Experiences with prefabricated vertical (wick) drains at Vernon, B.C.

1992 ◽  
Vol 29 (1) ◽  
pp. 67-79 ◽  
Author(s):  
C.B. Crawford ◽  
R. J. Fannin ◽  
L. J. Deboer ◽  
C. B. Kern
Keyword(s):  
Key Words ◽  
Pore Water ◽  
Field Observations ◽  
Case Record ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Pore Water Pressures ◽  
Input Parameters ◽  
Theoretical Predictions ◽  
Wick Drains

This case record describes the performance of two test embankments constructed over a soft compressible clay, one with prefabricated vertical drains and one without. The measured settlements were significantly different from the predicted settlements, and the pore-water pressures were inconsistent with the observed consolidation. The observed performance of the vertical drains is compared with theoretical predictions to assess the sensitivity of the predicted rate of consolidation to input parameters. Key words : case record, consolidation, field observations, prefabricated vertical drains, wick drains, preloading, settlements, test embankments.

Field observations of soft clay consolidation in the Fraser Lowland

1987 ◽  
Vol 24 (2) ◽  
pp. 308-317
Author(s):  
C. B. Crawford ◽  
L. J. DeBoer
Keyword(s):  
Key Words ◽  
Pore Water ◽  
Soft Clay ◽  
Field Tests ◽  
Maximum Load ◽  
Field Observations ◽  
Pore Pressures ◽  
Pore Water Pressures ◽  
Earth Embankment

This paper presents a 15-year record of consolidation settlements under an earth embankment where maximum settlements have exceeded 3 m since 1971. The rate of settlement was greatly accelerated by the use of sand drains under areas of maximum load. During construction, pore pressures in the subsoil were monitored and used to control the rate of loading, which had to be decreased to avoid failure. Settlements were underestimated and stability was overestimated on the basis of laboratory and field tests. Consolidation characteristics measured in the laboratory are compared with those calculated from field observations. Key words: settlements, consolidation, embankment, pore-water pressures, monitoring, in situ.

Modelling unanticipated pore-water pressures in soft clays

1994 ◽  
Vol 31 (5) ◽  
pp. 773-778 ◽  
Author(s):  
Jianhua Yin ◽  
James Graham ◽  
Jack I. Clark ◽  
Longjun Gao
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Creep Behaviour ◽  
Soft Clay ◽  
Field Observations ◽  
Soft Clays ◽  
Secondary Compression ◽  
Pore Water Pressures ◽  
Clay Layers

Field observations in thin soft clay layers may show pore-water pressures that increase for some time after the loading is applied. Reasons for these observations are not well understood. The paper shows how an elastic viscoplastic constitutive model incorporated into the consolidation equation can predict these pore-water pressure increases in soils that exhibit significant creep behaviour (or secondary compression). The phenomenon has been related to relaxation in regions of the profile from which drainage has not yet begun. Key words : clay, consolidation, creep, secondary compression, viscous, relaxation, pore-water pressure, elastic–plastic.

scholarly journals EVALUASI KINERJA VERTICAL DRAIN PADA PROYEK JALAN TOL DI SUMATERA DITINJAU DARI ASPEK KONSOLIDASI

2021 ◽  
Vol 4 (2) ◽  
pp. 417
Author(s):  
Erika Oktavia ◽  
Andryan Suhendra
Keyword(s):  
Pore Water ◽  
Theoretical Calculations ◽  
Soft Soil ◽  
Stable Condition ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Model Soil ◽  
Vertical Drain ◽  
Prefabricated Vertical Drain ◽  
The Difference

Over time, there has been more development, this has made less land for development. However, development still has to go on. One of the infrastructure that is currently needed is toll roads to increase the efficiency of movement from one place to another. One of the serious problems at this time is that many soils have small bearing capacity and large settlement, for example, such as soft soil. In order for this model soil to have a stable condition, the solution is loaded so that the pore water from the soil can be pressed out. However, it takes a long time to achieve the desired settlement, here the prefabricated vertical drain method is used to accelerate the settlement. Prefabricated vertical drain here makes the distance between the pore water that was previously thick as soft soil, to half the distance between prefabricated vertical drains. The analysis calculation in this thesis uses the one dimensional consolidation method, the finite element method, and the asaoka method as the calculation of the actual results from field data. The results of this study found that the difference in the degree of consolidation between the theoretical calculations and the Asaoka method was 3.4303%.

