Civ e 353 geotechnical engineering i direct shear test. Experimental and numerical analysis of direct shear test. Class 6 shear strength direct shear test geotechnical. The results from the direct shear testing performed at the minimum required compaction by a local testing firm are presented in table 1. May 18, 2017 in this video i have talked about the field conditions that affect the values of shear strength parameters like drained or undrained conditions and i have also discussed the direct shear test to. The test equipment consists of a metal box in which the soil specimen is placed the box is split horizontally into two halves vertical force normal stress is applied through a metal platen shear force is applied by moving one half of the box relative to the other to cause. Cep 701 pg lab mohrcoulomb failure criterion in terms of total stresses f c tan failu.
Usually, tack and adhesion decrease as shear strength increases. Direct shear test or box shear test is used to determine the shear strength of the soil. Generally, three or more specimens are tested, each under a. In the present study the straincontrolled method is adopted, i. The testing procedure of the direct shear tests is described in the following standards. Mar 14, 2017 2 derive the mohrcoulomb equation for shear stress in the soil, and explain when failure occurs in the soil. Chaoyang university of technology direct shear testing 5 dismantling stage when the test is over, the shearing stress is reduced to zero. Direct shear test chemical product engineering nature. A direct shear test is a laboratory or field test used by geotechnical engineers to measure the shear strength properties of soil or rock material, or of discontinuities in soil or rock masses the u. A large direct shear apparatus was used to test coarse granular soil.
Standard test method for direct shear test of soils under consolidated drained conditions. In shear tests with a small shear box, deformation in shear band is homogeneous and stress dilatancy relationships at prepeak and postpeak phases of shearing are similar. Standard test method for performing laboratory direct shear. Direct shear test of soils under consolidated drained conditions 55 9. Procedure for performing direct shear and sliding friction. Results are presented to show how the state of stress. Civil engineering texas tech university direct shear test cont. Direct shear test triaxial test linkedin slideshare. Standard test method for direct shear test of soils under. The direct shear test is commonly used to measure the frictional characteristics of soils and many other granular materials including everything from corn flakes to coal. Then specimen for the direct shear test could be obtained using the correct cutter provided. The shear strength parameters of the soil sample tested through direct shear test in laboratory are found to be c 0. Parit sulong has higher stress strain than parit nipah.
The normal load is then reduced to zero as quickly as possible and the apparatus dismantled. In the past 20 years or so, there has been an increasing use of. To determine the shearing strength of the soil using the direct shear apparatus. Normal stress is applied to the specimen by utilising a weight hanger, a lever arm amplification ratios of 9. Results are presented to show how the state of stress in the shear. Direct shear results conducted at 95% mmd astm d698.
In this video i have talked about the field conditions that affect the values of shear strength parameters like drained or undrained conditions and i. A soil sample is sheared under a normal stress a and a shear stress t. 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. Dem simulations of the direct shear test have been performed under both constant normal stress and constant volume conditions. Ppt direct shear test powerpoint presentation free to. Shear strength of a soil is its maximum resistance to shearing stresses. Standard test method for determining the shear strength of.
An experimental and numerical investigations of the direct shear test have been performed under constant vertical stress q const and constant sample volume h const. If shear stress increased, shear strain also increased. Depending on soil behavior and field application, other suitable criteria may be defined. A sheartrac ii unit can be configured to run direct shear, residual shear, direct simple shear, cyclic direct, simple shear, and incremental consolidation testing. The soil sample starts to rebound as soon as the normal load. Soil strength and consolidation testsdetermination of the shear strength of a soildirect shear test using a shear box 1 scope this standard sets out a method for determining the shear strength of a soil in terms of effective stress by direct shearing in a shear box. Direct shear tests are performed to provide the design engineer with the friction angle and adhesion coefficient for the various interfaces within the design. In common practice, the strength of the soil is defined as the peak strength points a and b. The user of results from this test method is cautioned that. Singlestage direct shear test stress parameters of expansive unsaturated soil in a dry density of 1. This test method covers the determination of the direct shear and sliding friction strengths of intact specimens and specimens that contain a natural or artificial joint or discontinuity. Strength back to shear strength peak strength critical state strength. The value is expressed in terms of failing stress per shear area.
For cohesionless soil sand, gravel and some silt the effective cohesion c is zero and the shear equation reduces to the direct shear test set up consists of placing a soil sample in a split box having a crosssectional. The test specimens and conditions, including normal stresses, are generally selected by the user. During the determination of soil shear strength in a laboratory by different test methods soil is loaded in a different way. In shear tests with a small shear box, deformation in shear band is homogeneous and stress dilatancy relationships at. Unconfined compression test the unconfined compression test astm 02166 is the most widely used laboratory test of.
