Ba-Phu Nguyen, Ananta Man Singh Pradhan, Tan Hung Nguyen, Nhat-Phi Doan, Van-Quang Nguyen and Thanh-Canh Huynh
The consolidation behavior of prefabricated vertical drain (PVD)-installed soft deposits mainly depends on the PVD performance. The purpose of this study is to propose a numerical…
Abstract
Purpose
The consolidation behavior of prefabricated vertical drain (PVD)-installed soft deposits mainly depends on the PVD performance. The purpose of this study is to propose a numerical solution for the consolidation of PVD-installed soft soil using the large-strain theory, in which the reduction of discharge capacity of PVD according to depth and time is simultaneously considered.
Design/methodology/approach
The proposed solution also takes into account the general constitute relationship of soft soil. Subsequently, the proposed solution is applied to analyze and compare with the monitoring data of two cases, one is the experimental test and another is the test embankment in Saga airport.
Findings
The results show that the reduction of PVD discharge capacity according to depth and time increased the duration required to achieve a certain degree of consolidation. The consolidation rate is more sensitive to the reduction of PVD discharge capacity according to time than that according to the depth. The effects of the reduction of PVD discharge capacity according to depth are more evident when PVD discharge capacity decreases. The predicted results using the proposed numerical solution were validated well with the monitoring data for both cases in verification.
Research limitations/implications
In this study, the variation of PVD discharge capacity is only considered in one-dimensional consolidation. However, it is challenging to implement a general expression for discharge capacity variation according to time in the two-dimensional numerical solution (two-dimensional plane strain model). This is the motivation for further study.
Practical implications
A geotechnical engineer could use the proposed numerical solution to predict the consolidation behavior of the drainage-improved soft deposit considering the PVD discharge capacity variation.
Originality/value
The large-strain consolidation of PVD-installed soft deposits could be predicted well by using the proposed numerical solution considering the PVD discharge capacity variations according to depth and time.
Details
Keywords
It is well known that the prefabricated vertical drain (PVD) installation process generates a significant soil disturbance around PVD. This disturbed zone significantly affects…
Abstract
Purpose
It is well known that the prefabricated vertical drain (PVD) installation process generates a significant soil disturbance around PVD. This disturbed zone significantly affects the rate of settlement and excess pore pressure dissipation. However, the characteristics of these zones were still uncertain and difficult to quantify; there remains large discrepancy among researchers. This study aims to develop a simple analytical solution for radial consolidation analysis of PVD-installed deposit considering mandrel-induced disturbance.
Design/methodology/approach
The proposed solution takes into account the nonlinear distributions of both horizontal hydraulic conductivity and compressibility toward the drain. The proposed solution was applied to analyze field behavior of test embankment in New South Wales, Australia.
Findings
Both effects significantly increased the time required to achieve a certain degree of consolidation. The effect of hydraulic conductivity on the consolidation rate was more significant than the effect of compressibility variation. And, the increased compressibility in the soil-disturbed zone due to mandrel installation significantly increased vertical strain of the PVD-improved soil deposit. The predicted results using the proposed analytical solution were in good agreement with the field measurements.
Practical implications
A geotechnical engineer could use the proposed analytical solution to predict consolidation behavior of drainage-installed ground.
Originality/value
Consolidation behavior of PVD-installed ground could be reasonably predicted by using the proposed solution with considering variations of both hydraulic conductivity and compressibility due to PVD installation.
Details
Keywords
Yun Tae Kim, Ba-Phu Nguyen and Dae-Ho Yun
It is well-known that consolidation rate of prefabricated vertical drain (PVD)-installed ground is closely related to the discharge capacity of PVD, which decreases with an…
Abstract
Purpose
It is well-known that consolidation rate of prefabricated vertical drain (PVD)-installed ground is closely related to the discharge capacity of PVD, which decreases with an increase in effective stress. This paper aims to present consolidation behaviors of PVD-improved ground considering a varied discharge capacity of PVD.
Design/methodology/approach
A simple equivalent vertical hydraulic conductivity (k′ve method) was proposed in plane strain numerical analysis, in which the effect of decreased discharge capacity with depth was considered. Numerical analysis was applied to analyze field behaviors of test embankment of soft mucky deposit.
Findings
Finite element method results indicated that consolidation behaviors of PVD-improved soil with a nonlinear distribution of discharge capacity with depth were in a good agreement with the observed field behaviors, compared with those with a constant discharge capacity and a linear distribution of discharge capacity. At a given time and depth, the consolidation rate in the case of discharge capacity with a nonlinear distribution is lower than that of a linear or constant distribution.
Practical implications
A geotechnical engineer could use the proposed method to predict consolidation behaviors of drainage-installed ground.
Originality/value
Consolidation behaviors of PVD-installed ground could be reasonably predicted by using the proposed method with considering effect of discharge capacity reduction.