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Advances in Geosynthetics
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Advances in Geosynthetics

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Civil Engineering".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 35266

Special Issue Editors

Prof. Dr. Xiaowu Tang

E-Mail Website
Guest Editor
Deputy-Dean of International College, Research Center of Costal and Urban Geotechnical Engineering, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China
Interests: geosynthetics; ground improvement and multi-function pile foundation; geoenvironmental engineering; tunneling engineering; heritage protection
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Chao Xu

E-Mail Website
Guest Editor
PI of Soil Engineeirng and Coastal Engineering Geology, Geotechnical Engineering Department, Civil Engineering College, Tongji University, Shanghai 200092, China
Interests: geosynthetics; ground improvement; geotechnical engineering investigation; coastal engineering geology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Geosynthetics is wildly used in civil engineering, hydraulic engineering, transportation engineering, mining projects, environmental protection, agricultural production, solutions for natural disasters, etc. to provide technical, environmental, and economic contributions. The Special Issue Advances in Geosynthetics will address the most recent developments in geosynthetics, stimulating fruitful technical and scientific interaction between professionals.

The following are some of the topics proposed for the Special Issue (not an exhaustive list):

  • Barrier systems and geoenvironment;
  • Hydraulics and filtration;
  • Reinforcement and soil stabilization;
  • Design approaches and numerical solutions;
  • Case histories and field experience;
  • Durability and long-term performance;
  • Natural fiber products and replacement of geosynthetics;
  • Innovative uses and sustainable development.

Prof. Dr. Xiaowu Tang
Prof. Dr. Chao Xu
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • geosynthetics
  • slope stability
  • ground improvement
  • behavior of geomaterials
  • hydraulic conductivity
  • GCL
  • hydration
  • soft clay
  • load transfer
  • piled embankment
  • shaking table
  • geosynthetic reinforced soil (GRS)
  • integrated bridge system (IBS)
  • centrifuge
  • shear strength
  • mechanically stabilized earth (MSE)
  • landfill
  • numerical modeling
  • smart soils
  • sustainability

Published Papers (18 papers)

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Research

16 pages, 5591 KiB  
Article
A Numerical Study of Chemical Compatibility of GCLs
by Juan Hou, Rui Sun, Chen-Xi Chu, Mpundu Karen and Marem Nasser
Appl. Sci. 2022, 12(4), 2182; https://0-doi-org.brum.beds.ac.uk/10.3390/app12042182 - 19 Feb 2022
Cited by 1 | Viewed by 1360
Abstract
A series of COMSOL numerical models were established to study the chemical compatibility of GCLs (geosynthetic clay liner). The effect of chemistry on the mesoscopic structure and the hydraulic conductivity of GCLs was investigated. The factors, including the initial mobile porosity, the swelling [...] Read more.
A series of COMSOL numerical models were established to study the chemical compatibility of GCLs (geosynthetic clay liner). The effect of chemistry on the mesoscopic structure and the hydraulic conductivity of GCLs was investigated. The factors, including the initial mobile porosity, the swelling ratio, the pore size, and the ionic strength, were discussed as well. The mesoscopic mechanism of the physical and chemical processes of GCLs was explored by the COMSOL models. The hypothesis that the final mobile porosity and the final pore size are the key factors of the hydraulic conductivity of GCLs was proven by the simulation. Meanwhile, when the ionic strength increased from low to medium, the changes in pore size, mobile porosity, and hydraulic conductivity were obvious. However, when the ionic strength increased from medium to high, the changes of these parameters tended to be gentle, and the changes in hydraulic conductivity were not obvious. Moreover, a theoretical model considering the effect of the initial particle size, the initial mobile porosity, and the ionic strength was developed to predict the hydraulic conductivity of GCLs in a chemical solution. This theoretical model was verified by experimental data. A good agreement was obtained. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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12 pages, 3391 KiB  
Article
Geosynthetic Interface Friction at Low Normal Stress: Two Approaches with Increasing Shear Loading
by Paolo Pavanello, Paolo Carrubba and Nicola Moraci
Appl. Sci. 2022, 12(3), 1065; https://0-doi-org.brum.beds.ac.uk/10.3390/app12031065 - 20 Jan 2022
Cited by 2 | Viewed by 1536
Abstract
The evaluation of geosynthetic interface friction is a key parameter for the stability of coupled geosynthetics, as in landfill capping liner. At the present time, few types of tests are suitable for measuring the interface friction at low normal stress: one of these [...] Read more.
