Forces in Plastic Vertical Drains during installation

During installation of Plastic Vertical Drains (PVD) large forces can occur that rupture the drain or filter fabric. To determine these forces laboratory and field tests are executed whereby the forces are measured by strain gages during installation of the drains. The tests showed that under circumstances these forces could exceed the requirements mentioned in certain norms. The forces were caused by the fact that high performance PVD installation rigs were used in combination with large depths and hard top layers. Also other circumstances can influence the forces in drains during installation. This paper describes all the factors that influence the forces in PVD.

RAM Connection V8i (SELECTseries 4) 8.0.0.23 1000 days trial

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Optimal Design of Vertical Drains in Soft Ground

A Final Report of a Student from Department of Civil and Structural Engineering, University of Sheffield.

This project is concerned with the design of a program to calculate the optimal solution for geotechnical problems involving the consolidation of soft ground by the use of prefabricated vertical drains. The effects being taken into account include smear, well resistance, ramped loading and multiple layers. The program has allowed the author to complete a series of parametric studies into the effects of the factors which contribute to the rate of consolidation using vertical drains. The final solution is a distributable program that uses an intuitive graphical user interface. This allows the user to input soil parameters and assumptions and then run the program to find the optimal spacing of drains to achieve a given consolidation in a given time. An element of probabilistic analysis has also been incorporated into the program to allow the creation of risk to cost curves for any parameters. This allows the user to make an educated decision based on the allowable cost and the degree of certainty in the soil parameters.

Acceleration of Self-Weight Consolidation Settlement by Prefabricated Vertical Drain Board

In dredging and reclamation, self-weight consolidation of marine clay need relatively long time. In this study, to accelerate self-weight consolidation time laboratory large size column test were performed using prefabricated vertical drain board. And also presented optimum time of prefabricated vertical drain board insert. Prefabricated vertical drain board-test result showed l/2 time to consolidation compared to Selfweight consolidation-test. Therefore, It can be judged that in reclamation of dredged marine clay, prefabricated vertical drain board can used to accelerate self-weight consolidation.

Managing the Construction Process (4th Edition)

Managing the Construction Process: Estimating, Scheduling, and Project Control, Fourth Edition, covers all areas of the Construction Management industry—with a balanced focus on both theory and practicality. Helping students gain a working knowledge of the whole Building Industry, this text provides the technical skills required to manage a construction project from conception through occupancy. Emphasizing current industry practices, it makes a useful reference for the construction professional.

Constitutive Modeling of Geomaterials: Principles and Applications

Evaluation of Discharge capacity of prefabricated vertical drain

Prefabricated vertical drains are widely used in Singapore for land reclamation to accelerate the consolidation process of the clay. There are several key properties that affects the performance of the vertical drain and in which national test standards have been established and adopted for used. However, one key parameter of the vertical drain is the discharge capacity in which the adopted test standard does not really measure the vertical drain performance. This paper highlights some of the performance parameters of the vertical drain used in Hong Kong and Singapore. At the same time it also highlights the various methods used in Singapore that attempts to measure the discharge capacity of the vertical drain. It also discusses some of the factors that will affect the discharge capacity results.

Predictions and Performances of Prefabricated Vertical Drain Stabilised Soft Clay Foundations

In this paper, the analytical solution for radial consolidation of soft soils is proposed considering the impacts of the variation of volume compressibility and permeability. The Cavity Expansion Theory is employed to predict the smear zone caused by the installation of mandrel driven vertical drains in soft clay. The smear zone prediction is then compared to the data obtained from the large-scale radial consolidation tests. Furthermore, the advantages and limitations of vacuum application through vertical drains in the absence of high surcharge embankments are discussed using the proposed solutions. The applied vacuum pressure generates negative pore water pressure, resulting in an increase in the effective stress, which leads to accelerated consolidation. Analytical and Numerical analysis incorporating the equivalent plane strain solution are conducted to predict the excess pore pressures, lateral and vertical displacements. The equivalent plane strain solution can be used as a predictive tool with acceptable accuracy due to the significant progress that has been made in the past few years through rigorous mathematical modelling and numerical analysis developed by the primary author and co-workers (Indraratna et al., 1992 – 2005).

Several case histories are discussed and analysed, including the site of the 2nd Bangkok International Airport. The predictions are compared with the available field data, confirming that the equivalent plane strain model can be used confidently to predict the performance with acceptable accuracy. Difficulties in assuring good performance can also be analysed and interpreted through mathematical modelling, thereby enabling due caution in the design and construction stages. The research findings verify that the role of smear, drain unsaturation, and vacuum distribution can significantly affect soil consolidation, hence, these aspects need to be modelled appropriately in any numerical analysis to obtain reliable predictions.