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The research is an investigation of soil filtration by geotextile fabrics, with the ultimate objective of improving design and long-term performance of underdrain systems in Indiana highways. Experiments were conducted in the laboratory using the best available techniques, Flexible Wall Gradient Ratio Test and Rapid Retention Test, in order to asse...
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Geotextile tubes have successfully been used to dewater a wide variety of low percent-solids sediments, slurries, by-products, and wastes. Because existing geotextile filter criteria have limited applicability in the geotextile tube environment, researchers and industry practitioners have adopted numerous indices to measure the retention and dewate...
Ecofriendly woven jute geotextile can be used as filter sheath in prefabricated vertical drains (PVDs) which are installed in saturated clayey soils such as marine clay to accelerate consolidation. The PVDs made from natural materials can be used as an alternate system to polymer based PVDs. One of the main concerns in using woven jute geotextile a...
Citations
... This value is slightly higher than the confining pressure at typical edge drains to hold the specimen in place, without significantly affecting the pore pressure readings. A unidirectional flow condition through the soil and geotextile was controlled throughout testing by applying a constant differential head H (see Fig. 4) with a hydraulic gradient of 5, which is typical of field conditions if partial leakage is allowed through the pavement boundary (Lee and Bourdeau, 2006). The internally imposed hydraulic gradient across the samples was measured to be approximately 3.33-5.33, ...
... Geotextile sample C is a needle-punched geotextile which is obtained by mechanically interweaving their fibers using high frequency alternate needle movement normal to the fabric plane. This results in a geotextile surface which can be deformed easily, therefore, resulting in a reduction of pore sizes (Lee and Bourdeau, 2006). Geotextile sample B has attributes of both heat bonded and needle-punched i.e. the geotextile is initially needle-punched and then thermal treatment is applied to one side of the geotextiles sample. ...
In many applications, geotextiles are subjected to dynamic loading conditions, for example, below roads and railways, for which a Gradient Ratio (GR) test is often used to assess filtration compatibility of soil-geotextile systems. This paper presents results from GR filtration tests with internally-stable and -unstable soils under dynamic loading conditions. In the tests, four non-woven geotextiles were used with varying types of soils under a hydraulic gradient of 5. Test results were interpreted in terms of GR values, permeability values, and mass and gradation characteristics of the soil before/after testing as well as the particles passing through the geotextiles. The test results show that the dynamic loading resulted in an increase of soil migration within the soil as well as an increase in the quantity of soil passing through the geotextiles. The available criteria for evaluating the internal stability of soils are evaluated based on the experimental data. Based on the test results, improvements to filter retention design criteria are suggested which take into account the internal stability of soils under dynamic loading.
... This subsequently reduces the quantities of materials required for construction (17). Furthermore, geotextiles are also extensively used for roadway drainage applications to reduce the detrimental impact of moisture on pavement layers (24)(25)(26)(27)(28)(29). ...
... Several studies have been done in the past to understand the hydraulic behavior of both woven and non-woven geotextiles for different soil classes (26)(27)(28). Conventional geotextiles are predominantly effective in draining the subsurface water, under the influence of gravity, through saturated soil; however, past studies have indicated that their efficacy decreases in an unsaturated environment (24,29). The ability of conventional geotextiles to drain out the water depends on the ratio between the coefficient of permeability of the saturated soil and the geotextile (29). ...
