Abstract In recent years, the study of the shear strength of soil with geosynthetics has caught the attention of scholars. In this study, by changing the traditional geogrid structure and adding polymeric anchors to the reinforcement grid, naming it Grid–Anchor (G–A), it is sought to experimentally analyze the performance of this new system by increasing the Coefficient of Interaction Ratio in Direct Shear (CIR DS ). To achieve this, 16 large-scale direct shear tests were conducted on a typical geogrid and G–A system. The results of this showed that CIR DS is, on average, 1.45 times greater. In other words, the interaction between soil and the reinforcement in G–A system increases by almost 50% compared to that of typical geogrid regarding direct shear mechanism.
#2Danial Esmaili(United States Department of Transportation)H-Index: 6
ABSTRACT: One main concern related to the performance of unsaturated soils during the construction and service life of earthen structures is loss of matric suction due to the seasonal variations of gravimetric water content (GWC), ground water infiltration and possible development of excess pore water pressure. In addition to reducing the soil shear strength, loss of matric suction as a result of wetting could also reduce the soil–reinforcement interface shear strength in comparison with the as-...
#1Nicola Moraci(Mediterranea University of Reggio Calabria)H-Index: 17
#2G. Cardile(Mediterranea University of Reggio Calabria)H-Index: 10
Last. Laura Carbone(Mediterranea University of Reggio Calabria)H-Index: 1
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The main objective of this paper is to discuss the experimental and theoretical approaches developed by different researchers in order to understand and to evaluate the soil geosynthetic interaction under different loading conditions. In the paper, the soil-geosynthetic interaction in pullout, direct shear, and inclined plane tests under both static and cyclic loading is analyzed based on the different theoretical and experimental results carried out by the authors and also available in literatu...
The time-dependent behavior of soils has been investigated extensively using onedimensional and triaxial tests. The phenomena associated with time effects in soils are creep, relaxation, strain rate and re-arrangement effects. The engineering properties of soil are often improved significantly with the elapse of time. The objective of this paper is to investigate the time-dependent effect on the shear strength parameters of sand–geosynthetic interface using large direct shear test apparatus. For...
This paper examines the effect of the opening between the shear boxes on the shear behavior in the direct shear box test (H=20 mm×D=60 mm) under a constant vertical stress using seven types of granular material. It is observed that the magnitude of shear strength and dilatancy decreases due to the outflow of sample with an increase in the opening. The two notions of the Threshold Point (TP) as the limit opening size and the Threshold Line (TL) offering the guideline of opening size is defined ac...
#1V. Kostkanová(TUD: Dresden University of Technology)H-Index: 1
#2Ivo Herle(TUD: Dresden University of Technology)H-Index: 17
If the free vertical movement of the upper rigid part of the shear box is hindered during shearing, a frictional force is mobilized between the specimen and the vertical walls of the shear box. This causes either unloading (for contractant soils) or additional loading (for dilatant soils) of the specimen during shearing. If no correction of the applied vertical load with respect to the wall friction is taken into account, the resulting shear strength can be either underestimated (for contractant...
Abstract Storage tank foundations with frequent discharges and filling or road embankments under repeated traffic loads are examples of foundations subjected to the cyclic loading with the amplitude well below their allowable bearing capacity. The concern exists for the amount of uniform and non-uniform settlement of such structures. The soil under such foundations may be reinforced with geosynthetics to improve their engineering properties. This paper deals with the effects of using the new gen...
This paper discussed the difference between the test results obtained from ASTM D5321, the direction shear test, and ASTM D6706, the pullout test for poor graded soil/geosynthetic systems. If the soil particles could be able to penetrate through the geosynthetic openings and to develop the passive bearing capacity resistance, the pullout resistance would not increase in proportion to the increase of soil normal pressure. The pullout interaction coefficient, Ci, would decrease as increasing the n...
This paper deals with soil/reinforced geotextile interface behaviour in direct shear and pullout movements. A soil/geosynthetic direct shear apparatus, developed in accordance to EN ISO 12957-1 (2004) and ASTM D5321-92 (1992) standards, is presented. Some details of the test (like: specimen fixation, influence of the vertical stress on the registered horizontal force, type of test and measurement of the vertical displacement) are discussed and modifications in the test procedures are adopted. Th...
