scholarly journals Feedback of the behaviour of a silo founded on a compressible soil improved by floating stone columns

2018 ◽  
Vol 149 ◽  
pp. 02008
Author(s):  
Ramdane Bahar ◽  
Omar Sadaoui ◽  
Fatma Zohra Yagoub
Keyword(s):  
Soft Soil ◽  
Limit State ◽  
Soil Improvement ◽  
Stone Columns ◽  
Soil Conditions ◽  
Deep Foundations ◽  
The Stability ◽  
Compressible Soil ◽  
The City ◽  
Ongoing Monitoring

The coastal city of Bejaia, located 250 kilometers east of the capital Algiers, Algeria, is characterized by soft soils. The residual grounds encountered on the first 40 meters usually have a low bearing capacity, high compressibility, insufficient strength, and subject to the risk of liquefaction. These unfavorable soil conditions require deep foundations or soil improvement. Since late 1990s, stone columns technique is used to improve the weak soils of the harbor area of the city. A shallow raft foundation on soft soil improved by stone columns was designed for a heavy storage steel silo and two towers. The improvement of 18m depth have not reached the substratum located at 39m depth. The stresses transmitted to the service limit state are variable 73 to 376 kPa. A rigorous and ongoing monitoring of the evolution of loads in the silo and settlements of the soil was carried out during 1400 days that is from the construction of foundations in 2008 to 2012. After the loading of the silo in 2010, settlement occurred affecting the stability of the towers due to excessive differential settlements. Consequently, the towers were inclined and damaged the transporter. This paper presents and discusses the experience feedback of the behavior of these structures. Numerical calculations by finite elements have been carried and the results are compared with the measurements.

scholarly journals Review on Lateral Stability of Piled Riverine Structures in the Estuaries of Sarawak

2018 ◽  
Vol 7 (3.18) ◽  
pp. 21
Author(s):  
Lee Lin Jye ◽  
Shenbaga R. Kaniraj ◽  
Siti Noor Linda bt Taib ◽  
Fauzan Bin Sahdi
Keyword(s):  
Soft Soil ◽  
Natural State ◽  
Soil Conditions ◽  
Silty Clay ◽  
River Bank ◽  
Soil Movement ◽  
Geotechnical Problem ◽  
Construction Activity ◽  
Lateral Soil Movement ◽  
The Stability

Soft soil conditions with very soft and deep silty clay have constantly endangered the stability of the riverine and estuarine structures in Sarawak. There have been many failures of jetties, wharves and bridges in Sarawak. In many cases of failures, the piles were not designed to resist the lateral movement, unless they were included to stabilize unstable slopes or potential landslides. This practice may be due to reasons such as erroneously judging the river bank as stable in slope stability analysis or simply due to the inexperience of designers. Also, when the river bank approaches the limiting stability in its natural state any construction activity on the river bank could result in lateral soil movement. This paper highlights this important geotechnical problem in Sarawak. Then it presents the details of a few failures of estuarine structures. A review of situations causing lateral loading of piles is then presented. The results of the in-soil and in-pile displacement measurements are shown in this paper and it is found that the computation made to compare between field and 3D modeling is agreeable.  

Seismic Performance of Improved Ground Sites during the 2010–2011 Canterbury Earthquake Sequence

2014 ◽  
Vol 30 (1) ◽  
pp. 111-129 ◽  
Author(s):  
Liam M. Wotherspoon ◽  
Rolando P. Orense ◽  
Mike Jacka ◽  
Russell A. Green ◽  
Brady R. Cox ◽  
...  
Keyword(s):  
Large Scale ◽  
Ground Improvement ◽  
Soil Improvement ◽  
Earthquake Sequence ◽  
Soil Conditions ◽  
Ground Failure ◽  
Canterbury Earthquake Sequence ◽  
Liquefaction Assessment ◽  
The City ◽  
Selection Of

