This document discusses shear strength and failure in soils. It begins by defining shear failure and explaining that soils generally fail in shear along a failure surface. It then discusses soil strength parameters, introducing the Mohr-Coulomb failure criterion where shear strength consists of cohesive and frictional components related to effective stresses. Various laboratory tests for measuring shear strength are described, including direct shear tests and triaxial compression tests on both drained and undrained soil samples. Pore pressure parameters that relate changes in stresses to changes in pore pressures during undrained loading are also introduced.
The document describes the standard penetration test (SPT) method for determining the bearing capacity of soils. SPT involves driving a split spoon sampler into the soil using a 63.5 kg hammer dropped from a height of 75 cm. The number of blows required to penetrate each 150 mm interval is recorded as the N-value. N-values are corrected for overburden pressure and dilatancy. Bearing capacity is then calculated using corrected N-values, soil properties like internal friction angle, and factors for shape, depth, inclination, and water table location. The SPT provides soil strength data and undisturbed samples needed to determine cohesion and friction angle for bearing capacity calculations.
Permeability Test of soil Using Constant and Falling Head MethodJameel Academy
1) The document describes laboratory tests to determine the coefficient of permeability of soil samples using the constant head and falling head methods.
2) For the falling head test on a sandy soil sample, the average permeability was found to be 0.00322 cm/sec.
3) For the constant head test on a second sample, the average permeability was determined to be 0.02069 cm/min.
Remote geosteering provides consistent supervision more effectively and safely than conventional methods. It allows for 24/7 supervision from offsite locations to make real-time decisions. This improves safety, reduces costs, enhances data flow and communication. Remote geosteering is used for horizontal wells drilled close to reservoir contacts or zones, nighttime supervision, and combining multiple objectives. It involves continuous monitoring, assessing stratigraphic location, optimizing well placement, providing timeline estimates and reports. This standardized approach improves knowledge sharing and reduces costs through centralized resources and reporting.
This document provides information about a soil mechanics course including the course code, class details, textbooks, evaluation methods, instructor details, course objectives, syllabus, and exam schedule. The key points are:
1) The course covers soil properties, behavior, testing and applications in geotechnical engineering.
2) The instructor has a PhD from Northwestern University and experience in construction and consulting.
3) Evaluation includes quizzes, midterms, and a final exam. The syllabus covers topics like soil composition, permeability, stress distribution, consolidation, and shear strength.
This document provides an overview of measurement while drilling (MWD), logging while drilling (LWD), rotary steerable systems (RSS), AutoTrak, and VertiTrak systems. It describes the components, operating principles, and objectives of MWD, LWD, and RSS. Key components of MWD include sensors, transmitters, telemetry systems, and surface systems. Mud pulse telemetry is highlighted as the commercially successful method to transmit downhole data to the surface. RSS systems allow continuous rotation while steering and are more complex than conventional systems but enable better penetration rates. The AutoTrak system uses a hybrid push-the-bit and point-the-bit approach in a closed-loop system to optimize well
Determination of consolidation properties (like CV, CC, CS, t90, mv, av) of the given soil specimen (Dhanauri Clay) by conducting one-dimensional consolidation test using fixed ring type setup.
Learning Outcomes:-
1. From consolidation test, the following information can be determined:
a) Amount of settlement experienced by a soil-structure after load application
b) Rate of consolidation of soil under a normal load
c) Degree of consolidation at any time
d) Pressure void ratio relationship
e) Coefficient of consolidation at various successively increasing pressure
f) Permeability of soil at various stages of loading
g) Compression index of soil
2. The general procedure for laboratory evaluation of consolidation characteristics of soils involves a one-dimensional consolidation.
This is necessary because of:
• Difficulty of instrumentation for recording volume change and natural strains.
• Complexities in mathematical analysis of three-dimensional consolidation.
3. The underlying assumptions in the derivation of the mathematical equations are as follows:
• The clay layer is homogeneous.
• The clay layer is saturated, the compression of the soil layer is due to the change in volume only, which in turn, is due to the squeezing out of water from the void spaces.
• Darcy’s law is valid.
• Deformation of soil occurs only in the direction of the load application.
4. Effects of ring friction
• During loading reduce stress acted on the specimen, specimen compresses less.
• During rebound reduce the swelling tendency specimen swell less.
• Flatten the swelling curve at low stress level.
5. Resultant Cv decreases with increasing stress, implying its NC clay.
6. Sample was preserved in polybag to check loss of moisture content.
This document provides a 3-sentence summary of a presentation by David Bowling, Regional Manager for GMI Geomechanics Services at Baker Hughes, about their geomechanical capabilities in the Asia Pacific region: Baker Hughes offers a broad range of geomechanics expertise through their GMI division to help clients in the Asia Pacific region with challenges like wellbore stability, fracture permeability modeling, and pore pressure prediction to improve drilling performance and reservoir management. GMI has offices across the Asia Pacific region and globally to provide local expertise while also drawing on Baker Hughes' international geomechanics specialists. The presentation outlines GMI's capabilities and applications of geomechanics across the project lifecycle from exploration through field development and production.
Determination of strength and stress-strain relationships of a cylindrical specimen of reconstituted specimen using Consolidated Drained (CD) Triaxial Test.
1. A series of drained triaxial tests under four different initial states were conducted on Yamuna River sand. The results consist of simple stress-strain relation, change in volume behaviour were plotted.
2. Basic stress-strain relation with volume behaviour was presented in plot. The results for densely prepared sand samples show an expected behaviour. There is a significant difference in peak and residual deviatoric stress (q) as can be depicted form the plot.
3. With increase in confining stress, load carrying capacity of specimen increases.
4. Saturation value ‘B’ must be acquired to be more than 0.95 before starting the isotropic consolidation phase in CD test.
