scholarly journals Probabilistic design of ground improvement by vertical drains for soil of spatially variable coefficient of consolidation

2014 ◽  
Vol 42 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Md. Wasiul Bari ◽  
Mohamed A. Shahin
Keyword(s):  
Variable Coefficient ◽  
Ground Improvement ◽  
Probabilistic Design ◽  
Coefficient Of Consolidation ◽  
Vertical Drains

Back-calculation of consolidation parameters from field measurements at a reclamation site

2001 ◽  
Vol 38 (4) ◽  
pp. 755-769 ◽  
Author(s):  
Lai Fa Cao ◽  
Ming-Fang Chang ◽  
Cee Ing Teh ◽  
Yung Mook Na
Keyword(s):  
Pore Pressure ◽  
Land Reclamation ◽  
Ground Improvement ◽  
Field Measurements ◽  
Coefficient Of Consolidation ◽  
Vertical Drains ◽  
Undisturbed Samples ◽  
Back Calculation ◽  
Reclamation Project ◽  
Consolidation Parameters

A pilot test was carried out at a land reclamation project site to study the effect of vertical drains on the rate of consolidation of a marine clay deposit in Singapore. Theoretical and numerical analyses were conducted to interpret the field measurements of pore pressure and settlement, and consolidation parameters were back-calculated. The back-calculated preconsolidation pressure is similar to that obtained from the laboratory consolidation test on undisturbed samples, but the field-deduced compression index is generally larger than that measured in the laboratory. The coefficient of consolidation back-calculated from the settlement measurement is larger than that from the pore-pressure measurement. The coefficient of consolidation for horizontal flow obtained from the Rowe cell test, which is comparable to that back-calculated from the field settlement measurement, is recommended for the preliminary design of vertical drains without the need of considering the smear effect.Key words: clays, consolidation, ground improvement, numerical modelling and analysis, permeability, vertical drains.

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 A rational design approach to peat ground improvement by vertical drains

2020 ◽  
Vol 60 (6) ◽  
pp. 1387-1404
Author(s):  
Nobutaka Yamazoe ◽  
Hiroyuki Tanaka ◽  
Hirochika Hayashi ◽  
Satoshi Nishimura
Keyword(s):  
Rational Design ◽  
Ground Improvement ◽  
Design Approach ◽  
Vertical Drains

scholarly journals Effect of Vertical Drains on Strength and Deformation Characteristics of Lithomargic Clay

2019 ◽  
Vol 9 (2) ◽  
pp. 3199-3204
Keyword(s):  
Ground Improvement ◽  
Drainage System ◽  
Excess Pore Pressure ◽  
Deformation Characteristics ◽  
Vertical Drains ◽  
Lithomargic Clay ◽  
Different Types ◽  
Consolidation Rate ◽  
Strength And Deformation ◽  
Different Diameters

During olden days, construction used to be carried out only on the sites having good strength. But now-a-days availability of sites with favourable properties are limited. So, there is a need to modify the properties of subsoil using different types of Ground Improvement Techniques. Depending upon the nature of soil, a suitable economical technique needs to be adopted. Soft soils have weaker strength and they are highly compressible and take a lot of time for settlement. So, these are typically problematic for construction. There is a need to improve the condition by accelerating the rate of consolidation. To achieve higher rate of consolidation, it is important to develop shorter paths for movement of the water. A vertical drainage system can be provided to accelerate the rate of consolidation and help to minimise excess pore pressure in the sub-soil. As a result of this, a stable situation is reached more quickly. Thus to enhance the strength of the soil and to accelerate the consolidation rate, vertical drains of different diameters and with varied spacing are employed. The improvement in properties of soft consolidating lithomargic clay is experimentally tested with vertical sand drains in developed prototype. The vertical sand drains installed with 1.905 (0.75 inch) diameter and 6 cm spacing is more effective in increasing Ultimate Bearing Capacity (UBC) of soil and also the rate of settlement of 35.26 % is significant up to 60 kg of preloads. Thus problematic lithomargic clay can be improved in its strength and settlement characteristics

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