Woven Geotextile Research Articles

Influence of Strain Rate on Tensile Strength of Woven Geotextile in the Selected Range of Temperature

Abstract Investigation of geosynthetics behaviour has been carried out for many years. Before using geosynthetics in practice, the standard laboratory tests had been carried out to determine basic mechanical parameters. In order to examine the tensile strength of the sample which extends at a constant strain rate, one should measure the value of the tensile force and strain. Note that geosynthetics work under different conditions of stretching and temperatures, which significantly reduce the strength of these materials. The paper presents results of the tensile test of geotextile at different strain rates and temperatures from 20 °C to 100 °C. The aim of this study was to determine the effect of temperature and strain rate on tensile strength and strain of the woven geotextile. The article presents the method of investigation and the results. The data obtained allowed us to assess the parameters of material which should be considered in the design of the load-bearing structures that work at temperatures up to 100 °C.

Geosynthetic applications in high-speed railways: a case study

A high-speed railway project for trains with speeds of 160–180 km/h was recently completed in Malaysia. An array of geosynthetics such as biaxial geogrids, non-woven geotextiles and woven geotextiles were extensively used in the project primarily for separation, filtration and reinforcement purposes. The geosynthetics were particularly used at locations of high embankments underlain by soft clays and loose sands. Ground improvement using geosynthetics in the project primarily included geogrid-reinforced piled embankments with individual pile caps, geogrids at bridge approach transitions, geogrids for ground treatment beneath culverts, geogrids for culverts supported by stone columns, woven geotextiles for cement column works, non-woven geotextiles for excavation works, non-woven geotextiles at the top of the railway subgrade layer, non-woven geotextiles for temporary retaining walls and non-woven geotextiles for slope protection works. This paper provides a detailed insight into the design and implementation of ground improvement using geogrids and geotextiles in this case study project, with a focus on the geogrid reinforcement design of piled embankments with individual pile caps. The use of geosynthetics in the various railway applications in the project was found to provide safe and cost-effective solutions to the various geotechnical engineering challenges encountered.

Performance of Reinforced–Stabilized Unpaved Test Sections Built over Native Soft Soil under Full-Scale Moving Wheel Loads

This paper presents the findings from an ongoing research study that evaluated two recently developed geosynthetic products: a triaxial geogrid and a high-strength woven geotextile for reinforcing or stabilizing roads constructed over native soft soil in the state of Louisiana. Six full-scale test lane sections were constructed: two were reinforced by one and two layers of triaxial geogrids, respectively, while high-strength geotextile was used to reinforce two of the other sections with aggregate layers of different thicknesses. The remaining two sections were left as controls: one was constructed over a sand embankment 30 cm thick representing the common practice in southern Louisiana. The unpaved test sections were subjected to a full-scale moving wheel load applied by the accelerated loading facility. A variety of instrumentation was used to measure the load-associated and the environment-associated pavement responses and performance. Results of the full-scale testing on the unpaved test sections demonstrated the benefits of geosynthetic reinforcement–stabilization in reducing the permanent deformation in the pavement structure. The test sections’ resilient behavior did not seem to be influenced by the presence of geosynthetics. In addition, instead of the soft soil subgrade, the aggregate layer was the primary contributor to the total permanent deformation–surface rutting of the unpaved sections under the testing conditions in this study. Geosynthetics were mobilized and generally exhibited a strain around 0.2%.

Laboratory Study of Downslope Erosion for 10 Different GCLs

The potential for downslope bentonite erosion from a geosynthetic clay liner (GCL) subjected to an imposed daily surface flow of deionized water is examined for 10 GCLs with different carrier and cover geotextiles, bentonite (powdered and fine and coarse grained and some with a polymer-enhancement additive), and a polypropylene coating on the carrier geotextile. The erosion was similar but more visible in products with a white geotextile than in those with a black geotextile. Also, the erosion features were similar but more visible with nonwoven geotextiles than with woven geotextiles. Polymer-enhanced sodium bentonite substantially slowed the formation of erosion features. A polypropylene coating over the upper geotextile prevented erosion features from developing by keeping water from penetrating into the bentonite layer when subjected to 60 daily imposed-flow/air-drying cycles.

