Summary: | This study conducted experimental tests on the undisturbed Nanjing Yangtze River floodplain soft soil using the bender element instrument to determine the maximum dynamic shear modulus of the Yangtze River floodplain overconsolidated soft soil. The <i>G</i><sub>max</sub> of floodplain soft soil with different overconsolidated ratio OCR, initial effective confining pressure <i>σ</i><sub>3c</sub>′, and void ratio <i>e</i> are discussed. The results indicated that <i>G</i><sub>max</sub> reduced as <i>e</i> rose for given <i>σ</i><sub>3c</sub>′ and OCR. In addition, an increase in OCR contributed to a gradual decrease in the decay rate of <i>G</i><sub>max</sub>, while the <i>G</i><sub>max</sub> decay rate is insensitive to the change of <i>σ</i><sub>3c</sub>′. The void ratio-normalized maximum shear modulus <i>G</i><sub>max</sub>/<i>F</i>(<i>e</i>) improved with the increase in the stress-normalized initial effective confining pressure <i>σ</i><sub>3c</sub>′/<i>P</i><sub>a</sub>, whereas the growth rate gradually drops, and a power relationship is then obtained between <i>G</i><sub>max</sub>/<i>F</i>(<i>e</i>) and <i>σ</i><sub>3c</sub>′/<i>P</i><sub>a</sub>. Based on the regression analysis, a <i>G</i><sub>max</sub> prediction method is established for reasonably characterizing Yangtze River floodplain soft soils with various over-consolidation states, initial stress conditions, and compactness levels, with a prediction error of less than 10%.
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