Geotextile Characteristics Research Articles

Permeability test of geotextile-soil system under different sand filling heights

Geotube dams are constructed by stacking geotubes, which are non-homogeneous structures composed of geotextiles and filled sand. Therefore, studying the permeability characteristics of the geotextile-soil system is of great significance for seepage analysis in geotube dams. While the permeability characteristics of geotextiles and filled sand have been extensively studied individually, there has been relatively little research on the permeability characteristics of the geotextile-soil system formed by the combination of geotextiles and soil. In this study, a self-designed permeameter was used to investigate the permeability characteristics of the geotextile-soil system under different sand filling heights. The test results indicate that the permeability coefficient of the geotextile-soil system decreases continuously with the increase in permeation time and eventually stabilizes. The permeability coefficient of the geotextile-soil system increases with the sand-filling height and finally approaches but remains slightly smaller than that of pure sand with the same gradation. The influence of geotextiles on the permeability of the geotextile-soil system is significant within the range of 0 to 5 cm. Additionally, the water permeability of geotextiles affects the permeability performance of the geotextile-soil system. Specifically, a larger porosity corresponds to higher water permeability, and a greater permeability coefficient of the geotextile leads to a higher permeability coefficient of the geotextile-soil system.

Permeability Prediction in Nonwoven Geotextiles Using Mathematical Modeling and Numerical Simulation

The vertical permeability coefficient is a pivotal hydraulic index of needle-punched nonwoven geotextiles. The accurate determination of the permeability coefficient is important for assessing engineering properties. This study employed mathematical modeling, numerical simulations, and physical experimentation to investigate the permeability behavior of nonwoven geotextiles. Mathematical modeling relies on the fiber and pore size characteristics of the geotextiles extracted through two-dimensional image analysis. The numerical simulation method was based on a pore network model acquired through three-dimensional image analysis. The results of the physical experiments served as benchmarks for evaluating the precision of the two methods. These findings underscore the efficacy of mathematical modeling and numerical simulation in predicting the permeability characteristics of nonwoven geotextiles.

Parameters affecting the development of capillary barriers due to conventional geotextiles

The objective of this study is to assess the formation of capillary barriers on unsaturated soils in contact with geotextiles that have been placed with the primary function of acting as a separator between soil or drainage layers, including the geotextile component of a geocomposite. A comprehensive experimental program involving soil column infiltration tests was conducted using a variety of material combinations to assess the hydraulic performance of interfaces between unsaturated clay and geotextiles. Soil moisture was recorded using time domain reflectometers. Custom made acrylic soil columns were comparatively small (20 cm diameter and 33 cm tall) in order to facilitate test setup and reduce total testing time. Multiple column tests were conducted, which included woven and nonwoven geotextiles selected to identify which geotextile characteristics may affect the formation of a capillary barrier. Other tests were conducted to assess the effect of varying relative compaction and inflow rate on the hydraulic performance. Based on data from the moisture sensors, all tests were found to clearly show the formation of a capillary barrier, which resulted in additional moisture storage in the overlying finegrained soil layer. The test results show that currently available conventional geotextiles create a capillary barrier and restrict moisture flow into the underlying soil or drainage layer until the overlying fine-grained soil has become essentially saturated. This includes nonwoven geotextiles that are commonly used as the top layer in geocomposite drainage products or as separators between a soil layer and an underlying gravel drainage layer. The strength of the capillary barrier was found to be similar for the multiple conventional polypropylene geotextiles investigated in this study.

Analisis Penurunan Tanah Timbunan Menggunakan Metode Elemen Hingga pada Ruas Jalan Tolango-Bulontio STA 47+600

Subsidence is a change in the composition of the soil and small spaces in the soil. The method that can be chosen to reduce the rate of decline that occurs on the road is preloading and adding geotextiles. The purpose of this study was to analyze the settlement that occurred in the embankment soil before and after the geotextile was applied. The research location is on Jalan Tolango-Bulontio STA. 47+600 Wubudu Village, East Sumalata District, North Gorontalo Regency. The primary data used is the characteristics of the embankment soil, while the secondary data is in the form of plan drawings, N-SPT values, and geotextile characteristics. Land subsidence analysis was carried out by modeling in two dimensions using the finite element method with the help of the Plaxis 2d v20 application. Structural modeling using plane strain model. The results showed that the settlement of the embankment using geotextiles that the settlement of the embankment soil at point A (shoulder) was 33 mm <65 mm, while the settlement of the embankment without geotextile was greatest at point A (shoulder) of 33 mm. mm < 65 m (allowable descent). The settlement value of the embankment without geotextiles and the use of geotextiles did not have a significant difference because the geotextiles used only functioned as filtration, not as reinforcement

Impact of the constrictions number on filtration characteristics of nonwoven geotextiles