Image-Segmentation Technique to Analyze Deformation Profiles in Different Direct Shear Tests

Abstract Results from interface shear tests on sand–geosynthetic interfaces are examined in light of surface roughness of the interacting geosynthetic material. Three different types of interface shear tests carried out in the frame of direct shear-test setup are compared to understand the effect of parameters like box fixity and symmetry on the interface shear characteristics. Formation of shear bands close to the interface is visualized in the tests and the bands are analyzed using image-segmentation techniques in MATLAB. A woven geotextile with moderate roughness and a geomembrane with minimal roughness are used in the tests. The effect of surface roughness of the geosynthetic material on the formation of shear bands, movement of sand particles, and interface shear parameters are studied and compared through visual observations, image analyses, and image-segmentation techniques.

Field performance of retaining walls reinforced with woven and nonwoven geotextiles

ABSTRACT: This paper presents an evaluation of the performance of two instrumented sections of a geosynthetic-reinforced soil wall, 5.6 m high, constructed using a lateritic fine-grained soil. Two sections with identical layout of a nonwoven and a woven geotextile were monitored for comparison purposes. The unconfined tensile stiffness of the nonwoven geotextile was three times smaller than that of the woven geotextile. This allowed direct evaluation of the effect of soil confinement on geotextile stiffness. Instrumentation was used to measure face displacements, reinforcement displacement and strains, and soil matric suction. Rainfall occurred both during and after construction, which facilitated evaluation of the effect of soil wetting on the walls performance. Ultimate and serviceability limit state analyses were conducted to gain further insight into the performance of the two walls. The results show that the performance of the section reinforced with nonwoven geotextile was equivalent to the one reinforced with woven geotextile, even after the observed reduction in matric suction after rainfall. For both sections, the overall deformations occurred during construction. Negligible deformations were observed during service. Maximum face displacements were measured in the lowest instrumented layer for the nonwoven geotextile section whereas it was in the highest layer for the woven geotextile section. These behaviours of face displacement distributions can be the result of the significant differences in global stiffness of the sections. Design analyses and field performance show that soil confinement has a beneficial effect on the nonwoven geotextile stiffness. The significant contribution of the soil cohesion of the lateritic soil played an important role in the behaviour of the nonwoven geotextile-reinforced wall.

Assessment of Engineering Properties of Geosynthetics with Seaming Methods

8 Geotextiles (; 4 woven and 4 nonwoven types), 4 geogrids and 2 geocomposites of [nonwoven/fibers/nonwoven] structure were used as raw materials and the different seaming methods were applied to compare the seam properties of 3 geosynthetics and transmissivity of geocomposites. Tensile strength retentions of these geosynthetics were evaluated as the degree of damage by chemical degradation. Woven geotextiles showed the higher seam strength in the order (SSd-1 < SSd-2) > (SSa-1 < SSa-2) > geospacer without regard to the design strength. For nonwoven geotextiles, the order of seam strength is geospacer > (SSa-1 < SSa-2). Geogrids showed the higher seam strength in the order of band > geospacers but reduction factors were increased in the order of band > geospacer without regard to the geogrid’s compositions. Finally, geocomposites showed the higher seam strength in the order of geospacer > (SSa-1 < SSa-2) but showed the transmissivity in the order of geospacer > (SSa-1 > SSa-2) without regard to the kinds of filled fibers and weight of geocomposite.

Shaking table studies on geosynthetic reinforced soil slopes

This paper describes shaking table model studies conducted on unreinforced and reinforced soil slopes. A computer controlled hydraulically driven single degree of freedom shake table was used in these tests. Model soil slopes were constructed using clayey sand (SC) in a laminar box. Two different slope angles were used in tests. Two different types of reinforcement, namely, a woven geotextile and a biaxial geogrid were used in the tests. The models were instrumented with ultrasonic displacement transducers and accelerometers at different locations. The slopes were subjected to horizontal base shaking of known acceleration and frequency and the displacement and acceleration were monitored for time increments. Comparison of displacement and acceleration of tests with different slope angles and with reinforcing layers of different stiffness values resulted in some important observations regarding the response of these soil slopes under seismic shaking conditions. Tensile stiffness of the reinforcement plays an important role in controlling the seismic deformations and the beneficial effects of reinforcement are more pronounced in flatter slopes. Acceleration amplifications did not alter with the inclusion of reinforcing layers in the model studies reported in this paper because of the dimensional limitations. Numerical modeling of the geosynthetic reinforced soil slopes subjected to base shaking is also presented and the models are verified with the experimental results.

