Geotextile Bags Research Articles

Load-Carrying Capacity of Strip Footing Resting on Sand Slopes Retained by Novel Construction Waste-Filled Geotextile Bags

Load-Carrying Capacity of Strip Footing Resting on Sand Slopes Retained by Novel Construction Waste-Filled Geotextile Bags

Experimental Study on the Shear Strength of Different Interfaces of Fine-Grained-Tailing-Filled Geotextile Tubes

As damming material, fine-grained tailings present challenges such as low dam strength and poor stability. To address these issues, this study employs geotextile tube technology to mix water with fine-grained tailings, forming a tailing slurry with a concentration of 60%, which is filled into a geotextile bag to form a geotextile tube, so as to improve the stability of fine-grained tailings. The shear strength characteristics of each interface under different consolidation times and different filling degrees were studied via an indoor shear experiment, including the shear strength of tailing particles, that between tailings and geotextiles, and that within geotextile tubes themselves. The results show that the shear strength of each interface conforms to the Mohr–Coulomb strength criterion, and that the interface cohesion is greatly affected by the consolidation time, while the interface friction angle is mainly affected by the filling degree. Moreover, the shear strength comparison, based on the comprehensive friction angle concept, indicates a substantial increase in shear strength at the interfaces between geotextile tubes compared to both that of the tailings themselves and the interface between tailings and geotextiles, highlighting the reinforcing effect of the geotextile tube filling technology on tailings’ shear strength.

Resistance and durability of high strength geotextile bags for hydraulic works

There is a need to build hydraulic works for riverside protection in case of flood as well as a mitigation project for high scour in places where rock material is very expensive or does not exist, therefore hard armour rock, rip rap or even concrete are unattractive alternatives. In several countries of the world, geotextile bags of high resistance have been used to achieve a valid and economical alternative. Themes related to stability of structures with bags that are very important have been dimensioned by some researchers, but there is still no information on how to relate the mechanical characteristics of the components of the bags with their manufacturing and also its service behaviour. This research offers details to be able to know the mechanical characteristics of thread types, geotextile and seaming according to the infill material type to be used to have an equivalent of a rock with the use of high resistance geotextile bags. This is also oriented to know its durability before abrasion, impact and UV radiation. Tests carried out in our laboratories are included as well as those carried out by other researchers both oriented to a methodology that provides an appropriate dimensioning of this type of structures. Some experiences where this methodology was used will be also included as well as the appropriate references.

Innovative polymer application using geotextile dewatering bags

Geotextile dewatering bags have been a construction industry standard for several decades. Erosion control supply companies often recommend them as a solution to achieve clean water for discharge compliance on project sites. The bags are effective at containing coarse sediments from pumping activities. They are not very effective at capturing fine particulate matter and often require additional measures to produce clean water that meets compliance limits for stormwater discharge activities. The inclusion of polymers in the dewatering process can effectively treat the fine particulate matter and produce very clean discharged water. Standard practices have introduced the polymer into the bag during pumping activities. The idea is that the polymer will react with the sediment laden water and be retained in the bag. Unfortunately, this often results in the bag becoming severely clogged. This restricts pumping flow rates and accelerates containment failure of the geotextile bag. Contractors must then use many more bags at a reduced flow rate to treat the needed water volume. An alternative method for polymer application is to introduce it after passing through the geotextile bag. The bag is then used as a pre-filter and a way to convert concentrated flow into sheet flow. A simple containment is built around the dewatering bag and is used to direct the water flow over polymer blocks for treatment. This treatment consists of a soil-matched polymer (optimal results), mixing area with contact time, and a particle capture area to remove polymer treated sediment.

Geosynthetic solutions for river and coastal protection works

Riverine floods and coastal erosion are some of the most frequent natural calamities in India that affect millions of people, cause loss of lives, and damage infrastructure and agriculture. Application of geosynthetic products provides a sustainable, eco-friendly, quick & economical solution among all the conventional river and coastal protection works. This paper focuses on geosynthetic solutions to the river and coastal erosion with the help of case studies. To safeguard against the frequent floods, the banks of the river Brahmaputra near Lakhimpur were strengthened while providing geosynthetic anti-erosion measures. A sandfilled geotextile mattress of 0.1m thickness was provided on the river bank slopes of the Brahmaputra River, Assam. Also, this paper reveals the successful application of specially engineered nonwoven geotextile bags with high abrasion resistance, to mitigate the effects of erosion of the banks of Churni River, West Bengal. This solution reinforces the embankment's edge and increases the factor of safety against repeated floods. The third case study discusses the coastal protection work at Kattupalli, Tamilnadu where a 620ms long shoreline was protected against progressive beach erosion. An embankment was formed using 6 numbers of 3.0m theoretical diameter and 20.0m long high-performance geotextile tubes in crosssection and a small geotextile tube was used for scour protection ahead of the structure. The embankment thus formed also provided ways for beach nourishment and land reclamation at the site.