The evaluation of geosynthetic interface friction is a key parameter for the stability of coupled geosynthetics, as in landfill capping liner. At the present time, few types of tests are suitable for measuring the interface friction at low normal stress: one of these is the inclined plane, usually carried out under a vertical stress of 5 kPa. This type of test is not without critical aspects, mainly due to the nonuniform normal stress state induced by the inclination of the plane, but, on the other hand, the most widespread direct shear test generally cannot be performed at such low values of normal stress. After a short discussion on the pros and cons of these two types of test, the paper presents a comparison of the interface friction angles obtained, for three interfaces, by means of an inclined plane and an unconventional direct shear apparatus, under the same low normal stress. The peculiarity of this latter device is of ensuring a gradual increase of the mobilized strength, in a way similar to what occurs during the inclined plane test. The good correspondence of the results of the two types of tests confirmed the validity of both the test approaches. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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15 pages, 5545 KiB  
Article
Analysis of the Working Performance of a Back-to-Back Geosynthetic-Reinforced Soil Wall
by Guangqing Yang, Yunfei Zhao, He Wang and Zhijie Wang
Appl. Sci. 2022, 12(1), 516; https://0-doi-org.brum.beds.ac.uk/10.3390/app12010516 - 05 Jan 2022
Cited by 2 | Viewed by 1960
Abstract
Back-to-back geosynthetic-reinforced soil walls (BBGRSWs) are commonly used in embankments approaching bridges and narrow spaces. However, the available literature and design guidelines for BBGRSWs are limited. The aims of this research were to develop a greater understanding of the working performance of BBGRSWs [...] Read more.
Back-to-back geosynthetic-reinforced soil walls (BBGRSWs) are commonly used in embankments approaching bridges and narrow spaces. However, the available literature and design guidelines for BBGRSWs are limited. The aims of this research were to develop a greater understanding of the working performance of BBGRSWs and to optimize the design method of a BBGRSW to ensure the cost-efficiency as well as the stability of the structure. On the basis of a monitored BBGRSW structure located in China, we established a numerical model. The parameters of the materials used in the actual project were determined through triaxial and tensile tests. The numerical results were compared with the measured results in the field to verify the correctness of the selected parameters. Two parameters were investigated by the FEM method: the reinforcement length and the arrangement. The FEM analysis indicated that post-construction deformations such as displacement and settlement could be reduced by reinforcing the same layer on both sides. Longer reinforcements were needed to achieve the same performance if the reinforcements were cross-arranged. Thus, BBGRSWs can have a superior performance if the reinforcements are connected in the middle from both sides. Even with longer reinforcements, the safety factor of the wall with a cross-arranged reinforcement was smaller than that with same-layered reinforcements. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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14 pages, 1484 KiB  
Article
Monitoring of the Variation in Pore Sizes of Woven Geotextiles with Uniaxial Tensile Strain
by Wenfang Zhao, Xiaowu Tang, Keyi Li, Jiaxin Liang, Weikang Lin and Xiuliang Chen
Appl. Sci. 2022, 12(1), 374; https://0-doi-org.brum.beds.ac.uk/10.3390/app12010374 - 31 Dec 2021
Cited by 2 | Viewed by 1672
Abstract
Characteristic pore-opening size O95 or O90 has been widely used in the filter design of woven geotextiles. These manufactured products have different pore size proportions of large pore diameters, medium pore diameters, and small pore diameters, respectively. Therefore, uncertainties still exist [...] Read more.
