Research

13 pages, 4910 KiB

Open AccessArticle

Study on Improvement Characteristics of a Novel Geotextile with Stitched Transverse Ribs

by Weichao Liu, He Li, Yan Yang, Peng Xu, Zhengjie Dai, Guangqing Yang, He Wang and Zhijie Wang

Appl. Sci. 2023, 13(3), 1536; https://doi.org/10.3390/app13031536 - 24 Jan 2023

Cited by 1 | Viewed by 1015

Abstract

Geotextile is one of the reinforcement materials adopted in many engineering structures. Conventional geotextiles have a limited reinforcement effect due to the insufficient friction strength between geotextiles and soils. This paper proposes a novel type of geotextile with stitched transverse ribs to improve [...] Read more.

Geotextile is one of the reinforcement materials adopted in many engineering structures. Conventional geotextiles have a limited reinforcement effect due to the insufficient friction strength between geotextiles and soils. This paper proposes a novel type of geotextile with stitched transverse ribs to improve the reinforcement effect. A series of large-scale direct shear tests have been conducted, and the improvement characteristics between conventional geotextiles, geogrids, and the novel geotextiles have been studied. The results show that the novel stitched transverse rib geotextiles can significantly increase the shear strength compared to conventional geotextiles and geogrids. Moreover, due to the restraint and friction effect of ribs on the soils, the reinforcement effect of the novel geotextile is increased with increasing ribs. Insights from this study can provide a new understanding of the novel stitched transverse ribs geotextile’s reinforcement mechanism in engineering. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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29 pages, 4840 KiB

Open AccessArticle

Filtration Performance of Nonwoven Geotextile Filtering Fine-Grained Soil under Normal Compressive Stresses

by Chunxue Du, Chao Xu, Yang Yang and Jiangfeng Wang

Appl. Sci. 2022, 12(24), 12638; https://doi.org/10.3390/app122412638 - 09 Dec 2022

Cited by 1 | Viewed by 1555

Abstract

To avoid serious clogging and loss of drainage capacity, which puts the underground structure at risk of anti-floating failure, the buried drainage filter must be equipped with a nonwoven geotextile layer. In this scenario, nonwoven geotextiles are subjected to normal compressive stress, which [...] Read more.

To avoid serious clogging and loss of drainage capacity, which puts the underground structure at risk of anti-floating failure, the buried drainage filter must be equipped with a nonwoven geotextile layer. In this scenario, nonwoven geotextiles are subjected to normal compressive stress, which can cause changes in geotextile porosity and structure, affecting the filtration behavior of the geotextile filter. In this paper, in order to evaluate the filtration compatibility of the soil–geotextile system, gradient ratio (GR) tests were performed under a hydraulic gradient of 1.0 using a specially designed gradient ratio filtration device capable of applying normal stress. In total four nonwoven geotextiles and two types of soil were used. The results of the gradient ratio filtration tests were discussed in terms of GR values, the permeability of the soil–geotextile system, and the amount of fines retained in geotextiles. It was shown that under a larger normal compressive stress, the GR value would also increase, while the permeability coefficient of the soil–geotextile system decreased. The filtration responses to various soil–geotextile combinations differed under normal compressive stress. A thick nonwoven geotextile with a small filtration opening size exhibited poor filtration performance while benefiting soil retention. Fines retention was influenced by geotextile thickness, soil type, and normal compressive stress magnitude. In addition, for nonwoven geotextiles filter fine-grained soil under normal compressive stress, the test results indicated that anticlogging design criteria should be improved. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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16 pages, 5984 KiB

Open AccessArticle

Analysis of Load Transfer and the Law of Deformation within a Pile-Supported Reinforced Embankment

by Da Zhang, Guangqing Yang, Xin Wang, Zhijie Wang and He Wang

Appl. Sci. 2022, 12(23), 12404; https://doi.org/10.3390/app122312404 - 04 Dec 2022

Viewed by 1211

Abstract

In this paper, the load-transfer mechanism and settlement behaviors of the pile-supported reinforced embankment are reviewed by laboratory model tests, and a series of finite element method (FEM) modellings are conducted to analyze the soil-arching geometry and embankment deformation patterns of the pile-supported [...] Read more.

