BEARING CAPACITY AND SETTLEMENT CHARACTERISTICS OF SOILS UNDER PRE-QUICKSAND CONDITIONS

Abstract

A Foundation Engineer sometimes come}across the problem of design and construction of foundation under upward hydraulic gradient causing pre-quicksand conditinn. Bearing capacity and settlement are the two main criterion for design of footing in such conditions. In this investigation model tests were conducted to study the effect of upward flo':! of water on bearing capacity and settlement characteristics. Tests were performed on square and rectangular footings of sizes 3 cm x 3 cm, 3 cm x 6 cm, 3 3 cm x 12 cm, and 3 cm. x 18 cm. Footings were tested in a specially designed arid fabricated tank of size 40 cm x 4n cm x 60 cm. The tank was fitted with all the accessories which were necessary for saturating the soil and creating the flow of water at various hydraulic gradients. All the tests were carried out on Ranipur sand. The footings .ere tested both at the surface and at depths such that Df/B = 0.5 and 1.0 where 7 f and B are the depth and width of footing respectively. Upward hydraulic gradient (i) was varied from 0 to .6 at an interval of 0.2. From load-settlement curves of each test, values of failure loads were obtained. By analysing the data, equation for estimating the bearing capacity in such condition was established. Non-dimensional plots and equation were obtained to compute settlement of the footing of any size, depth and at any stress level. Comparison of the experimental data with the previous investigations is also made. An exhaustive review of th avail- -able literature on the pertaining topic is included.