ظرفيت باربري پي سطحي واقع بر بستر ماسه اي به ژئوگريد مهارشده

چكيده انگليسي :

Bearing Capacity of Shallow Foundation on Sand Beds Reinforced with Anchored Geogrid layers Rasool Afshon R afshon@yahoo com Date of submission 05 10 1391 Department Collage of Civil Engineering Isfahan University of Technology Isfahan Iran Degree M Sc Language Farsi Supervisor Dr Mohamad Ali Rowshan Zamir Mohamali@ cc iut ac ir Abstract Soils are mostly weak in tensile strength and need to be strengthened by adding tensile elements Changing the soil performance to improve its engineering application called soil stabilization Soil stabilization may have several beneficial effects amongst which the most practical and important ones is shear strength improvement and consequently bearing capacity enhancement as well as settlement reduction Stabilization may be carried out in several methods amongst which soil reinforcement is more common If the structure footings rest on a weak soil it may not have adequate bearing capacity to withstand the loads and undergo additional settlement which may cause structural damages Conventional solutions for handling such problems may relay on replacing part of weak soil with granular quality soil increasing in density by mechanical compaction increasing in footing dimensions or a combination of these methods In such conditions however the most appropriate solution may be the use of geosynthetics for reinforcing the soil underneath footings The geosynthetics may cause better distribution of loading pressures within weak soil and transfer footing loads to deep soil layers which in turn increase the footing bearing capacity and reduce settlements So far numerous studies have been conducted by various researchers and their results were indicating on improvement of soil performance due to reinforcement In previous research works the effect of geogrid tensile strength have received considerable attention while the geogrid pull out resistance has been rarely studied The pull out resistance of geogrid layers may be increased by anchoring their ends A major problem in preparation of a reinforced bed is lot high costs due to the lengthy layers of geogrids which require a lot of excavations and refilling It seems that anchoring the geogrid layers at appropriate location on the reinforcement plane may decrease the required anchoring length to develop sufficient resistance at the interface soil reinforcement Thus any reduction in reinforcement length results in saving of gegrids as well as lowering excavations and replacement costs In this investigation the effect of end anchors of geogrid layers on bearing capacity of foundation was investigated The end anchors were steel U form bars used vertically at the end of geogrid layers to prevent slipping of them In this context the bearing capacity of footing models resting on a sand bed reinforced with various arrangement of end anchors were investigated The effects of leg height of anchors as well as their numbers were first investigated The effects of additional internal anchor rows of geogrid layers on bearing capacity were then considred The bearing capacity reached to 7 8 times of the unreinforced case with obtaining the optimized parameters and best arrangement of the geogrid layers While with anchored geogrid layers the footing bearing capacity increased up to 10 2 times of unreinforced case Finally using additional end anchors and rows the bearing capacity was reached to 11 7 times of unreinforced sand bed PDF created with pdfFactory trial version www pdffactory com

افشون، رسول

ظرفيت باربري پي سطحي واقع بر بستر ماسه اي به ژئوگريد مهارشده

خاك مسلح , حالت غير مسلح , مسلح شده با مهار