Characteristic pore-opening size O95 or O90 has been widely used in the filter design of woven geotextiles. These manufactured products have different pore size proportions of large pore diameters, medium pore diameters, and small pore diameters, respectively. Therefore, uncertainties still exist regarding the prediction of geotextile pore diameter variations under the uniaxial tensile strain. This paper investigates the variations in five characteristic pore-opening sizes O95, O80, O50, O30, and O10, with uniaxial tensile strain by using the image analysis method. The large pore diameters, medium pore diameters, and small pore diameters show different variation behaviors as the uniaxial tensile strain increases. Fifteen specific pores are selected and then their pore diameter variations are monitored under each tensile strain of 1%. The colorful pore size distribution diagram is a visual way to identify the variation of pores arranged in the tension direction (warp direction) and the direction perpendicular to tensile loads (weft direction). The various pore diameters are proved to agree well with the bell-shaped Gaussian distribution. The results exhibit an accurate prediction of the variation in large pore sizes, medium pore sizes, and small pore sizes, respectively, for all tested woven geotextiles with uniaxial tensile strain. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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16 pages, 4595 KiB  
Article
Experimental Investigation on the Behavior of Gravelly Sand Reinforced with Geogrid under Cyclic Loading
by Jia-Quan Wang, Zhen-Chao Chang, Jian-Feng Xue, Zhi-Nan Lin and Yi Tang
Appl. Sci. 2021, 11(24), 12152; https://0-doi-org.brum.beds.ac.uk/10.3390/app112412152 - 20 Dec 2021
Cited by 3 | Viewed by 2181
Abstract
In view of the dynamic response of geogrid-reinforced gravel under high-speed train load, this paper explores the dynamic characteristics of geogrid-reinforced gravel under semi-sine wave cyclic loading. A number of large scale cyclic triaxial tests were performed on saturated gravelly soil reinforced with [...] Read more.
In view of the dynamic response of geogrid-reinforced gravel under high-speed train load, this paper explores the dynamic characteristics of geogrid-reinforced gravel under semi-sine wave cyclic loading. A number of large scale cyclic triaxial tests were performed on saturated gravelly soil reinforced with geogrid to study the influence of the number of reinforcement layers and loading frequencies on the dynamic responses of reinforced gravelly sand subgrade for high speed rail track. The variation of cumulative axial and volumetric strains, excess pore pressure and resilient modulus with number of loading cycles, loading frequency, and reinforcement arrangement are analyzed. The test results reveal that the cumulative axial strain decreases as the number of reinforcement layers increases, but increases with loading frequency. The resilience modulus increases with the number of reinforcement layers, but decreases as the loading frequency increases. The addition of geogrid can reduce the excess pore water pressure of the sample, but it can slightly enhance the rubber mold embedding effect of the sand sample. As the loading frequency increases, the rubber mold embedding effect gradually weakens. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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20 pages, 4902 KiB  
Article
Application of a Geotextile in the Treatment of Post-Subsidence in Karst Areas
by Di Wu, Chen Luo, Yuankun Li, Yanxin Yang, Yihuai Liang and Jianjian Wu
Appl. Sci. 2021, 11(24), 11826; https://0-doi-org.brum.beds.ac.uk/10.3390/app112411826 - 13 Dec 2021
Cited by 2 | Viewed by 1874
Abstract
The use of a geotextile to treat subgrade subsidence after subsidence has occurred is investigated in this paper. To optimize the anchorage length and buried depth of the geotextile and evaluate the influences of the two factors on subgrade subsidence treatment, finite element [...] Read more.
The use of a geotextile to treat subgrade subsidence after subsidence has occurred is investigated in this paper. To optimize the anchorage length and buried depth of the geotextile and evaluate the influences of the two factors on subgrade subsidence treatment, finite element analysis is performed and validated with existing model tests. The soil pressure, displacement, tensile force and deformation of the geotextile are studied. The results showed that the geotextile prevented an upward development of subsidence and stabilized the upper soil. The increase of the anchorage length of the geotextile transferred greater soil pressure from the subsidence to a stable area, induced a greater tensile force in the geotextile, and resulted in less soil displacement. As the anchorage length of the geotextile increased from 375 mm to 1500 mm, the surface settlement was effectively reduced from 1.05% to 34.18% when comparing to the situation without a geotextile. As the buried depth of the geotextile increased from 2 m to 6 m, the percentage of surface settlement was effectively reduced from 29.14% to 65.91% when comparing with the settlement corresponding to a buried depth of 2 m. It is suggested that the anchorage length of a geotextile should be the length of the subsidence with respect to width and that the buried depth of the geotextile should be 3–4 m for subsidence treatment. This provides insight into the treatment of sinkholes using geosynthetic approaches in karst areas. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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14 pages, 2688 KiB  
Article
Model Test on Mechanical and Deformation Property of a Geomembrane Surface Barrier for a High Rockfill Dam
by Haimin Wu, Luming Feng, Zhaoming Teng and Yiming Shu
Appl. Sci. 2021, 11(23), 11505; https://0-doi-org.brum.beds.ac.uk/10.3390/app112311505 - 04 Dec 2021
Cited by 1 | Viewed by 1403
Abstract
The cushion of a geomembrane surface barrier of a high rockfill dam built on deep overburden is prone to crack and fail because of excessive flexural deformation. This study proposes a geomembrane surface barrier for a high rockfill dam on deep overburden. The [...] Read more.