The longevity and performance of a pavement section depend on the characteristics of the subgrade soil. A majority of the pavements in North Texas, U.S., are constructed on expansive soils. The deterioration of the pavement performance because of rutting, cracking, and differential heaving is a regular phenomenon in the regions predominantly distributed with expansive soils. The pavements, particularly those built for low-volume traffic conditions, experience distress because of the high swelling and shrinkage characteristics of the underlying problematic soils. Geosynthetics have been traditionally used to improve such poor subgrades because of their many benefits, such as ease of installation, and ample mechanical and hydraulic properties. In the last decade, a newly available wicking geotextile, with a moisture redistribution capacity, has been developed to improve the performance of pavements constructed over expansive and frozen soils. In this study, small-scale laboratory and full-scale field studies were conducted to comprehend the wicking ability of this innovative geotextile in an expansive soil environment. Full-scale test sections were constructed with reclaimed asphalt pavement aggregate and traditional crushed stone aggregates in the base layer near North Texas. Details of the construction and instrumentation procedure are discussed in this paper. A comparative study between the performance of the pavement sections subjected to traffic loads and moisture intrusion was also performed. Furthermore, the rutting life of the sections, estimated using a linear elastic model, was compared and validated using the in situ data. The observations during the initial phase indicated that the wicking geotextile has the potential to improve the long-term pavement performance.
... The stiffer layer of geotextile is also capable of increasing the overall stiffness of the pavement subgrade and consequently reduce the deformation of the pavement layers (Pilarczyk 2000). In addition to the mechanical functions, geotextiles have been extensively used to carry out various other functions, such as improving the hydraulic performance of a pavement system and subsurface drainage (Stormont and Morris 2000, Iryo and Rowe 2005, Lee and Bourdeau 2006, Bhattacherjee and Viswanadham 2015. ...
The pavements constructed on problematic subgrades suffer from longevity and serviceability issues due to surface cracking, rutting, and differential heaving. The common contributing factors include moisture intrusion from cracks, utility trenches, or subsoil capillary rise, which results in swelling and associated strains in the expansive subgrade. Maintenance and rehabilitation of such distressed pavements result in the delay of traffic operations and account for millions of dollars of annual expenditure. Application of an innovative wicking geotextile in a farm to market road in North Texas was found to improve the lateral moisture drainage capacity of the soil subgrade, creating a suction gradient between the saturated subgrade and the surrounding environment. The moisture draining efficacy was observed to extend to more than 12 in., below the geotextile, into the subgrade layer. Apart from wicking action, this innovative geotextile reduced the normal stresses on the subgrade through reinforcement action, which helped in reducing the permanent deformation on top of the subgrade. Overall, the performance of the reinforced section has shown a remarkable improvement over the traditional unreinforced section.
... Hameiri (2000) and Fannin and Pishe (2001) modified traditional GR test equipment (see Fig. 2) to perform cyclic tests. The traditional GR test equipment uses a rigid wall permeameter, which has limitations related to side wall leakage and limited control over stresses (Harney and Holtz, 2001;Lee and Bourdeau, 2006). Kermani et al. (2018) studied pumping of subgrade fines into the subbase of a flexible pavement using a rigid steel container. ...
... Several methods have been proposed for assessing the filtration behaviour of soil-geotextile composite systems under steady state conditions. These include the long-term flow test (Rollin and Lombard, 1988;Aydilek and Edil, 2003;Kutay and Aydilek, 2005;Veylon et al., 2016), hydraulic conductivity ratio test (Williams and Abouzakhm, 1989;Shan et al., 2001;ASTM D5567-94, 2018), and the Gradient Ratio (GR) test (Haliburton and Wood, 1982;Fannin et al., 1994;Fischer et al., 1999;Palmeira et al., 2005;Lee and Bourdeau, 2006;Hong and Wu, 2011). Among these test methods, the GR test is the most commonly used filtration test and is also the standard test method for measuring filtration compatibility of soil-geotextile systems (ASTM D5101-12, 2017). ...
... A hydraulic gradient of ≤1 is expected in pavement edge drains (Giroud, 2010). However, a hydraulic gradient as high as 5 is possible in realistic field conditions, for example, if partial leakage is allowed through a pavement boundary (Lee and Bourdeau, 2006). ...