Behavior of geotextile reinforced flyash + clay-mix by laboratory evaluation

The major factors that control the performance of reinforced soil structures is the interaction between the soil and the reinforcement. Thus it is necessary to obtain the accurate bond parameters to be used in the design of these structures. To evaluate the behavior of flyash + clay soil reinforced with a woven geotextile, 36 Unconsolidated-Undrained (UU) and 12 reinforced Consolidated.Undrainrained (CU) triaxial compression tests were conducted. The moisture content of soil during remolding, confining pressures and arrangement of geotextile layers were all varied so that the behavior of the sample could be examined. The stress strain patterns, drainage, modulus of deformation, effect of confinement pressures, effects of moisture content have been evaluated. The impact of moisture content in flyash + clay backfills on critical shear parameters was also studied to recommend placement moisture for compaction to MDDM. The results indicate that geotextile reinforced flyash + clay backfill might be a viable alternative in reinforced soil structures if good-quality granular backfill material is not readily available.

Laboratory investigation of GCL performance for covering arsenic contaminated mine wastes

The performance of three geosynthetic clay liners (GCLs) above arsenic-bearing gold mine tailings is examined based on a series of laboratory column experiments conducted over a two year period. The GCLs examined had either untreated or polymer-enhanced sodium bentonite and had different carrier geotextiles (a woven geotextile, a scrim-reinforced nonwoven geotextile, and a woven geotextile laminated with a polypropylene film). After 24 months, the hydraulic conductivity (k) of GCL with untreated sodium bentonite increased by almost an order of magnitude from 3×10−11m/s to 2×10−10m/s with the swell index decreasing from 26mL/2g to 7–11mL/2g and the exchangeable sodium percentage (ESP) decreasing from 65% to 12–21%. Samples of this GCL exhumed after 9 months of moisture uptake and cation exchange and then subjected to 15 extreme wet–dry cycles experienced an increase in k up to 6×10−10m/s. The GCL with polymer-enhanced bentonite maintained k less than 5×10−11m/s after 24 months (virgin k=1×10−11m/s) and experienced less cation exchange (ESP decreased from 78% to 39–42%) than the GCL with untreated bentonite. For this GCL, 15 extreme wet–dry cycles gave k<9×10−11m/s provided that the soil stress was 15kPa or higher (≥1.0m of cover soil above the GCL). The GCL with polymer-enhanced bentonite and carrier geotextile laminated with a polypropylene geofilm demonstrated the best performance with k<7×10−12m/s even with exposure to the extreme wet–dry cycling. In all cases, the GCL prevented arsenic migration into the overlying cover soil over the two year period examined.

Prediction of pore size characteristics of woven slit-film geotextiles subjected to tensile strains

Depending on the two-dimensional structure of woven geotextiles, analytical solutions have been proposed to predict the pore size characteristics of woven slit-film geotextiles under certain uniaxial tensile strains. The strained per cent open area (POA) and equivalent pore size have been expressed as functions of tensile strain. The physical properties of woven geotextiles, such as the mass per unit area of a geotextile and the density and size of slit films, have been used in predicting the strained pore size characteristics of woven slit-film geotextiles. The influence of uniaxial tensile strain on pore size characteristics of two woven slit-film polypropylene geotextiles was evaluated by image analysis. Several pore size parameters corresponding to different strains were measured, including POA, pore size distribution (PSD), and O95. A comparison has been made between the analytical and experimental results, and the experimental data of previous studies have been used to confirm the validity of the analytical solution. In addition, the image analysis results show that the POA and O95 increase with the uniaxial tensile strain. The PSDs move towards the direction of the large open sizes with increasing levels of stain.

Friction at Geosynthetic Interfaces on Inclined Plane Shear

This paper deals with inclined plane shear on geosynthetic–geosynthetic interfaces. Soils and geosynthetics properties are referred and test equipment and procedures are briefly described. The geosynthetic–geosynthetic interaction behaviour is studied. The influence of geosynthetic structure, material filling the upper box of the apparatus and soil particle size on geosynthetic–geosynthetic interaction behaviour are discussed by analysing the results of the inclined plane shear tests. The main conclusions that can be outlined from the present study are the following: There is a significant influence of the roughness of the geomembrane on geomembrane–geotextile interfaces resistance. In general, geosynthetic–geosynthetic interfaces resistance are lower when one of these materials is a non woven thermal bonded geotextile. For the woven geotextile, the higher interface resistance was achieved on geotextile–geomattress interface. For continuous lateral surfaces geosynthetic–geosynthetic interfaces a woodblock filling the upper box of the apparatus can be used, as test results are similar to those performed with soil filling that upper box. Soil filling the upper box of the apparatus has great influence on geotextile–geomattress interfaces resistance. This way, for non continuous lateral surfaces geosynthetic (ex: geogrids, geomattress)–geosynthetic interfaces the inclined plane shear test must be carried out with soil filling the upper box of the apparatus. Soil particle size has an important influence on the friction angle of geosynthetic–geosynthetic interfaces.

