Vacuum preloading consolidation of reclaimed land: a case study

1998 ◽  
Vol 35 (5) ◽  
pp. 740-749 ◽  
Author(s):  
J Q Shang ◽  
M Tang ◽  
Z Miao
Keyword(s):  
Land Reclamation ◽  
Soil Improvement ◽  
Large Area ◽  
Vacuum Preloading ◽  
Reclaimed Land ◽  
Improvement Project ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Soft Clays

This case study presents the design, operation, and results of a soil improvement project using the vacuum preloading method on 480 000 m2 of reclaimed land in Xingang Port, Tianjing, China. The areas treated with vacuum ranged from 5000 to 30 000 m2. The effects of soil improvement are demonstrated through the average consolidation settlement of 2.0 m and increases in undrained shear strengths by a factor of two to four or more. The study shows that the vacuum method is an effective tool for the consolidation of very soft, highly compressive clayey soils over a large area. The technique is especially feasible in cases where there is a lack of surcharge loading fills, extremely low shear strength, soft ground adjacent to critical slopes, and access to a power supply.Key words: vacuum preloading consolidation, soil improvement, soft clays, land reclamation, prefabricated vertical drains.

Solutions of Technical Problems in Ultra-Soft Soil Improving Projects

2013 ◽  
Vol 275-277 ◽  
pp. 1398-1402
Author(s):  
Yong Hua Cao ◽  
Chang Quan Yin
Keyword(s):  
Building Materials ◽  
Soft Soil ◽  
Soil Improvement ◽  
New Method ◽  
Vacuum Preloading ◽  
Typical Application ◽  
Prefabricated Vertical Drains ◽  
Technical Problems ◽  
Vertical Drains ◽  
Preloading Method

Ultra-soft soil improvement projects are new trend in present China because of the limitation of construction period. Technical problems occur when traditional vacuum preloading method is applied for ultra-soft soil. This paper firstly gave an analysis of the main technical problems which include construction channel problems for building materials and workers, portion division problems of project area, installation problems of prefabricated vertical drains and formation problems of horizontal drainage cushion. Then solutions for these problems were presented. Based on the solutions and traditional vacuum preloading method, a new method for ultra-soft soil improving was put forward. A typical application of this new method was give at the end of this paper.

The Experimental Research of Slurry Improvement with Different Kinds of Vertical Drains under New Vacuum Conditions

2013 ◽  
Vol 405-408 ◽  
pp. 396-401
Author(s):  
Jian Chen ◽  
Qiao Liang Tang ◽  
Shi Jing Liu
Keyword(s):  
Experimental Research ◽  
Ground Improvement ◽  
Soil Improvement ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Drain Spacing ◽  
Soil Zone ◽  
Reclaimed Soil ◽  
Improvement Effect

The results of experimental research are presented and discussed with focus on the ground improvement effect of slurry with different kinds of vertical drains under new vacuum conditions. In these conditions, horizontal sand cushion, which is requested in regular vacuum preloading method, is cancelled. Vertical drains are connected with sealed pipes, so the vacuum head can be transmitted into vertical drains without decreasing. For the experimental research, slurry taken from reclaimed soil zone is placed into six model casing boxes. Different kinds of vertical drains (prefabricated vertical drains (PVDs) and sand drains) are installed into the soil with different spacing (0.4 m and 0.8 m). A vacuum pressure of 80 kPa was applied continuously for 90 days. The effect of filter type of PVD, type of vertical drain and drain spacing under new vacuum preloading condition to slurry soil improvement is examined. Test results show that this new vacuum preloading condition can transmit vacuum head into vertical drains efficiently and the effect of drain filter to slurry improvement is affected by the drain spacing.

scholarly journals Numerical Investigation to the Effect of Suction-Induced Seepage on the Settlement in the Underwater Vacuum Preloading with Prefabricated Vertical Drains

2021 ◽  
Vol 9 (8) ◽  
pp. 797
Author(s):  
Shu Lin ◽  
Dengfeng Fu ◽  
Zefeng Zhou ◽  
Yue Yan ◽  
Shuwang Yan
Keyword(s):  
Practical Implication ◽  
Soil Surface ◽  
Small Strain ◽  
Seepage Flow ◽  
Excess Pore Pressure ◽  
Combined Effects ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
The Difference

Vacuum preloading combined with prefabricated vertical drains (PVDs) has the potential to improve the soft sediments under water, however, its development is partly limited by the unclear understanding of the mechanism. This paper aims to extend the comprehension of the influential mechanism of overlapping water in the scenario of underwater vacuum preloading with PVDs. The systematic investigations were conducted by small strain finite element drained analyses, with the separated analysis schemes considering suction-induced consolidation, seepage and their combination. The development of settlement in the improved soil region and the evolution of seepage flow from the overlapping water through the non-improved soil region into improved zone are examined in terms of the build-up of excess pore pressure. Based on the results of numerical analyses, a theoretical approach was set out. It was capable to estimate the time-dependent non-uniform settlement along the improved soil surface in response to the combined effects of suction-induced consolidation and seepage. The difference of underwater and onshore vacuum preloading with PVDs is discussed with some practical implication and suggestion provided.

Consolidation of cement-treated sewage sludge using vertical drains

2005 ◽  
Vol 42 (2) ◽  
pp. 528-540 ◽  
Author(s):  
J Chu ◽  
M H Goi ◽  
T T Lim
Keyword(s):  
Sewage Sludge ◽  
Land Reclamation ◽  
Model Tests ◽  
Waste Materials ◽  
Test Results ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Treated Sewage ◽  
The World

The disposal of sewage sludge and other waste materials has become a problem in many cities around the world. A study on the use of sewage sludge and other waste materials for land reclamation has been conducted. One of the methods studied is to dispose of the sludge after it has been mixed with binders or other waste materials and then to consolidate the mixture on site using surcharge and prefabricated vertical drains (PVDs). To study the consolidation behaviour of the sludge–binder mixtures around PVDs, model tests using a fully instrumented consolidation tank were conducted. Some of the test results are presented in this paper. The study shows that PVDs are effective in consolidating the sludge and binder mixtures, provided that the PVDs used can sustain large bending and resist corrosion by the chemicals in the sludge.Key words: consolidation, geoenvironmental, land reclamation, prefabricated vertical drains.

Measured and predicted performance of prefabricated vertical drains (PVDs) with and without vacuum preloading

2010 ◽  
Vol 28 (1) ◽  
pp. 1-11 ◽  
Author(s):  
J. Saowapakpiboon ◽  
D.T. Bergado ◽  
S. Youwai ◽  
J.C. Chai ◽  
P. Wanthong ◽  
...  
Keyword(s):  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains

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.

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