5. CD tests are performed at much slower strain rate as compared to CU tests for the same soil. The strain rate for CD test can be chosen approx. 8-10 times lower than the CU test.
6. It is important to have no pore water pressure generation throughout the shearing phase of CD test or in other words strain rate must be so small that pore water pressure must get dissipated quickly when specimen is subjected to compression loading in CD test.
7. In CD test, volumetric strain versus axial strain relationship shows contractive response for NC soils and dilative response for OC soils. (NC = Normally consolidated, OC = Over consolidated)
References:
1. IS: 2720 (Part 11):1993- Determination of the shear strength parameters of a specimen tested in unconsolidated undrained triaxial compression without the measurement of pore water pressure (first revision). Reaffirmed- Dec 2016.
2. IS: 2720 (Part 12):1981- Determination of Shear Strength parameters of Soil from consolidated undrained triaxial compression test with measurement of pore water pressure (first revision). Reaffirmed- Dec 2016.
3. ASTM D7181-11. Method for Consolidated Drained Triaxial Compression Test for Soils; ASTM: West Conshohocken, PA, USA, 2011.
The document describes the standard penetration test (SPT) method for determining the bearing capacity of soils. SPT involves driving a split spoon sampler into the soil using a 63.5 kg hammer dropped from a height of 75 cm. The number of blows required to penetrate each 150 mm interval is recorded as the N-value. N-values are corrected for overburden pressure and dilatancy. Bearing capacity is then calculated using corrected N-values, soil properties like internal friction angle, and factors for shape, depth, inclination, and water table location. The SPT provides soil strength data and undisturbed samples needed to determine cohesion and friction angle for bearing capacity calculations.
Permeability Test of soil Using Constant and Falling Head MethodJameel Academy
1) The document describes laboratory tests to determine the coefficient of permeability of soil samples using the constant head and falling head methods.
2) For the falling head test on a sandy soil sample, the average permeability was found to be 0.00322 cm/sec.
3) For the constant head test on a second sample, the average permeability was determined to be 0.02069 cm/min.
Remote geosteering provides consistent supervision more effectively and safely than conventional methods. It allows for 24/7 supervision from offsite locations to make real-time decisions. This improves safety, reduces costs, enhances data flow and communication. Remote geosteering is used for horizontal wells drilled close to reservoir contacts or zones, nighttime supervision, and combining multiple objectives. It involves continuous monitoring, assessing stratigraphic location, optimizing well placement, providing timeline estimates and reports. This standardized approach improves knowledge sharing and reduces costs through centralized resources and reporting.
This document provides information about a soil mechanics course including the course code, class details, textbooks, evaluation methods, instructor details, course objectives, syllabus, and exam schedule. The key points are:
1) The course covers soil properties, behavior, testing and applications in geotechnical engineering.
2) The instructor has a PhD from Northwestern University and experience in construction and consulting.
3) Evaluation includes quizzes, midterms, and a final exam. The syllabus covers topics like soil composition, permeability, stress distribution, consolidation, and shear strength.
This document provides an overview of measurement while drilling (MWD), logging while drilling (LWD), rotary steerable systems (RSS), AutoTrak, and VertiTrak systems. It describes the components, operating principles, and objectives of MWD, LWD, and RSS. Key components of MWD include sensors, transmitters, telemetry systems, and surface systems. Mud pulse telemetry is highlighted as the commercially successful method to transmit downhole data to the surface. RSS systems allow continuous rotation while steering and are more complex than conventional systems but enable better penetration rates. The AutoTrak system uses a hybrid push-the-bit and point-the-bit approach in a closed-loop system to optimize well
Determination of consolidation properties (like CV, CC, CS, t90, mv, av) of the given soil specimen (Dhanauri Clay) by conducting one-dimensional consolidation test using fixed ring type setup.
Learning Outcomes:-
1. From consolidation test, the following information can be determined:
a) Amount of settlement experienced by a soil-structure after load application
b) Rate of consolidation of soil under a normal load
c) Degree of consolidation at any time
d) Pressure void ratio relationship
e) Coefficient of consolidation at various successively increasing pressure
f) Permeability of soil at various stages of loading
g) Compression index of soil
2. The general procedure for laboratory evaluation of consolidation characteristics of soils involves a one-dimensional consolidation.
This is necessary because of:
• Difficulty of instrumentation for recording volume change and natural strains.
• Complexities in mathematical analysis of three-dimensional consolidation.
3. The underlying assumptions in the derivation of the mathematical equations are as follows:
• The clay layer is homogeneous.
• The clay layer is saturated, the compression of the soil layer is due to the change in volume only, which in turn, is due to the squeezing out of water from the void spaces.
• Darcy’s law is valid.
• Deformation of soil occurs only in the direction of the load application.
4. Effects of ring friction
• During loading reduce stress acted on the specimen, specimen compresses less.
• During rebound reduce the swelling tendency specimen swell less.
• Flatten the swelling curve at low stress level.
5. Resultant Cv decreases with increasing stress, implying its NC clay.
6. Sample was preserved in polybag to check loss of moisture content.
This document provides a 3-sentence summary of a presentation by David Bowling, Regional Manager for GMI Geomechanics Services at Baker Hughes, about their geomechanical capabilities in the Asia Pacific region: Baker Hughes offers a broad range of geomechanics expertise through their GMI division to help clients in the Asia Pacific region with challenges like wellbore stability, fracture permeability modeling, and pore pressure prediction to improve drilling performance and reservoir management. GMI has offices across the Asia Pacific region and globally to provide local expertise while also drawing on Baker Hughes' international geomechanics specialists. The presentation outlines GMI's capabilities and applications of geomechanics across the project lifecycle from exploration through field development and production.
Determination of strength and stress-strain relationships of a cylindrical specimen of reconstituted specimen using Consolidated Drained (CD) Triaxial Test.
