Şerit ankraj plakalarının çekme kapasitesi davranışının farklı koşullar altında sayısal analizi

There are many structures need a footing system that provides sufficient support by resisting loads that are affected by vertical and horizontal uplift forces. Examples include transmission towers, anchored bulkheads, submerged pipelines, and tunnels. Stability and support of such structures can be provided by transferring the loads from the structures foundation through the use of tension elements. These elements are soil anchors, which are generally fixed to structures and are embedded to sufficient soil depths to provide adequate amounts of support within required safety limits. Plate anchors are light structural members employed to withstand uplift forces. They are generally made of steel, precast concrete, poured concrete or timber and may be formed into shapes such as square, rectangular, circular and strip. Horizontal plate anchors can be constructed by excavating the ground to certain design depths, placing the plate in position, connecting to cable and then backfilling and compacting with good quality of soil material. In this study, uplift capacity of plate anchors in sand was investigated using finite element method. Finite element analyses were performed using commercially available computer program PLAXIS. The PLAXIS v8.2 program is a geotechnical finite element package specifically intended for twodimensional analysis of deformation and stability of any geotechnical engineering project. The simple graphical input procedure enables a quick generation of complex finite element models, and the enhanced output facilities provide a detailed presentation of the computational results. The calculation itself is fully automated and based on robust numerical procedures. In the analysis, strip shaped plates were used as anchor plates and was modeled under plain-strain conditions. The sand soil was modeled using two different soil model as Mohr-Coulomb and Hardening Soil model. In study, the effect of embedment depth (H/B=1-2-3- 4-5-6-7-8), the relative density of sand (=39°-44°) and width of the plate anchors (B=50cm-75cm- 100cm) on the uplift capacity were investigated. The H/B ratios were varied from 1.00 to 8.00. The results show that the general trends of finite element analysis agree well with those of the theoretical results. It can be seen that the ultimate uplift load, Tu increases significantly with an increase in embedment ratio, H/B. Plate anchor in maximum embedment ratio, H/B=8, had higher uplift capacity than in minimum embedment ratio such as H/B=1. Results show that the values of Tu increase with an increase in relative density of sand both theoretically and numerically. It is evidence that relative density of sand is one of the main parameters affecting the uplift capacity of the plate anchor. This increase in uplift capacity of plate anchor with relative density of sand can be attributed to the weight of soil and shearing resistance. The weight of the soil increases with relative density and embedment ratio. In addition those, failure surface length increases with embedment ratio. Thus, the uplift capacity of anchors in sand is strongly influenced by their embedment ratio and by the relative density of the sand. The results also show that Tu increase with an increase in width of the plate anchors. This increase in uplift capacity of plate anchor with plate width can be attributed to the weight of soil on the plate surface. The uplift capacity of strip plate anchors embedded in sand was investigated numerically. Based on the results, the following main conclusions can be drawn: Both experimental and theoretical studies show that uplift capacity for strip plate anchors in sand increase with an increase in anchor embedment ratio, relative density of sand and width of the plate anchor. A satisfactory agreement between the experimental and theoretical results on general trend of behaviour is observed. However, the values obtained from finite element analysis appears to be smaller than that obtained from the theoretical values. Finite element method has some advantages to recognize the failure nechanism of plate anchors in sand.