A Study on Bearing Capacity of Skirted Square Footings on Different Sands
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TECHNICAL NOTE
A Study on Bearing Capacity of Skirted Square Footings on Different Sands Adarsh Thakur1
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Rakesh Kumar Dutta1
Received: 23 November 2019 / Accepted: 22 May 2020 Ó Indian Geotechnical Society 2020
Abstract The paper discusses an experimental and numerical analysis assessing the bearing capacity on three sands (S1, S2, S3) of unskirted, singly and doubly skirted square footings. In this relation, laboratory plate load tests on unskirted, singly and doubly skirted square footings were carried out on three different sands mounted in a test tank at a relative density of 30%. The skirt depth was varied from 0.0B to 1.5B. Results revealed that numerically recorded bearing capacity was slightly higher compared to the one recorded experimentally for all footings on sands (S1, S2, S3). As the effective size and friction angle of the sand’s increase, the bearing capacity of the unskirted, singly and doubly skirted square footings increased. Further, the experimental results validated the results acquired numerically with an average deviation of 3.25%. Providing double skirt marginally benefits the enhancement in the bearing capacity and settlement in comparison with the singly skirted footings. Keywords Bearing capacity Sands Effective size Friction angle Square footing Singly skirted Doubly skirted
Introduction Alternative methods to improve load carrying capacity and footing settlement reduction have always been sought, although there are a number of well-known and proven soil & Adarsh Thakur [email protected] 1
stabilisation methods. Some of them may be costly and subject to the requirements of the site. Structural skirts are therefore a good alternative to enhancing load carrying capacity and reducing footing settlement on soil. The word skirted foundations were used to narrate shallow foundations with driven sheet piles fixed to its circumference. The skirts create an enclosure in which soil is purely confined and operates as a unit with overlain foundation and shift entire structure load to soil fundamentally at the skirt tip level. Circumferential skirts may be used in circular, rectangular, strip and square geometries with new and existing shallow foundations. They are also used to enhance piping and scouring safety. In addition, the soil under the foundation can be prohibited from squeezing out and any possible damage caused by excavations in adjacent building works, using peripheral skirt. Skirted foundations have been used extensively for offshore structures based on their ease and short time of installation compared with deep foundations such as piers and piles. Skirted foundations were first used in offshore hydrocarbon ventures in the early 1970s as a support unit for the floating structures. Nowadays, skirted footing is practiced for bridges, coastal structures and where water scouring is really a major problem. The paper provides a thorough laboratory testing on model unskirted, singly and doubly skirted square footings resting on various types of sands accompanied by a t