the soil.
This provides information about the characteristics of the soil grains themselves. Classification of the types of grains present in a soil does not account for important effects of the structure or fabric of the soil, terms that describe compactness of the particles and patterns in the arrangement of particles in a load carrying framework as well as the pore size and pore fluid distributions.
Engineering geologists also classify soils based on their genesis and depositional history. In the USCS, gravels given the symbol G and sands given the symbol S are classified according to their grain size distribution.
The Liquid Limit is the water content at which the soil behavior transitions from a plastic solid to a liquid. The Plastic Limit is the water content at which the soil behavior transitions from that of a plastic solid to a brittle solid. The Shrinkage Limit corresponds to a water content below which the soil will not shrink as it dries. The consistency of fine grained soil varies in proportional to the water content in a soil. As the transitions from one state to another are gradual, the tests have adopted arbitrary definitions to determine the boundaries of the states.
The liquid limit is determined by measuring the water content for which a groove closes after 25 blows in a standard test. The undrained shear strength of remolded soil at the liquid limit is approximately 2 kPa. The soil cracks or breaks up as it is rolled down to this diameter.
Remolded soil at the plastic limit is quite stiff, having an undrained shear strength of the order of about kPa. The Plasticity Index of a particular soil specimen is defined as the difference between the Liquid Limit and the Plastic Limit of the specimen; it is an indicator of how much water the soil particles in the specimen can absorb, and correlates with many engineering properties like permeability, compressibility, shear strength and others.
Generally, the clay having high plasticity have lower permeability and also they are also difficult to be compacted. According to the Unified Soil Classification System USCS , silts and clays are classified by plotting the values of their plasticity index and liquid limit on a plasticity chart. If the Atterberg limits plot in the"hatched" region on the graph near the origin, the soils are given the dual classification 'CL-ML'.
The effects of the water content on the strength of saturated remolded soils can be quantified by the use of the liquidity index , LI :. When the LI is 1, remolded soil is at the liquid limit and it has an undrained shear strength of about 2 kPa.
When the soil is at the plastic limit , the LI is 0 and the undrained shear strength is about kPa. However, if the water table is sloping or there is a perched water table as indicated in the accompanying sketch, then seepage will occur. For steady state seepage, the seepage velocities are not varying with time. If the water tables are changing levels with time, or if the soil is in the process of consolidation, then steady state conditions do not apply.
Darcy's law states that the volume of flow of the pore fluid through a porous medium per unit time is proportional to the rate of change of excess fluid pressure with distance.
Important Formulas for Geotechnical Engineering
Last Updated on April 10, by Admin. There are several formulae in a civil engineering subject. Formulae derived by various writers and authors have been compiled in this single book. Here, we are providing you with the best civil engineering formulas PDF book which will help you to revise the formulas. Hicks for free.
Download Important formulas for Soil Mechanics & Foundation GATE Question Paper with Solution , , , Download PDF
Important Formulas for Geotechnical Engineering
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, liquids, and gases and other matter. There's also a wide selection of languages available, with everything from English to Farsi. Index properties are the properties of soil that help in identification and classification of soil.
These notes are of EasyEngineering Team prepared notes. You all must have this kind of questions in your mind. Below article will solve this puzzle of yours. Just take a look.
These notes are of EasyEngineering Team prepared notes. You all must have this kind of questions in your mind.
Soil Mechanics Lecture Notes Pdf
Check your Email after Joining and Confirm your mail id to get updates alerts. May 18, at PM. Hope this post is helpful to you. They are very well wriiten in clear hand writting and print quality is awesome. Soil Mechanics and Foundation Engg. Bansal Book Free
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. Principles of soil mechanics are also used in related disciplines such as geophysical engineering , coastal engineering , agricultural engineering , hydrology and soil physics. This article describes the genesis and composition of soil, the distinction between pore water pressure and inter-granular effective stress , capillary action of fluids in the soil pore spaces, soil classification , seepage and permeability , time dependent change of volume due to squeezing water out of tiny pore spaces, also known as consolidation , shear strength and stiffness of soils. The shear strength of soils is primarily derived from friction between the particles and interlocking, which are very sensitive to the effective stress.
The book is also available in Dutch, in the file us97redmondbend.org Soil mechanics and Foundation engineering together are often denoted as Geotechnics. This formula expresses that the force on a small sphere, sinking in a viscous fluid.
Load Shear Failure For loose sand and soft clay. General Shear Failure Strip footing. Ressner Formula. Nagaraj and Murthy. Compression Index: 1. Gross Allowable Load.
These notes are of EasyEngineering Team prepared notes. You all must have this kind of questions in your mind. Below article will solve this puzzle of yours.