An Experimental and Theoretical Study on the Tailings Dam with Geotextile Bags

The friction performance and compression properties of geotextile bags under different degrees of consolidation are researched through the slope sliding test, direct shear test, and unconfined compression test in this study. The geotextile bags are made up of geotextile and tailings sands obtained from a construction site of a prototype tailings dam in Yunnan Province. The slope sliding test is considered as an easy method to study the friction performance of geotextile bags with different degrees of consolidation. Through the test, the friction coefficients between the bags were obtained. Given the geotextile bags can withstand the vertical load in practical engineering, the direct shear test is also proposed and conducted. The ultimate bearing capacity of the geotextile bags with different consolidation degrees is studied in the unconfined compression test. The test reveals that the ultimate bearing capacity of geotextile bags, although featured with different moisture contents before the test, stays the same under the condition of slow loading. Finally, a stability analysis method based on the limit equilibrium theory is developed to simulate the stability of the tailings dam using geotextile bags (TDGB). According to the test results, the TDGB has demonstrated an improved stability compared with the general tailings dam.

Performance of a green wall (Total Value Wall™) at high greywater loading rates and Life Cycle Impact Assessment

Nature-based greywater (GW) treatment and reuse in urban areas has become an up-and-coming option. A 14.4 m2 green wall system called Total Value Wall (TVW) was installed at a terraced house in Gent (Belgium) for treating GW and reusing the effluent for toilet flushing. In a previous study, the TVW was loaded at 7 L.m−2.d−1 and efficiently removed TSS (67%), COD (43%), BOD5 (83%) and total coliforms (log 2), but a number of issues were reported related to nutrient leaching from the substrate, and the excessive retention time in the storage tanks. In this study results are reported from a follow-up study during which an adapted TVW was subjected to both higher hydraulic and pollutant loading rates in order to investigate the treatment capability of TVW. The design of the system, i.e. substrate contained in geotextile bags, did not sustain the higher hydraulic loading rates as excessive leakage occurred. Despite this, the higher pollutant loading rates still resulted in an acceptable effluent quality with 15 mg.L−1 TSS (90%), 85 mg.L−1 COD (82%), and 15 mg.L−1 BOD5 (95%). Ammonium, E. coli and total coliforms were removed with removal rates of 98%, 63% (0.4 log units), and 36% (0.2 log units), respectively. Finally, a life cycle assessment (LCA) was performed for the TVW with and without treating GW to analyze the environmental burden. The LCA impacts showed that replacing tap water and chemical fertilizer by GW, and the reuse of effluent, have a positive impact. However, the energy use for pumping has a major impact and should be minimized by using an efficient pump and distribution system to reduce the overall footprint.

Immobilization of microorganisms in activated zeolite beads and alkaline pretreated straws for ammonium-nitrogen removal from urban river water

AbstractThe non-treated wastewater from residential areas contains high concentrations of ammonium-nitrogen (NH4+-N). When discharged into the drainage water system, it deteriorates the water quality in urban rivers. This study used two types of materials to form eco-bags, using activated zeolite bead (AZB) and alkaline pretreated straw (APS), in geotextile bags for easy recovery and reuse. The AZB and APS provided the breeding habitat for the microorganisms that promoted biofilm formation on their surface. The immobilization of engineered denitrification microorganisms facilitated the removal of NH4+-N from the urban river water. The NH4+-N removal in the AZB and APS bags were in the range of 64–73%, and 56–61%, respectively, while the chemical oxygen demand (COD) removal in the AZB and APS bags ranged from 33–36%, and 30–31%, respectively. In addition, as evident from DNA and microbial community analysis, the microorganisms demonstrated a greater proclivity to grow and proliferate on the surface of AZB and APS and improved the water quality of urban rivers.

