Geosynthetic Tubes Research Articles

Theoretical analyses and design methods of geosynthetic tubes

土工管袋技术具有制作简单、施工及运输快捷、经济环保等优点，近年来被广泛用于防洪防汛及水位控制、防波堤、海岸防侵蚀、堤坝、污水存贮和污水沉积等工程领域，根据制作材料和施工工艺的不同可将土工管袋分为土工膜管袋、土工织物管袋和橡胶坝三种。本文综合介绍了土工膜管袋、土工膜垫、土工织物管袋、支挡土工膜管袋以及橡胶坝等结构形式的土工管袋理论计算方法和相应的简化设计计算公式和图表，以期对类似的工程建设和设计起到一定的参考意义。

Geosynthetic-Encased Granular Columns Subjected to Vertical and Shear Loads

Granular columns are commonly used to support flexible structures over soft clay soils. The installation of such columns increases both the strength and stiffness of the ground. However, constructing these columns in clay soils having low cohesive strength of about 15 kPa is a challenge due to inadequate confinement. The columns may be encapsulated in geosynthetic tubes to enhance their constructability, strength and drainage properties. The geosynthetic encasement is also known to improve their performance under shear loading. This paper reviews the application of geosynthetic-encased granular columns for treatment of soft grounds. The design of these systems under vertical loads by two different methods is described in this paper. The performance of geosynthetic-encased granular columns under shear loads and the influence of geosynthetic encasement on the factor of safety of embankments supported on soft clay soils is discussed. The use of geosynthetic encasement of granular columns is seen to change the deep-seated foundation failure mechanism to toe failure mechanism.

Applications of Chapman-Richards model to geotechnical engineering

Abstract In this paper, the Chapman-Richards model is adapted to best fit three types of nonlinear curves that are generally encountered in geotechnical engineering practices, i.e. the degree of consolidation versus time factor curves in one-dimensional consolidation and plane strain consolidation under strip loading, the compressibility and permeability curves of soft clay, and the geometry parameters of geosynthetic tube versus pumping pressure curves. The methods of determining unknown parameters using the Chapman-Richards model are fully demonstrated. It is found that the Chapman-Richards model has its range of applications in geotechnical engineering and may provide unique insights into the complexity of geotechnical problems.

Geosynthetic tubes for pit lake bank stabilization

This article is not available for publication.

Coupled discrete and finite-element modelling of geosynthetic tubes filled with granular material

This paper presents the results of numerical modelling of geosynthetic tubes filled with granular material. In the present study, a numerical model coupling discrete and finite elements was used to describe the behaviour of the encapsulated granular media using clusters and the behaviour of the geosynthetic membrane using finite elements. Initially, a simple compressive loading was applied to the geosynthetic tube to establish the influence of the main parameters governing the mechanical behaviour of the tube. Next, a more complex behaviour was studied by considering an additional lateral action imposed by the backfill of the structure, showing that the influence of the backfill cannot be neglected in the analysis. In the third part of the numerical modelling, a bending test was performed to study the behaviour of the tube in the environment of localised sinkholes. The numerical results were validated by comparison with analytical formulations and were supported by the experimental results described in each section of the analysis. The obtained results and comparisons were reasonably good and a discussion of all the results completes the paper.

Simplified methods to analyze geosynthetic mattress resting on deformable foundation soil

ABSTRACTA special case of geosynthetic tubes is the geosynthetic mattress characterized by its larger width-to-height ratio and higher lateral-force-resisting capacity. When the geosynthetic mattresses are adopted for dike or breakwater construction in coastal engineering projects, they are often laid on deformable foundation soil. The induced ground settlement will influence the cross-sections and tensile forces of the geosynthetic mattresses. Two analytical methods, called the Winkler foundation method and the e–log p method, are proposed in this paper to analyze the geosynthetic mattresses resting on deformable foundation soil. For the Winkler foundation method, the subgrade soil is assumed as a Winkler elastic foundation represented by the modulus of subgrade reaction, Kf. For the e–log p method, the 1D consolidation relationship (e–log p curve) is adopted to describe the behavior of the subgrade soil within which the distribution of vertical surcharge is calculated using Boussinesq equation. The numerical analyses using FLAC are also conducted to evaluate the accuracy of the proposed methods. The differences between the analytical and numerical solutions are also discussed. It is found from this paper that the proposed e–log p method is more suitable than the Winkler foundation method for the calculation of the geosynthetic mattress resting on deformable foundation soil.