The city of Christchurch and the surrounding region on the South Island of New Zealand are underlain by large areas of recent alluvial sediments and fills that are highly susceptible to liquefaction and seismic ground failure. Thus, the widespread liquefaction that occurred following the successive large-scale earth-quakes, with moment magnitudes (MW) ranging from 6.0 to 7.1 that struck the Canterbury region in 2010–2011 was expected. Prior to the series of earthquakes, soil improvement had been used at several sites to mitigate the anticipated damage. This paper reviews the performance of improved sites during the Canterbury earthquake sequence. The existing soil conditions at each site and the design of the ground improvement are discussed, together with descriptions of the post-earthquake damage observed. Moreover, liquefaction assessment within and surrounding a selection of the ground improvement zones is presented.

scholarly journals Stability analysis of roadway embankments supported by stone columns with the presence of water table under short-term and long-term conditions

2018 ◽  
Vol 162 ◽  
pp. 01013 ◽  
Author(s):  
Shaymaa Tareq Kadhim ◽  
Ziad Bashar Fouad
Keyword(s):  
Water Table ◽  
Factor Of Safety ◽  
Soft Soil ◽  
Stone Columns ◽  
Stone Column ◽  
Stability Factor ◽  
Short Term ◽  
Long Term Conditions ◽  
The Stability

Use of stone column technique to improve soft foundation soils under roadway embankments has proven to increase the bearing capacity and reduce the potential settlement. The potential contribution of stone columns to the stability of roadway embankments against general (i.e. deep-seated) failure needs to be thoroughly investigated. Therefore, a two-dimensional finite difference model implemented by FLAC/SLOPE 7.0 software, was employed in this study to assess the stability of a roadway embankment fill built on a soft soil deposit improved by stone column technique. The stability factor of safety was obtained numerically under both short-term and long-term conditions with the presence of water table. Two methods were adopted to convert the three-dimensional model into plane strain condition: column wall and equivalent improved ground methods. The effect of various parameters was studied to evaluate their influence on the factor of safety against embankment instability. For instance, the column diameter, columns’ spacing, soft soil properties for short-term and long-term conditions, and the height and friction angle of the embankment fill. The results of this study are developed in several design charts.

scholarly journals Performance Analysis Of “Toga” Foundation With Cap On Thick Soft Soil Based On Laboratory Models And Finite Element Analysis

UKaRsT ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 222
Author(s):  
Melissa Kurnia ◽  
Paulus Pramono Rahardjo
Keyword(s):  
Soft Soil ◽  
Soil Conditions ◽  
Deep Foundations ◽  
3D Analysis ◽  
Element Analysis ◽  
Soil Layers ◽  
The Right ◽  
Laboratory Models ◽  
Deformation Relationship ◽  
Plaxis 3D

Various alternative foundations are offered depending on soil conditions from the results of soil investigations. In difficult soil types such as thick, soft soil layers, pile foundation is generally used to avoid the excess settlements, but deep foundations for small buildings are not the right solution when viewed from a cost perspective. One of the more economical foundations is to use the” toga” foundation, with a plate on top and a caisson underneath where the caisson can be inserted into the soil with an open end. Through this study, the carrying capacity of the” toga” foundation will be analyzed. Then the foundation will be made on a laboratory scale and tested with axial load. The load and deformation relationship were analyzed using PLAXIS 3D analysis. It can be concluded the performance of the ”toga” foundation on thick, soft soil can be used for two-floored buildings

scholarly journals METODE VACUUM CONSOLIDATION DENGAN PRELOADING UNTUK MEMPERCEPAT KONSOLIDASI TANAH PADA PERUMAHAN DI TANGERANG

2021 ◽  
Vol 4 (1) ◽  
pp. 171
Author(s):  
Jason Sastilaya ◽  
Gregorius Sandjaja Sentosa
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Drainage System ◽  
Soil Condition ◽  
Soil Improvement ◽  
Soil Conditions ◽  
Soil Plasticity ◽  
Calculation Results ◽  
Long Time

