CONSOLIDATION BEHAVIOR OF SATURATED UNDER-CONSOLIDATED FOUNDATION WITH VERTICAL DRAINS: EXAMPLE FROM UPSTREAM SEDIMENT IN FRONT OF DAM

Warping dams play an important role in the control of soil and water loss in the upper and middle reaches of the Yellow River, and "upstream sediment heightening fill" is a common construction method in the check dams reinforcement engineering. Aiming at the calculation problem of the sediment in front of the dam in a saturated and under-consolidated state, the radial large-strain under-consolidated settlement model(RSUC) of the silted foundation with prefabricated vertical drains(PVDs) is established using the piecewise linear method. The paper verifies the accuracy of the RSUC model, compares the different consolidation behaviors between under-consolidated and normally consolidated foundation with PVDs. Through engineering cases, the self-weight consolidation process of sediment is analyzed, and the influence of adding PVDs on the consolidation of sediment is discussed. The results show that the undissipated excess pore water pressure before constructing makes the consolidation speed of the under-consolidated sediment foundation slower than that of normally consolidated sediment foundation with PVDs. The void ratio and excess pore water pressure of the under-consolidated sediment during the drying period show non-linear changes with the relative elevation. The bottom consolidation speed and settlement value are relatively large. Apart from accelerating the consolidation speed of sediment and reducing post-construction settlement, installing the PVDs for silted foundation can reduce the maximum value of excess pore water pressure in the sediment and increase the stability of the dam foundation.