1. A series of drained triaxial tests under four different initial states were conducted on Yamuna River sand. The results consist of simple stress-strain relation, change in volume behaviour were plotted.
2. Basic stress-strain relation with volume behaviour was presented in plot. The results for densely prepared sand samples show an expected behaviour. There is a significant difference in peak and residual deviatoric stress (q) as can be depicted form the plot.
3. With increase in confining stress, load carrying capacity of specimen increases.
4. Saturation value ‘B’ must be acquired to be more than 0.95 before starting the isotropic consolidation phase in CD test.
5. CD tests are performed at much slower strain rate as compared to CU tests for the same soil. The strain rate for CD test can be chosen approx. 8-10 times lower than the CU test.
6. It is important to have no pore water pressure generation throughout the shearing phase of CD test or in other words strain rate must be so small that pore water pressure must get dissipated quickly when specimen is subjected to compression loading in CD test.
7. In CD test, volumetric strain versus axial strain relationship shows contractive response for NC soils and dilative response for OC soils. (NC = Normally consolidated, OC = Over consolidated)
References:
1. IS: 2720 (Part 11):1993- Determination of the shear strength parameters of a specimen tested in unconsolidated undrained triaxial compression without the measurement of pore water pressure (first revision). Reaffirmed- Dec 2016.
2. IS: 2720 (Part 12):1981- Determination of Shear Strength parameters of Soil from consolidated undrained triaxial compression test with measurement of pore water pressure (first revision). Reaffirmed- Dec 2016.
3. ASTM D7181-11. Method for Consolidated Drained Triaxial Compression Test for Soils; ASTM: West Conshohocken, PA, USA, 2011.
The aggregate impact test evaluates the toughness and resistance of aggregates to sudden impact. The test involves compacting aggregates between 10-14mm in a metal cylinder, dropping a 13.5-14kg hammer onto the aggregates from 380mm, and sieving the crushed material. For the sample tested, Sample 1 had an aggregate impact value of 15% and Sample 2 had 22%, indicating Sample 1 is strong while Sample 2 is close to the maximum allowable limit for good aggregates. The aggregate impact value gives a measure of an aggregate's resistance to impact forces experienced on roads.
Method for determination of shear strength of soil (Badarpur Sand) with a maximum particle size of 4.75 mm in drained conditions using Direct Shear Test apparatus.
It is a Floating Box type test in which upper half box is floating due to application of vertical loading resulting in lateral confinement thus generating sufficient friction which holds the upper half of shear box.
In the shear box test, the specimen is not failing along its weakest plane but along a predetermined or induced failure plane i.e. horizontal plane separating the two halves of the shear box. This is the main drawback of this test.
Moreover, during loading, the state of stress cannot be evaluated. It can be evaluated only at failure condition. Also, failure is progressive.
The angle of shearing resistance of sands depends on state of compaction, coarseness of grains, particle shape and roughness of grain surface and grading. It varies between 28° (uniformly graded sands with round grains in very loose state) to 46° (well graded sand with angular grains in dense state).
Direct shear test is simple and faster to operate. As thinner specimens are used in shear box, they facilitate drainage of pore water from a saturated sample in less time. This test is also useful to study friction between two materials – one material in lower half of box and another material in the upper half of box.
In general, loose sands expand and dense sands contract in volume on shearing. There is a void ratio at which either expansion contraction in volume takes place. This void ratio is called critical void ratio. Expansion or contraction can be inferred from the movement of vertical dial gauge during shearing.
1. The standard penetration test (SPT) involves driving a split-spoon sampler into the ground using a 63.5 kg hammer dropped from a height of 0.76 m. The number of blows required to drive the sampler over two intervals of 150 mm each is recorded as the SPT N-value.
2. The SPT N-value provides an approximate measure of soil resistance and a disturbed soil sample. It can be used to estimate soil strength parameters and bearing capacity through empirical correlations.
3. However, the SPT is highly dependent on the equipment and operator used, as factors like hammer efficiency, drill rod length, and borehole diameter can affect the N-value. Corrections are required
This document summarizes the results of a compaction test conducted on a soil sample. The test was performed at the CE building at Kasetsart University. Five trials were conducted to determine the water content of the soil, which ranged from 2.63% to 7.94%. Additional testing measured the wet and dry density of the soil at different water contents. The maximum dry density of 140.00 pcf occurred at the optimum water content of 7.00%.
1. The triaxial shear test is used to determine the shear strength parameters (c, φ) of soils by simulating the stresses around a soil sample in a three-dimensional state.
2. In the test, a soil specimen is enclosed in a triaxial cell where independent control is exerted on the cell pressure and axial load.
3. Based on drainage conditions during loading, there are three types of triaxial tests: consolidated-drained (CD), consolidated-undrained (CU), and unconsolidated-undrained (UU) tests. The CD test simulates long-term drained field conditions.
The document discusses shear strength of discontinuities in rock masses. It introduces concepts like shear strength of planar surfaces, shear strength of rough surfaces, Barton's estimate of shear strength which relates shear strength to joint roughness coefficient (JRC) and joint compressive strength (JCS). It discusses estimating JRC and JCS in the field and how these parameters are influenced by scale. It also summarizes the shear strength of filled discontinuities and the influence of water pressure on shear strength.
Porosity can be measured using sonic and density logs. Sonic logs measure the interval transit time of a sound wave through rock, with denser rock having faster transit times and more porous rock having slower times. There are two methods to calculate porosity from sonic logs: using an equation involving transit time and mud/rock properties, or using a sonic porosity chart. Similarly for density logs, porosity can be calculated from an equation using bulk and grain densities of the formation and mud, or looked up on a density porosity chart. Together, sonic and density logs provide good indications of porosity when used in combination.
