Analysis of Soft Soil Improvement Techniques Using Vertical Drains

This report delves into the crucial topic of soft soil improvement, focusing on the application of vertical drains to enhance soil properties. It explores various methods, including the use of prefabricated vertical drains (PVDs), vacuum preloading, and electro-osmosis techniques. The report highlights the benefits of these methods in accelerating soil consolidation, increasing soil strength, and improving the bearing capacity of soft ground. It also discusses the use of sand drains and geogrids. The analysis includes a review of the literature and case studies, emphasizing the importance of combining different techniques for optimal results. The report presents the advantages of PVDs, and the effectiveness of the vacuum preloading method, and three-dimensional (3D) finite component analysis using the modified cam-clay model. The report concludes with recommendations for the application of these techniques in civil engineering projects, such as railway levees, airports, and highways.

Running head: SOFT SOIL IMPROVEMENT BY USING VERTICAL DRAINS 1
Soft Soil Improvement by Using Vertical Drains
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Segments of sand if disseminated in habitual triangles and gravel pads heartened with the
geogrids were used with the aim of accelerating the mixture of the soft ground underneath to ensure the
improvement of the capacity that can be borne. The examination that was used by the investigators was
the limited three-dimensional (3D). This was conveyed using an altered Cam-clay model (Zi-Hang Dai
& Bao-Lin Chen 2017, p 56). Doing this greatly aids in the improvement of the outline level and the
analysis of the issue of building on the soft ground even though complex is viable and it thus changes
the exact settlement forecast. However, the method was found only in the application for only simple
nature of ground. The test carried out proved out that the membrane used to generate the airtight
condition and sand blanket deposit to enhance vacuum distribution. In enhancing soil (soft)
improvements, solar heating will increase the presentation of drainage by act of reducing drainage
retardation effects in the insult zone around the drain (Saowapakpiboon 2009, p 543).
Prefabricated vertical drains (PVD) are useful aspect in improvement of soft soils, and they
were developed for they were the cheapest ground enhancement method for the intensification of soil
strength and soil arduousness. According to (Bergado 2010, p 78) the high rates of reimbursement
contributed to lots of warm as a result of the fall of the earth’s structure which is the magnitudes of past
considerations. However, amalgamation and opening water procedure beside the drainage path dwells
sideways of the horizontal course alone and reason for a perpendicular path not mentioned. EVD
technique can be premeditated for the electro osmosis and pore water drainage and this results to a
2anode-1cathode which is superior to 1anode-1cathode conformation and the highest voltage gradient
seems to occur in the peak series. Electro kinetic fortifying of clay which is delicate and mounting
solids gratified in glops and the mining tailings. When exploitation of the geosynthetic together with
sustenance and PVDs progresses, barrier implementation bigheartedly changes than exploitation of the
strategies for soil change. Therefore, when applying the two methods in soil improvements will be

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effective than when one is applicable alone. Out of this examination, it is advisable when improvement
of soft soils is done application of the two methods be combined together (Taechakumthorn 2008, p
456).
Presentation of vacuum abetted before loading is a reliable means when a huge load is
needed to encounter the anticipated rate of reimbursement and undrained shear asset increases after the
consolidation. The presented prefabricated band designed drains and cardboard wick fixtures for
ground improvement. Characteristically, ready-made posse flows consist of an elastic core with a
longitudinal frequency surrounded by a strainer jacket to prevent obstruction. PVDs beneath an
embankment not only hastened by consolidation, but they also sway the subsoil pattern deformation
(Zheng et al. 2017). At the center streak of an embankment where adjacent displacement is
insignificant, unit cell clarifications are sufficient but elsewhere, particularly near the levee toe, any
forecast from a single drain analysis is not precise enough because of sideways deformation and
stagger.
Preloading of soft soil with vertical gutters tends to be the most prevalent methods used to
surge the sheer power of soft soil and device its post-construction defrayal. Due to the fact that the
porousness of soils is very little, merging time to the achieved preferred settlement or shear strength
may gross too long. Using prefabricated vertical drains means that the drainage route is abridged from
the soil layer thickness to the drain stimulus zone radius, which quickens consolidation (Hui Wu &
Liming Hu 2017, p 67). This structure application is to progress the properties of underpinning soil for
railway levees, airports, and highways. Over the previous three decades, the recital of various
categories of vertical drains, containing sand drains, and sand compaction heaps and manufactured
vertical drains, have been studied.