This paper presents a study of the micromechanics of granular materials as affected by the direct shear test scale using the discrete element method (DEM). Parametric studies were conducted to investigate the effects of specimen length and height scales (in relation to the particle size) on the bulk material shear strength and shear banding behaviour in the direct shear test. A mesh-free strain calculation method previously developed by the authors was used to capture and visualise the evolution...
There are many cases where the foundations of structures are subjected to cyclic loading in addition to static loading. Oil reservoir foundations with frequent discharges and lling or road embankments under repeatable trac loads are examples of such foundations. Although the amplitudes of the cyclic load is usually less than the permissible static load, the concern still exists for the amount of uniform and non uniform settlement of such structures. The soil under such foundations may be reinfo...
Abstract null null This study aims to improve the California Bearing Ratio (CBR) value of the weak subgrade soil using a modified form of geogrids with anchors. The tests are carried out with a single layer of geogrid as reinforcement to determine the optimum placement depth in the CBR mould. The modified geogrid with anchors positioned at the optimum placement depth for which the CBR value is 6.00 compared to the CBR value of 4.68 for the reinforced condition. The inclusion of anchors in the ge...
Abstract null null In this paper, more than 70 large-scale pullout tests were performed to evaluate the performance of an innovative composite geosynthetic strip (CGS) reinforcement in sandy backfill. The CGS reinforcement is composed of a geosynthetic strip (GS) and parts of a scrap truck tire as transverse members. The experimental pullout results for the CGS reinforcement were compared with the suggested theoretical equations and ordinary reinforcements, including the GS, the steel strip (SS)...
A transformed approach has been made to predict the impression of inclusion geogrid on the reinforced soil’s bearing capacity underneath the strip foundation. The influence of the friction factor of the tensile strength of the reinforcement element performs a significant purpose in estimating the tolerance of the strengthened soil. Analytical study and experimental tests have been performed to validate the proposed empirical approach. This study analyzed certain parameters that influence the eff...
Abstract null null In this research, the philosophy of manufacturing the geogrids in their conventional shape is modified to let the friction between the ribs and soil particles have a noteworthy effect on the final resistance of soil reinforced by geogrids. Inspired by the belts used to link gears, both surfaces of the conventionalBiaxial Geogridwere reformed by adding cubic cogs distributed in a sine wave order on both sides of the ribs. The proposed geogrid shall be denominated “ICB-GGR”as an...
Design of reinforced soil structures is greatly influenced by soil–geosynthetic interactions at interface which is normally assessed by costly and time consuming laboratory tests. In present research, using the results of large-scale direct shear tests conducted on soil–anchored geogrid samples a model for predicting Enhanced Interaction Coefficient (EIC) is proposed enabling researchers/engineers easily, quickly and at no cost to estimate soil–geosynthetic interactions. In this regard well and ...
Soil reinforcement employing geosynthetics is significantly influenced by interactions which are governed by friction and adhesion at interface. To enhance interactions at soil–geogrid interface under direct shear conditions, effects of attaching elements as anchors to reinforcement has been evaluated. A well and poorly graded sand, one geogrid type, anchors with three different size and clamping lengths of 2, 4 and 6 cm from shear surface were used. Samples were prepared with a relative density...
Last. Ali Noorzad(Shahid Beheshti University)H-Index: 13
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Both experimental and numerical investigations conducted on strip footing laying down over the geogrid reinforced fine sand bed. Firstly, an evaluation of the significance of geogrid reinforcement to enhance the soil’s strength is required to carry out a series of a small-scale model of reinforced and unreinforced soil beneath static loading. Next, the series of the large-scale numerical analyses were implemented to define the soil bed reaction modulus and bearing capacity ratio of reinforced sa...
Abstract Large-scale laboratory equipment was developed to assess interaction between soil and 3-D honeycomb shaped geocell reinforcement under normal and interface shear stress. An understanding of this interaction is vital in assessing mechanical behavior of geocell-reinforced soil mass. Specifically, the equipment allows evaluation of the load transfer mechanism with the measurements of strains, displacements and loads, including friction and passive resistance on the side surfaces and inside...
