Pullout resistance of cement-grouted soil nails is a key factor affecting the safety conditions of retaining walls, slopes and excavations. Hence, survey of resistence of pullout nail is the one of the most important parameters in designing of nailing functions. This parameter depends on critical factors including: instalation method, overburden pressure, grouting pressure, degree of saturation of the soil, the roughness of nail surface, changes of lengh & diameter of nail and the shear strengh of the soil. Sometimes, used soil nail layers affected by cyclic loads due of traffic passing, train and so on. Hence the research aimed to study influence of this kind loadings on resistence of nail post-cyclic pullout and affective factors on it. The study pointed to apply slopes and nailed retaining walls next to traffic loads and rail-roads. Several studies conducted,according to, vary factors influence on nail pullout behavior that buried into soil. Key studies carried out in form of impression of static loading on nail pullout resistance including: overburden stress, grouting stress, impression of an addition to grouting, nail geometry, nail spaces, using spiral nails, comparison laboratory results of pullout set with direct shear test in interface grouted-nail to earn identical ratio and etc. yet, it not examineted cyclic loading impression on post-cyclic pullout resistance in nails. The study just focus on geogrid. For the first time, this research provide impression of cyclic loading on post-cyclic pullout resistance in nails. This research used nail pullout set,able to apply static and cyclic loads in conditions of force or displacement controling with differnt frequencies and sinus shape of cyclic wave. This search used the notes of specifications of pullout set,also, sampling due to test and tables of done tests. In this research examined affection of variation of static, cyclic load rate. Resistance of post-cyclic pullout nail generally is more to static pullout resistance,even though, more affections of cyclic loading lead to decrease of resistance,also, observed in the cyclic part developing in displacement. Results shown increasing amplitude of cyclic loading in exchange of same satatic pullout force,is unlinear decreasing post cyclic resistance. Even though, increasing amplitude of cyclic loading in exchang of decreasing of static pullout force (when affection of complex of two mentioned parameters is unchanged), it is linear decreasing post cyclic pullout.

In this study a comprehensive set of pullout tests were conducted on geogrid. Apart from measuring the interface properties (i.e., the internal friction angle and dilatancy angle) between the geogrid and two soils, some interesting results concerning the mechanisms behind the behavior of reinforcement in pullout tests were obtained.

This paper presents the results of pullout tests on uniaxial geogrid embedded in silica sand under monotonic and cyclic pullout forces. The new testing device as a recently developed automated pullout test device for soil-geogrid strength and deformation behavior investigation is capable of applying load/displacement controlled monotonic/cyclic forces at different rates/frequencies and wave shapes, through a computer closed-loop system. Two grades of extruded HDPE uniaxial geogrids and uniform silica sand are used throughout the experiments. The effects of vertical surcharge, sand relative density, extensibility of reinforcement and cyclic pullout loads are investigated on the pullout resistance, nodal displacement distributions, post-cyclic pullout resistance and cyclic accumulated displacement of the geogrid. Tell-tale type transducers are implemented along the geogrid at several points to measure the relative displacements along the geogrid embedded length. In monotonic tests, decrease in relative displacement between soil and geogrid by increase of vertical stress and sand relative density are the main conclusions; structural stiffness of geogrid has a direct effect on pullout resistance in different surcharges. In cyclic tests it is observed that the variation of post-cyclic strength ranges from minus 10% to plus 20% of monotonic strength values and cyclic accumulated displacements are increased as normal pressure increase, but no practical specific comment can be made at this stage on the post-cyclic strength of geogrids embedded in silica sand. It is also observed that in loose sand condition, the cyclic accumulated displacements are considerably smaller as compared to dense sand condition.

This paper presents a recently developed automated pullout apparatus for soil-geogrid strength and deformation behavior investigation. The new apparatus is capable of applying load/displacement controlled monotonic/cyclic loads at different rates/frequencies, different wave shapes and loading patterns, through a computer closed-loop system. An extruded uniaxial geogrid and silica sand are used throughout the experiments. The effects of normal pressure (surcharge) and relative density are investigated on displacement distributions and pullout capacity of the geogrid in both monotonic and cyclic tests.In monotonic tests, it is observed that with increase in relative density and surcharge, pullout resistance has increased. In cyclic tests, despite some minor observations of post-cyclic strength increased, no specific comment can be made at this stage on the post-cyclic strength.

In recent decades, reinforced soil retaining walls have gained popularity due to their ease of construction and low costs. Utilizing polymeric straps for soil reinforcement provides a straightforward and economical way to enhance the strength and deformation characteristics of retaining earth walls. However, these polymeric straps lack adequate pullout resistance, owing to the absence of transverse members. To address this issue, a U-shaped end-bend can be added to the strap, which creates a surface that enhances passive resistance. Although construction codes generally emphasize the use of high-quality granular materials as backfills for reinforced soil retaining walls, many construction projects are characterized by local soils that consist of marginal cohesive materials, making them unsuitable for backfills. A promising solution to reduce project costs in reinforced wall construction is the sandwich method, which involves encasing the reinforcement in a thin layer of granular soil within the backfill. This technique not only improves the pullout resistance of the reinforcement but also allows the enclosed layer to serve as a drainage system. This research investigates the pullout behavior of straps with both direct and U-shaped ends in sand and clay backfills through a series of large-scale pullout tests. Additionally, the impact of the sandwich method on enhancing the pullout resistance of U-shaped polymeric straps is examined.