METHODS FOR DESIGNING PARTIALLY INFLATED GEOTUBES

A widely used technique in constructing dikes for land reclamation is to use tubes made of sewn geosynthetic sheets. These tubes are usually filled with slurry comprising soils, such as sand, silt, and clay. The tension stress that develops in geosynthetic tubes during tube filling is the dominant factor considered in constructing safe dikes. Existing design methods are effective for sausage-shaped tube designs; however, they cannot be directly applied in flat tubes, which are commonly used in dike construction. This paper presents a procedure that can determine the relationships among tube size, pumping pressure, unit weight of the slurry, and tension stress in geosynthetic tubes. All these approaches are programmed to enable dike designers to select a suitable geosynthetic design for dike profiles.

Model tests on methods to improve dewatering efficiency for sludge-inflated geotextile tubes

ABSTRACT: Geotextile tubes made of woven geotextile materials have been widely applied to dewater waste sludge such as digested bio-solids, sewage sludge, dredged materials, industrial solid wastes, fly ash and coal slurry. However, the dewatering process of single geotextile tubes is time consuming. Two methods to accelerate the dewatering process of slurry in geosynthetic tubes were studied using laboratory model tests. The first method was to stack one tube on top of another and use the weight of the top tube to preload the bottom one. The second method was the vacuum method proposed in this paper to use vacuum pressure to consolidate the slurry in the geosynthetic tube. A 2.0-mm-thick woven polypropylene geosynthetic sheet was selected for the geotextile tubes. The deformation, pore water pressure and tensile forces monitored during the model tests against time are presented and analysed in this paper. The properties of the soil after consolidation were also measured and compared. The model test data showed that the vacuum method resulted in a lower water content and higher deformation rate than the two-layer stacking geotextile tube method. Compared with the stacking method, the vacuum method could reduce the risk to the geotextile sheet from explosion.

Simplified analytical solution for geosynthetic tube resting on deformable foundation soil

When geosynthetic tubes are placed on soft ground, the ground settlement can be large enough to influence the design and performance of geosynthetic tubes. The existing method to model the ground deformation for the design of geosynthetic tubes is to use the Winkler model. In this paper, an analytical solution is proposed to calculate the impermeable geosynthetic tubes resting on deformable foundation soil. The proposed analytical method adopts the 1-D consolidation relationship (the e − log p curve) to describe approximately the stress–strain behavior of the soil. The vertical surcharge pressure distribution within the soil mass is calculated using the Boussinesq solution. The numerical analyses are also carried out using FLAC to evaluate the accuracy of the proposed method. The results from the analytical method agree well with those from the numerical analysis.

Experimental and analytical studies of geosynthetic tubes filled with expanded clay lightweight aggregate

ABSTRACT: A new type of mechanically stabilised earth structure composed of geosynthetic tubes filled with expanded clay lightweight aggregate and backfill with geosynthetic reinforcement is introduced. The results of the study demonstrate that alternative solutions such as expanded clay lightweight aggregates can be used in interaction with geosynthetics in comparison to classical soil. The new type of geosynthetic tubes filled dynamically with expanded clay lightweight aggregate was tested in situ under compressive loading. The geosynthetic tube was instrumented with load cell transducers and the characteristic cross-section was obtained from three-dimensional scanner measurements after loading. Next, a simplified engineering formulation for geosynthetic tubes under compressive loading and unloading was evaluated including the influence of volume variation of the tube. It is based on the classical approach from soil mechanics and it produces the required design tensile force of the tube dependent on geosynthetic stiffness. The experimental results of compressive loading tests were compared with analytical equations. The results are discussed and show the influence of the geosynthetic stiffness on the behaviour of the tube in terms of loading capacity, volume variation and cross-section of the tube. The agreement between theoretical analyses and experimental results was reasonably good and can be formally accepted for a given volume variation of the geosynthetic tube.

Stability Analysis and Design of offshore Submerged Breakwater Constructed Using Sand Filled Geosynthetic Tubes

Kadalur Periyakuppam (KPK) is a fishing village located 70km south of Chennai in Tamil Nadu. The coastline of KPK was subjected to severe erosion due to high energy waves during Thane (2011), Nilam (2012) and Madi (2013) cyclones. The Tamil Nadu Fisheries department facilities located near the coast is subjected to damage as the coastline has receded by 45 m in the last few years following the severe erosion caused by cyclones. Since most of the erosion occurred after the storm waves hit the shoreline, sustainable option for shoreline protection would be to shift wave breaking to deeper depths. Based on numerical model studies and assessment of shoreline behaviour over two years, it is proposed to construct a submerged segmented breakwater. The submerged breakwater is proposed to be constructed at 4 m water depth up to a height of 3.5 m using sand filled geosynthetic tubes. Geosynthetic tubes shall be placed in a stacked manner with 2 tubes of 1.5 m high each at the bottom and a tube of 2.5 m height at the top accounting for height loss due to settlement. Design and stability checks are carried out by using available literature as no standard methods or design codes are available for design or stability checks for the geosynthetic tubes. The breakwater structure is checked for stability against sliding, overturning and bearing capacity. The geosynthetic tube material specifications such as tensile strength, ultra violet ray resistance, apparent opening size and fabric material are calculated using suitable design methods. The scouring, in front and behind the breakwater structure under prevailing wave conditions, is estimated for designing scour protection.