The use of nonwoven geotextile filters is common in geoenvironmental and geotechnical engineering applications. The main requirements for successful performance of drainage and geotextile filters are soil retention, permeability and clogging resistance. In case of anti-clogging capabilities, the most popular method to evaluate the filtration behaviour of nonwoven geotextile in contact with soils is gradient ratio test. Also the number of constrictions of nonwoven geotextile should be determined on the basis of fibre diameter, thickness and porosity. The number of constrictions has been found to explain the different filtration behaviours of nonwoven geotextiles with similar or even the same opening sizes but different structures for various soil conditions. This paper presents the gradient ratio test program for internally unstable soil and nonwoven geotextiles with different structures. Test results show a significant impact of the number of constrictions on the filtration characteristics of geotextile. What is more some modifications to the filter design criteria are proposed based on interpretation of the experimental results.

Influence of polyurethane foam on chemical clogging of nonwoven geotextile and tailings caused by ferrous iron

The chemical clogging of geotextiles filters is a common issue, which threatens the safety of engineering projects. To reduce the chemical clogging of nonwoven geotextiles and enhance their drainage capability, a polyurethane foam was innovatively placed under the nonwoven geotextiles in this paper. A series of column tests were conducted to study the mechanism of the polyurethane foam to reduce the chemical clogging of the nonwoven geotextile filters in tailings caused by ferrous iron. In addition, the influence of the concentration of Fe2+, hydraulic gradient and thickness of the tailings specimen on the chemical clogging of the polyurethane foam and nonwoven geotextiles was examined. Less chemical clogging of geotextiles caused by polyurethane foam was observed and the related mechanism was firstly explained. The polyurethane foam under the geotextile reduced the contact between the geotextile and air. As a result, the chemical clogging of the geotextile was alleviated, which increased the drainage capability of the geotextiles. A high water saturation of the polyurethane foam would help to a reduce the extent of the chemical clogging of the geotextile. The chemical clogging characteristics of geotextiles and polyurethane foam under different concentrations of Fe2+ and hydraulic gradients were observed.

Comparison of bio-clogging characteristics of geotextiles in MSW and bottom ash co-disposal landfills

Comparison of bio-clogging characteristics of geotextiles in MSW and bottom ash co-disposal landfills

Comparisons between Geotextile Pore Sizes Obtained from Capillary Flow And Dry Sieving Tests

Abstract In the United States of America, two standard methods of measuring the largest pore size of a geotextile have been accepted: Dry Sieving Test (ASTM D4751, Standard Test Methods for Determining Apparent Opening Size of a Geotextile) and Capillary Flow Test (ASTM D6767, Standard Test Method for Pore Size Characteristics of Geotextiles by Capillary Flow Test). Despite several drawbacks of Dry Sieving Tests, such as the amount of time required; tendency of glass beads to become trapped, including trapping of glass beads inside the geotextiles; likelihood of imprecise preparation of glass beads; and potential electrostatic effects, the largest pore size (apparent opening size [AOS], O95) results obtained from Dry Sieving Test still determines many filtration criteria. Although the Capillary Flow Test was approved in 2002, it is still not widely adopted, despite the fact that it provides the largest pore size (Bubble Point, O98) and a complete pore size distribution of a geotextile. Decades of analyses searched for a correlation between the Dry Sieving and Capillary Flow Test results; however, none of them have been widely accepted because of the limited number of geotextiles used and a lack of proper calibration. The current study investigates a possible correlation between the Dry Sieving and Capillary Flow Test results with 51 woven, nonwoven, and composite geotextiles. The Capillary Flow Porometer was calibrated using four thin metal plates with known pore openings and two membranes. This study describes the challenges experienced during the Capillary Flow Test and factors affecting the test results. One finding is that the cleaning of calibration materials and equipment with Methanol plays an important role in the Capillary Flow Test results. The use of different shape factors, contact angles, and wetting liquids in the analyses are also considered. The outliers of Capillary Flow Test results were removed from the analysis using a box plot and whisker diagram, and a good correlation between AOS and Bubble Point (R2 = 0.78) was established.

Small Dam Drainage with Nonwoven Geotextile after 40 Years of Exploitation

Synthetic materials such as nonwovens, mats and membranes have been commonly used in civil engineering for many years. The changes of geotextile characteristics in time (permeability, porosity, etc.) are poorly understood. Many authors have presented the changes in the properties of synthetic materials, mainly based on laboratory tests. The studies on geotextile samples taken from working hydraulic structures are not so many. Over 40 years, the reduction in the permeability of nonwoven geotextile was about four-fold. Probably the reason for that reduction is mechanical clogging caused by fine particles which have moved from the earth dam soil to the nonwoven geotextile. Over 40 years of operations, despite the reduction in permeability of the nonwoven geotextile, the drainage worked properly. The experiment was conducted in the field and laboratory and a two-dimensional numerical model built in software package HYDRUS (two-dimensional/three-dimensional (2D/3D)) Standard was proposed. The field measurements allow calibration and validation of the numerical model. The conducted simulations showed that at a maximum water level in the reservoir equal to 3.32 m, the water supply to the drainage is higher from upstream than from downstream. Particularly, water supply from above to the drainage is absent.