In this paper, the load-transfer mechanism and settlement behaviors of the pile-supported reinforced embankment are reviewed by laboratory model tests, and a series of finite element method (FEM) modellings are conducted to analyze the soil-arching geometry and embankment deformation patterns of the pile-supported reinforced embankment. The results show that: the embankment load distribution is significantly impacted by the filling cohesion because of the effect of cohesion on the interaction between particles. The soil pressure difference between the center and corner of the pile caps decreases with the increase of filling cohesion. The pile-subsoil stress ratio decreases with the increase of filling cohesion. The embankment deformation behavior and soil-arching geometry are less affected by the change in filling cohesion compared with the influence of pile spacing. That may because of the fact that although the cohesion of the embankment filling has been increased, the granular material’s properties have not been fundamentally changed. Pile-subsoil different settlement decreases with the increase of embankment filling cohesion, and the different settlement at the mid-span between four piles decreases by 4.09% and 6.34%, respectively, as filling cohesion increases from 0 kPa to 11 kPa and 25 kPa. The height of the soil-arching crown decreases with the increase of filling cohesion, and the height of the soil-arching crown between horizontal adjacent piles decreases by 3.85%, 7.69%, and 9.62%, as filling cohesion increases from 5 kPa to 15 kPa, 25 kPa and 45 kPa. The rate of decrease in soil-arching height gradually decreases with increasing cohesion. The height of the soil-arching between the horizontal adjacent piles is about

1.0 (s - a)

. The height of soil arching between the diagonal adjacent piles is about

1.0 \sqrt{2} (s - a)

. The differential settlement at the same height inside the embankment decreases with the increase of filling cohesion, and the height of the equal settlement plane is basically the same as the height of soil arching. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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15 pages, 10171 KiB

Open AccessArticle

Investigation of the Static Characteristics of a Geogrid-Reinforced Embankment

by Yanfu Duan, Jianjun Cheng and Jie Liu

Appl. Sci. 2022, 12(23), 12115; https://doi.org/10.3390/app122312115 - 26 Nov 2022

Viewed by 981

Abstract

The research object of this paper is a geogrid-reinforced embankment. Through numerical simulation and data monitoring, the characteristics of vertical displacement, horizontal displacement, vertical earth pressure, horizontal earth pressure, and internal force in a geogrid-reinforced embankment are studied. The results show that: (1) [...] Read more.

The research object of this paper is a geogrid-reinforced embankment. Through numerical simulation and data monitoring, the characteristics of vertical displacement, horizontal displacement, vertical earth pressure, horizontal earth pressure, and internal force in a geogrid-reinforced embankment are studied. The results show that: (1) According to the analysis of monitoring data, the cumulative horizontal displacement decreases and the cumulative vertical displacement increases with time. Additionally, the cumulative vertical displacement is greater than the cumulative horizontal displacement. (2) The vertical pressure of the fill and tensile stress of the geogrid are largest at the center of the structure section, and the horizontal earth pressure is also largest on both sides of the structure. (3) The numerical simulation value and actual monitoring value of the project are compared with the design value. It is found that the tensile force, horizontal pressure, vertical pressure, horizontal displacement, and vertical displacement of the geogrid are less than the design value. The simulated characteristic value is greater than the actual monitored characteristic value. The research results provide a reference for the design of similar geogrid-reinforced embankments. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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15 pages, 3913 KiB

Open AccessArticle

Effect of Zeolite Content on Permeability of Stone Chip-Bentonite-Zeolite Mixture Using a Single Solution

by Sifa Xu, Yajun Fu, Jun Wang, Jianwei Lv, Xiaobing Xu, Weiwei Wei and Zhe Wang

Appl. Sci. 2022, 12(22), 11732; https://doi.org/10.3390/app122211732 - 18 Nov 2022

Cited by 2 | Viewed by 1052

Abstract

Bentonite is frequently utilized as a landfill lining material due to its high impermeability. Due to the fact that heavy metal ions in leachate can alter the permeability of bentonite liner, the impermeability and metal adsorption effect of bentonite liner is typically enhanced [...] Read more.

