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dc.contributor.advisor Adams, Herbert G. en Larson, Robert A. en 2016-12-09T22:49:57Z en 2016-12-09T22:49:57Z en 1995 en 1995-06 en
dc.identifier.uri en
dc.description Includes bibliographical references (leaves 124-135) en
dc.description California State University, Northridge. Department of Geological Sciences. en
dc.description.abstract The primary goal of this study was to determine the predictive capabilities of a state- of- the- art geotechnical analysis of soil failures on natural slopes. This was achieved by reviewing previous work and conducting investigations at three sites in conjunction with laboratory analysis. The infinite slope model was used to estimate the stability of soil, which occurs as a relatively thin layer over weathered rock on slopes. This model is most sensitive to the cohesion value of shear strength and the height of the water saturated zone within the soil. The types of soil commonly found on slopes 1n southern California are granular, and thus by definition, frictional and noncohesive. Frictional soils have shear strength derived entirely from the angle of internal friction. Soil laboratories commonly indicate soil cohesion of 200 pounds per square foot using test-dependent and state-dependant shear strength tests. This tested value, which is an interpretation of apparent cohesion due to negative pore water pressures and inappropriately applied normal stress, is sufficient to demonstrate soil slope stability to local government agencies. However, tests on soil samples obtained carefully by hand for this study and completed according to soil mechanics theory, with the appropriate normal stress (overburden) and after saturation, demonstrate that the soils are truly cohesionless, in agreement with the definition. The infinite slope model was applied to three test sites where soil slips occurred. Water from prolonged rain infiltrated the soil and accumulated within the soil above the contact with rock or above other relatively impermeable layers. As water accumulates, positive pore water pressures occur, which effectively reduce the frictional component of shear strength of the soil, resulting in failure. I was not able to measure the pore water pressure and distribution of water within a slope for this study, such that I was unable to verify the degree of saturation. Applying the infinite slope model to the three sites using the tested soil properties indicates failure of the soil would occur on the slopes prior to full saturation of the soil. It can only be assumed that in those areas adjacent to the soil slips, where slope failure did not occur, stability was due to insufficient saturation of the soil, which was likely due to higher soil or bedrock permeabilities. The results of this study indicates that analysis of the stability of soil on natural slopes should include in-situ pore-water pressure measurements or assume full saturation of the soil, as well as careful soil sampling and appropriate testing. en
dc.description.statementofresponsibility by Robert A. Larson en
dc.format application/pdf en
dc.format.extent xiv, 135 pages en
dc.language.iso en en
dc.publisher California State University, Northridge en
dc.rights.uri en
dc.subject.other Dissertations, Academic -- CSUN -- Geology. en
dc.title Stability of soil on natural slopes en
dc.type Thesis en 2016-12-09T22:49:57Z en
dc.contributor.department Geological Sciences en M.S. en
dc.contributor.committeemember Howard, Robert B. en
dc.contributor.committeemember Tabidian, M. Ali en
dc.contributor.committeeMember Howard, Robert B. en
dc.contributor.committeeMember Tabidian, M. Ali en
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