scholarly journals The effect of stone column area replacement ratio on seismic behaviour of foundation

2020 ◽  
Vol 800 ◽  
pp. 012041
Author(s):  
I Safkan ◽  
S Derogar ◽  
J Anywar
Keyword(s):  
Stone Column ◽  
Seismic Behaviour ◽  
Replacement Ratio ◽  
Area Replacement Ratio

scholarly journals Settlement Behaviour of Soft Soil Reinforced with Geogrid Encased Stone Column under Sustained Loading

2019 ◽  
Vol 9 (2) ◽  
pp. 1307-1311
Keyword(s):  
Ground Improvement ◽  
Soft Soil ◽  
Stone Columns ◽  
Stone Column ◽  
Replacement Ratio ◽  
Sustained Loading ◽  
Settlement Behavior ◽  
Column Material ◽  
Area Replacement Ratio ◽  
Different Diameters

The use of stone columns in improving the bearing capacity of soft soil is well researched, but the understanding of settlement requires further studies. This paper presents the results of a series of laboratory tests carried out to study the settlement behavior of soft soil bed reinforced with ordinary stone column (OSC) and Geogrid encased stone columns (GESC). Kaolin was used as the soft soil and stones of size from 2.5 to 10 mm were used as column material. The stone columns of four different diameters were installed, by the method of replacement, into the soil having undrained shear strength of 22.5 kPa. The OSC and GESC test beds were subjected to pressure of 250 and 300 kPa. Each pressure was sustained for 24 hours and the settlement of the composite soil with time was noted. It is found that Geogrid encased stone columns have small settlement than the corresponding ordinary stone columns. The SRR (settlement reduction ratio) being a measure of ground improvement, is found increasing with the area replacement ratio. Further, at a particular sustained pressure SRR is found more for GESC than the corresponding value for OSC.

Embankment Supported by Low Area Replacement Ratio Stone Columns, Monitoring and Numerical Studies

2021 ◽  
Author(s):  
Mario V. Riccio F ◽  
Marcio S. S. Almeida ◽  
Silvana M. Vasconcelos ◽  
Liliana G. S. Pires ◽  
Luiz F. Nicodemos R
Keyword(s):  
Stone Columns ◽  
Replacement Ratio ◽  
Low Area ◽  
Numerical Studies ◽  
Area Replacement Ratio

Bearing capacity of spread footings on aggregate pier–reinforced clay: updates and stress concentration

2020 ◽  
Vol 57 (5) ◽  
pp. 717-727 ◽  
Author(s):  
Taeho Bong ◽  
Armin W. Stuedlein ◽  
John Martin ◽  
Byoung-Il Kim
Keyword(s):  
Stress Concentration ◽  
Bearing Capacity ◽  
Cross Validation ◽  
Slenderness Ratio ◽  
Ground Improvement ◽  
Analytical Models ◽  
Loading Test ◽  
Replacement Ratio ◽  
Area Replacement Ratio ◽  
Reinforced Clay

Aggregate piers represent an economical ground improvement technique used to increase bearing capacity and reduce settlements of weak soils. Several approaches have been developed to estimate the bearing capacity of aggregate pier–reinforced clay, but these models exhibit large prediction bias and uncertainty. This study uses newly developed footing loading test data to investigate the relationship between the bearing capacity and the area replacement and slenderness ratios. The bearing capacity of a single aggregate pier, whether isolated or in groups, below a loaded footing increases as the area replacement ratio decreases due to increase in extent of confined soil surrounding the pier. The length and diameter of an aggregate pier is also shown to result in significantly increased bearing capacity, an effect that diminishes with increasing slenderness. New modifications are proposed to existing simplified and cavity expansion models to account for the effect of confinement, area replacement ratio, and slenderness ratio using a leave-one-out cross-validation technique. The cross-validation analysis resulted in robust bearing capacity models that are more accurate than existing analytical models. Additionally, the stress concentration ratio for shallow foundations supported by aggregate pier–reinforced plastic soils at failure was estimated and compared with the available data, indicating its sensitivity to design variables and showing that this critical design parameter may be predicted using the updated models.

scholarly journals Sustainable ground improvement method using encapsulated polypropylene (PP) column reinforcement