1. The document describes the direct shear test procedure used to determine the shear strength properties of soils. It involves applying a normal load to a soil sample confined in a shear box and measuring the shear stress and displacement as the sample is sheared.
2. The direct shear test can be conducted as unconsolidated-undrained (UU), consolidated-undrained (CU), or consolidated-drained (CD) tests. Shear strength parameters such as cohesion and friction angle are determined from graphs of shear stress versus shear displacement and shear stress versus normal stress.
3. The purpose of the direct shear test is to examine the shear strength of soil samples along
This document presents information on determining the Atterberg limits of soils, which are important properties used to characterize soils in engineering. It discusses the purpose and procedures for determining the liquid limit and plastic limit through laboratory tests. The liquid limit is the moisture content where a soil changes from plastic to liquid state, while the plastic limit is where it changes from semi-solid to plastic. Factors like clay content and type, organic matter, and exchangeable cations can affect the Atterberg limits. The document describes the apparatus used and discusses the meaning and applications of these tests.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
El documento describe el ensayo de consolidación de suelos, el cual determina la magnitud de la consolidación de una muestra de suelo sometida a cargas de diversas magnitudes. Se requiere obtener una muestra de suelo, equipos como un consolidómetro y celda de consolidación, y seguir el procedimiento de colocar la muestra en un anillo, aplicar cargas progresivas y medir deformaciones. Los resultados permiten calcular parámetros que predicen el asentamiento del suelo bajo cargas.
Engineering geology is the application of the science of geology to the technology of ground engineering. The subject requires a comprehensive knowledge of geology, as well as an understanding of engineering properties and behaviour of the geological materials. The practice involves site investigation and site characterization specific to the needs of the engineering project. The geotechnical engineer plays a key role in most civil engineering projects as most structures are built on or in the ground. Geotechnical engineers assess the properties and behaviour of soil and rock formations.
O documento apresenta exemplos de exercícios relacionados a índices físicos do solo como teor de umidade, peso específico dos grãos, índice de vazios e porosidade. As equações para calcular esses índices são fornecidas, seguidas por 4 exercícios que pedem o cálculo de vários desses índices para amostras de solo sob diferentes condições.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
The document discusses various types of loads and pressures that act on underground tunnels, including:
1) Earth/rock pressures and water pressure are the most important potential loads. Live loads from surface traffic can usually be neglected.
2) Dimensions of tunnel sections must account for overburden weight (geostatic pressure) or loosening pressure (weight of loosened rock zone).
3) Lateral pressures, bottom pressures, and rock pressures are discussed. Several theories for estimating vertical and lateral loads are presented, including those by Bierbaumer, Terzaghi, and Tsimbaryevitch.
4) Rock pressures depend on factors like the quality of rock, stresses/strains around the
Class 6 Shear Strength - Direct Shear Test ( Geotechnical Engineering )Hossam Shafiq I
This document describes the direct shear test procedure used in a geotechnical engineering laboratory class to determine the shear strength parameters of soils. It discusses how the direct shear test is conducted by applying a normal stress and increasing shear stress to a soil sample until failure. Key steps of the test procedure are outlined, and the document explains how shear strength parameters like cohesion (C') and the internal friction angle (f) can be calculated from the test results and plotted on a Mohr-Coulomb failure envelope graph.
This is an academic lecture for Diploma in Engineering 7th Semester Mining and Mine Survey Technology. The Course related to this presentation is Basic of well planning.
This document provides an overview of lost circulation, which occurs when drilling fluid is lost into porous or fractured formations. It discusses the types and severity of lost circulation, as well as methods for preventing, locating, and treating lost circulation zones. Key points include that lost circulation can lead to blowouts if not addressed, and that preventing excessive downhole pressure and identifying weak formations are important. Locating lost zones involves surveys to detect where fluid flows into formations, while treatments require sealing fractures or pores with lost circulation materials.
This document discusses determining the shear strength of soils. It explains that soils fail in shear and their shear strength can be determined using laboratory tests like direct shear tests or triaxial tests on soil samples. The Mohr-Coulomb failure criterion describes the shear strength of a soil using parameters like cohesion (c) and friction angle (φ). These parameters can be estimated from the results of shear tests and used to assess shear strength and stability of soils under different field conditions.
The document discusses shear strength of soils. It defines shear strength as the soil's resistance to shearing stresses and deformation from particle displacement. Shear strength depends on cohesion between particles and frictional resistance, as modeled by the Mohr-Coulomb failure criterion. Laboratory tests like direct shear and triaxial shear tests are used to determine the shear strength parameters (c, φ) that describe a soil's failure envelope.
The aggregate impact test evaluates the toughness and resistance of aggregates to sudden impact. The test involves compacting aggregates between 10-14mm in a metal cylinder, dropping a 13.5-14kg hammer onto the aggregates from 380mm, and sieving the crushed material. For the sample tested, Sample 1 had an aggregate impact value of 15% and Sample 2 had 22%, indicating Sample 1 is strong while Sample 2 is close to the maximum allowable limit for good aggregates. The aggregate impact value gives a measure of an aggregate's resistance to impact forces experienced on roads.
Method for determination of shear strength of soil (Badarpur Sand) with a maximum particle size of 4.75 mm in drained conditions using Direct Shear Test apparatus.
It is a Floating Box type test in which upper half box is floating due to application of vertical loading resulting in lateral confinement thus generating sufficient friction which holds the upper half of shear box.
In the shear box test, the specimen is not failing along its weakest plane but along a predetermined or induced failure plane i.e. horizontal plane separating the two halves of the shear box. This is the main drawback of this test.
Moreover, during loading, the state of stress cannot be evaluated. It can be evaluated only at failure condition. Also, failure is progressive.
The angle of shearing resistance of sands depends on state of compaction, coarseness of grains, particle shape and roughness of grain surface and grading. It varies between 28° (uniformly graded sands with round grains in very loose state) to 46° (well graded sand with angular grains in dense state).
