1 AIT Asian Institute of Technology

Effects of applied stress path on the stress-strain behaviour and strength characteristics of soft Nong Ngoo Hao clay

AuthorChaudhry, A. Rauf
Call NumberAIT Thesis no. 760
Subject(s)Clay--Thailand--Nong Ngoo Hao--Analysis
NoteA thesis submitted in partial fulfillment of the requirements for degree of Master of Engineering at the Asian Institute of Technology, Bangkok, Thailand.
PublisherAsian Institute of Technology
AbstractThis thesis presents the experimental investigation on the stress-strain behaviour and strength characteristics of normally consolidated saturated specimens of Soft Bangkok Clay. The specimens were taken from the Nong Ngoo Hao Clay deposit (at depths of 5.5-6.0 m) and were tested under different applied stress paths in the conventional axi-symmetric triaxial apparatus. The different types of tests carried out are (i) Consolidated undrained tests (CIU) (ii) Consolidated drained tests (CID) (iii) Constant mean normal stress tests (CIP*) (iv) Anisotropic consolidation tests (c~) All tests were carried out under controlled stress conditions. The experimental observations from each series of tests are presented in the normalized stress-strain plots. Unique relationships are observed between the normalized stresses and strains. Also for each types of tests unique relationships are obtained between the stress ratios (q*/p* and o1/03) and the strains. The end points of all the specimens sheared under constant p* conditions and fully drained (with constant cell pressure) conditions lie on the same straight lines in the (q, p) and (q*, p*) plots. The value of critical state t parameter M is about 0.925 and the values of strength parameters are c = O, = 23.7°. The corresponding values for undrained tests are M = 1.05, c = O, and 6 = 27°. The experimental observations obtained in the author's testing program are also compared with the results of other research workers, who have carried out extension tests on the same clay. The strength parameters for undrained tests under extension conditions are c = 0 and i = 37°. The corresponding values for drained tests under extension conditions being 26.2°. Unique water content strength relationship exists for all types of tests when plotted in the (wf, log q*) plot. Also, the projection of the critical state line was unique and parallel to the isotropic consolidation line in the (wf, log p*f) space, During anisotropic consolidation, the strain increment ratio was a constant and the void ratio varied linearly with the logarithm of the mean normal stress (the slope of the line is the same, A = 0.51 as that for isotropic consolidation. Unique state boundary surface was obtained for all types of tests when plotted in the (q*/p*e, p*/p*e) space. Strains were predicted using the concept of unique state boundary surface and were compared with the experimental observations. The incremental stress-strain theory and the Revised Theory successfully predicted the strains for constant p* and fully drained (constant cell pressure) tests.
Year1975
TypeThesis
SchoolStudent Research Before 1980
DepartmentOther Field of Studies (No Department)
Academic Program/FoSThesis (Year <=1979)
Chairperson(s)Balasubramaniam, A.S.
Examination Committee(s)Moh, Za-Chieh ;Brenner, R.P.
Scholarship Donor(s)British Government
DegreeThesis (M. Eng.) - Asian Institute of Technology,1975


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