Bentonite is frequently utilized as a landfill lining material due to its high impermeability. Due to the fact that heavy metal ions in leachate can alter the permeability of bentonite liner, the impermeability and metal adsorption effect of bentonite liner is typically enhanced by the use of external admixtures. In this investigation, zeolite was combined with stone chips and bentonite. Using a flexible wall permeation test, zeta potential test, and X-ray diffraction test, the effect of zeolite on the permeability and adsorption properties of the mixture was investigated. The results indicate that the addition of zeolite can enhance the impermeability of the mixed soil. The permeability coefficient of the mixed soil in DIW is 3.74 × 10⁻⁷ cm/s when bentonite is incorporated at 11% and decreases to 6.55 × 10⁻⁸, 4.65 × 10⁻⁸, and 5.10 × 10⁻⁸ cm/s when 12.50%, 25%, and 50% of zeolite are incorporated; the permeability coefficient of the mixed soil in DIW was 3.74 × 10⁻⁷ cm/s when the permeate concentration was 0.01 mol/L of ZnCl₂ solution, the permeation coefficients were 5.73 × 10⁻⁷, 5.98 × 10⁻⁸, 5.8 × 10⁻⁸, and 5.7 × 10⁻⁸ cm/s when the zeolite doping was 0, 12.50, 25, or 50%, respectively, and the Zn²⁺ concentration of the leachate decreased compared to the no-zeolite case by 92.48, 97.29, and 98.65%, respectively; the competitive adsorption of metal ions by zeolites in ionic solutions of different concentrations reduced the ionic concentration in the solution and decreased the inhibition of bentonite swelling, while the adsorption characteristics of stone chip-bentonite-zeolite mixture on Zn²⁺ were measured by the Langmuir and Freundlich et al. model. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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16 pages, 8016 KiB

Open AccessArticle

Study of Stress Distribution Characteristics of Reinforced Earth Retaining Walls under Cyclic Loading

by He Wang, Jian Ma, Guangqing Yang and Nan Wang

Appl. Sci. 2022, 12(20), 10237; https://doi.org/10.3390/app122010237 - 12 Oct 2022

Cited by 1 | Viewed by 1663

Abstract

The stress-distribution angle is an important parameter for the design of retaining walls and foundation beds and has a non-negligible role in the rationality of engineering design. There is a lack of research on stress distribution in reinforced earth-retaining walls under cyclic loading. [...] Read more.

The stress-distribution angle is an important parameter for the design of retaining walls and foundation beds and has a non-negligible role in the rationality of engineering design. There is a lack of research on stress distribution in reinforced earth-retaining walls under cyclic loading. In order to study the stress distribution characteristics of geogrid-reinforced soil-retaining walls (GRSW) under cyclic loading, the stress distribution characteristics of GRSW under a different number of load cycles were analyzed by field tests, and the effects of the length of reinforcement, the friction coefficient of the reinforcement–soil interface and the modulus of reinforcement on the stress distribution characteristics of GRSW were analyzed by numerical simulation. The results show that, with the increase in the number of load cycles, the vertical dynamic earth pressure shows a noticeable decreasing trend from high to low along the wall height. The vertical dynamic earth pressure increases first and then decreases along the length of reinforcement. When the number of load cycles increases to more than 100,000, the stress-distribution angle of the GRSW does not change much, the upper part remains at 35~79°, and the middle part remains at 47~68°. The influence depth of stress distribution in GRSW is about 1.13 times the wall height. The interfacial friction coefficient of reinforced soil has a superior influence on the stress distribution in GRSW, followed by the length and modulus of reinforcement. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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18 pages, 7089 KiB

Open AccessArticle

Dynamic Response and Geogrid Strain Analysis of GRS Retaining Wall

by Jiaquan Wang, Wentao Zhong, Zhinan Lin and Yi Tang

Appl. Sci. 2022, 12(19), 9930; https://doi.org/10.3390/app12199930 - 02 Oct 2022

Cited by 5 | Viewed by 2476

Abstract

Modular Geogrid Reinforced Soil (GRS) retaining walls, as flexible structures, usually have a certain deformation capacity. However, the deformation damage of the facing panels will directly affect the durability performance of the retaining wall and pose a threat to the safety and operation [...] Read more.