Application of polyelectrolytes for improving the dewatering performance of drinking water treatment sludge using geotextiles

The sludge generated at drinking water treatment plants (WTPs) is a high-moisture content residue, and therefore difficult to handle, transport, dispose of or recover. During the last decades, geotextile tubes have been successfully applied to reduce the residue volume, facilitate its handling and subsequent reuse. This study aimed to understand the factors that interfere in the filtration and dewatering efficiencies and to experimentally analyze the dewatering process of WTPs sludge, evaluating different test procedures and investigating the influence of the type and dosage of polymeric additives on dewatering performance. Geotextile cone dewatering tests and geotextile bag dewatering tests were performed, using four different woven geotextile samples and an aluminum sulfate WTP sludge sample. The results showed that the use of geotextile cone dewatering tests for geotextile selection and for additive selection and dosage was representative for the dewatering process intended, reflecting the results verified in the geotextile bag dewatering tests. Sludge chemical conditioning increased dewatering rate and solids retention during the tests’ early stages, but it did not result in a higher final solids content sludge cake.
 Keywords: dewatering systems, geosynthetics, waste management.

Laboratory Investigation of Geobag Revetment Performance in Rivers

Geobag (sand-filled geotextile bags) revetments have recently emerged as long-term riverbank protection measures in developing countries; however, their performance is still not well understood. The hydraulic stability of geobag revetments used for riverbank protection has been studied within an extensive laboratory programme to improve our understanding of the complete failure processes of geobag revetments. A 1:10 scale distorted physical model was tested in a laboratory flume, comparing a range of different construction methods and revetment side slopes, subjected to different flow loading. The results indicate that whilst failure mechanisms are highly dependent on water depth and revetment slope, the construction method had no noticeable impact. It was thus concluded that the dominating factor is the friction between individual geobags, which itself is dependent on bag longitudinal overlap rather than a specific construction method.

Experiments for Enhancing Tailings Slurry Drainage and Geotechnical Performance Using Nonsegregation Flocculation and Geotextile

Abstract Pumping tailings slurry into geotextile bags is a burgeoning method employed to build tailings dams with improved tailings management. Fine contents bring great challenges for tailings stability. In this article, nonsegregation flocculation was selected for fine tailings. Experiments were carried out in three campaigns: nonsegregation flocculation of tailings slurry to reduce fine content in supernatant (low turbidity); water drainage evaluation via filtration tests, plus the measurement of capillary suction time; and the study of geotechnical properties, including hydraulic conductivity and yield strength. From the results, it is demonstrated that the tailings slurry without flocculation showed apparent particle segregation and poor drainage performance compared to tailings with nonsegregation flocculation. The yield strength with nonsegregation tailings was enhanced by two times to initial values. Scanning electron microscopy image analysis was used to check the attachment status of solid particles on geotextile surfaces after being used for filtration tests. The mechanism of enhancing geotextile drainage revealed that increased permeability and reduced geotextile pore-plugging should account for the enhanced water drainage and tailings stability. A pattern of achieving optimal drainage strategy of geotextile bag was recommended for building a tailings dam, which is to use large-sized flocs plus geotextiles with large pore sizes (up to 0.6 mm).

Drainage test on soil-filled geotextile bag

The drainage rate of soil-filled geotextile bag is an important factor to embankment project.Laboratory tests are carried out to study the drainage behavior of soil-filled geotextile bag. Results show: (1) drainage rate of soil-filled geotextile bag is nonlinear reduced with time, The drainage rate is large at initial phase, and then decrease rapidly as mud structure is formed on the inner surface of the bags; (2) The drainage effect is larger with less clay content, show two nonlinear law. When the clay content is lower than 22%, the reduction of soil-filled geotextile bag is small with the clay content; (3)The drainage effect is larger with larger equivalent opening size, the drainage effect of 2# geotextile with 0.155mm equivalent opening size is better than the 1# geotextile with 0.096mm equivalent opening size, and can increase 20% of clay content.

模袋注浆技术中模袋材料力学性能研究

模袋注浆技术中模袋材料力学性能研究

Numerical Analysis on the Sandy Slope Reinforced with Sand Bags

In recent decades, many expressways and railways have been construction in Western China. One of important projects is Menghua Railway as a major energy transportation line. Since most of its Contract I routine is located in Maowusu Desert, it seems the first choice is to utilize the sandy soil to construct the railway subgrade. The sand bag structure is explored as a reinforcement method for as railway sandy subgrade by numerical analysis. The Flac3D is selected as the calculation tool with its GeogridSEL structural element used to simulate the function of geotextile bag. It is assumed the geotextiles remain elastic in the calculation, and the failure occurs at the interface between geotextiles and surrounding soil. The results show that when bagged sand is used, the internal friction angle of sandy soil can be appropriately reduced, or a steeper slope can be used, but the friction angle between bagged sand and geotextile is required to be larger. At the same time, if the internal friction angle of sand is small, in order to obtain a smaller slope, geotextile is required to be subjected to a larger tensile stress.

