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1.
Ehsan Izadi Tijl Decraene Steven De Strijcker Adam Bezuijen Dirk Vinckier 《Geotextiles and Geomembranes》2018,46(1):91-100
This paper focuses on the impact resistance of geotextiles when subjected to impact loadings induced by dropping of stones. Such scenarios occur when geotextiles are used as a protective measure for fine granular material where is prone to be washed away. Usually, these geotextiles are restrained by placement of stones on top of them. A laboratory testing program is performed to expose a woven geotextile under dropping of a concrete block with various dropping energies and geometries. The induced damage on the geotextiles is inspected after the drop. Results indicate that as the drop energy increases, not only the possibility of puncturing of geotextiles increases but, in case of puncturing, the punctured area of geotextile expands as well. In addition, it is found that the geometry of the concrete block, where it collides on the geotextile, plays an important role on the survivability of geotextiles. In addition, PIV analysis has been performed to better understand the deformation pattern of the geotextile under impact loading. Based on the PIV results a simple scheme is suggested to estimate the drop energy threshold that the geotextile can survive under certain block geometry. 相似文献
2.
《Geotextiles and Geomembranes》2023,51(4):56-71
The accurate estimation of the frictional resistance of interfaces between soils and geosynthetics plays a central role in stability and serviceability of geosynthetic reinforced earth structures. Contamination with hydrocarbons generally impairs soil geotechnical properties; however, its effect on the behavior of soil-geosynthetic interfaces has seldom been examined precisely. For this reason, an extensive series of direct shear tests was performed to investigate the consequence of gas-oil contamination on the mobilization of shear strength and volume change response of gas-oil contaminated angular sand in contact with woven geotextile (WGTX). Complementary tests on the interfaces between glass beads as a replicate for sands with high degree of sphericity and roundness in contact with WGTX were also performed to explore the effect of particle shape. Gas-oil contamination is observed to causes decrease of the peak and critical state friction and dilation angles in both the sand-WGTX and glass bead-WGTX interfaces. However, gas-oil contamination-induced decrease in the frictional efficiency in the glass bead-WGTX interfaces was greater than that in the angular sand-WGTX interfaces. Calibration of a state-dependent sand-structure interface model against the laboratory data of gas-oil contaminated soils-WGTX interfaces results in a reasonable agreement between the model simulations and the laboratory data. 相似文献
3.
《Geotextiles and Geomembranes》2022,50(5):1004-1019
Wicking geotextile can reduce water contents in pavement layers under unsaturated conditions due to capillary action through grooves of wicking fibers. Reduction of soil water content under the pavement can minimize pavement distresses. So far, there have been limited use and verification of the wicking geotextile in reducing water content of soil under concrete pavements in the field. In this field study, moisture sensors were installed in three test sections under a newly-built concrete pavement during its re-construction. The base course in one test section had a higher percentage of small particles than those in other two sections. The wicking geotextile was used between the base course and the subgrade in two test sections while a nonwoven geotextile was used in one test section. All test sections were subjected to precipitations and temperature variations. Field monitoring data showed that the wicking geotextile reduced the volumetric water content (VWC) of an aggregate base more than the nonwoven geotextile and its wicking ability decreased as the content of small particles increased. In addition, the wicking ability of the wicking geotextile decreased as the temperature decreased due to the reduction in the evaporation rate and the increase in the water retention capacity of the soil at low temperatures. 相似文献
4.