Changes in geosynthetic clay liner (GCL) properties after 2 years in a cover over arsenic-rich tailings

A test cover comprised of three different needle-punched geosynthetic clay liner (GCL) products and covered with up to 1 m of cover soil (gravelly sand) was built over arsenic-rich tailings at a former gold mine in Nova Scotia, Canada, to evaluate the performance of the GCLs under local climatic conditions. Of the GCLs examined, one had untreated and two had polymer-enhanced natural sodium bentonite. The three GCLs each had different carriers: one with a woven geotextile, one with a scrim-reinforced nonwoven geotextile, and one with a woven geotextile laminated with a polypropylene film. At some locations, each type of GCL was placed in direct contact with the tailings. At other locations, each GCL was separated from the tailings by 0.15 m of cover soil. Samples of each GCL, tailings, and cover soil were recovered 1 and 2 years after construction. Tests show that the GCL with untreated bentonite maintained a low hydraulic conductivity (≤5 × 10−11 m/s) at locations where there was ≥0.7 m of cover soil above the GCL even though there was significant cation exchange of the sodium in the GCL with divalent cations in the tailings-soil porewater (the mole fraction of sodium (exchangeable sodium percentage (ESP)) decreased from 65% to 10%–17%). The GCL with polymer-enhanced bentonite had a lower hydraulic conductivity (≤3 × 10−11 m/s under ≥0.7 m of cover soil above the GCL) and experienced less cation exchange (ESP decreased to 19%–28%) than the standard GCL. The other GCL with polymer-enhanced bentonite and a carrier geotextile coated with a geofilm demonstrated the best hydraulic performance regardless of the thickness of cover soil or presence of an initially uncontaminated foundation layer. The presence of a foundation layer between the GCL and tailings impeded the migration of arsenic from the tailings into the GCLs. All GCLs were serving as an effective barrier to arsenic migration.

A monolithic layered nonwoven–woven geotextile for use with drainage geocomposites in coal combustion residual projects

A layered monolithic filter consisting of a nonwoven needlepunched and a woven monofilament geotextile is presented in this paper. The two geotextiles are mechanically bonded in a needlepunching process to produce a hybrid geotextile on a commercial scale. The fuzzy woven side of the geotextile, resulting from the needlepunching process, is ideally suited for lamination to a geonet, although a standalone filter application is also possible. Filter press tests on the geotextile against a fly ash slurry of 500% yielded a retention efficiency of 99.6%. Gradient ratio values of 1.0–1.5 and hydraulic conductivity ratio values of 0.5–1.0 were obtained against fly ash and FGD gypsum from four power plants. Four field basin tests were performed under the CCRs wherein effluent parameters of total suspended solids, total dissolved solids, turbidity, conductivity and pH were monitored with time. The field tests showed that the fly ash and FGD gypsum contained in the test basins were not migrating with time.

Experimental study on water permittivity of woven polypropylene geotextile under tension

Water permeability of woven geotextile, usually measured in uncompressed state or under compressive stresses, varies significantly under tensile loads. To study the permeability behaviours of woven geotextile in the tensioned state, a series of laboratory experiments were carried out on one type of woven polypropylene geotextile with tensile strength of 20–30 kN/m. The experimental results show that the permittivity of geotextile under tension load in the warp direction first decreases rapidly, then approaches to a value that is 10–25% of the one in the absence of the load. On the contrary, the permittivity increases with the increase of the tension force in the weft direction and no steady value is observed. Since the tension load in the warp direction has obviously influence on the water permeability of geotextile, about 2–3% tensile strain is recommended to be applied on the warp fibres initially for determining a reasonable permittivity in laboratory test.

Interface Behavior of Woven Geotextile with Rounded and Angular Particle Sand

AbstractThe behavior of soil-geosynthetics interfaces depends on the different properties of soil, including particle size, particle shape, density, gravimetric water content, degree of saturation, and properties of geosynthetics that include structure, texture, and other elements. This paper pertains to the study of the influence of the particle shape of sand on the behavior of the sand-geotextile interface. Experiments were conducted using a conventional-sized direct shear box modified for interface testing. In the present study, two different natural sands (one with angular particles and the other with rounded particles) and two different geotextiles were used. The results showed that particle shape significantly influences the interface behavior, especially the postpeak behavior.

