Comparison of the Effect of Soil Treatment Methods Used in Highway Widening Projects

2013 ◽  
Vol 663 ◽  
pp. 3-7
Author(s):  
Min Zhao ◽  
Wei Ping Cao ◽  
Qi Chao Shi
Keyword(s):  
Rapid Development ◽  
Heavy Traffic ◽  
Soft Soil ◽  
Cost Effective ◽  
Stone Columns ◽  
Engineering Practice ◽  
Soft Soils ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Effective Choice

The rapid development of China’s economics makes it urgent to widen the existing highways especially those located in the south-eastern coastal areas over thick soft soils. Adding a new embankment adjacent to the existing highway embankment is a cost effective choice compared with the traditional methods to build another new one and can reduce the heavy traffic pressure. However, it may also cause some engineering problems including the excessive settlements settlements, road cracks, excessive tensile stresses on the pavement even local or global instability of embankments. So some proper measures should be taken to solve the problems caused by widening is of great importance in engineering practice. A numerical analysis was performed to investigate the effect of different kinds of soft soil treatments including rigid piles, stone columns and prefabricated vertical drains (PVDs) usually used in highway widening projects located in the thick soft soils. It was found that the rigid piles can effectively reduce the additional settlements of the existing embankment induced by widening as well as the settlements of the widened embankment. While the stone columns and PVDs play little role in controlling the additional settlements caused by widening.

Influence of Widened Embankment on the Slope of Existing Pavement on Soft Soils

2012 ◽  
Vol 256-259 ◽  
pp. 1889-1892
Author(s):  
Wei Ping Cao ◽  
Qi Chao Shi ◽  
Wei Wei Hu
Keyword(s):  
Heavy Traffic ◽  
Early Period ◽  
Cost Effective ◽  
Engineering Practice ◽  
Global Instability ◽  
Soft Soils ◽  
Soft Foundation ◽  
Engineering Problems ◽  
Effective Choice ◽  
Embankment Height

Adding a new embankment adjacent to the existing highway embankment is a cost effective choice compared with building another new one and can mitigate the heavy traffic pressure. However, it may also cause some engineering problems including the change of slope of existing pavement or even local or global instability of embankments especially those on soft soils. How to prevent excessive change of the slope of the existing pavement induced by widening the existing embankments is of great importance in engineering practice. A numerical analysis by using a commercial FEM program was performed to explore the influence of the thickness of soft foundation soils, the widening width and the embankment height as well as the starting time of widening construction on the slope of the existing pavement. The results indicate that the bigger the thickness of the foundation soils as well as the bigger the widening width will result in bigger values of the slope of the existing pavement, especially at the early period of reconsolidation. Adverse slope will be induced by widening of the existing embankment.

scholarly journals Ground settlement prediction of embankment treated with prefabricated vertical drains in soft soil

2018 ◽  
Vol 195 ◽  
pp. 03014
Author(s):  
Siswoko Adi Saputro ◽  
Agus Setyo Muntohar ◽  
Hung Jiun Liao
Keyword(s):  
Numerical Study ◽  
Soft Soil ◽  
Soil Permeability ◽  
K Value ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Prefabricated Vertical Drain ◽  
Actual Settlement ◽  
Final Settlement ◽  
Best Fit

Excessive settlement due to consolidation can cause damage to the structure’s rest on soft soil. The settlement takes place in relatively longer. The preloading and prefabricated vertical drain (PVD) is often applied to accelerate the primary settlement. The issue in this research is the estimation of the settlement. The Asaoka method and the finite element method using PLAXIS-2D are used to estimate the final settlement of a PVD treated embankment. For the former, a complete record of the settlement was required; for the latter, some ground parameters are needed for the PLAXIS-2D analysis, such as the permeability of the soil. Because the installation process of PVD tends to influence the permeability of the in-situ soil around the PVD, the soil permeability after the installation of PVD needs to be adjusted. The numerical results were compared with actual settlement data to find out the best-fit input parameters (i.e. soil permeability) of the actual data. It was found that the best-fit soil permeability (k) used in the numerical study was about one-half of the k value determined from the laboratory test. The Root Mean Square Deviation shows that the settlement predicted by the numerical analysis has approximately 30% of the actual settlement.