The expansion of housing in big cities cannot be denied given the rapid population growth in Indonesia. One of the areas that is currently expanding housing is Kosambi City, Tangerang. Soil conditions in Kosambi City are soft soil with high moisture content and soil plasticity, low permeability and soil bearing capacity, and high pore water pressure. This soft soil condition makes the consolidation decline take a very long time. To overcome the problem of the length of time for this consolidation settlement, it is necessary to improve the land. Soil improvement is being carried out, namely the method of vaccum consolidation with preloading. The combination of these methods is carried out by installing a vertical drainage system in the form of prefabricated fabricated drain (PVD) in soft soil, then the initial load is given in the form of preloading on the soil. The calculation results show that the amount of consolidation reduction that occurs when clay soil is loaded with a stockpile of 1.2 m high, a water surcharge of 1.3 m and a vaccum load is 0.3929 m and 0.6968 m for 85 years. The combined method of preloading and PVD is proven to be able to accelerate the time of consolidation, where Preloading and PVD are installed in a triangle pattern between 0.80 m to a depth of 12 m, capable of achieving a consolidation degree of 90% within 8 weeksPerluasan perumahan di kota besar tentu tidak dapat dipungkiri mengingat pesatnya pertumbuhan penduduk di Indonesia. Salah satu daerah yang sedang dilakukan perluasan perumahan yaitu Kosambi City, Tangerang. Kondisi tanah di Kosambi City merupakan tanah lunak dengan kadar air dan plastisitas tanah yang tinggi, permeabilitas dan daya dukung tanah yang rendah, serta tingginya tekanan air pori. Kondisi tanah lunak ini membuat penurunan konsolidasi membutuhkan waktu yang sangat lama. Untuk mengatasi masalah lamanya waktu penurunan konsolidasi ini, perlu dilakukan perbaikan tanah. Perbaikan tanah yang dilakukan yaitu metode vaccum consolidation dengan preloading. Kombinasi pada metode ini dilakukan dengan cara memasang sistem drainase vertikal berupa prefabricated fabricated drain (PVD) di dalam tanah lunak, kemudian diberikan beban awal yaitu berupa timbunan (preloading) pada tanah tersebut. Hasil perhitungan menunjukkan besar penurunan konsolidasi yang terjadi jika tanah lempung dibebani dengan timbunan setinggi 1,2 m, water surcharge setinggi 1,3 m dan beban vaccum  adalah 0,3929 m dan 0,6968 m selama 85 tahun. Metode kombinasi preloading dan PVD terbukti mampu mempercepat waktu konsolidasi, dimana Preloading dan PVD dipasang dengan pola segitiga berjarak 0,80 m hingga kedalaman 12 m, mampu mencapai derajat konsolidasi 90% dalam waktu 8 minggu. 

scholarly journals Geosynthetic Encased Columns Supporting Rail Infrastructure – Perspectives on Research and Case Studies

2020 ◽  
Author(s):  
Erol Guler ◽  
Cihan Cengiz ◽  
Oliver Detert
Keyword(s):  
Case Studies ◽  
Ground Improvement ◽  
Soft Soil ◽  
Academic Research ◽  
Major Effect ◽  
Economic Benefits ◽  
Shaking Table ◽  
Stone Columns ◽  
Soil Conditions ◽  
Rail Network

Significant investments are being made towards enhancing the reach of the railway infrastructure due to the vast economic benefits it brings. An inevitable consequence of the expansion of the rail network is the soft soil conditions encountered in the alignment. Geosynthetic encased columns (GEC) is a proven ground improvement technology which can be adapted as soil remediation technique for such conditions. In this paper, first an introduction to the concept of GECs will be given. Then the recent advances in the academic research on the GECs will be elaborated. As it is known, earthquakes are one of the most devastating disasters and certainly also have a major effect on transportation infrastructure. In this paper results of shaking table tests to compare ordinary stone columns and GECs behavior under earthquake loading conditions will also be presented. The brief recap of the state of the art on the geosynthetic encased columns including their earthquake behavior will be followed by case studies on three major projects where the site conditions and project requirements will be discussed. The significant benefits of geosynthetic encased columns in relation to project requirements will also be elaborated.

scholarly journals Methods for mitigating effects induced by tunnelling on nearby existing buildings in cities