Pitthaya Jamsawang Thanawan Suansomjeen Piti Sukontasukkul Pornkasem Jongpradist Dennes T. Bergado 《Geotextiles and Geomembranes》2018,46(4):414-425
This research investigates the influence of seven different fiber types on the flexural performance of compacted cement-fiber-sand (CCFS) with four fiber fractions (0.5, 1, 1.5 and 2% by volume). The seven types of fibers are 12?mm polypropylene, 19?mm polypropylene, 40?mm polypropylene, 55?mm polypropylene, 33?mm steel, 50?mm steel and 58?mm polyolefin fibers. The overall CCFS performance was divided into seven sub design performance indicators: (1) peak strength; (2) peak strength ratio; (3) residual strength ratio; (4) ductility index; (5) toughness; (6) equivalent flexural strength ratio; and (7) maximum crack width. The interaction mechanism of the fiber/cement-sand interface was investigated by scanning electron microscopy. Finally, the effectiveness of each fiber type was compared and rated in terms of the overall performance. The results show that the 50?mm steel fiber provided the best overall sub performance, resulting in an excellent overall flexural performance; in comparison, the 12?mm polypropylene fiber exhibited very poor performance. However, the 19?mm polypropylene and 33?mm steel fiber specimens provided very good and good overall performances, respectively. The nature of the fiber surface and the fiber length affects the overall performance of CCFS. The surface of the steel fibers, compared to the other synthetic fiber types, is more hydrophilic and is more compacted in a cemented-sand matrix without separation of the interfacial zone, providing the best overall flexural performance. 相似文献
5.
Composite geotextiles with polyester yarn reinforcement have been commonly used in combination with unsaturated soils. Both unsaturated and saturated shear strength of the interfaces were investigated between a composite geotextile and three major types of materials: silty sand (SM), low-plasticity silt (ML) and high-plasticity clay (CH) in a direct shear box. The interfaces were formed using two methods (A and B) to reflect the wide range of possible contact conditions in practice. Method A involved statically compacting the soil directly on top of the composite geotextile, while for Method B, the soil was statically compacted in a separate mold and later brought into contact with the composite geotextile. Type B interfaces required a larger displacement to mobilize the shear strength than Type A interfaces. The ultimate failure envelopes of SM and ML soils were similar to those of their interface shearing. Notably, the failure envelopes for the clay-geotextile interface of both types were higher than that of clay alone. The unsaturated soil-only shearing had a higher peak strength and tended to dilate more than saturated soil-only shearing, while unsaturated soil-interface shearing appeared to be more contractant than saturated interface shearing. The strength variations with suction for all tested soils and interface shearing were clearly non-linear. A new model that takes account of the condition of soil-geotextile contact intimacy is proposed for predicting the variation of interface strength with suction, based on the variation of the soil's apparent cohesion with suction and the geotextile-water retention curve. 相似文献
6.
A full-scale geotextile-reinforced soil wall was built in order to assess the characteristics of water infiltration and its effect on the structure performance. Nonwoven geotextiles were selected as inclusions in order to provide not only reinforcement, but also internal drainage to the fine-grained soil used as backfill material. The structure was built in a laboratory setting, which facilitated implementation of a thorough instrumentation plan to measure volumetric water content changes of soil, suction, facing displacements and reinforcement strains. An irrigation system was used to simulate controlled rainfall events. The monitoring program allowed the evaluation of the advancement of infiltration and internal geosynthetic drainage. Evaluation of the effect of the hydraulic response on the overall performance of the structure included assessment of the development of capillary breaks at soil-geotextiles interfaces. Capillary breaks resulted in water storage above the geotextile reinforcements and led to retardation of the infiltration front in comparison to the infiltration that would occur without the presence of permeable reinforcements. After breakthrough, water was also found to migrate along the geotextiles, suggesting that the reinforcement layers ultimately provided in-plane drainage capacity. While generation of positive pore water pressures was not evidenced during the tests, the advancing infiltration front was found to affect the performance of the wall. Specifically, infiltration led to increasing reinforcement strains and facing displacements, as well as to the progressive loss of suction. While the accumulation of water due to the temporary capillary break also resulted in an increased backfill unit weight, its effect on deformation of the wall was not possible to be captured but it is intrinsic on the overall behavior observed in this study. Correlations between reinforcement strains/face displacement and the average of suction in the backfill soil, as measured by tensiometers in different locations within the backfill mass, point to the relevance of the suction as a representative indicator of the deformability of the geotextile-reinforced wall subjected to water infiltration. Reinforcement strains and face displacements were found to reduce more significantly with reduction of suction until a certain value of suction from which the rate of decreasing declines. 相似文献
7.
