scholarly journals Analytical solutions and design curves for vacuum-assisted consolidation with both vertical and horizontal drainage

2007 ◽  
Vol 44 (2) ◽  
pp. 188-200 ◽  
Author(s):  
Cholachat Rujikiatkamjorn ◽  
Buddhima Indraratna
Keyword(s):  
Analytical Modeling ◽  
Excess Pore Pressure ◽  
Soil Consolidation ◽  
Factor Analyses ◽  
Soil Permeability ◽  
Vacuum Preloading ◽  
Vertical Drains ◽  
Design Charts ◽  
Horizontal Drainage ◽  
Degree Of Consolidation

A system of vertical drains combined with vacuum preloading is an effective method for promoting radial flow to accelerate soil consolidation. This study presents the analytical modeling of the consolidation of vertical drains incorporating vacuum preloading considering both vertical and horizontal drainage. The effects of a number of dimensionless parameters involving the drain length, soil permeability, and vacuum pressure are examined through average excess pore pressure, degree of consolidation, associated settlement, and time factor analyses. An analysis of selected case histories compliments the use of the proposed solutions. Design charts are also presented for practical use.Key words: analytical solution, consolidation, design charts, vertical drains.

scholarly journals Analytical and numerical solutions for a single vertical drain including the effects of vacuum preloading

2005 ◽  
Vol 42 (4) ◽  
pp. 994-1014 ◽  
Author(s):  
Buddhima Indraratna ◽  
Cholachat Rujikiatkamjorn ◽  
Iyathurai Sathananthan
Keyword(s):  
Finite Element ◽  
Plane Strain ◽  
Numerical Solutions ◽  
Soft Clay ◽  
Vacuum Pressure ◽  
Excess Pore Pressure ◽  
Soil Consolidation ◽  
Vacuum Preloading ◽  
Element Analysis ◽  
Vertical Drains

A system of vertical drains combined with vacuum preloading is an effective method to accelerate soil consolidation by promoting radial flow. This study presents the analytical modeling of vertical drains incorporating vacuum preloading in both axisymmetric and plane strain conditions. The effectiveness of the applied vacuum pressure along the drain length is considered. The exact solutions applied on the basis of the unit cell theory are supported by finite element analysis using ABAQUS software. Subsequently, the details of an appropriate matching procedure by transforming permeability and vacuum pressure between axisymmetric and equivalent plane strain conditions are described through analytical and numerical schemes. The effects of the magnitude and distribution of vacuum pressure on soft clay consolidation are examined through average excess pore pressure, consolidation settlement, and time analyses. Lastly, the practical implications of this study are discussed.Key words: consolidation, finite element method, soft clay, vacuum preloading, vertical drains.

scholarly journals Numerical Investigation to the Effect of Suction-Induced Seepage on the Settlement in the Underwater Vacuum Preloading with Prefabricated Vertical Drains

2021 ◽  
Vol 9 (8) ◽  
pp. 797
Author(s):  
Shu Lin ◽  
Dengfeng Fu ◽  
Zefeng Zhou ◽  
Yue Yan ◽  
Shuwang Yan
Keyword(s):  
Practical Implication ◽  
Soil Surface ◽  
Small Strain ◽  
Seepage Flow ◽  
Excess Pore Pressure ◽  
Combined Effects ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
The Difference

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.

scholarly journals An educational software for teaching soil consolidation

2017 ◽  
Author(s):  
Gonzalo García Ros ◽  
Manuel Cánovas Vidal ◽  
Juan Francisco Sánchez Pérez ◽  
Iván Alhama Manteca
Keyword(s):  
Educational Software ◽  
Low Cost ◽  
Surface Settlement ◽  
Excess Pore Pressure ◽  
Soil Consolidation ◽  
Depth Of Penetration ◽  
Consolidation Process ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Graphical Environment

The educational tool SICOMED_3D has been created to simulate problems of soil consolidation by prefabricated vertical drains. Thanks to its nice interface of windows, the introduction of data is very fast and easy for the students, while providing users with simple handling and powerful calculations. Its graphical environment allows to get representations of the excess pore pressure, local settlements and total surface settlement. SICOMED_3D can also generate an animation that recreates the evolution of the surface settlement during the consolidation process. The software presents, like commercial softwares, the most common options (e.g., save and open cases files, save animations and representations, etc.). Although the program is created to be used in several fields, among others as an engineering or research tool, the main use of interest for this work is for educational purposes. Another important application is as low-cost laboratory practices, as students can experiment by modifying the soil properties, including the depth of penetration of the vertical drain, in a quick, simple and intuitive way.