2020 ◽  
Vol 61 (HTCS6) ◽  
pp. 57-65
Author(s):  
Ngan Minh Vu ◽  
Luyen Van Nguyen ◽  
Lam Phuc Dao ◽  
Keyword(s):  
Urban Areas ◽  
Soft Soil ◽  
Soil Improvement ◽  
Soil Conditions ◽  
Existing Buildings ◽  
Tunnel Design ◽  
Negative Impacts

Tunnelling in urban areas in soft soil conditions has risks of negative impacts on nearby existing buildings. When buildings are in/on influence zones induced by tunnelling, they can be damaged in the case of without any mitigating methods applied. This paper summarizes and presents a three category classification of mitigating effects induced by tunneling including methods in tunnel design and tunnelling process, and soil improvement methods, as well as reinforcement for buildings. On the basis of the study, designers and engineers can obtain suitable solutions for their safe tunnel projects.

scholarly journals Effect of Spacing between Stone Columns on the Behavior of Soft Soil

2021 ◽  
Vol 318 ◽  
pp. 01006
Author(s):  
Zeena A. Al-Kazzaz ◽  
Moataz A. Al-Obaydi
Keyword(s):  
Bearing Capacity ◽  
Soft Soil ◽  
Soil Improvement ◽  
Stone Columns ◽  
The Finite Element Method ◽  
Slight Improvement ◽  
Short Columns ◽  
Sectional Shape ◽  
The Impact ◽  
Spacing Length

Soil improvement by stone columns is extensively used, especially for the soft ones. This is because of their efficiency and no environmental impact. Several factors affect its efficiency in improving the mechanical properties of the soil, and the most important of these factors are the spacing, length, and diameter of the stone columns. In this study, the finite element method was used to study the impact of the spacing between the stone columns on the amount of settlement and the bearing capacity of the soil. The study comprises three different spaces (s) that were taken in relation to the columns’ diameter (d), which are (s/d= 3, 4, and 5). In addition, three types of the sectional shape of column involved circular, rectangular, and square sections with different lengths of (L/d=2, 4, 6, 8, and 10). The results showed that the spacing between the stone columns is effective when the vertical load is greater than 30 kN/m2, and below this, there is no effect of the spacing. In general, the settlement decreases, and the bearing capacity increases with the decrease in the spacing between the stone columns. The spacing becomes a more pronounced effect with the longer length of the stone columns. All sections of the stone columns with a short length of (L/d=2) showed the same settlement of 271 mm at a distance (s/d=5), which decreases by 7.4, 6.6, and 8.9% at a distance (s/d=3) for the circular, rectangular and square sections respectively. In the case of long columns (L/d=10), the settlement at (s/d=3) improves by about 27.5% which drop to about 18% at (s/d=5). A slight improvement in the soil's bearing capacity is associated with decreases in the spacing between the stone columns. The improvements in the bearing of soil treated with short columns (L/d=2) are 6.0, 6.5, and 4.7% for circular, rectangular, and square sections, respectively, when changing the distance from (s/d=5) to (s/d=3). Whereas they become greater when increasing the columns’ length to (L/d=10) to be 7.9, 9.2, and 6.4%.

scholarly journals CALCULATION OF VERTICAL DEFORMATIONS OF THE FOUNDATIONS ON THE SOFT SOIL IMPROVED BY GEOTEXTILE ENCASED STONE COLUMNS

2020 ◽  
Vol 11 (3) ◽  
pp. 64-76
Author(s):  
R. I Shenkman ◽  
A. B Ponomaryov
Keyword(s):  
Numerical Modeling ◽  
Soft Soil ◽  
Experimental Studies ◽  
Elementary Cell ◽  
Stone Columns ◽  
Soil Conditions ◽  
Good Convergence ◽  
Engineering Technique ◽  
Calculation Results ◽  
Vertical Deformations