In this study, three-dimensional numerical analyses were carried out to investigate the effects of reinforcement pullout resistance including facing connection strength on the behavior of geosynthetic-reinforced soil (GRS) piers under a service load condition. Three different piers were investigated in this study, which simulated different levels of reinforcement pullout resistance. Each pier had two cases with different reinforcement stiffness J and reinforcement spacing Sv but the same ratio of J/Sv. Numerical results showed that reinforcement pullout resistance had a significant effect on the behavior of GRS piers. When the pullout mode prevailed, the case with small Sv and low J had smaller lateral facing displacements and vertical strain of the pier under the same applied pressure as compared to the case with large Sv and high J when the ratio of J/Sv was kept constant. When the pullout mode did not prevail, two cases with the same ratio of J/Sv showed similar performance despite different combinations of Sv and J were used. To more effectively mobilize reinforcement strength and improve GRS pier performance, small reinforcement spacing or high-strength facing connection should be considered when sufficient reinforcement pullout resistance cannot be guaranteed otherwise. 相似文献
8.
《Geotextiles and Geomembranes》2020,48(4):419-430
The assessment of the internal stability of geosynthetic-reinforced earth retaining walls has historically been investigated in previous studies assuming dry backfills. However, the majority of the failures of these structures are caused by the water presence. The studies including the water presence in the backfill are scarce and often consider saturated backfills. In reality, most soils are unsaturated in nature and the matric suction plays an important role in the wall's stability. This paper investigates the internal seismic stability of geosynthetic-reinforced unsaturated earth retaining walls. The groundwater level can be located at any reinforced backfill depth. Several nonlinear equations relating the unsaturated soil shear strength to the matric suction and different backfill type of soils are considered in this study. The log-spiral failure mechanism generated by the point-to-point method is considered. The upper-bound theorem of the limit analysis is used to evaluate the strength required to maintain the reinforced soil walls stability and the seismic loading are represented by the pseudo-dynamic approach. A parametric study showed that the required reinforcement strength is influenced by several parameters such as the soil friction angle, the horizontal seismic coefficient, the water table level, the matric suction distribution as well as the soil types and the unsaturated soils shear strength. 相似文献
9.
The selection of geosynthetic reinforcements in the design of geosynthetic-reinforced soil (GRS) retaining walls has been based on the requirement on the long-term strength. However, the mobilized loads in the reinforcements are related to both the reinforcement stiffness and soil deformation, and the desired factor of safety may not exist in the earth structure if they are not properly considered. Therefore, it is also important to take into account the long-term reinforcement stiffness when designing GRS retaining walls. In this study, a simplistic analytical method is proposed to determine the required reinforcement stiffness with given factor of safety on the backfill soil. The method takes into account soil-reinforcement interaction, nonlinear stress-strain behavior of soil, and soil dilatancy. The reinforcement strains predicted by the proposed method were compared to those analyzed by validated nonlinear Finite Element analyses, and close agreement was obtained. 相似文献
10.
《Geotextiles and Geomembranes》2022,50(6):1244-1251
The level of reinforcement loads in a reinforced soil retaining wall is important to its satisfactory operation under working stress conditions since it basically determines the wall deformation. Consequently, proper estimation of the reinforcement load is a necessary step in the service limit-state design of this type of earth retaining structures. In this study, a force equilibrium approach is proposed to quantify the influence of facing batter on the reinforcement loads of reinforced soil walls under working stress conditions. The approach is then combined with a nonlinear elastic approach for GRS walls without batter to estimate the reinforcement loads neglecting toe restraint. The approximate average mobilized soil strength in the retaining wall is employed in the force equilibrium analysis. The predictions of reinforcement loads by the proposed method were compared to the experimental results from four large-scale tests. It is shown that the proposed semianalytical approach has the capacity to reproduce the reinforcement loads with acceptable accuracy. Some remaining issues are also pinpointed. 相似文献
11.