The cushion of a geomembrane surface barrier of a high rockfill dam built on deep overburden is prone to crack and fail because of excessive flexural deformation. This study proposes a geomembrane surface barrier for a high rockfill dam on deep overburden. The proposed geomembrane surface barrier uses polyurethane bonded aggregates as the cushion material. The loading and deformation performance of the barrier system under uniform water pressure was investigated using a self-developed structure model test device. The mechanical and deformation property of each layer of the barrier, and the interaction mode between adjacent layers, were obtained through external videos and internal sensor monitoring. The results demonstrated that the polyurethane bonded aggregate cushion exhibited good adaptability to flexural deformation during the entire loading process and maintained good contact and coordinate deformation with the upper protective and the lower transition layers. The geomembrane surface barrier created using polyurethane bonded aggregates as the cushion material can adapt to the flexural deformation of a high rockfill dam surface on deep overburden. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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18 pages, 5851 KiB  
Article
Anisotropic Shear Strength Behavior of Soil–Geogrid Interfaces
by Jun Zhang, Mingchang Ji, Yafei Jia, Chenxi Miao, Cheng Wang, Ziyang Zhao and Yewei Zheng
Appl. Sci. 2021, 11(23), 11387; https://0-doi-org.brum.beds.ac.uk/10.3390/app112311387 - 01 Dec 2021
Cited by 3 | Viewed by 1929
Abstract
This paper presents an experimental study on the anisotropic shear strength behavior of soil–geogrid interfaces. A new type of interface shear test device was developed, and a series of soil–geogrid interface shear tests were conducted for three different biaxial geogrids and three different [...] Read more.
This paper presents an experimental study on the anisotropic shear strength behavior of soil–geogrid interfaces. A new type of interface shear test device was developed, and a series of soil–geogrid interface shear tests were conducted for three different biaxial geogrids and three different triaxial geogrids under the shear directions of 0°, 45° and 90°. Clean fine sand, coarse sand, and gravel were selected as the testing materials to investigate the influence of particle size. The experimental results for the interface shear strength behavior, and the influences of shear direction and particle size are presented and discussed. The results indicate that the interface shear strength under the same normal stress varies with shear direction for all the biaxial and triaxial geogrids investigated, which shows anisotropic shear strength behavior of soil–geogrid interfaces. The soil–biaxial geogrid interfaces show stronger anisotropy than that of the soil–triaxial geogrid interfaces under different shear directions. Particle size has a great influence on the anisotropy shear strength behavior of soil–geogrid interfaces. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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13 pages, 2062 KiB  
Article
A Study of the Effects of Geosynthetic Reinforced Soil and Reinforcement Length on GRS Bridge Abutment
by Myoung-Soo Won and Christine Patinga Langcuyan
Appl. Sci. 2021, 11(23), 11226; https://0-doi-org.brum.beds.ac.uk/10.3390/app112311226 - 26 Nov 2021
Cited by 3 | Viewed by 1962
Abstract
The geosynthetic reinforced soil (GRS) bridge abutment with a staged-construction full height rigid (FHR) facing and an integral bridge (IB) system was developed in Japan in the 2000s. This technology offers several advantages, especially concerning the deformation behavior of the GRS-IB abutment. In [...] Read more.
The geosynthetic reinforced soil (GRS) bridge abutment with a staged-construction full height rigid (FHR) facing and an integral bridge (IB) system was developed in Japan in the 2000s. This technology offers several advantages, especially concerning the deformation behavior of the GRS-IB abutment. In this study, the effects of GRS in the bridge abutment with FHR facing and the effects of geosynthetics reinforcement length on the deformation behavior of the GRS–IB are presented. The numerical models are analyzed using the finite element method (FEM) in Plaxis 2D program. The results showed that the GRS–IB model exhibited the least lateral displacements at the wall facing compared to those of the IB model without geosynthetics reinforcement. The geosynthetics reinforcement in the bridge abutment with FHR facing has reduced the vertical displacement increments by 4.7 times and 1.3 times (maximum) after the applied general traffic loads and railway loads, respectively. In addition, the numerical results showed that the increase in the length-to-height (L/H) ratio of reinforcement from 0.3H to 1.1H decreases the maximum lateral displacements by 29% and the maximum vertical displacements by 3% at the wall facing by the end of construction. The effect of the reinforcement length on the wall vertical displacements is minimal compared to the effect on the wall lateral displacements. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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15 pages, 3544 KiB  
Article
Response of Mechanical Properties of Polyvinyl Chloride Geomembrane to Ambient Temperature in Axial Tension
by Xianlei Zhang, Zhongyang Ma, Yunyun Wu and Jianqun Liu
Appl. Sci. 2021, 11(22), 10864; https://0-doi-org.brum.beds.ac.uk/10.3390/app112210864 - 17 Nov 2021
Cited by 4 | Viewed by 1847
Abstract
Aiming at the mechanical response of geomembrane (GEM) in membrane-faced rockfill dam (MFRD) to different ambient temperatures, the mechanical properties in axial tension of polyvinyl chloride (PVC) GEM were studied by experiment and theoretical analysis. First, fifteen groups of axial tensile tests for [...] Read more.