Performance and design of modified geotextile tubes during filling and consolidation

The performance of geotextile tubes is affected by many factors such as the pumping pressure, fill material and geotextile properties, and so on. Hence, obtaining hydraulic compatibility between geotextiles and fill materials containing a variety of coarse and fine particles – that is, silty sand – is complex. For this reason, the modified geotextile tube (MGT) was invented to optimize the filling and dewatering or consolidation performance of geotextile tubes. To assess the behavior of MGTs, experimentation and theoretical analysis were conducted. The MGT retention performance, filling time, and water pressure were evaluated through a geotextile bag experiment while the MGT geometry, tension force, strain, water content distribution, and consolidation performance, were investigated through a parametric study. The two-dimensional MGT solution presented in this study is based on a combination of various modeling concepts that were modified or extended to be able to sufficiently describe the MGT behavior. Results showed that the performance of geotextile tubes can be optimized in a variety of ways by interchanging the geotextile placement, by changing the circumferential lengths, and by using geotextiles with different properties. With the methods presented in this study, modified geotextile tube design is made possible.

Predicting Aggregate Degradation in Forest Roads in Northwest Oregon

In the Pacific Northwest, forest roads have the potential to cause significant environmental degradation, especially to water resources due to increased sediment production. The goal of this research is to improve the understanding of road degradation during hauling by improving our understanding of the aggregate degradation process. We correlate the wear rates to standard material property tests that may allow for improved prediction of the impacts from forest roads based on the selection of aggregate surfacing. Finally, we determine the changes in stress distribution between the subgrade and aggregate interface. High-, medium-, and low-quality aggregates were used from three quarries in western Oregon for this project. These aggregates are indicative of the range of materials used on forest roads in the region. Two material property tests, namely the Los Angeles (LA) abrasion and micro-Deval tests, were used to determine their ability to predict aggregate performance during hauling by relating values for aggregate wear to these aggregate properties. Eighteen nonwoven geotextile bags were created, measuring 60 cm (two-feet long) and 20 cm (eight inches) in diameter, with a pore size equivalent to a 0.149 mm (# 100) sieve. They were filled with a known quantity and particle size distribution of aggregate and embedded into a newly constructed forest road. Stress gages were installed in the road surface between the aggregate and subgrade levels to record the changes in stress at the subgrade level. Samples were subjected to three levels of traffic (500, 950, and 1500 passes) using a loaded dump-truck that had a steering axle and one tandem drive axle, weighing 25,038 kg or 55,200 lb. The results showed that less breakage occurred with the medium- and high-quality aggregates than the low-quality aggregate. There was a correlation between the material property test (either the micro-Deval or the LA abrasion test) and the fine index, indicating the predictability of these tests in terms of aggregate performance. Finally, the higher quality aggregate was able to better distribute the stresses from the wheel better than the lower quality aggregate and was able to reduce the stress reaching the subgrade. Although the results are limited to the three types of rock used in this study, they indicate the ability of the high-quality aggregate to lessen the environmental impacts from forest roads.

Geobag stability for riverbank erosion protection structures: Numerical model study

Flexible, sand-filled, geotextile bags (geobags) have been used in both India and Bangladesh along the banks of the Brahmaputra for protection against riverbank erosion. Geotextile containers have been researched extensively for their use in coastal structures; however, there is a gap in knowledge of the application of smaller geobags used in riverbank protection structures. In 2018, flume experiments (scaled 1:7) were performed to study the incipient motion of geobags and the methodology for sizing geobags. Building on the data collected from the flume experiments, numerical models have been employed to gain further insight into the hydraulic forces acting on the bags. The numerical models have been created using ANSYS CFX. While there is not enough data to obtain a Shields parameter which can be used for design purposes, initial estimates find the Shields value for geobags lies around 0.09, which is much larger than the value for rocks, around 0.045. The results from this study suggest that the Shields parameter varies with fill percentage of the bags. This paper also presents first results on the roughness of underwater geobag aprons.