The results of an experimental study conducted to investigate the beneficial use of woven coir geotextiles as reinforcing material in a two-layer pavement section, are presented. Monotonic and repeated loads were applied on reinforced and unreinforced laboratory pavement sections through a rigid circular plate. The effects of placement position and stiffness of geotextile on the performance of reinforced sections were investigated using two base course thicknesses and two types of woven coir geotextiles. The test results indicate that the inclusion of coir geotextiles enhanced the bearing capacity of thin sections. Placement of geotextile at the interface of the subgrade and base course increased the load carrying capacity significantly at large deformations. Considerable improvement in bearing capacity was observed when coir geotextile was placed within the base course at all levels of deformations. The plastic surface deformation under repeated loading was greatly reduced by the inclusion of coir geotextiles within the base course irrespective of base course thickness. The optimum placement position of coir geotextile was found to be within the base course at a depth of one-third of the plate diameter below the surface. 相似文献
12.
This paper presents an analytical method for determining the modulus improvement factor (MIF) in geocell-reinforced soil layers. Using a modified version of the hyperbolic soil model as a constitutive model, the method is developed based on the soil-reinforcement interaction relating nonlinear elastic soil behavior to the linear elastic response of the reinforcement. The proposed method, in an original way, explicitly takes into account the geometry of the geocell pocket, effects of soil and geocell-reinforcement stiffness, compaction-induced stresses, soil strength and strain compatibility. The method can be used both analytically and using simple and presented non-dimensional charts. Parametric analyses show that the reinforcement, soil relation and the stresses induced during the compaction procedure are the major factors influencing MIF. An evaluation using data from several laboratory, full-scale and field experiments in works is presented showing good predictive capability of proposed method. An application procedure for calculating MIF is presented. 相似文献
13.
Large scale tests on geosynthetic reinforced unpaved roads subjected to surface maintenance 总被引:1,自引:0,他引:1
Geosynthetic can be effectively used as reinforcement in paved and unpaved roads. This paper presents a study on the use of geosynthetic to reinforce unpaved roads on poor subgrade. A large equipment was used to perform the tests under cyclic loading and a nonwoven geotextile and a geogrid were used as reinforcing layers installed at the fill-subgrade interface. Displacements along the fill surface and stresses and strains in the subgrade were measured during the tests. Three cyclic loading stages were applied in each test up to a rut depth at the fill surface of 25 mm be reached in each stage. At the end of a loading stage the fill surface was repaired for the following loading stage. Monotonic loading tests were also carried out for comparisons. The results obtained show the significant contribution of the presence of the reinforcement layer in increasing the number of load cycles for a given rut depth to be reached and in reducing the stresses and strains in the subgrade, particularly when geogrid reinforcement was used. It was also observed that monotonic loading tests underestimated the contribution from the reinforcement. A simple cost-effectiveness analysis showed that the reduction of maintenance works due to the use of geosynthetic reinforcement may yield to significant savings in this type of problem, seldom considered in the analysis of the economics of this type of application on a routine basis. 相似文献
14.
15.
For constructions on extremely soft foundation medium, the most common practice is to allow the soft soil to consolidate under the application of surcharge which generally consists of applying the necessary superimposed preload. However, because of low permeability of the in-situ soil, this often becomes a time consuming affair and also large quantities of material may have to be applied in the form of overburden. In some of the very fine grained soils encountered in practice, it may not be feasible to apply the surcharge without the danger of exceeding the bearing capacity of the existing formation soil. In such cases jute geotextiles may actually permit the construction to be carried out successfully and in a cost effective manner. A quantitative study on the efficacy of jute geotextile for consolidation purposes has been made and the outcome seems interesting. A design methodology involving selection and application of jute geotextile drains in weak foundation soil is suggested. Further, comparison of published standards with available properties of jute geotextile reveals that the fabric meets the criterion required for such purposes. Hence it may be judicious to explore the technically feasible, environmentally compatible and economically viable use of jute geotextile, as a suitable drainage medium for dealing with drainage problems encountered in the field. 相似文献
16.