scholarly journals Compression and consolidation behaviors of lime-treated dredging slurry under vacuum pressure

2021 ◽  
Author(s):  
Xueyu Geng
Keyword(s):  
Mechanical Characteristics ◽  
Vacuum Pressure ◽  
Laboratory Model ◽  
Log P ◽  
Soil Permeability ◽  
Lime Treatment ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Oedometer Tests

Dredging slurry is treated by a combination of lime treatment and vacuum preloading. However, the mechanical characteristics and consolidation mechanics of lime-treated slurry under vacuum loading is not fully understood, making it difficult to predict slurry settlement. In this study, we develop a laboratory model of lime-treated slurry and subject it to vacuum preloading to investigate the compression and consolidation behaviors. The results demonstrate the reduction of the risk of clogging around the prefabricated vertical drains, the increase in soil permeability, and the improvement of vacuum preloading upon lime treatment. log (1 + e)-log p curves for soils with different percentages of lime content are obtained through a series of modified oedometer tests. Based on these curves, an analytical solution for lime-treated slurry settlement under vacuum preloading was derived and validated through laboratory tests. The solution can be used to predict lime-treated slurry settlement under vacuum pressure effectively.

scholarly journals Teaching and learning experience in soil consolidation aided by computer software

2018 ◽  
Author(s):  
García Ros Gonzalo ◽  
Sánchez Pérez Juan Francisco ◽  
Fernández García Martina ◽  
Del Cerro Velázquez Francisco
Keyword(s):  
Teaching And Learning ◽  
Learning Experience ◽  
Computer Software ◽  
Data Entry ◽  
Excess Pore Pressure ◽  
Soil Consolidation ◽  
Abstract Concepts ◽  
Personal Motivation ◽  
Degree Of Consolidation ◽  
The Subject

The present article shows how the learning and personal motivation of the students in Geotechnics are improved through the realization of computer practices and thanks to the use of a software adapted to their needs. By means of a simple interface of data entry and output of results, students will master abstract concepts such as the excess pore pressure and the average degree of consolidation, while reinforcing their personal motivation, both to face the content of the subject and those of other disciplines of the Civil Engineering Degree.

Radial consolidation modelling incorporating the effect of a smear zone for a multilayer soil with downdrag caused by mandrel action

2010 ◽  
Vol 47 (9) ◽  
pp. 1024-1035 ◽  
Author(s):  
Cholachat Rujikiatkamjorn ◽  
Buddhima Indraratna
Keyword(s):  
Lower Layer ◽  
Soil Layer ◽  
Soil Consolidation ◽  
Soil Permeability ◽  
Soil System ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Design Procedures ◽  
Surcharge Preloading ◽  
Time Required

A system of prefabricated vertical drains with surcharge preloading is an effective method for promoting radial drainage and accelerated soil consolidation. A piecewise technique is employed to analyse the radial consolidation in a multilayer soil system to include (i) the effect of soil downdrag and (ii) a smear zone having linearly varying soil permeability. The effect of soil dragged down from the upper soil layer into the lower layer has been analysed in terms of the time required for consolidation. It can be seen that the consolidation of the multilayer soil depends on smear zone characteristics, the permeability ratio between upper and lower soil layers, penetration depth, and drain spacing. Design procedures are described with the help of an example.

Electroosmosis-enhanced preloading consolidation via vertical drains

1998 ◽  
Vol 35 (3) ◽  
pp. 491-499 ◽  
Author(s):  
J Q Shang
Keyword(s):  
Electric Field Intensity ◽  
Treatment Time ◽  
Spatial Configuration ◽  
Soil Improvement ◽  
Excess Pore Pressure ◽  
Vertical Drains ◽  
Soft Clays ◽  
Surcharge Preloading ◽  
Surcharge Load ◽  
Degree Of Consolidation

An analytical model of electroosmosis-enhanced preloading consolidation via vertical drains is developed for the design of the combined preloading and electroosmotic consolidation of clay soils. The excess pore pressure and average degree of consolidation are computed and examined for the effects of surcharge load, electric field intensity, treatment time, spatial configuration of electrodes, drainage path, and soil properties. The model is evaluated using the results of a well-known electroosmotic consolidation field test reported in the literature.Key words: consolidation, electroosmosis, surcharge preloading, vertical drains, soil improvement, soft clays.