After the peak shear stress is obtained, shear displacement continues to increase up to point a see figure 3, but at a somewhat slower rate than during prepeak shear. The result shows that, direct simple shear test of stress strain that tested on hemic is more relevant than a direct shear box because dss shear the entire specimen of peat while dsb only shear at the center of the specimen. In shear tests with a small shear box, deformation in shear band is homogeneous and stress dilatancy relationships at pre. The dss test generates a fairly homogeneous state of shear stress throughout the specimen, which provides initial stress condition, stress path, and deformation configuration that models numerous field loading conditions more closely than any other strength tests such as triaxial.
Direct shear test machine cooper research technology. Shear strength is an extremely important property to attain in the field of geotechnical engineering as it is often required to determine the. Both the tests yield varying internal angle of friction when carried out on the same specimen and conditions. Download limit exceeded you have exceeded your daily download allowance. Astm d 308098 1998 standard test method for direct shear test of soils under consolidated drained conditions and as 12896. This test can be performed under drained or undrained conditions with rock, soil, or asphalt samples. Direct shear test objectives to determine the shearing strength of the soil using the direct shear apparatus introduction in many engineering problems such as design of foundation, retaining walls, slab bridges, pipes, sheet piling, the value of the angle of internal friction and cohesion of the soil involved are required for the design. British standard methods of test for soils for civil engineering purposes, part 7 shear strength tests total stress astm d308004. The purpose of the direct shear test of soil is to obtain its ultimate shear resistance, its angle of internal friction, its cohesion, and its shear stress deformation characteristics.
Test confining stress psf shear stress psf peak residual 1 2000 1405 1405. However, in tests with a large shear box, the prepeak and postpeak stress dilatancy relationships are different. Shear stress under different matric suctions, and vertical pressure concluded from figure 5 are presented in table 5. Direct shear testing of a marginal material using a large. In a direct shear test, two types of shear application are possible. Critical wall shear stress for the ehedg test method the phicometer. As thinner specimens are used in shear box, they facilitate drainage of pore water from a saturated sample in less time. In common practice, the strength of the soil is defined as the peak strength points a and b in figure 123 measured in the test. Mar 12, 2019 a large direct shear apparatus was used to test coarse granular soil. During early stages of a shear test, a rock specimen has increasing shear strain with increasing shear load. Cyclic direct simple shear, cyclic dss test equipment. Direct shear test 25 direct shear test analysis of test results note crosssectional area of the sample changes with the horizontal displacement 26 direct shear tests on sands stress strain relationship 27 direct shear tests on sands how to determine strength parameters c and f 28 direct shear tests on sands direct shear tests are drained and. Direct shear test of soils under consolidated drained conditions.
The test is carried out on either undisturbed samples or remoulded samples. Standard test method for performing laboratory direct. Summary of test method this test method consists of placing the test specimen in the direct shear device, applying a predetermined normal stress. Legally binding document step out from the old to the newjawaharlal nehru invent a new india using knowledge.
Direct shear test an overview sciencedirect topics. The direct shear test is also used as a form of quality control to ensure product compliance to dard direct shear test method is commonly used for determining. Fesimulations of a direct wall shear box test pdf free. The direct shear test is is one of the most widely used laboratory tests to determine the shear strength of soil, rock, and other materials.
Young bureau of reclamation denver office denver co 80225 12. Direct shear test of soils under consolidated drained. Effective stress effective angle of shearing resistance. Methods of testing soils for engineering purposes method 6. Direct or simple shear parameters used for analysis. The test covers the determination of consolidated drained shear strength of a soil material by direct shear.
For rock the test is generally restricted to rock with. Direct shear test for coarse granular soil springerlink. To facilitate the remoulding purpose, a soil sample may be compacted at optimum moisture content in a compaction mould. The shear test measures the time required to pull a defined area of psa from the test panel under a constant load. Direct simple shear test dss soil testing for the investigation of stress strainstrength relationships for horizontal loading situations.
Results reveal that the internal angle of friction obtained from a direct shear test is lower than that obtained from the ring shear test. Two stress deformation curves are shown in figure 123. While the test has many shortcomings nonuniform and rotating state of stress, nonuniform state of. Direct shear tests used in soilgeomembrane interface friction studies august 1994 6. Ts2060 automatic direct residual shear test machine is motorized and floor mounted.