A simplified method for design of geosynthetic tubes

A simplified method for the design of impermeable geosynthetic tubes inflated using liquid is proposed in this paper. Adopting a computer program for an existing theoretical model, relationships between pumping pressure and geometric parameters for geosynthetic tubes can be established. A set of simplified dimensionless design equations are then derived using the Chapman–Richard curve fitting method. The validity of this simplified method was verified using other established methods and laboratory model tests. The proposed simplified method can thus be used for routine or preliminary design.

Analysis of geosynthetic tubes inflated by liquid and consolidated soil

When permeable geosynthetic tubes are used for dewatering of waste sludge or construction of dikes or embankments, the tubes have to be inflated using sludge or soil slurry several times. After each inflation, the soil slurry is consolidated into solid. Hence from the second inflation onwards, the geosynthetic tube is filled by both slurry and consolidated soil. In this paper, a new analytical method is proposed to provide a solution to the above specific case. Friction between geosynthetic sheet and soil, and friction between geosynthetic tube and subgrade, are considered. Parametric studies are also carried out to compare the design between geosynthetic tubes inflated using pure slurry and that using slurry and consolidated soil to study the key factors affecting the design. The study shows that tensile forces vary along the cross-section of the geosynthetic tube with the minimum value occurring at the center of the base. The effect of friction and lateral earth pressure on the geometry and tensile forces of the geosynthetic tube is insignificant when the height of the consolidated soil in the tube is small, but increases considerably with an increase in the height.

Analytical solutions for geosynthetic tube resting on rigid foundation

Geosynthetic tubes inflated with water, clay slurry or sand have been widely used for large dike construction in land reclamation projects. In this paper, analytical solutions for geosynthetic tube resting on rigid foundation is presented by adopting an approach similar to that presented by Leshchinsky et al. (1996). The proposed method allows a quick preliminary design to be made for using a closed-form solution. To simplify the analysis, relationships between geometrical parameters and pumping pressure are established using numerical method. The analytical solutions were compared with several existing solutions and good agreements were achieved.

Geosynthetic mattress: Analytical solution and verification

A new application of geosynthetic tube for offshore dike construction is geosynthetic mattress in which its horizontal dimension is much greater than the vertical one. This makes it more stable than the sausage shaped geosynthetic tube. However, the existing analytical or numerical methods developed for the sausage shaped geosynthetic tube may not be applicable directly to geosynthetic mattresses as the solution may not converge. In this paper, a closed-form solution was derived for a direct determination of the cross-section of geosynthetic mattress. Laboratory large scale model tests were also carried out to verify the proposed analytical method. The cross-sections of the geosynthetic mattresses obtained from the closed-form solutions agreed well with the data obtained from model tests. The tensile forces measured from the model tests were rather scattered but showed a consistent thread as those from the closed-form solutions.

Similarity Shapes of a Fully Liquid-Filled Membrane on an Incline

AbstractMembranes, such as geosynthetic tubes, have been widely used in civil construction and as storage tanks. Estimation of the shape, structural tension, and internal pressure are essential for effective and safe use of these structures. Motivated by a numerical study on the case of a partially liquid-filled membrane, this study presents a novel general mathematical static analysis of a fully liquid-filled geosynthetic-tube membrane section anchored on an incline. The membrane problem can be modeled analytically as a set of simultaneous nonlinear ordinary differential equations with some undetermined boundary conditions. A close examination of possible analytical solutions for increasing the cross-sectional area of the membrane identifies that the membrane sections have four similarity (or canonical) shapes. Integration of the curvature expression results in a similarity solution of the canonical shape, expressed in terms of analytical elliptic integrals. Using the analysis method developed, the range...