2021 ◽  
Vol 930 (1) ◽  
pp. 012016
Author(s):  
M Hasan ◽  
M S I Zaini ◽  
N A W Hong ◽  
A Wahab ◽  
K A Masri ◽  
...  
Keyword(s):  
Shear Strength ◽  
Soil Sample ◽  
Ground Improvement ◽  
Soft Soil ◽  
Control Sample ◽  
Replacement Ratio ◽  
Replacement Method ◽  
Penetration Ratio ◽  
Area Replacement Ratio ◽  
Strength Improvement

Abstract This study investigates the effectiveness of encapsulated polypropylene (PP) column in enhancing the undrained shear strength of kaolin (soft clay). The usage of PP in treating problematic soil is a more sustainable and cost-effective alternative compared to other materials. The installation of granular column can be done by using vibro-replacement method. Several geotechnical tests to determine the properties of materials were conducted. The shear strength of treated kaolin sample was examined by using Unconfined Compression Test (UCT). There are seven (7) batches of soil sample in total which included a control sample, three (3) batches of 14 mm and three (3) batches of 20 mm diameter PP column. Different diameters of PP column were examined with 60 mm, 80 mm and 100 mm height, respectively with soil sample of 50 mm in diameter and 100 mm in height. The shear strength improvement of kaolin is 33.82%, 46.51%, and 49.88% when implanted with a PP column with a 7.84 area replacement ratio and 0.6, 0.8 and 1.0 penetration ratio. The soft soil treated using 16.00 area replacement ratio with 0.6, 0.8 and 1.0 penetration ratio has a shear strength increment of 25.22%, 33.39% and 37.59% respectively. In short, the shear strength improvement of the kaolin clay depends on the parameter of the PP column used to reinforce the sample.

Influence of gravel density in the behaviour of soft soils improved with stone columns

2015 ◽  
Vol 52 (12) ◽  
pp. 1968-1980 ◽  
Author(s):  
Marina Miranda ◽  
Almudena Da Costa ◽  
Jorge Castro ◽  
César Sagaseta
Keyword(s):  
Relative Density ◽  
Soil Column ◽  
Experimental Results ◽  
Stone Columns ◽  
Small Scale ◽  
Replacement Ratio ◽  
Soft Soils ◽  
Stress Concentration Ratio ◽  
Area Replacement Ratio ◽  
Horizontal Slice

Stone columns are frequently employed to improve the bearing capacity of soft soils, to reduce settlements, and to increase the speed of consolidation. Their behaviour depends on several factors, such as the density of the aggregate that forms the column and the area replacement ratio. This paper presents a study of the influence of the density of the gravel forming the columns on the deformation and stresses around end-bearing stone columns installed in soft soils. For this purpose, the behaviour of a horizontal slice of a unit cell has been analyzed by small-scale laboratory tests performed in a Rowe–Barden cell. Tests have been performed with a gravel relative density of Dr = 30% and with two area replacement ratios. Their results have been analyzed along with those from similar tests performed with a gravel density of Dr = 100%. The study is focused on the soil–column stress concentration ratio and the reduction of settlements. Finally, the experimental results are compared with numerical simulations. The results show that a reduction of settlements around 10% occurs when the relative density of the gravel increases from Dr = 30% to 100%. Numerical analyses reproduce well the behaviour of stone columns and are in good agreement with the experimental results.

Calculation Method of Soil-Column Area Replacement Ratio in the Composite Foundation

2013 ◽  
Vol 405-408 ◽  
pp. 216-220
Author(s):  
Jing Qin ◽  
Wei Lu ◽  
Yun Zhao
Keyword(s):  
Soil Column ◽  
Engineering Application ◽  
Composite Foundation ◽  
Replacement Ratio ◽  
Pile Diameter ◽  
Error Ratio ◽  
Spacing Ratio ◽  
Pile Arrangement ◽  
Area Replacement Ratio ◽  
Two Parameters

