The Taylor series expansion approach is used to develop a new P-L yield function based on the modified Cam-clay (MCC) model yield function,which can reasonably describe the yield surfaces of different types of soil. The P-L yield function can satisfies the basic assumptions of critical state mechanics and the normal vector of the yield locus at the intersection point is perpendicular to the p-axis. After reaching the critical state, no unrealistic volumetric deformation is produced in soil samples by assuming an associated flow rule. The extra introduced parameter α is defined as the ratio between the mean effective pressure at the critical state and the preconsolidated pressure. The yield functions of the original Cam-clay (CC) and MCC models can be obtained by letting α be 0.368 and 0.5, respectively. The predicted yield locus using the P-L yield function will be expanded along with the critical state line in the p-q plane as α increases. Through fitting the yield surface of Pancrudo rockfill, it can be seen that the modified P-L yield function can better describe the true geometric shape of the yield surface. Using the P-L yield function, a new extended modified Cam-clay (ExMCC) model was proposed in the current work to account for the effect of the shapes of the yield locus on the model performance. By comparing the model calculation results with the undrained triaxial compression test results of normally consolidated remolded Weald clay and Kaolin clay, it is found that appropriately adjusting the geometric shape of the yield surface helps to improve the calculation accuracy of the model. Especially for Kaolin clay, more accurate undrained shear strength and effective stress path can be calculated under undrained shear conditions. In view of the advantages of simple form and high calculation accuracy of the extended modified ExMCC model, it has broad application prospects in the field of geotechnical deformation calculation.
Li Haichao
,
Li Xinyu
,
He Zuoyue
. An Extended Modified Cam-Clay Model Based on the P-L Yield Function[J]. Chinese Journal of Underground Space and Engineering, 2024
, 20(S2)
: 602
-608
.
DOI: 10.20174/j.JUSE.2024.S2.11
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