Aiming at the mechanical response of geomembrane (GEM) in membrane-faced rockfill dam (MFRD) to different ambient temperatures, the mechanical properties in axial tension of polyvinyl chloride (PVC) GEM were studied by experiment and theoretical analysis. First, fifteen groups of axial tensile tests for longitudinal/transverse specimens were conducted at different temperatures in the temperature environment laboratory, the stress–strain curve and Young’s modulus were obtained, and the variation of Young’s modulus with temperature was analyzed by Boltzmann function fitting. Second, the glass transition temperature of PVC GEM was obtained by differential scanning calorimetry (DSC), and the difference in mechanical properties between longitudinal and transverse specimens of PVC GEM was analyzed by thermomechanical analyzer (TMA) thermodynamic test. The results showed that the lower the temperature, the greater the Young’s modulus, and the smaller the linear interval of stress and strain, while the higher the temperature, the result is opposite. The difference in mechanical properties between the two directions is related to the ambient temperature. The orientation of polymer structure accounts for the difference in mechanical properties by theoretical analysis. The fitting results of Boltzmann function have a certain reference value for numerical simulation. In design of the membrane impervious structure in MFRD, the ambient temperature should be considered fully, and the longitudinal/transverse welding splicing should be avoided as far as possible. The current test specification should test the mechanical performance of GEM at normal operating temperature of reservoir instead of the test and quality evaluation at a single temperature. The temperature should be considered comprehensively in construction to avoid damaging the performance of impervious structure and ensure the service life. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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14 pages, 2773 KiB  
Article
Investigation of the Mechanical Behavior of Polypropylene Fiber-Reinforced Red Clay
by Jia Liu, Xi’an Li, Gang Li and Jinli Zhang
Appl. Sci. 2021, 11(22), 10521; https://0-doi-org.brum.beds.ac.uk/10.3390/app112210521 - 09 Nov 2021
Cited by 4 | Viewed by 1419
Abstract
Red clay is not easy to use as a natural foundation because of its high water content, high plasticity index, large void ratio, and susceptibility to shrinkage and cracking. In this study, consolidated undrained triaxial tests were conducted to examine the mechanical properties [...] Read more.
Red clay is not easy to use as a natural foundation because of its high water content, high plasticity index, large void ratio, and susceptibility to shrinkage and cracking. In this study, consolidated undrained triaxial tests were conducted to examine the mechanical properties of polypropylene fiber-reinforced red clay and to analyze the influence of the fiber content (FC), fiber length (FL), and cell pressure on its shear strength. By performing a regression analysis on the test data, a hyperbolic constitutive model that considers the influence of FC, FL, and cell pressure was established, and a method was developed to estimate the parameters of the model. The findings show that, in contrast with the nonreinforced red clay, the fiber-reinforced red clay had a stress-strain curve characterized by typical strain hardening, with the shear strength increasing with FC, FL and cell pressure. The calculated results of the model coincide with the test results well, confirming that the hyperbolic model could appropriately describe the stress-strain relationship of polypropylene fiber-reinforced red clay and have reference value for the design and construction of fiber-reinforced red clay foundations. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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17 pages, 4819 KiB  
Article
Analysis of Layered Geogrids–Sand–Clay Reinforced Structures under Triaxial Compression by Discrete Element Method
by Lan Cui, Wenzhao Cao, Qian Sheng, Mingxing Xie, Tao Yang and Ping Xiao
Appl. Sci. 2021, 11(21), 9952; https://0-doi-org.brum.beds.ac.uk/10.3390/app11219952 - 25 Oct 2021
Cited by 1 | Viewed by 1576
Abstract
Compared with the commonest geosynthetics-reinforced soil structures, layered geogrids–sand–clay reinforced (LGSCR) structures (School of Architecture and Civil Engineering, Shenyang University of Technology, Shenyang 110870, China) can replace granular materials with clay as the primary backfill material. Up until now, the performance of LGSCR [...] Read more.