Geotextile tubes as submerged dykes for shoreline management in Malaysia

The shoreline in Malaysia has experienced severe erosion due to the impact of high energy waves, both on the predominantly mud coasts and the predominantly sandy coasts. This perennial process has resulted in the deterioration of the quality of the beach on the sandy coasts and loss of valuable land. Several measures had, in the past, been implemented to mitigate these adverse effects but these had mostly been hard solutions. The application of geosynthetic tubes for shoreline management was introduced in the State of Terengganu on the east coast of Peninsular Malaysia which experiences severe erosion during the North-East Monsoon period. A pilot project, utilising geotextile tubes installed as submerged dykes, was undertaken in 2006 to address the erosion problems and arrest the further erosion of the shoreline at Teluk Kalong, Kemaman, Terengganu. The geotextile tubes comprise of high strength woven geotextile in-filled with sand slurry. Subsequently in 2008, the state implemented a similar shoreline protection project at Pantai Batu Buruk, protecting a 5 km stretch of beach. These works comprise of the installation of 3.5 m diameter geotextile tubes, as submerged dykes, approximately 150 m offshore. The geotextile fabric allows consolidation of the sand to create a long sausage-like gravity structure. Post-installation surveys carried out indicated that the shoreline has improved with much wider foreshore area. Significant sand deposition was also recorded on the foreshore area, which contributes to the long term shoreline management and promoting sustainable protection of the shoreline. This article discusses the concept of shoreline management using geotextile tubes as submerged dykes. The details of these two projects and the outcome of the projects are presented.

Design parameters for geosynthetic dewatering tubes derived from pressure filtration tests

ABSTRACT: Geosynthetic tubes are increasingly being used for dewatering projects processing many different types of sludge, such as dredged materials, industrial and sewage sludge. Although there is still a lack of reliable design procedures, especially with respect to determination of the time needed for the dewatering of sludge inside a geosynthetic tube, a variety of scientific publications have applied pressure filtration tests to determine the one-dimensional filtration and consolidation characteristics of various combinations of sludge and geotextile filters. A series of pressure filtration tests were conducted on different combinations of dredged materials and geotextile filters to observe the benefits and limitations of the method with respect to geotextile tube dewatering. In this paper the application possibilities and derived values of pressure filtration tests are discussed. The main limitations could be detected for those derived values that are dependent on the test set-up. Each of the research institutes that has published on pressure filtration testing used a different apparatus. Thus the dependence of the derived results on the specific test set-up limits both the analysis itself, and the comparability of results. In particular, the value of filtration efficiency, which has frequently been used by researchers, proved to be of little significance in describing a filtration project.

Effect of subgrade soil stiffness on the design of geosynthetic tube

Water or soil filled geotextile or geosynthetic tubes have been used for coastal or river protection projects in recent years. How to design and analyze geosynthetic tube is still an important research topic. Although a number of solutions for geosynthetic tube have been proposed in the past, most of these solutions assume that the geosynthetic tube is resting on a rigid foundation. In this paper, a two-dimensional analysis of geosynthetic tube resting on deformable foundation soil is presented. The deformable foundation is assumed to be an elastic Winkler type represented by the modulus of subgrade reaction, K f. The study shows that the smaller the modulus, the smaller the height of the geosynthetic tube above the ground surface and the higher the tensile force in the geotextile or geosynthetic given the other conditions the same. When the foundation soil has a modulus higher than 1000 kPa/m which is representative of soft clay, the foundation soil can be assumed to be rigid in the analysis. The results obtained from the method proposed in this paper are compared with those from the solutions of Leshchinsky et al. and Plaut and Suherman for verification. The differences between the solutions are also discussed.

Analysis of geosynthetic tubes filled with several liquids with different densities

A two dimensional model of a geosynthetic tube sitting on a rigid horizontal foundation and filled with several separated liquids with different densities is proposed. The material from which the tube is made is a special synthetic fabric which is inextensible, perfectly flexible, and leakproof. Such a model is useful for modeling a consolidations process in the tube filled with a slurry. The equilibrium equations of the model are formulated. Unknown values like the pressure on the top and bottom of the tube, the tension in the geosynthetic fabric, the length of the contact zone between the tube and the rigid foundation are searched with respect to the given perimeter, the volumes and densities of liquids. Such a problem is solved by the Newton’s method. The initial approximation is obtained by solving a simplified problem with one liquid with the average density. The problem is implemented in a MATLAB code for geosynthetic tubes filled with two, three, and four liquids with different densities. The tubes filled with two different liquids are studied in more detail. The graphs of the relations are compared with the graphs for the tube filled with the single liquid whose density is the average of the densities of the liquids. The comparison enables to discuss the influence of the consolidation process on the height, the contact zone, the pressures and the tension of the tube. The results of the proposed model for a tube filled with a single liquid are compared with another model.