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

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.

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Performance of clay samples reinforced with vertical granular columns

Canadian Geotechnical Journal ◽

10.1139/t06-081 ◽

2007 ◽

Vol 44 (1) ◽

pp. 89-95 ◽

Cited By ~ 35

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.

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

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.a5030.129219 ◽

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.

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

Canadian Geotechnical Journal ◽

10.1139/cgj-2019-0026 ◽

2020 ◽

Vol 57 (5) ◽

pp. 717-727 ◽

Cited By ~ 1

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.

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Settlement Behaviour of Soft Clay Bed Reinforced with Stone Column under Sustained Loading

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.b2516.129219 ◽

2019 ◽

Vol 9 (2) ◽

pp. 1744-1749

Keyword(s):

Ground Improvement ◽

Soft Soil ◽

Soft Clay ◽

Reinforced Soil ◽

Sustained Load ◽

Stone Column ◽

Sustained Loading ◽

Settlement Behavior ◽

High Area ◽

Area Replacement Ratio

This research paper investigates the behaviour of soft clay reinforced with stone column under sustained loading. Experiments were conducted in the laboratory on stone column reinforced prepared soft soil bed of kaolin having strength of 7.5 kPa with aggregate of size 2.5 to 10 mm as column material. The stone column with four diameters of 38.1, 50.8, 63.5 and 76.2mm were constructed which correspond to low to high area replacements ratios (i.e. 6.93% - 26.49%). The plain and reinforced soft clay beds were subjected to a sustained load of 150, 200, 250 and 300 kPa where each applied load has been maintained for 24 hours and the settlement behavior of composite ground was taken into account. The test results represent the settlement of reinforced soil bed decreases with increase of column diameters. The settlement reduction ratio is a measure of ground improvement which increases with area replacement ratio. The experimental and theoretical results values were compared as per IS15284 (Part 1): 2003 with reference of stress concentration ratio ‘n’(The ratio of stress in the column to the stress of surrounding ground area). The % variation in theoretical and experimental results is in the range of 50% and therefore the theoretical procedure needs to be revised.

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Study on the Strength Performance of Recycled Aggregate Concrete with Different Ages under Direct Shearing

Materials ◽

10.3390/ma14092312 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2312

Author(s):

Xin Liang ◽

Fang Yan ◽

Yuliang Chen ◽

Huiqin Wu ◽

Peihuan Ye ◽

...

Keyword(s):

Shear Strength ◽

Shear Force ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Displacement Curve ◽

Direct Shear ◽

Replacement Ratio ◽

Aggregate Concrete ◽

Concrete Failure ◽

Load Displacement

In order to study the mechanical properties of recycled aggregate concrete (RAC) at different ages, 264 standard cubes were designed to test its direct shear strength and cube compressive strength while considering the parameters of age and recycled aggregate replacement ratio. The failure pattern and load–displacement curve of specimens at direct shearing were obtained; the direct shear strength and residual shear strength were extracted from the load–displacement curves. Experimental results indicate that the influence of the replacement ratio for the front and side cracks of RAC is insignificant, with the former being straight and the latter relatively convoluted. At the age of three days, the damaged interface between aggregate and mortar is almost completely responsible for concrete failure; in addition to the damage of coarse aggregates, aggregate failure is also an important factor in concrete failure at other ages. The load–displacement curve of RAC at direct shearing can be divided into elasticity, elastoplasticity, plasticity, and stabilization stages. The brittleness of concrete decreases with its age, which is reflected in the gradual shortening of the elastoplastic stage. At 28 days of age, the peak direct shear force increases with the replacement ratio, while the trend is opposite at ages of 3 days, 7 days, and 14 days, respectively. The residual strength of RAC decreases inversely to the replacement ratio, with the rate of decline growing over time. A two-parameter RAC direct shear strength calculation formula was established based on the analysis of age and replacement rate to peak shear force of RAC. The relationship between cube compressive strength and direct shear strength of recycled concrete at various ages was investigated.

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Uplift and Settlement Prediction Model of Marine Clay Soil e Integrated with Polyurethane Foam

Open Engineering ◽

10.1515/eng-2019-0054 ◽

2019 ◽

Vol 9 (1) ◽

pp. 481-489

Author(s):

D.C. Lat ◽

I.B.M. Jais ◽

N. Ali ◽

B. Baharom ◽

N.Z. Mohd Yunus ◽

...

Keyword(s):

Polyurethane Foam ◽

Clay Soil ◽

Ground Improvement ◽

Soft Soil ◽

Soft Clay ◽

Effective Thickness ◽

Marine Clay ◽

Uplift Pressure ◽

Pu Foam ◽

Improvement Method

AbstractPolyurethane (PU) foam is a lightweight material that can be used efficiently as a ground improvement method in solving excessive and differential settlement of soil foundation mainly for infrastructures such as road, highway and parking spaces. The ground improvement method is done by excavation and removal of soft soil at shallow depth and replacement with lightweight PU foam slab. This study is done to simulate the model of marine clay soil integrated with polyurethane foam using finite element method (FEM) PLAXIS 2D for prediction of settlement behavior and uplift effect due to polyurethane foam mitigation method. Model of soft clay foundation stabilized with PU foam slab with variation in thickness and overburden loads were analyzed. Results from FEM exhibited the same trend as the results of the analytical method whereby PU foam has successfully reduced the amount of settlement significantly. With the increase in PU foam thickness, the settlement is reduced, nonetheless the uplift pressure starts to increase beyond the line of effective thickness. PU foam design chart has been produced for practical application in order to adopt the effective thickness of PU foam within tolerable settlement value and uplift pressure with respect to different overburden loads for ground improvement works.