The work here investigates the correlation between microstructural features and mechanical properties of similar and dissimilar resistance spot welds of low carbon steel (LCS) and dual phase steel (DP600) in the tensile-shear test. Correlations between the critical fusion zone size required to ensure pullout failure mode, the weld microstructure and the weld hardness characteristics were developed. Results showed that the critical fusion zone size is a function of hardness profile characteristics (ratio of fusion zone hardness to average hardness of the base metal). Expriments showed that similar DP600/DP600 and dissimilar DP600/LCS welds exhibit the highest and the lowest tendency to fail in interfacial failure mode, respectively. Finally, peak load and energy absorption of similar and dissimilar resistance spot welds are compared.

Geosynthetics are mainly used to stabilize and reinforce different types of earth structures such as slopes, retaining walls, bridge abutments, and foundations. In these cases, the interaction between soil and geosynthetic plays a significant role. In order to investigate the factors affecting the static, cyclic, and post-cyclic pullout behavior of a type of geogrid produced in Iran under the brand name of GPGRID80/30 embedded in uniform sand, an experimental study was carried out using a large-scale pullout apparatus. In order to study the monotonic and post-cyclic pullout behavior of geogrid in different conditions, a series of monotonic pullout tests and multistage pullout tests were performed. Given the effect of vertical effective stress on the pullout resistance, the maximum apparent friction coefficient of the surface of the geogrid and soil and deformation along the geogrid was investigated using monotonic tests. In the multistage pullout test, the influence of vertical effective stress, cyclic load amplitude, frequency, and number of tensile load cycle on the post-cyclic pullout resistance was studied. The results indicated that with an increase in the vertical effective stress, the pullout resistance of the geogrid and the maximum apparent coefficient of friction would increase and decrease, respectively. A comparison of the results of the multistage pullout tests and constant rate pullout tests with the vertical stress of 60 kPa showed that the cyclic loading had no significant effect on the post-cyclic pullout strength compared to the static pullout strength of the embedded geogrid in the sandy soil; however, with vertical effective stresses of 20 and 40kPa, a reduction in the maximum post-cyclic pullout strength was more evident than the pullout strength. Increasing the effective vertical stress and cyclic load amplitude in the second stage of the multi-stage test would enhance the cumulative displacements along the geogrid sample. A comparison between the loading-unloading tensile stiffness at the end of the second stage and tensile stiffness at the beginning of the second stage suggested that the cyclic loading would increase the tensile stiffness and finally, at the third stage of the experimental multistage test, the tensile stiffness would decrease as the displacement increased until it reached the corresponding value in the constant-rate displacement test.

This paper presents the effect of geogrid tensile strength by calculating the pullout resistance and the geogrid-soil interaction mechanism. In order to investigate this interface, a series of pullout tests have been conducted by a large scale reformed direct shear test apparatus in the both cohesive and granular soils. In numerical, the finite difference software FLAC3D has been carried out on experimental tests and the results are compared with findings from laboratory tests and to complete investigation results. The results show tensile strength of geogrids has an important role in the interface behavior. The effect of the soil type also is discussed. The obtained results show that the geogrids with low tensile strength have higher pullout resistance in the low normal stress on the surface, this effect reversed as the normal applied stress is increased. Numerical analysis only estimates the pullout strength with good agreement in the high normal stresses. Furthermore, it is found that the effective particle size of soil is close to the geogrid thickness by comparing two sands with different grain size.

In this study, the displacement finite element method was employed to evaluate the load-displacement response and estimate the ultimate pullout capacity of anchor plates. A detailed comparison was conducted between conventional and non-conventional shaped single-plate and multi-plate horizontal anchors. The analysis focused on square and plus-shaped anchors, examining the influence of anchor geometry, embedment depth, plate thickness, tie rod diameter, soil relative density, and spacing between plates on their pullout performance. The results indicated that pullout capacity increases with greater relative density, plate thickness, and embedment depth but decreases with larger tie rod diameters. Square anchors demonstrated 15–40% higher pullout capacities than plus-shaped anchors due to their larger contact area. Multi-plate configurations significantly improved pullout resistance compared to single plates, with critical plate spacing optimizing performance: 1.5b for square anchors and 1b for plus-shaped anchors. For dense sand, plus-shaped multi-plate anchors exhibited comparable pullout capacities to square single-plate anchors despite a 25% reduction in anchor area. At an embedment depth of 15 m, square triple-plate anchors achieved a pullout capacity of 360.6 MPa, while plus-shaped anchors reached 256.8 MPa. Stress distribution analysis revealed localized failure patterns above the anchors, with higher stress concentrations near the plates. These findings highlighted the effectiveness of multi-plate configurations and optimized geometries in improving anchor performance, offering practical solutions for geotechnical applications requiring high pullout resistance in sandy soils. Overall, plus-shaped double-plate and triple-plate anchors can effectively replace square-shaped single-plate anchors.