Compared with the commonest geosynthetics-reinforced soil structures, layered geogrids–sand–clay reinforced (LGSCR) structures (School of Architecture and Civil Engineering, Shenyang University of Technology, Shenyang 110870, China) can replace granular materials with clay as the primary backfill material. Up until now, the performance of LGSCR structures under triaxial compression has been unclear. In this paper, the discrete element method was used to simulate the triaxial compression test on the LGSCR samples. Based on the particle flow software PFC3D, three types of cluster particle-simulated sand and the reinforced joints of the geogrid were constructed by secondary development. The effects of the geogrid embedment in sand layers, the number and thickness of sand layers in relation to the deviatoric stress, and the axial strain and the shear strength index of the LGSCR samples were analyzed. The results showed that laying the sand layers in the samples can improve their post-peak strain-softening characteristics and increase their peak strengths under a high confining pressure. A geogrid embedment in sand layers can further enhance the ductility and peak strength of the samples, and in terms of the shear strength index, there is a 41.6% to 54.8% increase in the apparent cohesion of the samples. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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17 pages, 3435 KiB  
Article
Effect of Boundary Conditions on the Mechanical Behavior of the Geogrid–Soil Interface
by Zheng Zuo, Guangqing Yang, Zhijie Wang, He Wang and Jing Jin
Appl. Sci. 2021, 11(21), 9942; https://0-doi-org.brum.beds.ac.uk/10.3390/app11219942 - 25 Oct 2021
Cited by 3 | Viewed by 1621
Abstract
Geogrid-reinforced structures are extensively adopted in various engineering fields. At present, the influence of boundary conditions was not considered in design methods, bringing hidden dangers to the safety of the structure. In the current study, a series of pullout tests were carried out [...] Read more.
Geogrid-reinforced structures are extensively adopted in various engineering fields. At present, the influence of boundary conditions was not considered in design methods, bringing hidden dangers to the safety of the structure. In the current study, a series of pullout tests were carried out on high-density polyethylene (HDPE) geogrid-reinforced coarse sand. The magnitude and growth pattern of pullout resistance and the variation laws of interfacial shear strength indexes under four types of boundary conditions were analyzed. Additionally, the boundary reduction coefficient (BRC) was introduced to establish the relationship between rigid and flexible boundary for the design of the structure. The tests results showed that the boundary conditions cannot be ignored in the design of structures, especially in the front. When the normal loading was up to 120 kPa, the BRC-top and BRC-positive could be taken as 0.9 and 0.5, respectively, and verified by fitting results. The boundary conditions affected the pullout resistance, while the vertical loading corresponding to the maximum pullout resistance was not related to boundary conditions. Investigating the interaction of the geogrid–soil under different boundary conditions can help to improve the understanding of the behavior of reinforced soil structure, and to achieve a more efficient and economical design. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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18 pages, 20752 KiB  
Article
Analysis of Factors for Compacted Clay Liner Performance Considering Isothermal Adsorption
by Xing Zeng, Hengyu Wang, Jing Yao and Yuheng Li
Appl. Sci. 2021, 11(20), 9735; https://0-doi-org.brum.beds.ac.uk/10.3390/app11209735 - 18 Oct 2021
Cited by 2 | Viewed by 1828
Abstract
The concentration profiles and breakthrough curves of the 2 m thick compacted clay liner (CCL) given in the specification were compared, considering three different adsorption isotherms (upper convex, linear, and lower concave). In addition, the effects of transport parameters, sorption isotherms, and source [...] Read more.