A new image-based technique for measuring pore size distribution of nonwoven geotextiles

The use of digital images to evaluate geotextile characteristics has appeared in the scientific literature, particularly for estimating the pore size distribution (PSD) of nonwoven geotextiles used for filtration purposes. While numerous image analysis techniques for PSD curve estimation have been proposed, automation of the analysis methods has received almost no attention. The goal of the present study is to quantify PSD curves from images of representative geotextile specimens using a fully automatic algorithm and considering the concept of largest inscribing opening size. These features are incorporated in a software program (GeotexInspector) developed by the second author. GeotexInspector is based on the concept of classification using the Support Vector Machine technique and digital image processing. These techniques are combined to develop a tool with a robust learning algorithm to identify geotextile fibers and pores. PSD curves from continuous filament and staple fiber nonwoven geotextiles are estimated using GeotexInspector and then compared with theoretical models that have appeared in the literature. The results indicate that the curves obtained from image analysis are in good agreement with model outcomes for models focused on the structure of geotextiles that are similar to the geotextiles used in this study.

Comparison of the behaviour of various geotextiles used in the filtration of clayey sludge: An experimental study

Comparison of the behaviour of various geotextiles used in the filtration of clayey sludge: An experimental study

The influence of uniaxial tensile strain on the pore size and filtration characteristics of geotextiles

The influence of uniaxial tensile strain on the pore size and filtration characteristics of geotextiles

Soil–geotextile filter interaction under high stress levels in the gradient ratio test

This paper presents the results of gradient ratio tests on different soil–geotextile systems under normal stresses up to 2000 kPa. Different types of soil and geotextiles were tested, and the soil particles that passed through the geotextile and those retained in it were collected for particle size analyses. The results obtained show that the use of definitions of gradient ratio based on the measurement of water heads close to the geotextile layer can be useful for a better identification of geotextile-clogging mechanisms. The entrapment of soil particles in the geotextile increases its retaining capacity and alters the conditions for further clogging. The dimensions of the entrapped soil particles can be greater than the geotextile pore dimensions under unconfined conditions and are controlled by soil and geotextile characteristics and by the soil sample preparation technique employed. The results suggest that current retention and permeability criteria for geotextile filters can be excessively conservative. Discussions on geotextile performance in the test and under field conditions are also presented as well as limitations and new proposals for the interpretation of the gradient ratio test.

Pull-out resistance of geogrid reinforcements

Pull-out resistance of geogrid reinforcements

Short-term strength and deformation characteristics of geotextiles under typical operational conditions : Ling, H I; Wu, J T H; Tasuoka, F Geotext GeomemV11, N2, 1992, P185–219

Short-term strength and deformation characteristics of geotextiles under typical operational conditions : Ling, H I; Wu, J T H; Tasuoka, F Geotext GeomemV11, N2, 1992, P185–219

Short-term strength and deformation characteristics of geotextiles under typical operational conditions

Short-term strength and deformation characteristics of geotextiles under typical operational conditions

Evaluation of geotextile/soil filtration characteristics using the hydraulic conductivity ratio analysis

Evaluation of geotextile/soil filtration characteristics using the hydraulic conductivity ratio analysis

Characteristics of geotextiles: measurements, specifications and control (in French) : Blivet, J C; Delmas, P; Puig, J; Schaeffner, M Bull Liaison Lab Ponts ChausseesN142, March–April 1986, P45–57

Characteristics of geotextiles: measurements, specifications and control (in French) : Blivet, J C; Delmas, P; Puig, J; Schaeffner, M Bull Liaison Lab Ponts ChausseesN142, March–April 1986, P45–57

The applicability of Darcy's law in determining the water permeability of geotextiles

The applicability of Darcy's law in determining the water permeability of geotextiles

Permeability Testing for Geotextile and Geotextile/Soil Systems

The permeability properties of geotextiles and geotextile/soil systems were studied using gradient ratio testing apparatus improving on the type of U. S. Army Engineer Waterways Experiment Station.It is suggested that the permittivity is better than permeability to evaluate the characteristics of geotextiles as filter materials. From the results on six geotextiles, it is confirmed that the decrease of permittivity according to the surcharge load is very slight, although the thickness decreases greatly.It is also obtained from the results of long term permeability tests for the geotextile/soil systems, that the permeability decrease with time by clogging of geotextiles. Further, the trend is approximately straight on the log-log diagram.