Direct shear test is simple and faster to operate. As thinner specimens are used in shear box, they facilitate drainage of pore water from a saturated sample in less time. This test is also useful to study friction between two materials – one material in lower half of box and another material in the upper half of box.
In general, loose sands expand and dense sands contract in volume on shearing. There is a void ratio at which either expansion contraction in volume takes place. This void ratio is called critical void ratio. Expansion or contraction can be inferred from the movement of vertical dial gauge during shearing.
1. The standard penetration test (SPT) involves driving a split-spoon sampler into the ground using a 63.5 kg hammer dropped from a height of 0.76 m. The number of blows required to drive the sampler over two intervals of 150 mm each is recorded as the SPT N-value.
2. The SPT N-value provides an approximate measure of soil resistance and a disturbed soil sample. It can be used to estimate soil strength parameters and bearing capacity through empirical correlations.
3. However, the SPT is highly dependent on the equipment and operator used, as factors like hammer efficiency, drill rod length, and borehole diameter can affect the N-value. Corrections are required
This document summarizes the results of a compaction test conducted on a soil sample. The test was performed at the CE building at Kasetsart University. Five trials were conducted to determine the water content of the soil, which ranged from 2.63% to 7.94%. Additional testing measured the wet and dry density of the soil at different water contents. The maximum dry density of 140.00 pcf occurred at the optimum water content of 7.00%.
1. The triaxial shear test is used to determine the shear strength parameters (c, φ) of soils by simulating the stresses around a soil sample in a three-dimensional state.
2. In the test, a soil specimen is enclosed in a triaxial cell where independent control is exerted on the cell pressure and axial load.
3. Based on drainage conditions during loading, there are three types of triaxial tests: consolidated-drained (CD), consolidated-undrained (CU), and unconsolidated-undrained (UU) tests. The CD test simulates long-term drained field conditions.
The document discusses shear strength of discontinuities in rock masses. It introduces concepts like shear strength of planar surfaces, shear strength of rough surfaces, Barton's estimate of shear strength which relates shear strength to joint roughness coefficient (JRC) and joint compressive strength (JCS). It discusses estimating JRC and JCS in the field and how these parameters are influenced by scale. It also summarizes the shear strength of filled discontinuities and the influence of water pressure on shear strength.
Porosity can be measured using sonic and density logs. Sonic logs measure the interval transit time of a sound wave through rock, with denser rock having faster transit times and more porous rock having slower times. There are two methods to calculate porosity from sonic logs: using an equation involving transit time and mud/rock properties, or using a sonic porosity chart. Similarly for density logs, porosity can be calculated from an equation using bulk and grain densities of the formation and mud, or looked up on a density porosity chart. Together, sonic and density logs provide good indications of porosity when used in combination.
1. The document describes the direct shear test procedure used to determine the shear strength properties of soils. It involves applying a normal load to a soil sample confined in a shear box and measuring the shear stress and displacement as the sample is sheared.
2. The direct shear test can be conducted as unconsolidated-undrained (UU), consolidated-undrained (CU), or consolidated-drained (CD) tests. Shear strength parameters such as cohesion and friction angle are determined from graphs of shear stress versus shear displacement and shear stress versus normal stress.
3. The purpose of the direct shear test is to examine the shear strength of soil samples along
This document presents information on determining the Atterberg limits of soils, which are important properties used to characterize soils in engineering. It discusses the purpose and procedures for determining the liquid limit and plastic limit through laboratory tests. The liquid limit is the moisture content where a soil changes from plastic to liquid state, while the plastic limit is where it changes from semi-solid to plastic. Factors like clay content and type, organic matter, and exchangeable cations can affect the Atterberg limits. The document describes the apparatus used and discusses the meaning and applications of these tests.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
El documento describe el ensayo de consolidación de suelos, el cual determina la magnitud de la consolidación de una muestra de suelo sometida a cargas de diversas magnitudes. Se requiere obtener una muestra de suelo, equipos como un consolidómetro y celda de consolidación, y seguir el procedimiento de colocar la muestra en un anillo, aplicar cargas progresivas y medir deformaciones. Los resultados permiten calcular parámetros que predicen el asentamiento del suelo bajo cargas.
Engineering geology is the application of the science of geology to the technology of ground engineering. The subject requires a comprehensive knowledge of geology, as well as an understanding of engineering properties and behaviour of the geological materials. The practice involves site investigation and site characterization specific to the needs of the engineering project. The geotechnical engineer plays a key role in most civil engineering projects as most structures are built on or in the ground. Geotechnical engineers assess the properties and behaviour of soil and rock formations.
O documento apresenta exemplos de exercícios relacionados a índices físicos do solo como teor de umidade, peso específico dos grãos, índice de vazios e porosidade. As equações para calcular esses índices são fornecidas, seguidas por 4 exercícios que pedem o cálculo de vários desses índices para amostras de solo sob diferentes condições.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
The document discusses various types of loads and pressures that act on underground tunnels, including:
1) Earth/rock pressures and water pressure are the most important potential loads. Live loads from surface traffic can usually be neglected.
2) Dimensions of tunnel sections must account for overburden weight (geostatic pressure) or loosening pressure (weight of loosened rock zone).
3) Lateral pressures, bottom pressures, and rock pressures are discussed. Several theories for estimating vertical and lateral loads are presented, including those by Bierbaumer, Terzaghi, and Tsimbaryevitch.