17.
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. 相似文献
18.
《Geotextiles and Geomembranes》2019,47(5):610-617
Soilbags have good reinforcement effect on soil slopes. In this paper, traditional soilbag is modified by adding a tail to it. Model tests have been used to study the influence of soilbag tail length on the reinforcement effect in soilbags reinforced slopes. Moreover, a permissive failure pattern and a corresponding velocity field have been established based on the experimental results. Then, the ultimate failure heights of the reinforced slopes are obtained by using the upper-bound solution theory and compared with the experimental results. Both the experimental and analytical results show that within a certain limit, the reinforcement effect improves with the increase of tail length. However, when the tail length is over a certain value, the increase of the tail length does not improve the reinforcement effect any more. This provides theoretical basis to the optimized design of soilbags reinforced slopes. 相似文献
19.
《Geotextiles and Geomembranes》2022,50(4):590-606
This paper explores the influence of polymer enhancement on water uptake and retention by geosynthetic clay liners (GCLs) across a wide suction range (up to 106 kPa), including the low suction regime (0.1–10 kPa) typically omitted in past studies. The suction measurement methods used enabled elucidation of water uptake and retention behaviour through the framework of GCL pore structures and their corresponding suction regimes. Polymer enhanced GCLs (PE-GCLs) have high maximum water uptake, and both the water entry and air expulsion values tend to be high. Due to high swelling, the onset of geotextile confinement for PE-GCLs was observed at high suctions. The impact of polymer becomes more apparent when the bentonite achieves a pseudo-two-layer interlayer hydration state at a suction of about 40 MPa (RH = 75%). The hydration mechanism for the polymer fraction in bentonite is unique to the specific polymer type, polymer dosage, and manufacturing process. The water retention behaviour at the low suction range is caused by the in-filling of geotextile pores, bentonite swelling and extrusion, and polymer water adsorption. Insights from this study can form the basis for developing a more suitable bimodal generalised model for fitting the water retention curves of GCLs. 相似文献
20.
L. H. Li Q. Wang N. X. Wang J. P. Wang 《Bulletin of Engineering Geology and the Environment》2009,68(2):277-285
This paper reports a study of vacuum dewatering using horizontal geosynthetic drainage blankets as a more economical and effective
method of reclamation using layers of dredged material. Laboratory tests were carried out on samples from two different sites
in eastern China, Qingdao City and Lianyungang City. The study showed that the method is feasible and results in a significant
time saving as the construction of the dyke, dredging of the fill and consolidation can be done in a successive process. Using
geosynthetics as the drainage material allows vacuum dewatering in areas where sand is lacking. The strength and stability
of the muck is also enhanced by the placement of horizontal geosynthetic drainage blankets.
Résumé La présente dissertation est consacrée à l’étude sur la déshydratation sous vide en mettant œuvre les couvertures horizontales de drainage en géosynthétique. Cette méthode de restauration des sols est considérée comme plus économique et plus efficace en utilisant des couches de résidu de dragage. Les tests laboratoires ont été effectués sur des échantillons provenant de deux sites différents dans l’est de la Chine, soit la ville de Qingdao et la ville de Lianyungang. L’étude a montré que la méthode est faisable et que les résultats requis dans les meilleurs délais tels que la construction de digue, la drague de remplissage et la consolidation peuvent être réalisés dans un processus successif. L’utilisation des géosynthétiques comme matériels de drainage permet d’appliquer la déshydratation sous vide dans des zones où le sable fait défaut. La force et la stabilité des déblais seront également renforcées par la mise en œuvre des couvertures horizontales de drainage en géosynthétique.相似文献