scholarly journals ANALISIS PENGGUNAAN PREFABRICATED VERTICAL DRAINS (PVD) PADA TANAH LEMPUNG LUNAK YANG TERDAPAT LAPISAN LENSA

2020 ◽  
Vol 3 (1) ◽  
pp. 119
Author(s):  
Andreyan Prasetio ◽  
Aniek Prihatiningsih
Keyword(s):  
Soft Soil ◽  
Soil Improvement ◽  
Cohesive Soils ◽  
Consolidation Process ◽  
Prefabricated Vertical Drains ◽  
Soil Layers ◽  
Vertical Drains ◽  
Vertical Drain ◽  
Installation Depth ◽  
Consolidation Time

Problem that often occurs in soft cohesive soils is settlement caused by consolidation process. If  construction activities doing when the soils has not been consolidated, settlement can occur. To accelerate  the consolidation process, soil improvement are usually do, one method of soil improvement to accelarate the consolidation process is vertical drain using prefabricated vertical drains (PVD). The soft soil layers in the field are not always continuous, sometimes found soft soil layers that have a lens layer. In this study, will discuss about the settlement and consolidation time of soft  soil layers that have a lens layer which has been improved by PVD with 1 meter distance. Infrastructure that stand on a location that is installed by PVD is taxiway and loading by Airbus A380 aircraft of 18,22ton/m2. Analysis using the 1 dimensional consolidation theory of Terzaghi. For PVD installation to a depth of 50 meters, preloading settlement of 234,80 cm with a consolidation time of  2260 days for the square pattern PVD and 1918 days for triangle pattern PVD. Post loading settlement for PVD installation depth of 50 meters by 2,50 cm. AbstrakMasalah yang sering terjadi pada tanah kohesif dan lunak adalah penurunan yang disebabkan proses konsolidasi. Penurunan dapat menyebabkan keretakan pada struktur konstruksi yang berada di atasnya. Jika suatu kegiatan konstruksi dilakukan saat tanah belum terkonsolidasi, maka konstruksi tersebut dapat mengalami penurunan.. Untuk mempercepat proses konsolidasi biasanya dilakukan perbaikan tanah, salah satu metode perbaikan tanah untuk mempercepat proses konsolidasi yaitu vertical drain dengan menggunakan prefabricated vertical drains (PVD). Lapisan tanah lunak yang terdapat di lapangan tidak selalu kontinu, terkadang ditemukan lapisan tanah lunak yang terdapat lapisan lensa. Pada penelitian ini, penulis akan membahas mengenai waktu konsolidasi yang dibutuhkan oleh lapisan tanah kohesif dan lunak yang terdapat lapisan lensa yang telah diperbaiki dengan menggunakan PVD berjarak 1 meter. Infrastruktur yang berdiri di atas lokasi yang dipasang PVD berupa taxiway dengan beban berupa pesawat Airbus A380 sebesar 18,22 ton/m2. Analisis dilakukan menggunakan teori konsolidasi 1 dimensi Terzaghi. Untuk pemasangan PVD hingga kedalaman 50 meter diperoleh penurunan pra pembebanan sebesar 234,80 cm dengan waktu konsolidasi selama 2260 hari untuk pemasangan PVD pola persegi dan selama 1918 hari untuk pola segitiga . Penurunan pasca pembebanan untuk pemasangan PVD hingga kedalaman 50 meter sebesar 2,5 cm.

scholarly journals Research on Horizontal Coefficient of Consolidation of Vietnam’s Soft Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Nu Nguyen Thi ◽  
Bui Truong Son ◽  
Do Minh Ngoc
Keyword(s):  
Experimental Study ◽  
Laboratory Tests ◽  
Soft Soil ◽  
Coefficient Of Consolidation ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Constant Rate ◽  
Different Types ◽  
Cell Test ◽  
Dissipation Test