4) Rock pressures depend on factors like the quality of rock, stresses/strains around the
Class 6 Shear Strength - Direct Shear Test ( Geotechnical Engineering )Hossam Shafiq I
This document describes the direct shear test procedure used in a geotechnical engineering laboratory class to determine the shear strength parameters of soils. It discusses how the direct shear test is conducted by applying a normal stress and increasing shear stress to a soil sample until failure. Key steps of the test procedure are outlined, and the document explains how shear strength parameters like cohesion (C') and the internal friction angle (f) can be calculated from the test results and plotted on a Mohr-Coulomb failure envelope graph.
This is an academic lecture for Diploma in Engineering 7th Semester Mining and Mine Survey Technology. The Course related to this presentation is Basic of well planning.
This document provides an overview of lost circulation, which occurs when drilling fluid is lost into porous or fractured formations. It discusses the types and severity of lost circulation, as well as methods for preventing, locating, and treating lost circulation zones. Key points include that lost circulation can lead to blowouts if not addressed, and that preventing excessive downhole pressure and identifying weak formations are important. Locating lost zones involves surveys to detect where fluid flows into formations, while treatments require sealing fractures or pores with lost circulation materials.
This document discusses determining the shear strength of soils. It explains that soils fail in shear and their shear strength can be determined using laboratory tests like direct shear tests or triaxial tests on soil samples. The Mohr-Coulomb failure criterion describes the shear strength of a soil using parameters like cohesion (c) and friction angle (φ). These parameters can be estimated from the results of shear tests and used to assess shear strength and stability of soils under different field conditions.
The document discusses shear strength of soils. It defines shear strength as the soil's resistance to shearing stresses and deformation from particle displacement. Shear strength depends on cohesion between particles and frictional resistance, as modeled by the Mohr-Coulomb failure criterion. Laboratory tests like direct shear and triaxial shear tests are used to determine the shear strength parameters (c, φ) that describe a soil's failure envelope.
This document provides an overview of shear strength of soils. It defines shear strength as the maximum shear stress a soil can sustain without failure. Several factors that affect shear strength are discussed, including soil composition, initial state, structure, drainage conditions, and loading. The key concepts of principal stresses, Mohr's circle, and the Mohr-Coulomb failure criterion are explained. Common laboratory tests to evaluate shear strength parameters (c, φ) are also summarized, including direct shear testing, unconfined compression testing, and triaxial compression testing.
This document discusses shear strength and failure criteria in soils. It introduces the Mohr-Coulomb failure criterion, where shear strength consists of cohesive and frictional components. It describes Mohr circles and how they relate to failure envelopes. It also summarizes different types of triaxial tests (consolidated drained, consolidated undrained, and unconsolidated undrained) used to measure shear strength parameters.
This document discusses determining the shear strength of soils. It explains that shear strength is the maximum shear stress a soil can withstand before failing. There are two main types of shear strength - drained and undrained. Laboratory tests like direct shear tests and triaxial tests are used to determine the shear strength parameters (c, φ) by simulating the in-situ stress conditions. The Mohr-Coulomb failure criterion relates shear strength to effective normal stress and describes shear failure. Parameters c' and φ' define the failure envelope in effective stress space.
This document provides an overview of shear strength of soils. It discusses different types of shear failures in soils and the Mohr-Coulomb failure criterion. It describes the components of shear strength - cohesion and friction angle. It also summarizes different types of triaxial tests conducted to measure the shear strength parameters, including consolidated drained, consolidated undrained, and unconsolidated undrained tests. Furthermore, it discusses stress paths and pore pressure parameters related to shear strength testing of soils.
The document discusses shear strength of soils. It describes how soils fail in shear when the shear stress along the failure surface reaches the shear strength. It then covers the Mohr-Coulomb failure criterion and how it relates the shear strength of a soil to the normal stress and shear stress parameters c, φ. Laboratory tests like direct shear tests and triaxial tests are used to determine the shear strength parameters from soil specimens.
The document discusses shear strength of soils. It describes how soils generally fail in shear when the shear stress along the failure surface reaches the shear strength. It introduces the Mohr-Coulomb failure criterion, which states that the shear strength of a soil consists of a cohesive and frictional component. It also describes laboratory tests used to determine the shear strength parameters, including direct shear tests and triaxial shear tests.
1) Shear strength is the resistance of soil to failure along internal surfaces and is dependent on factors like composition, structure, and initial state.
2) Common laboratory tests to determine shear strength parameters (cohesion c and friction angle φ) include direct shear tests and triaxial compression tests.
3) The Mohr-Coulomb failure criterion describes the shear strength of a soil in terms of the normal and shear stresses required to cause failure along an internal plane.
1) Shear strength is the resistance of soil to shear stresses and failure along internal surfaces. It is influenced by factors like mineralogy, density, pore water, and stress history.
2) Common laboratory tests to evaluate shear strength are the direct shear test and triaxial shear test, which apply stresses to soil samples to induce shear failure.
3) The Mohr-Coulomb failure criterion describes the shear strength of a soil in terms of cohesion and internal friction angle parameters, which can be determined from a series of direct shear tests under different normal stresses.
Triaxial shear test and shear strength properties of soilsatish dulla
1. The triaxial shear test is used to determine the shear strength parameters (c, φ) of soils by simulating the stress conditions around a soil element in the field.
2. In a consolidated-drained (CD) test, the soil sample is first consolidated under cell pressure and then sheared under drained conditions, allowing pore pressures to dissipate. This simulates long-term drained field conditions.
3. The results of multiple CD tests under varying cell pressures can be used to construct the Mohr-Coulomb failure envelope and determine the effective stress shear strength parameters c' and φ'.
1. The document discusses shear failure in soils and the factors that influence a soil's shear strength.
2. It introduces the Mohr-Coulomb failure criterion, where shear strength is equal to the sum of the soil's cohesion and the frictional resistance along the failure plane.
3. It describes different types of triaxial tests (consolidated drained, consolidated undrained, and unconsolidated undrained) that are used to measure the shear strength parameters of cohesion, friction angle, and pore pressure characteristics.
