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.

Predicting the long-term performance of a wide embankment on soft soil using an elastic–viscoplastic model

2010 ◽  
Vol 47 (2) ◽  
pp. 244-257 ◽  
Author(s):  
M. R. Karim ◽  
C. T. Gnanendran ◽  
S.-C. R. Lo ◽  
J. Mak
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Element Analysis ◽  
Foundation Soil ◽  
Vertical Permeability ◽  
Input Material ◽  
Modified Cam Clay ◽  
Long Term Performance ◽  
Term Performance

This paper presents modelling of the consolidation of foundation soil under a wide embankment constructed over soft soil. An elastic–viscoplastic (EVP) constitutive model is used to represent the foundation soil for the coupled finite element analysis (FEA). A unit-cell analysis is carried out to capture the maximum settlement and the development of excess pore-water pressure with time below the centreline of the embankment for a long period (9 years). A new function for capturing the varying nature of the creep or secondary compression coefficient is proposed and used in association with the EVP model. The input material parameters for this study were determined from extensive laboratory experiments except for the equivalent horizontal permeability, which was systematically estimated by using vertical permeability data obtained from one-dimensional consolidation tests and by back-analysing the first 12 months of field settlement data. Comparisons are made among the predictions obtained adopting an elastoplastic modified Cam clay model and the EVP model with constant and varying creep coefficients for the foundation soil and the corresponding field data. The predictions with the EVP model are found to be better than those with the elastoplastic model and the use of a varying creep coefficient for the EVP model seems to further improve its predicting ability.

Comparison of Field Performance between Bamboo-Geotextile Composite Embankment and High Strength Geotextile Embankment

2012 ◽  
Vol 587 ◽  
pp. 77-80
Author(s):  
Aminaton Marto ◽  
Bakhtiar Affandy Othman ◽  
Fauziah Kasim ◽  
Ismail Bakar
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Field Performance ◽  
High Strength ◽  
Foundation Soil ◽  
Excess Pore Water Pressure ◽  
Excess Pore

Trial embankment approximately 3 meters height, 10 meters of length, 16 meters width, and a slope of 1V: 2H was completed on soft clay site at RECESS, UTHM, Batu Pahat, Johor, Malaysia. Two embankments were respectively reinforced by a high strength geotextile (HSG) and the combination of bamboo and low strength geotextile or bamboo-geotextile composite (BGC) at the interface between embankment fill and foundation soil. Each embankment was installed with the same geotechnical instrumentation scheme for monitoring purposes. The purpose of this paper is to analyse the field performance for both embankments in terms of improving settlement embankment under the embankment. For this purpose, the settlement under the embankment, settlement at the surface of the embankment and the excess pore water pressure response were measured through geotechnical instrumentation for over 418 days. The results showed that the BGC system is more practical than HSG in terms of settlement and also in terms of cost, without compromising the quality of the embankment performance.

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.

Numerical modeling of vertical drains with smear and well resistance installed in soft clay

2000 ◽  
Vol 37 (1) ◽  
pp. 132-145 ◽  
Author(s):  
B Indraratna ◽  
I W Redana
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Field Measurements ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Modified Cam Clay ◽  
Lateral Displacements ◽  
Strain Model ◽  
Cam Clay

This study describes the behavior of embankments stabilized with prefabricated vertical drains installed in soft clay foundations, based on several fully instrumented case histories selected from Thailand and Malaysia. A multidrain analysis is conducted based on an equivalent, plane strain model developed by the authors. The deformation of soft clay beneath an embankment (i.e., along and away from the centerline) is predicted and compared with the available field measurements. The effects of both smear and well resistance are incorporated in the analytical formulation, which is used in conjunction with the modified Cam-clay theory. It is demonstrated that the installation of vertical drains significantly increases the rate of settlement, improves the dissipation of pore-water pressure, and decreases the lateral deformation of the soft clay foundation. To obtain better predictions, especially of pore pressures and lateral displacements, the equivalent discharge capacity of the drains needs to be modeled appropriately. The inclusion of the effects of smear and well resistance in the analysis of vertical drains improves the accuracy of predictions significantly, in comparison with the field measurements.Key words: clay, consolidation, embankment, finite element method, settlement, smear zone, vertical drain.