The soil-geotextile filtration mechanism is a complex process which depends on physical compatibility between the geotextile and the soil to be retained. Several methods have been proposed by researchers for assessing the filtration behaviour of soil-geotextile composite systems under steady state conditions. The Gradient Ratio (GR) test is the most commonly used method for measuring filtration compatibility of soil-geotextile systems. This paper describes the design of a modified GR permeability test apparatus to overcome disadvantages associated with traditional GR test devices. The apparatus can perform filtration tests under static and dynamic conditions and can be used to evaluate the filtration compatibility of fine-grained soils with geotextiles. The apparatus is incorporated within a triaxial testing system, hence representative field stress conditions can be applied to test specimens. Some exemplar GR tests performed on coarse and fine-grained soils with a non-woven geotextile are presented in this paper. Unidirectional dynamic loads are applied within the filtration tests to replicate highway traffic loading. Test results show that dynamic loading affects the filtration behaviour at the soil-geotextile interface by increasing the fine particles migration towards the geotextile, but that, for the soil evaluated here, this effect was small.
... The traditional GR test equipment use a rigid wall permeameter. There are issues associated with the rigid 4 wall permeameter to carry out filtration tests such as side wall leakage as well as incomplete control over stresses (Acar et al., 1985;Harney & Holtz, 2001;Lee & Bourdeau, 2006;Madsen & Mitchell, 1989). ...
... Sufficient number of openings also ensures that the flow will be less disturbed if clogging of some of the filtration paths of geotextile occur. Porosity is closely related to geotextile density (mass per total volume) (Lee & Bourdeau, 2006). A geotextile may meet the permeability criterion even if the filter has small number of openings per unit area. ...
... However, a higher hydraulic gradient is possible in realistic field conditions, for example, if partial leakage is allowed through pavement boundary. Lee and Bourdeau (2006) The filtration behaviour of soil-geotextile specimens was observed under unidirectional flow during the static stage. The test was run for one to two hours until constant readings of pore pressure and permeability were observed. ...
The soil-geotextile filtration mechanism is a complex process which depends on physical compatibility between the geotextile and the soil to be retained. Geotextiles often perform well under steady state conditions like those found in dams. However, when the soil-geotextile interface is subjected to dynamic loading, the requirements for successful filtering are uncertain and/ or conservative as the controlling factors are not well understood in these circumstances. There are few filter design criteria available for dynamic flow conditions. These criteria do not properly address the internal instability of soils for which the rearrangement of particles adjacent to the filter interface is complex. Unstable soils may exist in roadway bases adjacent to pavement edge drain. Therefore, this research work was carried out to better understand the filtration behaviour of non-woven geotextiles with internally stable and unstable soils beneath roads. To carry out the filtration tests, a flexible wall gradient ratio (GR) apparatus was developed. The GR tests were performed to investigate the effect of different factors on the filtration performance of the soil-geotextile interface under dynamic conditions. The factors included hydraulic gradient, vertical stress and frequency of loading, soil gradation and geotextile properties. Test results were interpreted in terms of head loss within the soil and across the geotextile, GR values, permeability ratio, mass and gradation of particles passed through geotextiles, microscopic images of geotextiles after test, partial geotextile clogging levels and hydrometer sieve analyses of soil samples to compare the gradation of samples after test with the original gradation. All the tests were performed under a hydraulic gradient of five. The internal stability of soil samples were evaluated by three geometric criteria. The test results showed that a high hydraulic gradient has the ability to lead to the internal instability of soils which resulted in migration of fines towards the geotextiles. The dynamic loading resulted in increase of soil migration within the base soil as well as washing out of soil particles through geotextiles. No significant effect of increase in frequency and vertical stress was observed on filtration behaviour of soil-geotextile combinations. The geotextile pore size was found to be the main factor controlling the filtration behaviour as compared to other geotextile properties. The Kenney and Lau (1985) and the Kezdi (1979) criteria predicted well the internal instability of soils under dynamic conditions. In this research study, a new method was suggested which is able to measure the pore sizes along the entire thickness of geotextiles. The filtration tests showed that geotextiles having the same large openings but different pore size distributions may result in different filtration performances. Based on the test results, filter design criteria were suggested for piping and blinding limits which were compared with the existing design criteria. These new filter criteria were found to be more appropriate in terms of piping and blinding limit states.