1. The document discusses shear failure in soils and the factors that influence a soil's shear strength.
2. It introduces the Mohr-Coulomb failure criterion, where shear strength is a function of cohesion, friction angle, and normal stress.
3. It describes different types of triaxial tests (consolidated drained, consolidated undrained, and unconsolidated undrained) that are used to measure shear strength parameters.
1. The document discusses shear failure in soils and the factors that influence a soil's shear strength.
2. It introduces the Mohr-Coulomb failure criterion, where shear strength is equal to the sum of the soil's cohesion and the frictional resistance along the failure plane.
3. It describes different types of triaxial tests (consolidated drained, consolidated undrained, and unconsolidated undrained) that are used to measure the shear strength parameters of cohesion, friction angle, and pore pressure characteristics.
1. The document discusses shear failure in soils and the factors that influence a soil's shear strength.
2. It introduces the Mohr-Coulomb failure criterion, where shear strength is equal to the sum of the soil's cohesion and the frictional resistance along the failure plane.
3. It describes different types of triaxial tests (consolidated drained, consolidated undrained, and unconsolidated undrained) that are used to measure the shear strength parameters of cohesion, friction angle, and pore pressure characteristics.
Lecture 11 Shear Strength of Soil CE240Wajahat Ullah
Shear Strength of Soil
Shear strength in soils
Introduction
Definitions
Mohr-Coulomb criterion
Introduction
Lab tests for getting the shear strength
Direct shear test
Introduction
Procedure & calculation
Critical void ratio
The document discusses triaxial shear testing of soils. It begins by explaining that soils fail primarily in shear and defining shear strength. It then details the process of a triaxial shear test, including sample preparation and testing stages. The key types of triaxial tests - consolidated drained (CD), consolidated undrained (CU), and unconsolidated undrained (UU) - are explained. Specifically, the document focuses on CD testing, showing how volume change is monitored during shearing and how stress-strain behavior varies with soil density. It also demonstrates how shear strength parameters (c, φ) are determined from CD test results and how the parameters relate to effective stresses and long-term soil behavior analysis.
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Tema 2 shear strengthofsoil
1. 1
Shear Strength of Soils
ChihChih--Ping LinPing Lin
NationalNational ChiaoChiao TungTung Univ.Univ.
cplin@mail.nctu.edu.twcplin@mail.nctu.edu.tw
Soil Mechanics −
2
Outline
Shear FailureShear Failure
Soil StrengthSoil Strength
MohrMohr--Coulomb Failure CriterionCoulomb Failure Criterion
Laboratory Shear Strength TestLaboratory Shear Strength Test
Direct shearDirect shear
TriaxialTriaxial
Stress PathStress Path
Pore Pressure ParametersPore Pressure Parameters
2. 3
Shear failure
Soils generally fail inSoils generally fail in shearshear
strip footing
embankment
At failure, shear stress along the failure surface
reaches the shear strength.
failure surface mobilised shear
resistance
Shear Failure
4
Shear failure
The soil grains slide over
each other along the
failure surface.
No crushing of
individual grains.
failure surface
Shear Failure
3. 5
Shear failure
σ
τ
τ
At failure, shear stress along the failure surface
(τ) reaches the shear strength (τf).
Shear Failure
6
Soil (Shear) Strength
Soils are essentiallySoils are essentially frictional materialsfrictional materials
the strength depends on the applied stressthe strength depends on the applied stress
Strength is controlled byStrength is controlled by effective stresseseffective stresses
water pressures are requiredwater pressures are required
Soil strength depends onSoil strength depends on drainagedrainage
different strengths will be measured for a given soildifferent strengths will be measured for a given soil
a)a) deforms at constant volume (deforms at constant volume (undrainedundrained) and) and
b)b) deforms without developing excess pore pressuresdeforms without developing excess pore pressures
(drained)(drained)
Soil Strength
4. 7
Mohr-Coulomb Failure Criterion
τ
σ’
'tan'' φστ += cf
c’
φ
failure envelope
cohesion
friction angle
τf is the maximum shear stress the soil can take
without failure, under normal stress of σ’.
τf
σ’
τ σ’
Mohr-Coulomb
8
Mohr-Coulomb Failure Criterion
'tan'' φστ ff c +=
Shear strength consists of two
components: cohesive and frictional.
σ’f
τf
φ’
τ
σ’
c’
σ’f tan φ
c cohesive component frictional
component
Mohr-Coulomb
5. 9
c’ and φ’ are measures of shear strength.
Higher the values, higher the shear strength.
The parameters c’, φ’ depend on
Soil composition
Stress state of the soil (OCR)
The MohrThe Mohr--Coulomb criterion is an empirical criterion,Coulomb criterion is an empirical criterion,
and the failure locus is only locally linear.and the failure locus is only locally linear.
Extrapolation outside the range of normal stressesExtrapolation outside the range of normal stresses
for which it has been determined is likely to be unreliable.for which it has been determined is likely to be unreliable.
Mohr-Coulomb
10
Mohr Circles & Failure Envelope
Y
Initially, Mohr circle is a point
σ’c
σ’c
σ’c
∆σ’
σ’c+∆σ’
∆σ’
The soil element does not fail if
the Mohr circle is contained
within the envelope
GL
Mohr-Coulomb
6. 11
Mohr Circles & Failure Envelope
Y
σ’c
σ’c
σ’c
∆σ’
GL
As loading progresses, Mohr
circle becomes larger…
.. and finally failure occurs
when Mohr circle touches the
envelope
Mohr-Coulomb
12
Orientation of Failure Plane
Y
σ’c
σ’c
σ’c
∆σ’
GL
σ’c+∆σ’
90+φ’
φ’
45 + φ’/2
Failure plane
oriented at 45 + φ/2
to horizontal (σ’1)
45 + φ’/2
Y
Mohr-Coulomb
7. 13
Mohr circles in terms of σ & σ’
X X X
σv
σh
σv’
σh’
u
u
= +
total stresses
effective stresses
σvσhσv’σh’
u
Mohr-Coulomb
14
Envelopes in terms of σ & σ’
Identical specimens
initially subjected to
different isotropic stresses
(σc) and then loaded
axially to failure
σc
σc
σc
σc
∆σf
Initially… Failure
uf
At failure,
σ3 = σc; σ1 = σc+∆σf
σ3’ = σ3 – uf ; σ1’ = σ1 - uf
c, φ
c’, φ’
in terms of σ
in terms of σ’
Mohr-Coulomb
8. 15
Effective stress failure criterion
tanφστ ′+=c
c′ and φ′ are known as the effective (or drained) strength
parameters.
