Abstract
Vacuum preloading combined with prefabricated vertical drains (PVDs) has the potential to improve the soft sediments under water, however, its development is partly limited by the unclear understanding of the mechanism. This paper aims to extend the comprehension of the influential mechanism of overlapping water in the scenario of underwater vacuum preloading with PVDs. The systematic investigations were conducted by small strain finite element drained analyses, with the separated analysis schemes considering suction-induced consolidation, seepage and their combination. The development of settlement in the improved soil region and the evolution of seepage flow from the overlapping water through the non-improved soil region into improved zone are examined in terms of the build-up of excess pore pressure. Based on the results of numerical analyses, a theoretical approach was set out. It was capable to estimate the time-dependent non-uniform settlement along the improved soil surface in response to the combined effects of suction-induced consolidation and seepage. The difference of underwater and onshore vacuum preloading with PVDs is discussed with some practical implication and suggestion provided.
Highlights
Considering these, the aim of this study is to investigate the influential mechanism of overlapping water and interpret the counteraction mechanism of consolidation and seepage in the scenario of underwater vacuum preloading with prefabricated vertical drains (PVDs), and develop a method to predict the contribution of seepage on the consolidation settlement
A series of discrete negative pressure regions shaped in ribbon pattern were generated, and the soil around PVDs slightly settled (Figure 4a). (ii) Transient phase with consolidation mainly occurring in the improved soil region (T = 0.002; see Figure 4b)
The influential mechanism sponse in the underwater vacuum preloading with PVDs
Summary
The recent development of marine resources has increased the need for engineers to improve the soft sediments under water. Vacuum preloading combined with prefabricated vertical drains (PVDs) is the commonly employed ground improvement technique suitable for soft deposits to accelerate the dissipation of pore pressure resulted in an earlier settlement and a gain in undrained shear strength [1,2,3]. Several successful engineering practices have shown their validity and economy in improving the submarine soil [4,5,6,7]. The success has proved the feasibility of underwater vacuum preloading, and it would be more competent with the advance of vacuum process
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