... Both woven and nonwoven geotextiles, are commonly used for reinforcement and/or drainage purposes in civil engineering practice. Researchers have investigated the behavior of geotextiles for hydraulically-related applications including (1) hydraulic properties and behavior of geotextiles included in different types of soils (Stormont et al., 1997(Stormont et al., , 2010Ho, 2000;Iryo and Rowe, 2005;Bhattacherjee and Viswanadham, 2015); (2) design methods and criteria for geotextiles to meet drainage requirements (Holtz et al., 1997;Lee and Bourdeau, 2006); and (3) used as capillary barriers Zornberg et al., 2010). Most of the studies have been focused on the drainage of water through geotextiles under the influence of gravity. ...
A new type of woven geotextile, referred to as wicking geotextile, was developed and introduced to the market. Since this wicking geotextile consists of wicking fibers, they can wick water out from unsaturated soils in a pavement structure thus resulting in an increase of soil resilient modulus and enhance performance of roadways. In this study, a physical model test was developed to evaluate the effectiveness of the wicking geotextile in soil moisture reduction for roadway applications. A test box with a dimension of 1041 mm in length, 686 mm in width, and 584 mm in height was used in this study. Two HDPE plastic panels were used to separate the box into two sections, one containing a dehumidifier and the other backfilled with soil. The dehumidifier was adopted to collect the water, which was wicked out from the soil by the wicking geotextile and evaporated into air. Test results show that (1) the wicking geotextile wicked water out from the soil even at the moisture content close to the optimum moisture content and (2) the comparison of soil moisture contents before and after rainfall demonstrated that the wicking geotextile maintained the soil moisture contents after rainfall close to those before rainfall and had an effective distance for the soil moisture reduction.
... Geotextiles have been commonly used in roadways for drainage purposes. Related research on geotextiles for hydraulic applications has been done mostly in two areas: (1) hydraulic properties and behavior of geotextiles included in different types of soil (Stormont et al. 1997;Ho 2000;Rowe 2004, 2005); and (2) design methods and criteria for geotextiles to meet drainage requirements (Holtz et al. 1997;Koerner 2012;El-Gamal and El-Shafey 2000;Lee and Bourdeau 2006). The drainage of water through conventional geotextiles requires soil saturation and a hydraulic gradient. ...
Global warming and climate change have increased the frequency of heavy precipitation. Heavy rainfall results in a large amount of water entering roadways within a short time period. Water remains in the pavement system for a certain time period, reduces strengths and moduli of granular bases and subgrades, and induces pavement distresses. Geotextiles are commonly used in roadways for drainage purposes, which require soil saturation. However, soil saturation does not always exist in roadways to enable gravity drainage of water by conventional geotextiles. Wicking geotextile, a new type of woven geotextile, was recently introduced to the market to remove moisture from unsaturated soils. The wicking geotextile includes special hydrophilic and hygroscopic 4 deep groove fibers with multichannel cross sections, which can induce high capillary force to wick water out of moist soil without saturation of soil. The ability and rate of this geotextile to remove water from moist soil depends on several factors, including temperature and relative humidity. In this study, a series of laboratory tests under controlled temperature and relative humidity were conducted to quantify the water removal rate of the wicking geotextile. A half length of the wicking geotextile was submerged in water tanks, and the other half was hung outside of the tanks. The water wicked from the tank into the geotextile evaporated into the air. Such tests were conducted under 12 different test conditions (i.e., different temperatures and relative humidities). Test results demonstrated that the wicking geotextile could remove water from the water tank at a certain rate. Three commonly used methods available in the literature were adopted to quantify the water removal rate of the wicking geotextile based on vapor pressure, temperature, and relative humidity. A new concept of equivalent water evaporation length of a wicking geotextile is proposed in this study. It should be pointed out that the tests presented in this paper aimed to determine the maximum water removal capacity of the geotextile given sufficient water supply.