Long-term performance of a wide embankment on soft clay improved with prefabricated vertical drains

2008 ◽  
Vol 45 (8) ◽  
pp. 1073-1091 ◽  
Author(s):  
S. R. Lo ◽  
J. Mak ◽  
C. T. Gnanendran ◽  
R. Zhang ◽  
G. Manivannan
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Foundation Soil ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Long Term Performance ◽  
Term Performance

This paper presents the long-term performance of a wide geogrid-reinforced road embankment constructed on soft clay improved with prefabricated vertical drains (PVDs) at a freeway extension site 150 km north of Sydney in Australia. The foundation soil and the embankment were instrumented and monitored for about 400 days for excess pore-water pressure, earth pressure, and reinforcement tension, and for 9 years for displacement profiles. The embankment was constructed in stages and surcharged in an attempt to reduce post-construction settlement. As the embankment width was wide relative to the thickness of the soft clay, the settlement near the centre was modelled by a unit cell analysis. The equivalent horizontal permeability was determined by back analysis of the central zone using the first 12 months of settlement data. All other soil parameters were determined from the laboratory and field testing. The predicted pore-water pressure response over the first 400 days showed reasonable agreement with measured values. The same analysis was then continued to predict settlement over a period of 9 years. The predicted settlement was, however, smaller than the measured value at the centre region of the embankment.

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.

Finite element analysis of an embankment on a soft estuarine deposit using an elastic–viscoplastic soil model

2009 ◽  
Vol 46 (3) ◽  
pp. 357-368 ◽  
Author(s):  
Curtis Kelln ◽  
Jitendra Sharma ◽  
David Hughes ◽  
James Graham
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Element Analysis ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Deformation Response ◽  
Soil Model ◽  
Excess Pore

A new elastic–viscoplastic (EVP) soil model has been used to simulate the measured deformation response of a soft estuarine soil loaded by a stage-constructed embankment. The simulation incorporates prefabricated vertical drains installed in the foundation soils and reinforcement installed at the base of the embankment. The numerical simulations closely matched the temporal changes in surface settlement beneath the centerline and shoulder of the embankment. More importantly, the elastic–viscoplastic model simulated the pattern and magnitudes of the lateral deformations beneath the toe of the embankment — a notoriously difficult aspect of modelling the deformation response of soft soils. Simulation of the excess pore-water pressure proved more difficult because of the heterogeneous nature of the estuarine deposit. Excess pore-water pressures were, however, mapped reasonably well at three of the six monitoring locations. The simulations were achieved using a small set of material constants that can easily be obtained from standard laboratory tests. This study validates the use of the EVP model for problems involving soft soil deposits beneath loading from a geotechnical structure.

scholarly journals Comparative Analysis of Settlement and Pore Water Pressure of Road Embankment on Yan soft soil Treated with PVDs

2019 ◽  
Vol 5 (7) ◽  
pp. 1609-1618
Author(s):  
Rufaizal Che Mamat ◽  
Anuar Kasa ◽  
Siti Fatin Mohd Razali
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Coefficient Of Determination ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Significant Difference

The application of prefabricated vertical drains (PVDs) in the road embankment construction has been successfully performed in many projects throughout the country. The simulation of finite element method (FEM) can assist engineers in modelling very complex structures and foundations. This paper presents a plane–strain numerical analysis that was performed to verify the effectiveness of the model embankment stabilised with PVD using Plaxis 2D version 8. This study employed the smear effect of permeability ratio (kr) of 3 in the PVD modelling. The data of settlement and pore water pressure in the left and right sides of road embankment were monitored for 177 days, then the data were collected and compared by a numerical simulation. The coefficient of determination (R2) was used to assess the performance of the comparative analysis. The results of numerical simulation on settlement and pore water pressure obtained a coefficient of determination of greater than 0.9 which has reached a good agreement with those of the field measurement. On other the hand, there was no significant difference in the performance between both sides of the embankment. The smear effect parameter (kr = 3) is recommended for PVD designs and can provide accurate FEM prediction.

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