Construction of In-situ Coastal Experimental Station to Continue Assessing Shoreline Protection Performance of Geotextile Sandbags

Li Y.-Q.; You Z.-J.; Shi H.-Y., and Ren, B., 2020. Construction of in-situ coastal experimental station to continue assessing shoreline protection performance of geotextile sandbags. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 267–271. Coconut Creek (Florida), ISSN 0749-0208.Storm-induced coastal erosion is one of main natural hazards on the coast of China and appears over one-third of the Chinese coastline. How to protect the valuable coastline from extensive erosion is of enormous economic and social values. In this study, a 74 m-long erosive coastline with high dune of about 8 m on the coast of Chudao in China has been ecologically protected with durable geotextile sandbags and then served as an in-situ permanent experimental station to continuously assess the shoreline protection performance of geotextile sandbags. The in-situ station consists of three different test segments (S1, S2, S3) and each of them was designed differently to optimize the stability and construction cost of geotextile sandbags. The sand-filled geotextile bags are designed to have the same dimensions of 1.3 m long, 0.8 m wide, and 0.2 m high and last for about 20∼30 years. Before and after the in-situ station has been built, the essential field data are collected: (1) monthly surveying of 20 permanent beach profiles to evaluate the beach profile changes; (2) monthly collection of numerous sand samples to analyze sediment grain size changes; and (3) monthly monitoring of maximum wave runup levels and sandbags stability. In analyzing the collected filed data, it is found that high wave runup is main driver for the shoreline erosion at this study site and the test segment (S2) together with geogrids is most effective and economic of the three test segments. The test segment (S2) will be redesigned to further assess the effects of sandbag size, revetment height and geogrid meshing on the performance of geotextile sandbags at this in-situ station.

Long-term monitoring emphasizes impacts of the dredging on dissolved Cu and Pb contamination along with ultraplankton distribution and structure in Toulon Bay (NW Mediterranean Sea, France)

A long-term monitoring during dredging and non-dredging periods was performed. Total and dissolved Cu and Pb concentrations, DGT-labile Pb, ultraphytoplankton abundance and structure were monitored at four sites: dredging site, dumping site (inside/outside of a geotextile bag) and reference site. During the reference period (non-dredging), an increasing contamination in Pb, Cu and a progressive shift from Synechococcus to photosynthetic picoeukaryotes dominance was observed from reference to dumping site. Pb concentrations were significantly higher during dredging period, pointing out sediment resuspension as Pb major source of contamination. Unlike Pb, Cu concentrations were not statistically different during the two periods. Dredging period did not impact on ultraphytoplankton abundance and structure but influence heterotrophic prokaryotes abundance. Sediment resuspension is therefore a major driver of chemical and biological qualities in Toulon Bay. Furthermore, although the geotextile bag reduces particulate transport of the dredged sediment, the transport in the dissolved phase remains a major problem.

Evaluation of chemical polymers as coagulation aids to remove suspended solids from marine finfish recirculating aquaculture system discharge using a geotextile bag

Traditionally used in the construction and excavation industries to remove solids from runoff, geotextile fabric tube (Geotube) technology has been adopted by freshwater aquaculture facilities as a method of effluent management. The effectiveness of a Geotube is improved by using chemical polymers to bind suspended solids in the effluent for greater retention; however, polymers used in freshwater systems may not be effective in marine systems. Using laboratory jar tests, seven organic polymers of different molecular weights and ionic charges were evaluated at doses ranging from 0 to 50 ppm for solids removal efficiency (SRE) from effluent from a marine (33 ppt) finfish RAS growing black sea bass. Of the seven polymers screened, two cationic high molecular weight polyacrylamide polymers Drewfloc (DF) 2449 and DF 2468 had high SRE of total suspended solids (TSS) (36.1–84.4 %). Further tests using miniature geotextile bags confirmed that DF 2449 at 10 ppm and DF 2468 at 5 ppm had high SRE (73.3–75.9%) compared to the untreated control (43.4 %). When applied to a commercial-scale Geotube, DF 2449 at 10 ppm removed 92.1 % of the TSS in the effluent of the marine finfish RAS growing black sea bass. Rinsing the saline biosolids with freshwater at a rate of 1.63 L per 100 g dry solids reduced the salinity to < 1 ppt, a level safe for land application, while 4.43 L per 100 g dry solids were needed to reduce the salinity to 0.16 ppt. Geotube systems are effective at removing TSS from intensive, marine RAS discharge as well as meeting NPDES discharge compliance and reducing the impact of aquaculture on local waters.