To investigate the effect of interface temperature on the soil-reinforcement interaction mechanism, a series of pullout tests were conducted considering different types of reinforcement (geogrid and non-woven geotextile), backfill (dry sand, wet sand, and clay), and six interface temperatures. The test results indicate that at interface temperatures of 0 degrees C and above, reinforcement failure didn't occur during the pullout tests, whereas it predominantly occurred at subzero temperatures. Besides, the pullout resistance for the same soil-reinforcement interface gradually decreased as the interface temperature rose. At a given positive interface temperature, the pullout resistance between wet sand and reinforcement was significantly higher than that of the clayreinforcement interface but lower than that of the dry sand-reinforcement interface. Compared with geotextile reinforcements, geogrids were more difficult to pull out under the same interface temperature and backfill conditions. In addition, the lag effect in the transfer of tensile forces within the reinforcements was significantly influenced by the type of soil-reinforcement interface and the interface temperature. Finally, the progressive deformation mechanism along the reinforcement length at different interface temperatures was analyzed based on the strain distribution in the reinforcement.

The geogrid-soil interaction, which is crucial to the safety and stability of reinforced soil structures, is determined by the key variables of both geogrids and soils. To investigate the influence of backfill and geogrid on their interface behavior of the reinforced soil retaining walls in Yichang of Shanghai-Chongqing- Chengdu high-speed railway, a series of laboratory pullout tests were carried out considering the influence of water content and compaction degree of the backfill as well as tensile strength of the geogrid. The development and evolution law of pullout force- pullout displacement curves and interface characteristics between geogrid and soil under various testing conditions were analyzed. The results showed that with increasing water content, the geogrid pullout force decreased under the same pullout displacement. The interfacial friction angle of the geogrid-soil interface showed a slowly increasing trend with increasing water content. The variation of the interfacial friction angle ranged between 9.2 degrees and 10.7 degrees. The interfacial cohesion, however, decreased rapidly with increasing water content. With increasing degree of compaction, the interfacial friction angle and the interfacial cohesion of the geogrid-soil interface gradually increased. The change of the interfacial cohesion with the compaction degree was more significant. When the degree of compaction increased from 0.87 to 0.93, the interfacial cohesion increased around 7 times. The tensile strength of geogrid has certain influence on its pullout force-pullout displacement relationship. High-strength geogrid could significantly improve the mechanical properties of the geogrid-soil interface. The investigation results can provide some reference for the design and construction of geogrid reinforced soil structures.

This paper investigates the pullout behaviours of horizontal rectangular plate anchors under inclined loading in sand using three - dimensional finite element (3D-FE) analysis. An advanced bounding surface plasticity model incorporating the critical state framework is developed to capture the stress-strain relationship of sand. The model is firstly validated against various analytical solutions and centrifuge test data. Then, a series of FE analysis is conducted to consider the effects of plate anchor aspect ratio, initial embedment depth, sand relative density and inclined loading angle on the pullout capacities. Results show that shallow anchors develop failure zones reaching the soil surface, and vertical pullout capacity exceeds that under pure vertical loading when the load is slightly inclined. For deep anchors, failure zones are confined below the surface, and horizontal pullout capacity exceeds that under pure horizontal loading when the load is slightly inclined. The transitional embedment depth depends on anchor aspect ratio and sand density. A modified analytical solution is proposed to estimate the vertical pullout capacity of plate anchors from shallow to deep depths. Failure envelopes established from probe tests provide practical guidance for assessing rectangular anchor failures under various inclined loadings.

The study investigates the interaction between geogrids and two distinct granular backfill materials, Yamuna sand and coal mine overburden through a combination of laboratory experiments and numerical simulations. It evaluates the physical and mechanical properties of coalmine overburden and Yamuna sand, and the pullout performance of geogrid embedded in both materials. A large-scale pullout box was utilised to conduct the experiments, and the results showed that coalmine overburden offers higher pullout resistance than Yamuna sand. The effect of physical parameters such as elasticity of geogrid, geogrid geometry and angle of inclination were analysed using the discrete element method. The pullout resistance of geogrids mainly depends on the elastic properties of the material. The study also shows the existence of an optimum spacing between longitudinal and transverse ribs.

This study focuses on predicting the impacts of a heating-cooling cycle on the pullout capacity of energy piles installed through a soft clay layer. Geotechnical centrifuge physical modeling was used to evaluate temperature, pore water pressure, volume change, and undrained shear strength profiles in clay layers surrounding energy piles heated to different maximum temperatures to understand their impacts on the pile pullout capacity. During centrifugation at 50 g, piles were jacked-in at a constant rate of penetration into a kaolinite clay layer consolidated from a slurry in a cylindrical aluminum container, heated to a target temperature after stabilization of installation effects, cooled after completion of thermal consolidation requiring up to 30 hours (1250 days in prototype scale), then pulled out at a constant rate. T-bar penetration tests were performed after the heatingcooling cycle to assess differences in clay undrained shear strength from a baseline test. The pullout capacity of an energy pile heated to 80 degrees C then cooled to ambient temperature was 109 % greater than the capacity in the baseline test at 23 degrees C, representing a substantial improvement. The average undrained shear strength measured with the T-bar at a distance of 3.5 pile diameters from the pile heated to 80 degrees C was 60 % greater than at 23 degrees C but followed the same trend as pile capacity with temperature. An empirical model for the pullout capacity was developed by combining predictions of soil temperature, thermal excess pore water pressure, thermal volumetric strain, and undrained shear strength for different maximum pile temperatures. The empirical model predictions matched well with measured pullout capacities.