... Physical clogging is the phenomenon caused by the retention of inert suspended material that agglomerates in soil pores and reduces progressively the flow channels. Physical clogging associated to fine migration has been widely studied in drainage layers for landfills Makram 1990, Ng andLo 2010), roads (Lee and Bourdeau 2006), agriculture (Nia et al. 2010) and underground structures (Reddi et al. 2000). (2010) Note: k is hydraulic conductivity, e is void ratio, e L is void ratio at liquid limit, w L is liquid limit, d is dry density, CEC [meq/g] is the cation exchange capacity of bentonite, EXC i [meq/g] is the exchange capacity of the exchangeable cation i, k i is the hydraulic conductivity of two montmorillonite parallel-plate layers at the exchangeable cation i, aw and μ aw are the density and dynamic viscosity of interlayer water between two montmorillonite parallel-plate layers, and d i [m] is half the distance between two montmorillonite layers, sv [%] is the swelling specific strain, C is clay content, A and B are fitting parameters, PI is plastic index, C k is a scaled pore-shape factor, is the volume fraction of the solids, p is the particle thickness, m and n are constants, k e is the expected hydraulic conductivity, k c is the hydraulic conductivity of the clay, e b is the ballast void ratio, bs and cs are density of ballast solids and clay solids, respectively. ...
Presence of organic and inorganic contaminants in soils impacts soil and groundwater quality. The hydraulic conductivity of porous media controls the displacement of liquids in the soil pores and affects the fate and transport of contaminants in the environment. This chapter presents the influence of relevant soil and permeating liquid properties on liquid displacement and mass transport in soils including diffusion, advection, retardation, reaction, solubilization and immiscible flow. Then, we address the relevance of micro-heterogeneities on the displacement and generation of ganglia during the simultaneous flow of water and non-aqueous phase liquids (NAPL). Finally, we discuss the importance of soil hydraulic conductivity and mass transport mechanisms in relation to geoenvironmental applications such as permeable reactive barriers (PRB), soil liners (SL) and smart permeable reactive barriers (SPRB).
Longitudinal cracks develop on roads constructed on expansive subgrade soils. For severaldecades, state DOTs in the US have used geosynthetic reinforcement to mitigate theenvironmentally incited longitudinal cracks. However, only a small amount of field data hasbeen collected to date to understand the reinforcing mechanism. Recently, the virtual loadmethod (VLM) has been developed to identify expansive soil-induced stresses in thegeosynthetic-reinforced pavement. This research integrates the VLM in the study on a low-volume rural hot mix asphalt road in Texas to evaluate the effectiveness of the geosynthetics anddifferent reinforcement location options within the pavement layers. The soil-geosyntheticinteraction is characterized by applying the subgrade heave/shrinkage-induced reaction pressureto the ground surface, with the heave/shrinkage deformations being computed from the field-measured moisture content variations data. The optimum location of geosynthetic reinforcementis determined based on the tensile force absorption value by observing the two extreme weatherconditions. The results demonstrate that the tensile force absorption increases by shifting thegeosynthetics towards the bottom of the pavement and achieves the most significance when it isplaced between the base layer and subgrade layer in the model.
Wicking geotextile (WG) is considered as a possible countermeasure to reduce water content in unsaturated soil. In this research, rainfall tests were carried out to verify the drainage performance of WG. And capillary rise tests were conducted to study the effect of WG on the prevention of capillary rise. Test results indicated that WG with good drainage performance could drain gravitational and capillary water out of kaolinite soil. For kaolinite soil column with water content of 12% and compaction degree of 90%, the whole process of capillary rise in soil column with a layer of WG was a typical two-stage mode, and the maximum capillary height was about 380 mm, which provided that the WG could work as a barrier to prevent capillary rise effectively. In addition, the total vertical influential regions of WG in kaolinite soil above and below the WG layer were 400 and 100 mm, respectively.