Soil behaviour is controlled by effective stresses, and the
effective strength parameters are the fundamental strength
parameters. But they are not necessarily soil constants.
If the soil is at failure the effective stress failure criterion will
always be satisfied.
Mohr-Coulomb
16
Total stress failure criterion
uuc φστ tan+=
If the soil is taken to failure at constant volume (undrained) then the
failure criterion can be written in terms of total stress as
cu and φu are known as the undrained strength parameters
These parameters are not soil constants, they depend strongly on the
moisture content of the soil.
The undrained strength is only relevant in practice to clayey soils
that in the short term remain undrained. Note that as the pore
pressures are unknown for undrained loading the effective stress
failure criterion cannot be used.
Mohr-Coulomb
9. 17
Laboratory Tests for Shear Strength Parameters
Direct shear testDirect shear test
TriaxialTriaxial testtest
Direct simple shear testDirect simple shear test
Plane strainPlane strain triaxialtriaxial testtest
TorsionalTorsional ring shear testring shear test
Shear Strength Test
18
Direct Shear Test
Motor
drive
Load cell to
measure
Shear Force
Normal load
Rollers
Soil
Porous plates
Top platen
Measure relative horizontal displacement, dx
vertical displacement of top platen, dy
Direct Shear
11. 21
Pros:
Simplest and most economical for sandy soil
Applicable for soil/structure interface
Cons:
Soil not allowed to fail along the weakest plane.
Shear stress distribution is not uniform.
Direct Shear
22
Triaxial Test Apparatus
porous
stone
impervious
membrane
piston (to apply deviatoric stress)
O-ring
pedestal
perspex cell
cell pressure
back pressure
pore pressure or
volume change
water
soil sample at
failure
failure plane
Triaxial
12. 23
Types of Triaxial Tests
Under all-around
cell pressure σc
Shearing
(loading)
Is the drainage valve open? Is the drainage valve open?
deviatoric stress (∆σ)
yes no yes no
Consolidated
sample
Unconsolidated
sample
Drained
loading
Undrained
loading
Triaxial
24
Types of Triaxial Tests
Depending on whether drainage is allowed
or not during
initial isotropic cell pressure application, and
shearing,
there are three special types of triaxial tests
that have practical significances. They are:
Consolidated Drained (CD) test
Consolidated Undrained (CU) test
Unconsolidated Undrained (UU) test
Triaxial
13. 25
Granular soils have
no cohesion.
c = 0 & c’= 0
For normally consolidated
clays, c’ = 0 & c = 0.
For unconsolidated
undrained test, in
terms of total
stresses, φu = 0
Triaxial
26
CD, CU and UU Triaxial Tests
no excess pore pressure throughout the test
very slow shearing to avoid build-up of pore
pressure
Consolidated Drained (CD) Test
gives c’ and φ’
Can be days!
∴ not desirable
Use c’ and φ’ for analysing fully drained
situations (e.g., long term stability,
very slow loading)
Triaxial
15. 29
Triaxial
30
CD, CU and UU Triaxial Tests
pore pressure develops during shear
faster than CD (∴preferred way to find c’ and φ’)
Consolidated Undrained (CU) Test
gives c’ and φ’
Measure σ’
Triaxial
17. 33
CD, CU and UU Triaxial Tests
pore pressure develops during shear
very quick test
Unconsolidated Undrained (UU) Test
analyze in terms of σ gives cu and φu
Not measured
∴σ’ unknown
= 0; i.e., failure envelope
is horizontal
Use cu and φu for analysing undrained
situations (e.g., short term stability,
quick loading)
Triaxial
34
UU test on saturated clay
Triaxial
19. 37
σ’1 and σ’3 at Failure
Triaxial
38
Stress Point
t
s
τ
σσh
σv
(σv-σh)/2
(σv+σh)/2
stress point stress point
2
hv
s
σσ +
=
2
hv
t
σσ −
=
X
σv
σh
Stress Path
20. 39
Stress Path
t
s
Stress path is
the locus of
stress points
Stress path
Stress path is a convenient way to keep track of the
progress in loading with respect to failure envelope.
During loading…
τ
σ
Stress Path
40
Failure Envelopes
τ
σ
t
s
c
φ
c cos φ
tan-1 (sin φ)
failure
During loading (shearing)….
stress path
Stress Path
21. 41
Pore Pressure Parameters
Y
∆σ1
∆σ3
∆u = ?
A simple way to estimate the pore
pressure change in undrained
loading, in terms of total stress
changes ~ after Skempton (1954)
[ ])( 313 σσσ ∆−∆+∆=∆ ABu
Skempton’s pore pressure
parameters A and B
Pore Pressure Parameters
42
Pore Pressure Parameters
For saturated soils, B ≈ 1.
A-parameter at failure (Af)
For normally consolidated clays Af ≈ 1.
B-parameter
B = f (saturation,..)
Af = f(OCR)
For heavily overconsolidated clays Af is negative.
Pore Pressure Parameters
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