Modular Geogrid Reinforced Soil (GRS) retaining walls, as flexible structures, usually have a certain deformation capacity. However, the deformation damage of the facing panels will directly affect the durability performance of the retaining wall and pose a threat to the safety and operation of the road and related facilities. In order to study the influence of different load factors on the deformation mode and failure characteristics of the retaining wall, an indoor large-scale model test was carried out. The test load considers the average load, peak value, amplitude and frequency of load under traffic load. The changes in settlement and horizontal deformation, geogrid strain and acceleration response of the GRS retaining wall are compared and analyzed. The results show that in the dynamic test, the two wall damage modes are “wall facing outward tilt” and “wall facing outward curved”. The maximum strain of the geogrid was 4.5% and 3.6%, respectively, which did not reach the damage strain. The peak load is the largest mechanical response of all load factors, followed by the load magnitude and average value, and finally the load frequency. In addition, combining the existing GRS retaining wall deformation and earth pressure calculation theory, a set of calculation methods for the strain of tendons under external load is proposed. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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13 pages, 19024 KiB

Open AccessArticle

Experimental Study on the Mechanical Behaviors of Loess Reinforced with Randomly Distributed Basalt Fiber

by Honggang Kou, Qiang Ma and Shunli Han

Appl. Sci. 2022, 12(19), 9744; https://doi.org/10.3390/app12199744 - 28 Sep 2022

Cited by 1 | Viewed by 1064

Abstract

Loess has the structural characteristics of porous, weakly cemented and under compacted, leading to its collapsible, disintegrative and dissolute features. To study the mechanical behaviors of basalt fiber-reinforced loess, consolidated undrained triaxial tests were carried out to investigate the effects of fiber length [...] Read more.

Loess has the structural characteristics of porous, weakly cemented and under compacted, leading to its collapsible, disintegrative and dissolute features. To study the mechanical behaviors of basalt fiber-reinforced loess, consolidated undrained triaxial tests were carried out to investigate the effects of fiber length (FL), fiber content (FC) and cell pressure (σ₃) on the shear strength. Based on the test results, a constitutive model considering the effects of the σ₃, FL and FC was established using regression analysis, and the estimation method for the model parameters was proposed. The results show that the stress–strain curve of the unreinforced loess exhibited a strain-softening type, while the reinforced loess displayed a strain-hardening type. The peak strength of the reinforced loess was significantly higher than that of the unreinforced soil, and increased with increasing of FL, FC and σ₃. Compared with the peak strength when FL was 8 mm, the peak strength increased slightly when the FL was 12 and 16 mm, respectively. The anchoring effect and bridging effect between soil particles and fibers improved the cohesion and friction of reinforced soil, resulting in the increment in the shear strength. The experimental results are in good agreement with the model predictions, indicating that the established model and the parameter estimation method are suitable for describing the relationship between the stress and strain of basalt-fiber-reinforced loess. The research results can provide guidance of the design and construction of fiber-reinforced soil in loess areas. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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17 pages, 4870 KiB

Open AccessArticle

Study of the Subsidence Width Influence on the Geotextile Control of a Subgrade Collapse Based on a Half-Symmetric Model Test

by Di Wu, Yihuai Liang, Yanxin Yang and Jianjian Wu

Appl. Sci. 2022, 12(19), 9504; https://doi.org/10.3390/app12199504 - 22 Sep 2022

Viewed by 969

Abstract

The geotextile can be used to treat a subgrade collapse in karst areas. The subsidence width is an important factor affecting the geotextile to treat subgrade collapses. However, the available studies on the influence of the subsidence width on geotextile treatment settlement are [...] Read more.

The geotextile can be used to treat a subgrade collapse in karst areas. The subsidence width is an important factor affecting the geotextile to treat subgrade collapses. However, the available studies on the influence of the subsidence width on geotextile treatment settlement are limited. To study the effect of the subsidence width on the geotextile control of subgrade collapses, the half-symmetric model test had been established. To make up for the deficiencies of the model test, the optimized subsidence width was probed through a numerical calculation under ten different situations conducted by the finite element analyses. Previous full-section model test results were used to verify the rationality of the half-symmetric model and calibrate the input parameters of the numerical models. The influence of the subsidence width on soil pressure, tensile force and deformation of the geotextile, and soil settlement was analyzed. With the increase of the subsidence width, more loads of the subsidence area were transferred to a stable area via the geotextile, the vertical normal stress at the edge increased rapidly, the tensile force of the geotextile and vertical soil displacement in the subsidence area increased noticeably. When the anchorage ratio of L ≤ 2.0B, the geotextile fracture or soil failure occurred during the model test which indicated the geotextile treatment of the subgrade collapse was not suitable for projects with an anchorage ratio of L ≤ 2.0B. The geotextile might be reaching the limit of its tensile stiffness when the anchorage ratio of L = 2.22B. This is providing an insight into the treatment of a subgrade collapse in karst areas using geotextile. Full article

(This article belongs to the Special Issue Advances in Geosynthetics, Volume II)

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