플라즈마 표면처리 지오텍스타일의 공학적 성능 평가 및 장기성능 고찰

Woven and nonwoven geotextiles and geotextile composites were used to examine engineering property improvement by plasma surface treatment. Hydrophobic and hydrophilic plasma treatment were applied to these geotextile samples with plasma gas, electric power, plasma treatment time and gas flow rate. It is seen that tensile strength of geotextile samples increased after plasma treatment, but chemical resistance had not significantly changed. Finally, long-term performance of plasma treated geotextiles was reviewed through application of Arrehenius equation as an accelerated analysis.

Dewatering and Utilization of Fly Ash Slurries Using Geotextile Tubes

About one billion metric tons of coal ashes are produced annually around the world, among which 700 million tons are fly ash wastes that must be disposed of. The practice of wet fly ash disposal has increased environmental concerns due to fly ash leachate, ground water contamination, and the limitation of pond capacity. Therefore, alternatives to the current disposal methods should be addressed. Geotextile tube dewatering is an efficient dewatering method that can decrease the volume of fly ash slurry and at the same time provides containment of dry fly ash. In this study, pressure filtration tests were conducted to evaluate the dewatering performance of Class C fly ash with seven woven geotextiles having a wide range of hydraulic properties. Anionic polymer flocculant was used to evaluate the effect of polymer conditioning on dewatering performance. In addition, the increase in filter cake strength due to flocculants was evaluated. Lastly, chemical analysis of the effluent was performed to quantify the concentration of contaminants present in the geotextile tube effluent. The results of this study indicate that hydraulic properties of the geotextile do not have a significant effect on the dewatering performance of fly ash. It was found that polymer conditioning significantly increased the strength of the filter cake, making fly ash filled geotextile tubes suitable for use in geotechnical engineering applications. It was also found that geotextile tube dewatering does not retain fly ash trace elements that can leach out with effluent, meaning that proper safety measures must be taken in fly ash reutilization projects.

Retention performance of woven geotextiles subjected to cyclic-flow conditions

ABSTRACT: Woven geotextiles are widely used as filters in geotechnical, hydraulic, and environmental applications. Depending on the application, geotextile filters can be subjected to uni-directional, bi-directional, or cyclic-flow conditions, with cyclic flow occurring in two directions repeatedly over time. The selection of a suitable geotextile filter is of critical importance, particularly for cyclic-flow conditions. Cyclic-flow conditions can rapidly lead to an excessive loss of fine soil particles and failure of a soil–geotextile system. Although these conditions are frequently encountered, limited work has been done to evaluate the retention behavior of geotextiles under cyclic-flow conditions. In this study, the retention performance of nine different woven geotextiles with five different soils under cyclic-flow conditions was modeled using a bi-directional hydrodynamic filtration test (BHFT). Based on the results of this research, a retention criterion of AOS/d85 of 1.62 is proposed for woven geotextiles subjected to cyclic-flow conditions, where AOS is the apparent opening size of the geotextile or O95 as determined by dry sieving ( ASTM D4751 ) and d85 is the soil particle diameter corresponding to 85% by weight of finer soil particles. Additionally, an allowable soil-loss limit less than 5000 g/m2 is proposed.

Creep behavior of geosynthetics using confined-accelerated tests

ABSTRACT: The creep behavior of geosynthetics has commonly been determined using standardized creep tests, which are time consuming and very expensive. In addition, these tests involve the use of in-isolation specimens. Thus they are not likely to consider the overall effect of soil confinement. Confined creep tests conducted at elevated temperature can be used to address these negative aspects of standardized creep tests. This paper presents a pioneering laboratory apparatus developed in order to conduct confined, accelerated and confined-accelerated creep tests. In addition, preliminary tests were performed to assess the new equipment's capability of conducting confined and accelerated creep tests. These tests were performed using a biaxial geogrid, a woven geotextile, and a nonwoven geotextile. The new equipment allowed different conditions to be reproduced. The creep behavior of the nonwoven geotextile and the geogrid was found to be very sensitive to soil confinement. On the other hand, the woven geotextile presented a creep behavior independent of soil confinement. The geogrid results did not agree with reports in the technical literature. Accordingly, these results showed the importance of characterizing the effect of soil confinement in geosynthetics creep behavior. Additionally, these preliminary results showed the potential of the new device to overcome the main negative aspects of standardized creep tests on geosynthetics.