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A sheath less vacuum preloading technique can also be used in the improvement of soft soil.
The approach offers some benefits over other conformist preloading (vacuum) where the membrane is
used in forming the airtight condition and sand extensive layer to dispense vacuum. To improve the
soil (soft) to accommodate large structures can also be enhanced by columns of dust being distributed
in regular trios and sand cushions reinforced with geogrids to hasten the soft ground consolidation
underneath the embankment and expand its bearing capacity (Wen 2017, p 96). In the sand study, a
three-dimensional (3D) finite component analysis is carried out using the modified cam-clay model to
boost the design level and investigation of this applied engineering problematic of soft-ground
enhancement regarding accurate extrapolation of the settlement. The prophesied settlement and
horizontal dislocation of the embankment sub grade found to agree well with the actual capacities. In
line with the estimate of a consolidation degree of ninety-five percentage level finally, the 340th day
was resulted to be the optimum date on which to eradicate the supplement (Bergado, Chai, Miura &
Balasubramaniam 1998, p 89). In count, the 3D consequence of the variation of surplus pore-water
pressure was evidently revealed. The outcomes also proved that the 3D nonlinear arithmetic method
obtainable in the paper as scientific and unswerving for intricate practical engineering complications
involving soft-ground perfection.
According to (Huayang Lei, 2016 p 561) the preloading (new) technique scoffs less power
when juxtaposed with conventional stratagem. The technique is financially practicality and ecological
considerate technique for application in low bearing soils and soils of high compressibility.

SOFT SOIL IMPROVEMENT BY USING VERTICAL DRAINS 5
References
Bergado, D. T., Chai, J. C., Miura, N., & Balasubramaniam, A. S. (1998). PVD improvement of
soft Bangkok clay with combined vacuum and reduced sand embankment preloading.
Geotechnical Engineering, 29(1).
Chai, J. C., & Miura, N. (1999). Investigation of factors affecting vertical drain behavior.
Journal of Geotechnical and Geoenvironmental Engineering, 125(3), 216-226.
Indraratna, B., Sathananthan, I., Rujikiatkamjorn, C., & Balasubramaniam, A. S. (2005).
Analytical and numerical modeling of soft soil stabilized by prefabricated vertical drains
incorporating vacuum preloading. International Journal of Geomechanics, 5(2), 114-124.
Ladd, C. C. (1991). Stability evaluation during staged construction. Journal of Geotechnical
Engineering, 117(4), 540-615.
Leo, C. J. (2005). Closure to “Equal Strain Consolidation by Vertical Drains,” by Chin Jian
Leo. Journal of geotechnical and geoenvironmental engineering, 131(10), 1317-1317.
Pothiraksanon, C., Saowapakpiboon, J., Bergado, D. T., Voottipruex, P., & Abuel-Naga, H. M.
(2010). Soft ground improvement with solar-powered drainage. Proceedings of the
Institution of Civil Engineers-Ground Improvement, 163(1), 23-30.
Wu, H., Hu, L., & Wen, Q. (2017). Numerical simulation of electro-osmotic consolidation
coupling non-linear variation of soil parameters. Computers & Geosciences, 103, 92-98.
Zheng, G., Liu, J., Lei, H., Rahman, M. S., & Tan, Z. (2017). Improvement of very soft ground
by a high-efficiency vacuum preloading method: A case study. Marine Georesources &
Geotechnology, 35(5), 631-642

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