The retaining wall with reinforced soil is exposed to various types of loads, including static active earth pressure caused by the self-weight of the backfill soil, seismic loads due to earthquakes, vehicle/railroad loads, and cyclic loads induced by seasonal temperature changes causing contraction/expansion. To ensure the internal stability of the retaining wall, the pullout resistance of the installed geogrid must be secured. This study presents the pullout load test results for a geogrid installed in sandy soil under cyclic loading, either in displacement-controlled or load-controlled conditions. In the pullout tests, factors such as the frequency, amplitude, and number of cycles of the pullout load were varied to consider various cyclic loading characteristics. The trends in the maximum pullout resistance and the initial pullout stiffness were analyzed. The analysis showed that under displacement-controlled cyclic loading, as the amplitude increased, both the pullout resistance and stiffness significantly decreased, with the degree of decrease intensifying as the displacement amplitude increased. This trend was also observed in the analysis of changes in pullout stiffness under cyclic loading. On the other hand, under load-controlled cyclic loading, the pullout resistance and cumulative pullout displacement both tended to decrease as the frequency increased over a fixed period, while the pullout resistance decreased and the cumulative displacement increased as the amplitude increased.

Tree roots play a crucial role in hillslope stability, but quantifying their reinforcement remains challenging. This study aims to quantify the root reinforcement provided by Cunninghamia lanceolata across varying slope gradients based on in-situ pullout experiments. A total of 120 soil profiles were excavated to map root distribution across four slope gradients. Subsequently, 304 in-situ pullout experiments were conducted encompassing root diameters ranging from 1 to 8 mm. The Root Bundle Model Weibull was calibrated and coupled with root distribution data to quantify reinforcement contributions from a single tree to stands. It was found slope gradient significantly influences root distribution, with steeper slopes harboring coarser and more widely distributed roots. In-situ experiments revealed substantial variability in pullout stiffness and peak displacement for roots of the same diameter, with thicker roots exhibiting higher stiffness and greater displacement. Calculations indicate that root reinforcement exhibits an exponential decline with increasing distance from the stem but shows a marked positive association with slope gradient due to the influence on root distribution. Statistical analysis reveals that the area experiencing root reinforcement exceeding 10 kPa on a 40 degrees slope is roughly double that of 0 degrees and 20 degrees stands.

The majority of existing studies on the soil-geogrid interaction were based on the assumption that the surrounding geotechnical media was a homogeneous material. However, the different composition, structure and history of the geotechnical media resulted in significant differences in mechanical behavior. This discrepancy could lead to an overestimation of the pullout capacity of the soil-geogrid, which could in turn cause failures in the engineering practice. The influcence of the uncertainty of the geotechnical media on the pullout behavior of the soil-geogrid was investigated in this article. A number of groups of random distributions of the properties of soils, associated with the strain-softening constitutive model, were incorporated in the numerical simulation. The results demonstrated that the pullout behavior of the soil-geogrid, including the ultimate pullout capacity and the post-peak softening behavior, was highly impacted by the uncertainty of the mechanical properties of the surrounding inhomogenous media, in constrast to the case that with the homogeneous geotechnical media.

The tensile deformation of fibers is often overlooked in traditional analyses of fiber reinforcement mechanisms, with pullout failure being considered as the primary failure mode in fiber-reinforced soil. In recent years, flexible fibers have increasingly been used in fiber-reinforced soil. However, their failure modes have not yet been revealed. In this study, plastic fibers are used for pullout tests conducted by a modified horizontal tensile testing apparatus. The mechanical characteristics of the fiber-soil interface and the deformation characteristics of plastic fibers have been analyzed. It has been found that the failure modes of plastic fibers in reinforced soil can be categorized into three cases: pullout failure with elastic tensile deformation, pullout failure with plastic tensile deformation, and fracture failure with plastic tensile deformation. A theoretical calculation method is proposed to describe the progressive pullout behavior, and the pullout force-displacement relationship can be determined. The pullout force calculated using this method is less than that obtained from traditional methods due to the incorporation of the fiber's deformation characteristics. Through a comparison between the pullout test results and the predicted results, the effectiveness of the proposed method in capturing the pullout force-displacement relationship of flexible fibers in soil is verified.

As the latest development and benchmark of a gravity installed anchor (GIA), the OMNI-Max anchor stands as a cutting-edge achievement and benchmark, finding increasingly widespread use within mooring systems due to its exceptional operational performance and adaptability. Notably, while investigations into the pullout capacity of OMNI-Max anchors have been conducted extensively in clay, the relevant studies are seldom observed in sand. Actually, the mechanical properties of sand are quite different from those of clay, and sand is also widely distributed in seabed soil. Full knowledge of OMNI-Max anchors not only in clay but also in sand is necessary to a wider application of the anchors. In the present work, the large deformation finite element (LDFE) method is adopted combined with the coupled Eulerian-Lagrangian (CEL) technique to study the end-bearing characteristics of the OMNI-Max anchor in sand seabeds. A bounding-surface plasticity model is taken as the constitutive model to capture the characteristics of sand. Through investigation and analysis, OMNI-Max anchors are closely related to the anchor embedment depth, the soil relative density, the anchor orientation, the loading angle and the bearing area, so the working conditions related to these five factors are designed and calculated. An explicit expression of the end-bearing capacity factor is finally derived to provide a simple and fast tool of evaluating the pullout capacity of the anchor in sand under multiple factors. Validation cases and orthogonal tests have confirmed the effectiveness and applicability of the explicit expression.