The calculation equations of soil-column area replacement ratio (m) recommended by Chinese code Technical Code for Ground Treatment of Buildings (JGJ79-2012) have many limits in the practice. In this document, general equations of m value are derived by subdividing the composite soil element under the different pile arrangements. The results show that m value is determined by the two parameters: interval number among piles (n) and pile diameter-spacing ratio (d/s). m value greatly decreases with the increase of d/s at the constant n, whereas m slightly decreases with the increase of n at the constant d/s, and the larger n, the smaller drop of m value. Under triangular pile arrangement, the Chinese code recommended equations can be used with less than 10 percent of error ratio of m value when the width of composite foundation is above 10 m, but the general equations should be applied when the width is below 10 m. Under square pile arrangement, the recommended equations can be used when the width of composite subgrade is above 15 m, but the general equations should be applied when the width is below 15 m. The general calculation equations of m value derived in this paper can provide certain reference for theoretical calculation and engineering application.

Performance of clay samples reinforced with vertical granular columns

2007 ◽  
Vol 44 (1) ◽  
pp. 89-95 ◽  
Author(s):  
J Black ◽  
V Sivakumar ◽  
J D McKinley
Keyword(s):  
Shear Strength ◽  
Ground Improvement ◽  
Stress Path ◽  
Undrained Shear Strength ◽  
Replacement Ratio ◽  
Replacement Method ◽  
Single Column ◽  
Undrained Strength ◽  
Area Replacement Ratio ◽  
Undrained Shear

This paper reports an experimental study in which samples of soft kaolin clay (100 mm in diameter and 200 mm in height) were reinforced with vertical columns of sand and tested under triaxial conditions. Samples were reinforced with either a single column of sand of 32 mm diameter or three columns of sand, each of 20 mm diameter. The replacement method was used to form the columns. The columns were installed in the clay to depths of 120 and 200 mm. Tests were also carried out on samples that were not reinforced with sand columns. The samples were compressed under both drained and undrained conditions. It was found that the undrained shear strength of samples containing full-depth columns was greatly improved compared with that of the unreinforced samples. In the fully drained tests, the sample installed with a single column of 32 mm diameter exhibited better performance than the sample with three columns of 20 mm diameter, although the area replacement ratio in the case of the three 20 mm diameter columns was higher than that of the single 32 mm diameter column. However, the undrained strength of the composite material was not particularly affected by the number of columns.Key words: Ground improvement, undrained shear strength, consolidation, stress path, settlement.

Assessment of an Existing Hot Tap Connection on the Bord Gáis Éireann Brighouse Bay Gas Export Terminal

2014 ◽  
Author(s):  
Peter Boothby ◽  
Graham Canty ◽  
Robert Andrews ◽  
Simon Slater
Keyword(s):  
Stress Analysis ◽  
Shell Thickness ◽  
Critical Assessment ◽  
Conference Paper ◽  
Replacement Ratio ◽  
Element Analysis ◽  
Fit For Purpose ◽  
Area Replacement Ratio ◽  
The Uk ◽  
Design Stress

A previous IPC conference paper (1) described the technical challenges associated with the installation of a new hot tap connection, supplementary to an existing hot tap connection, on the Bord Gáis Éireann Brighouse Bay high pressure gas export terminal in the UK. Work carried out to verify that the hot tap connection would be fit for purpose included a pipe stress analysis, Finite Element Analysis (FEA) and Engineering Critical Assessment (ECA). These assessments were performed because the split tee shell thickness and consequently also the circumferential fillet weld leg lengths did not achieve the 2 × carrier pipe thickness criterion required by UK specifications for applications where design stress levels exceed 30% specified minimum yield strength. Subsequently, it was identified that the existing hot tap connection installed in 2001 also did not meet the 2 × carrier pipe thickness criterion. Furthermore the material grade was lower than that for newer hot tap, i.e. P355 compared with P460 and the tee had been chamfered down from 50 mm to 40 mm at the ends, leading to reduced section circumferential fillet welds. This resulted in a leaner design than that for the newer hot tap and an ASME B31.3 area replacement calculation revealed that the area replacement ratio barely achieved the 1.0 requirement of the code suggesting a limited tolerance to system loading. Consequently similar stress analysis, FEA and ECA assessments to those previously undertaken were also subsequently performed for the existing hot tap connection. This paper provides details of the analyses and results obtained to determine the integrity of the existing hot tap split tee assembly which required a bespoke approach and a need to challenge conventional thinking.

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