Finite difference analysis of prefabricated vertical drains assisted with surcharge preloading of Hiep Phuoc soft clay in Vietnam

2022 ◽  
pp. 1-40
Author(s):  
Cong-Oanh Nguyen ◽  
Thi Van-Tram Dao ◽  
Thi-Thanh Tran
Keyword(s):  
Finite Difference ◽  
Pore Water Pressure ◽  
Container Terminal ◽  
Water Pressure ◽  
Soft Clay ◽  
Soft Ground ◽  
Prefabricated Vertical Drains ◽  
Difference Analysis ◽  
Finite Difference Analysis ◽  
Constant Rate

A series of finite difference analysis of the soft ground treatment with PVDs application has been performed with the application of the newly developed consolidation model. The model utilizes the concept of multi-compression indices and coefficients of consolidation to investigate the behaviors of the soft ground deposit on pore water pressure dissipation, surface and sub-layered ground settlement and to validate the newly developed CONSOPRO finite-difference procedure. Furthermore, the pre-consolidation pressures of the soft ground deposit are characterized with the combination of the piezocone penetration profiling and constant rate of strain consolidation tests under 0.02 %/min. on undisturbed samples which were retrieved at the investigated site, Saigon Premier Container Terminal (SPCT) in the South of Vietnam. On the comparison of the back-calculation results to the field observing data, the correlation between the coefficients of consolidation determined by constant-rate-of-strain (CRS) consolidation tests and those from piezocone dissipation tests, which were carried out after the soil improvement, is developed.

scholarly journals Effect of Improvement and Application of Composite Prefabricated Vertical Drain Method in Marine Soft Ground: A Case Study

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Jianqing Jiang ◽  
Reqiang Liu
Keyword(s):  
High Speed ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ground Improvement ◽  
Field Monitoring ◽  
Hyperbolic Model ◽  
Soft Ground ◽  
Prefabricated Vertical Drains ◽  
Prefabricated Vertical Drain

One of the commonly used techniques to improve marine soft ground is the drainage consolidation method by plastic board drains (PBDs). But some complex marine soft ground will cause construction inconvenience of PBDs in certain areas of these sites, thus affecting the improvement effect. An alternative possible approach to overcoming these deficiencies may be the combination of PBDs and sand wick drains (SWDs) (i.e., composite prefabricated vertical drains (CPVDs)) as vertical drainage channels in the same site. In order to verify the suitability and performance of this method in marine soft ground improvement, a case study was performed based on the field monitoring and construction of the marine soft ground of an intercity express railway project in China. The construction procedure using the CPVD system, the field monitoring instrumentation scheme, and the design of fill surcharge level were described, and the field monitoring data were presented. The settlement characteristics, dissipation features of pore water pressure, and the horizontal movement pattern were assessed. In addition, predictions of ultimate settlement, postconstruction settlement, and consolidation degree were discussed by applying a modified hyperbolic model. The results show that the marine ground improved by the CPVD system is suitable for the construction of intercity express railway and high-speed railway. The improvement construction period of complex marine soft ground will be greatly shortened by the proposed parallel construction programme. This work will provide technical supports and application reference for the improvement of the similar marine soft ground.

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.

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.

Research on Simulation of Land Subsidence Characteristics under the Groundwater Level Fluctuation

2013 ◽  
Vol 368-370 ◽  
pp. 1697-1700
Author(s):  
Long Zhang ◽  
Xue Wen Lei ◽  
Qing Shang Meng
Keyword(s):  
Finite Element ◽  
Land Subsidence ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Level Fluctuation ◽  
Finite Element Software ◽  
Coastal Cities ◽  
Groundwater Level Fluctuation

Based on the characteristics of frequent land subsidence events caused by groundwater level fluctuation in coastal cities in China and studying on the quaternary sedimentary soft clay in Shanghai, the effects of groundwater level fluctuation on the deformation of soft clay is simulated by Geo-Studio finite element software. It has summarized the law of deformation, effective stress with the change of groundwater level fluctuation, especially the process of dissipation of pore water pressure with the groundwater level fluctuation. The low can be sued as a reference for similar engineering and land subsidence prevention.

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