Study on Reinforce Saturated Soft Clay Foundation with Dynamic Consolidation by Drainage

2013 ◽  
Vol 438-439 ◽  
pp. 1171-1175
Author(s):  
Zhi Li Sui ◽  
Zhao Guang Li ◽  
Xu Peng Wang ◽  
Wen Li Li ◽  
Tie Jun Xu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Soil Layer ◽  
Good Effect ◽  
Loading Test ◽  
Test Plate ◽  
Dynamic Consolidation ◽  
Saturated Soft Clay

Dynamic consolidation method has been widely used in improving soft land, but always inefficient to saturated soft clay land, which is hard to improve, and even leads to rubber soil. Dynamic and drain consolidation method will deal with it well, with drainage system, pore-water can be expelled instantly from saturated soft clay as impacting. The pore-water pressure and earth pressure test in construction, the standard penetration test, plate loading test, geotechnical test after construction, which are all effective methods for effect testing. There is a comprehensive detection through different depth of soil layer with different detecting means on construction site. The results show that improving saturated soft clay land with dynamic and drain consolidation method has obtained good effect, and the fruit can be guidance for such construction in the future.

scholarly journals Prediction of long-term settlement and evaluation of pore water pressure using particle filter

2019 ◽  
Vol 59 (1) ◽  
pp. 67-83 ◽  
Author(s):  
Toshifumi Shibata ◽  
Takayuki Shuku ◽  
Akira Murakami ◽  
Shin-ichi Nishimura ◽  
Kazunori Fujisawa ◽  
...  
Keyword(s):  
Particle Filter ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure

Effective stress paths and yielding in soft clays below embankments

1985 ◽  
Vol 22 (3) ◽  
pp. 357-374 ◽  
Author(s):  
D. J. Folkes ◽  
J. H. A. Crooks
Keyword(s):  
Pore Water ◽  
Effective Stress ◽  
Strain Softening ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Stress Path ◽  
Excess Pore Water Pressure ◽  
Soft Clays ◽  
Effective Stress Path

Current methods of predicting the response of soft clays to surface loading are often unsuccessful because the assumed constitutive relationships, including effective stress path behaviour, are incorrect. In particular, the transition from small-strain to large-strain behaviour (i.e. yielding) is frequently not taken into account. Recent laboratory testing has demonstrated that the behaviour of soft clays is largely controlled by yielding. The locus of effective stress states causing yield is known as the yield envelope (YE).The effective stress paths (ESP's) in soft clay foundations below the centre of six fills were determined from computed total stresses and measured pore-water pressures. Yield behaviour is clearly indicated by ESP shapes. The yield envelopes inferred from analyses of field data are similar to those obtained from laboratory testing. Effective stress path shapes vary widely, depending on a variety of factors, including imposed stress level, rate of construction, and boundary drainage conditions. This finding contradicts an earlier conclusion that soft clay behaviour can be characterized by a single ESP. Because of the wide range of possible ESP shapes, the parameters [Formula: see text] does not provide an adequate basis for determining the effective stress state in a soft clay.The ESP/YE analyses indicate that yield can occur either during loading or during excess pore-water pressure dissipation following completion of loading. Yield of sensitive soils during loading is usually followed by strain softening. However, in some soils, dilatant behaviour appears to occur. Yield during dissipation of excess pore-water pressure is characterized by a dramatic change in cv and increased compressibility. Key words: soft clay, yield, effective stress paths, field behaviour, strain softening, rate of consolidation.

Calculation of Consolidation Coefficient and Percent Consolidation from Measured Pore Water Pressure of Soft Clay

2011 ◽  
Vol 250-253 ◽  
pp. 1889-1892
Author(s):  
Yong Mou Zhang ◽  
Jian Chang Zhao
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soft Clay ◽  
Coefficient Of Consolidation ◽  
Consolidation Process ◽  
Consolidation Coefficient

Consolidation coefficient and percent consolidation of soft clay were calculated according to the measured pore water pressure of a project in Pudong Shanghai. Calculated coefficient of consolidation was one magnitude larger than the experimental one. This was in conformity with the actual consolidation process of dynamically-consolidated soft soil.

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