scholarly journals Consolidation Effect of Prefabricated Vertical Drains with Different Lengths for Soft Subsoil under Vacuum Preloading

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Chenhui Lou ◽  
Junfeng Ni ◽  
Jingchun Chai ◽  
Hongtao Fu ◽  
Xiuqing Hu ◽  
...  
Keyword(s):  
Laboratory Model ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Shallow Layer ◽  
Pore Water Pressures ◽  
Practical Engineering ◽  
Different Depths ◽  
Degree Of Consolidation ◽  
Consolidation Effect

The application of vacuum preloading to prefabricated vertical drains (PVDs) with different lengths is widely used in practical engineering to investigate their consolidation at the same depths of even and multilayer subsoils from the seabed. In a laboratory, model experiment was conducted using even subsoil and embedded PVDs with lengths of 0.6 and 1.2 m. The obtained results showed that in the even subsoil, the 1.2 m PVDs maintained a higher vacuum pressure in the shallow layer and demonstrated better consolidation behavior as compared to those of the 0.6 m PVDs. In the upper subsoil layer, the average vane shear strengths of these two systems increased to 18.2 and 22.6 kPa, respectively. The degree of consolidation of the upper subsoil layers in the two model experiments calculated from the pore water pressures under boundary drainage conditions were 51% and 68%, respectively. For practical verification purposes, similar experiments were conducted for multilayer subsoil by inserting PVDs with lengths of 6 and 15 m into different test sites. As a result, the vane shear strengths of the upper 6 m subsoil layers increased to 26.3 and 33 kPa, while the degree of consolidation were 72.1% and 80.9%, respectively, although some irregularities were observed at different depths.

Design charts for vertical drains considering construction time

2001 ◽  
Vol 38 (5) ◽  
pp. 1142-1148 ◽  
Author(s):  
Guofu Zhu ◽  
Jian-Hua Yin
Keyword(s):  
Design Procedure ◽  
Technical Note ◽  
Engineering Properties ◽  
Construction Time ◽  
Vertical Drains ◽  
Vertical Drain ◽  
Design Charts ◽  
Degree Of Consolidation ◽  
Free Strain ◽  
Consolidation Time

This technical note presents design charts for use in determining the required drain spacing explicitly using free strain assumption. The influence of time-dependent loading is incorporated in the design charts. The design procedure is also described. When the radius of vertical drain, required degree of consolidation, time available, and pertinent geotechnical engineering properties of a soil are given, the charts can be used to design a vertical drain system without unnecessary trial and error processes.Key words: consolidation, vertical drain, design charts, time dependence, drainage.

Study on Soil Consolidation Coefficient on CPTU Model Test

2011 ◽  
Vol 201-203 ◽  
pp. 2587-2592
Author(s):  
Yan Chun Tang ◽  
Gao Tou Meng ◽  
Qiu Feng Mao
Keyword(s):  
Pore Pressure ◽  
Model Test ◽  
Vertical Direction ◽  
Test Methods ◽  
Excess Pore Pressure ◽  
Soil Consolidation ◽  
Consolidation Test ◽  
Consolidation Coefficient ◽  
Degree Of Consolidation ◽  
Excess Pore

Through analyzing excess pore pressure dissipation datum measured by CPTU probe and pore pressure mini-transducers on CPTU model test, the consolidation coefficient of soil of CPTU model test has been computed. Based on axis-symmetric consolidation model and Terzaghi consolidation theory, the computing equation of soil horizontal consolidation coefficient on CPTU model test has been acquired; on CPTU model test 50% degree of consolidation has been applied as calculate standard to compute soil horizontal consolidation coefficient, and dissipating time of 50% degree of consolidation can be acquired by normalized excess pore pressure dissipation curves based on excess pore pressure dissipation datum; through a series of indoor consolidation tests, the consolidation coefficient of remolded soil of CPTU model test sampling by horizontal and vertical direction has been acquired, and the results show that vertical consolidation coefficient is about 1.6 times greater than horizontal consolidation coefficient on indoor consolidation test, and large difference between horizontal and vertical property of remolded clay soil on CPTU model test has been existed; compared with the value of two test methods, the value of horizontal consolidation coefficient acquired by CPTU model test is roughly 100 times greater than the value of horizontal consolidation coefficient acquired by indoor consolidation test. The achieved result can provide a foundation for further study for CPTU mechanism.

Sign in / Sign up

Export Citation Format

Share Document