The concentration profiles and breakthrough curves of the 2 m thick compacted clay liner (CCL) given in the specification were compared, considering three different adsorption isotherms (upper convex, linear, and lower concave). In addition, the effects of transport parameters, sorption isotherms, and source concentrations on pollutant migration were analyzed. The results showed that the dimensionless breakthrough curves of different source concentrations considering the linear adsorption isotherm coincided with each other, as the partition coefficient of the linear adsorption isotherm was constant. For the lower concave isotherm, the migration of a large source concentration was slowest, because the partition coefficient of the lower concave isotherm increased with an increase in concentration. For the upper convex isotherm, the migration of a large source concentration was fastest, because the partition coefficient decreased with an increase in concentration. The effects of the nonlinear isotherms on the shape of the outflow curve were similar to the effects of a change in the hydrodynamic dispersion (Dh): the concentration front of the upper convex isotherm was narrower, which was similar to the effect of a reduction in Dh (i.e., PL), and the concentration front of the lower concave isotherm was wider and similar to the effect of an increase Dh (i.e., PL). Therefore, the diffusion and adsorption parameters were fitted separately in the study, in case the nonlinear adsorption behavior was mistakenly defined as linear adsorption. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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15 pages, 15549 KiB  
Article
DEM-FDM Coupled Numerical Study on the Reinforcement of Biaxial and Triaxial Geogrid Using Pullout Test
by Jianjun Fu, Junfeng Li, Cheng Chen and Rui Rui
Appl. Sci. 2021, 11(19), 9001; https://0-doi-org.brum.beds.ac.uk/10.3390/app11199001 - 27 Sep 2021
Cited by 1 | Viewed by 2111
Abstract
The key to modeling the interlocking of geogrid-reinforced ballast is considering both the continuous deformation characteristics of the geogrid and the discontinuity of the ballast particles. For this purpose, pullout tests using biaxial and triaxial geogrids were simulated using the coupled discrete element [...] Read more.
The key to modeling the interlocking of geogrid-reinforced ballast is considering both the continuous deformation characteristics of the geogrid and the discontinuity of the ballast particles. For this purpose, pullout tests using biaxial and triaxial geogrids were simulated using the coupled discrete element method (DEM) and finite difference method (FDM). In this coupled model, two real-shaped geogrid models with square and triangular apertures were established using the solid element in FLAC3D. Meanwhile, simplified shaped clumps were used to represent the ballast using PFC3D. The calibration test simulation showed that the accurately formed geogrid model can reproduce the deformation and strength characteristics of a geogrid. The pullout simulation results show that the DEM-FDM method can well predict the relationship between pullout force and displacement, which is more accurate than the DEM method. For ballast particles of 40 mm in size, both the experiment and simulation results showed that the triaxial geogrid of 75 mm is better than the 65-mm biaxial geogrid. In addition, the DEM-FDM method can study the interaction mechanism between the particles and the geogrid from a microscopic view, and also reveal the similar deformation behavior of the geogrid in the pullout process. Therefore, the DEM-FDM coupled method can not only investigate the interlocking mechanism between the ballast and particles but can also provide a great method for evaluating the performance of different types of geogrids. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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11 pages, 2093 KiB  
Article
The Influence of Discrete Fibers on Mechanical Responses of Reinforced Sand in Direct Shear Tests
by Chidochashe Clemency Nhema, Han Ke, Pengcheng Ma, Yunmin Chen and Shiyu Zhao
Appl. Sci. 2021, 11(19), 8845; https://0-doi-org.brum.beds.ac.uk/10.3390/app11198845 - 23 Sep 2021
Cited by 2 | Viewed by 1705
Abstract
To investigate the influences of discrete fiber strips on the mechanical properties of reinforced sand, a series of direct shear tests were conducted. A method to strictly control the initial orientation of fiber strips in specimen preparation was developed. Under the same normal [...] Read more.
To investigate the influences of discrete fiber strips on the mechanical properties of reinforced sand, a series of direct shear tests were conducted. A method to strictly control the initial orientation of fiber strips in specimen preparation was developed. Under the same normal pressure, the peak strength of sand specimens was proportional to the fiber content and was inversely proportional to the fiber initial orientation angle. The influences of initial fiber orientation on peak strength may depend on the stress mobilization in fibers. When the fiber strips distributed at a certain orientation angle were subjected to tensile stress in shearing, they could play an effective role in the peak strength gain of sand and vice versa. Due to the restriction of fibers on the volume dilation of sand specimens, the residual strength of reinforced sand also increased. However, the initial stiffness of reinforced sand was smaller than that of pure sand, which may be related to the precompression of flexible fiber strips and the density inhomogeneity of specimens induced in the specimen preparation process. In addition, the ductility of sand specimens was improved by the introduction of fiber strips, intuitively reflected by the increase in displacement failure. This may also be attributed to the restriction of fiber strips on the deformation of sand specimens. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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17 pages, 8880 KiB  
Article
DEM Simulation of the Load Transfer Mechanism of a GRPS Embankment with a Fixed Geogrid Technique
by Jun Zhang, Yafei Jia, Yewei Zheng and Chenxi Miao
Appl. Sci. 2021, 11(19), 8814; https://0-doi-org.brum.beds.ac.uk/10.3390/app11198814 - 22 Sep 2021
Cited by 3 | Viewed by 1694
Abstract
As a new technique, a fixed geogrid in a geogrid-reinforced and pile-supported (GRPS) embankments has been used to reduce the total and differential settlement. To investigate the load transfer mechanism of the fixed geogrid technique of a GRPS embankment, three discrete element method [...] Read more.