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Research to build technological procedure for soft ground improvement using sea sand-cement-fly ash column

Journal of Mining and Earth Sciences ◽

10.46326/jmes.htcs2020.01 ◽

2020 ◽

Vol 61 (HTCS6) ◽

pp. 1-9

Author(s):

Thinh Duc Ta ◽

Phuc Dinh Hoang ◽

Thang Anh Bui ◽

Trang Huong Thi Ngo ◽

Diu Thi Nguyen ◽

...

Keyword(s):

Fly Ash ◽

Load Capacity ◽

Ground Improvement ◽

Soft Soil ◽

Soil Reinforcement ◽

Soft Ground ◽

Design Calculation ◽

Sea Sand ◽

Composite Ground ◽

Soft Ground Improvement

Sea sand-cement-fly ash column technology for soft soil treatment is a new technology in the process of completing the theoretical basis, the experimental basis, and the construction of the ground treatment technological procedure. The paper presents the results of scientific research on design, calculation, construction, and acceptance of sea sand-cement-fly ash column. The scientific basis for the design of column is to consider the role of the column in composite ground, that is to use the column as soft ground improvement or soft soil reinforcement. The important parameters for the column design are: cement and fly ash content; column length; column diameter; number of columns; distance among columns; load capacity and settlement of composite ground. The sequence of steps of construction and acceptance of column includes: selection of construction equipment, preparation of construction sites, trial construction, official construction, evaluation of ground quality after treatment and preparation of document for acceptance.

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Geosynthetic Encased Column: comparison between numerical and experimental results

Soils and Rocks ◽

10.28927/sr.2021.073121 ◽

2021 ◽

Vol 44 (4) ◽

pp. 1-12

Author(s):

Nima Alkhorshid ◽

Gregório Araújo ◽

Ennio Palmeira

Keyword(s):

Pore Water Pressure ◽

Water Pressure ◽

Ground Improvement ◽

Soft Soil ◽

Experimental Tests ◽

High Permeability ◽

Soft Soils ◽

Column Comparison ◽

Surrounding Soil ◽

Granular Column

The use of granular column is one of the ground improvement methods used for soft soils. This method improves the foundation soils mechanical properties by displacing the soft soil with the compacted granular columns. The columns have high permeability that can accelerate the excess pore water pressure produced in soft soils and increase the undrained shear strength. When it comes to very soft soils, the use of granular columns is not of interest since these soils present no significant confinement to the columns. Here comes the encased columns that receive the confinement from the encasement materials. In this study, the influence of the column installation method on the surrounding soil and the encasement effect on the granular column performance were investigated using numerical analyses and experimental tests. The results show that numerical simulations can reasonably predict the behavior of both the encased column and the surrounding soil.

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Performance of soft clay stabilized with sand columns treated by silica fume

MATEC Web of Conferences ◽

10.1051/matecconf/201816201007 ◽

2018 ◽

Vol 162 ◽

pp. 01007

Author(s):

Zeena Samueel ◽

Hussein Karim ◽

Mohammed Mohammed

Keyword(s):

Silica Fume ◽

Carrying Capacity ◽

Construction Projects ◽

Ground Improvement ◽

Soft Clay ◽

Road Construction ◽

Reduction Ratio ◽

Area Replacement Ratio ◽

Second Category ◽

Improvement Ratio

In many road construction projects, if weak soil exists, then uncontrollable settlement and critical load carrying capacity are major difficult problems to the safety and serviceability of roads in these areas. Thus ground improvement is essential to achieve the required level of performance. The paper presents results of the tests of four categories. First category was performed on saturated soft bed of clay without any treatment, the second category shed light on the improvement achieved in loading carrying capacity and settlement as a result of reinforcing with conventional sand columns at area replacement ratio = 0.196. The third set investigates the bed reinforced by sand columns stabilized with dry silica fume at different percentages (3, 5 and 7%) and the fourth set investigates the behavior of sand columns treated with slurry silica fume at two percentages (10 and 12%). All sand columns models were constructed at (R.D= 60%). Model tests were performed on bed of saturated soil prepared at undrained shear strength between 16-20 kPa for all models. For all cases, the model test was loaded gradually by stress increments up to failure. Stress deformation measurements are recorded and analyzed in terms of bearing improvement ratio and settlement reduction ratio. Optimum results were indicated from soil treated with sand columns stabilized with 7% dry silica fume at medium state reflecting the highest bearing improvement ratio (3.04) and the settlement reduction ratio (0.09) after 7 days curing. While soil treated with sand columns stabilized with 10% slurry silica fume provided higher bearing improvement ratio 3.13 with lower settlement reduction ratio of 0.57 after 7-days curing.

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