The article provides information on research in the field of improving weak clay bases by installing vertical soil piles in a shell of geosynthetic materials (geotextile encased stone columns). This method has proven to be effective for strengthening the foundations of large areal objects in certain soil conditions, but has not become widespread as a method for improving the foundations of building foundations, which, among other things, is due to the lack of simple engineering methods for calculating the improvement parameters. The article presents an engineering technique for determining the settlement of shallow foundations on a weak clay base which is improved by the geotextile encased stone columns. The technique is based on considering the elementary cell of the improved foundation for which the pressure distribution in the weak soil and the improvement element is determined by the iterative enumeration process. This distribution should ensure equality of the vertical deformations of the improvement element and the soft soil, which should be the same due to the stiffness of the foundation of the building or structure. The calculation of the deformations of a geotextile encased stone columns is carried out by solving the Lamé problem and the deformations of soft soil by standard methods presented in the regulatory literature. Comparison of the calculation results by the proposed method with the data of numerical modeling in an axisymmetric setting is presented. In the numerical modeling of the soil, the Mohr-Coulomb elastic-plastic model was used. Geosynthetic reinforcement was modeled using a special element that only accepts tensile stresses. The rigidity of the foundation of the base is taken to be infinitely large. The analysis of the presented simulation results showed good convergence of the calculations with the data of experimental studies and the data of numerical simulation using the finite element method.

scholarly journals RECALQUES EM FUNDAÇÕES PROFUNDAS – ANÁLISE EM ESTACAS HÉLICE CONTÍNUA

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Pedro Lucas Prununciati ◽  
Jean Rodrigo Garcia ◽  
Tiago Garcia Rodriguez
Keyword(s):  
Sampling Error ◽  
Load Capacity ◽  
Limit State ◽  
Load Test ◽  
Limiting Factor ◽  
Deep Foundations ◽  
Slow Type ◽  
Load Tests ◽  
Penetration Tests ◽  
The City

RESUMO:  O recalque em fundações profundas e sua influência numa edificação tem se mostrado um parâmetro crítico, já que em diversos projetos a capacidade de carga não é o fator limitante, mas sim o recalque que a estrutura pode suportar em seu estado limite de serviço (ELS). Neste trabalho, são analisados resultados de deslocamento para uma estaca, estimados a partir dos métodos de Poulos e Davis (1980), Vésic (1969, 1975a) e Cintra e Aoki (2010), comparando-os com o valor recalque obtido por ensaios de prova de carga. Para tal, se apresentam três ensaios com carregamento do tipo lento, seguindo instruções da NBR12131 (ABNT, 2006), executados em estacas hélice contínua instrumentadas, com comprimentos de 14,75 m, 12,85 m e 21,80 m e diâmetros de 70 cm, 60 cm e 70 cm, respectivamente. Essas estacas foram ensaiadas no munícipio de Itatiba, em uma região onde sondagens à percussão demonstram a predominância de areia e silte. Para as estacas analisadas, o método proposto por Cintra e Aoki (2010) mostrou melhor resultado para a estimativa do recalque, quando comparado aos resultados de recalque obtidos em prova de carga. O método Poulos e Davis (1980) obteve desempenho menos satisfatório, resultando uma margem de erro de 16%, para mais ou para menos. O método de Vésic (1969, 1975a) se mostrou conservador e, nos casos analisados, resultou uma superestimativa de 138%, quando comparados aos valores de prova de carga.ABSTRACT: The settlement in deep foundations and its influence appears to be a critical parameter, as in many projects, the load capacity of a pile is not the limiting factor, but the settlement which the structure can suffer on its serviceability limit state (SLS) is. In this research, the settlement results of a pile, estimated by the methods of Poulos e Davis (1980), Vésic (1969, 1975a) and Cintra e Aoki (2010) will be analyzed, to be compared with the value of settlement obtained from load tests. Three slow type load tests, following the instructions of NBR12131 (ABNT, 2006) are presented, carried out in instrumented continuous flight augers, with lengths of 14,75 m, 12,85 m and 21,80 m and diameters of 70 cm, 60 cm and 70 cm, respectively. Those piles were tested in the city of Itatiba, in a region where standard penetration tests evidenced the predominance of sand and silt. In the analyzed piles, the Cintra e Aoki (2010) method has shown the best result for a settlement estimate, when compared with the value obtained by a load test. The Poulos e Davis method (1980) obtained a less satisfactory performance, resulting a margin of sampling error of plus or minus 16%. The Vésic method (1969, 1975a) has shown to be conservative, resulting, in the analyzed cases, an overestimate of 138%, when compared with the load tests values.

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