As a new technique, a fixed geogrid in a geogrid-reinforced and pile-supported (GRPS) embankments has been used to reduce the total and differential settlement. To investigate the load transfer mechanism of the fixed geogrid technique of a GRPS embankment, three discrete element method (DEM) models of pile-supported embankments were established, including an unreinforced embankment, a geogrid reinforced embankment, and a fixed geogrid reinforced embankment. The efficacy of the pile, the evolution law of the contact force chain and the axial force of the reinforcement, and the microscopic load-bearing structure of the soil were investigated. Numerical simulation results showed that the embankment self-weight and surcharge load were transferred to the pile through the soil arching and tensile membrane effect. The settlement could be effectively reduced via the addition of the reinforcement, and the fixed geogrid technique was more conducive to improving the load-bearing ratio of the pile than the traditional reinforcement technique. Compared with the traditional technique of a GRPS embankment, the fixed geogrid technique had a better effect on reducing the total and differential settlement. With the increase in the surcharge load and the settlement of the soft subsoil, the reinforcement transferred a greater load to the pile. The results also showed that the stress of the embankment fill was concentrated at the pile top in all three models. The GRPS embankment with a fixed geogrid technique had a lower soil stress concentration than the other two cases. The contact force chain and stress in the embankment also showed that the reformation of the microscopic load-bearing system of the embankment fill was the internal mechanism that caused the development of the soil arching and the redistribution of stress. Furthermore, the evolution of the fabric parameters in the arching area could reflect the evolution of the soil arching structure. In the fixed geogrid case, the proportion of the load transferred to the pile from the soil arching effect was reduced, and the vertical load transferred to the pile top by the tensile membrane effect accounted for 22–28% in this study. Under the combined effect of the tensile membrane and the soil arching, the efficacy of the pile could increase by 10%. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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15 pages, 3219 KiB  
Article
A Review of the Methods Calculating the Horizontal Displacement for Modular Reinforced Soil Retaining Walls
by Xiaoguang Cai, Shaoqiu Zhang, Sihan Li, Honglu Xu, Xin Huang and Chen Zhu
Appl. Sci. 2021, 11(18), 8681; https://0-doi-org.brum.beds.ac.uk/10.3390/app11188681 - 17 Sep 2021
Viewed by 1790
Abstract
Most of the damage to reinforced retaining walls is caused by excessive deformation; however, there is no calculation method for deformation under static and dynamic loads in the design codes of reinforced soil retaining walls. In this paper, by collecting the measured displacement [...] Read more.
Most of the damage to reinforced retaining walls is caused by excessive deformation; however, there is no calculation method for deformation under static and dynamic loads in the design codes of reinforced soil retaining walls. In this paper, by collecting the measured displacement data from four actual projects, four indoor prototype tests and two indoor model tests under a total of 10 static load conditions, and comparing the calculation results with seven theoretical methods, the results show that the FHWA method is more applicable to the permanent displacement prediction of indoor prototype tests and that the CTI method is more applicable to the permanent displacement prediction of actual projects and indoor model tests. Two yield acceleration calculation methods and four permanent displacement calculation formulas were selected to calculate the displacement response of two reinforced soil test models under seismic loads and compared with the measured values, and the results showed that the Ausilio yield acceleration solution method was better. When the input peak acceleration ranges from 0.1 to 0.6 g, the Richards and Elms upper limit method is used, and when the input peak acceleration is 0.6–1.0 g, the Newmark upper limit method can predict the permanent displacement of the retaining wall more accurately. Full article
(This article belongs to the Special Issue Advances in Geosynthetics)
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