The horizontal coefficient of consolidation is the most important parameter for designing the improvement of soil soft by prefabricated vertical drains (PVDs) combined with surcharge and vacuum preloading. This paper presents the experimental study on the horizontal coefficient of consolidation (ch) of some soft soils distributed in Vietnam. The ch value was determined by the laboratory test and CPTu dissipation test. The laboratory tests included the Rowe consolidation cell test and constant rate of strain consolidation with radial drainage test. Two types of consolidation laboratory tests were performed. The experimental results indicated that the ch value is always larger than the vertical coefficient of consolidation of soil (cv). The ratio of ch/cv depends on the consolidated pressure, type of soil, and the anisotropy of soil. The ratio of ch/cv is different in different types of soft soil in Vietnam. In the normally consolidated state, the ch/cv ratio ranges from 1.35 to 10.59. It was necessary to choose the ch value at the consolidated stress level for calculating the PVD spacing.

scholarly journals Uncertainty Analysis in Prediction of Settlements for Spatial Prefabricated Vertical Drains Improved Soft Soil Sites

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 42
Author(s):  
Jemal Jibril Muhammed ◽  
Priyantha W. Jayawickrama ◽  
Stephen Ekwaro-Osire
Keyword(s):  
Granular Layer ◽  
Soft Soil ◽  
Contributing Factors ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Class A ◽  
Numerical Predictions ◽  
Soil Deposits ◽  
Class C ◽  
Test Embankment

This paper presents the quantification of uncertainties in the prediction of settlements of embankments built on prefabricated vertical drains (PVDs) improved soft soil deposits based on data collected from two well-documented projects, located in Karakore, Ethiopia, and Ballina, Australia. For this purpose, settlement prediction biases and settlement distributions were statistically computed based on analyses conducted on two Class A and Class C numerical predictions made using PLAXIS 2D finite element modelling. From the results of prediction bias, Class C predictions agreed well with the field measured settlements at both sites. In Class C predictions, the computed settlements were biased to the measured values. For Class A predictions, the calculated settlement values were in the range of mean and mean minus 3SD (standard deviations) for Karakore clay, and they were within mean and mean minus 2SD limit for the Ballina soil. The contributing factors to the settlement uncertainties of the Karakore site may include variability within the soil profile of the alluvial deposit, particularly the presence of interbedded granular layer within the soft layers, and the high embankment fills, and the limited number of samples available for laboratory testing. At the Ballina test embankment site, the uncertainties may have been associated with the presence of transitional layers at the bottom of estuarine clay and sensitivity of soft soil to sample disturbances and limitations in representing all the site conditions.

scholarly journals A Review on the Behaviour of Combined Stone Columns and Pile Foundations in Soft Soils when Placed under Rigid Raft Foundation

2021 ◽  
Vol 16 ◽  
pp. 1-8
Author(s):  
Danish Ahmed ◽  
Siti Noor Linda Bt Taib ◽  
Tahar Ayadat ◽  
Alsidqi Hasan
Keyword(s):  
Ground Improvement ◽  
Soft Soil ◽  
Research Work ◽  
Stone Columns ◽  
Attractive Alternative ◽  
Soft Soils ◽  
Ongoing Research ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Raft Foundations

In the last few decades, it has been observed that raft foundations are very commonly used as a foundation solution for moderate to high rise structures either by resting on stone columns or on piles in soft soils. It is believed that, combining stone columns and piles in one foundation system is the more suitable foundation for medium rise structures. The combined foundation system provides a superior and more economical alternative to pile, and a more attractive alternative to stone columns in respect to ground improvement. This paper presents the review of existing studies reported in the literature in the last two decades about the behaviour of stone columns under raft foundations and piled raft foundation in soft soil, notably the failure mechanism and the bearing capacity. Also, a limited work from the literature concerning the performance of combined (pile/stone columns) foundation system in soft soil is comprised. Furthermore, very extensive ongoing research work regarding the investigation and study on the performance of combined (pile/stone columns) foundation system in soft soils is discussed. The main goals and methodology to study the performance of the combined (pile/stone columns) foundation systems in soft soil are also addressed.

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