General Consideration A floating foundation for a building is defined as a foundation in which the weight of the building is approximately equal to the full weight including water of the soil removed from the site of the building. This principle of flotation may be explained with reference to Fig. 14.4. Fig. 14.4(a) shows a Full Article…

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In this category has 3 Shallow Foundation chapter. Ultimate Bearing Capacity, Safe Bearing Pressure and Settlement calculation and Combined footings and Mat foundations

# Design of Mat Foundations by Elastic Plate Method

Many methods are available for the design of mat-foundations. The one that is very much in use is the finite difference method. This method is based on the assumption that the subgrade can be substituted by a bed of uniformly distributed coil springs with a spring constant ks which is called the coefficient of subgrade Full Article…

# Design of Combined Footings by Elastic Line Method

The relationship between deflection, y, at any point on an elastic beam and the correspondingÂ bending moment M may be expressed by the equation The equations for shear V and reaction q at the same point may be expressed as where x is the coordinate along the length of the beam. From the basic assumption of Full Article…

# Design of Mat Foundation by Rigid Method

In the conventional rigid method the mat is assumed to be infinitely rigid and the bearing pressure against the bottom of the mat follows a planar distribution where the centroid of the bearing pressure coincides with the line of action of the resultant force of all loads acting on the mat. The procedure of design Full Article…

# Design of Combined Footings by Rigid Method (Conventional Method)

The rigid method of design of combined footings assumes that 1. The footing or mat is infinitely rigid, and therefore, the deflection of the footing or matÂ does not influence the pressure distribution, 2. The soil pressure is distributed in a straight line or a plane surface such that the centroid ofÂ the soil pressure coincides with Full Article…

# Proportioning of Cantilever Footing

Strap or cantilever footings are designed on the basis of the following assumptions: 1 . The strap is infinitely stiff. It serves to transfer the column loads to the soil with equal andÂ uniform soil pressure under both the footings. 2. The strap is a pure flexural member and does not take soil reaction. To avoid Full Article…

# Safe Bearing Pressures for Mat Foundations on Sand and Clay

Mats on Sand Because the differential settlements of a mat foundation are less than those of a spread foundation designed for the same soil pressure, it is reasonable to permit larger safe soil pressures on a raft foundation. Experience has shown that a pressure approximately twice as great as that allowed for individual footings may Full Article…

# The Coefficient of Subgrade Reaction

The coefficient of subgrade reaction is defined as the ratio between the pressure against the footingÂ or mat and the settlement at a given point expressed asÂ The coefficient of subgrade reaction is defined as the ratio between the pressure against the footing or mat and the settlement at a given point expressed as Â eq 14.2 Full Article…

# Case History of Failure of the Transcona Grain Elevator

One of the best known foundation failures occurred in October 1913 at North Transcona,Â Manitoba, Canada. It was ascertained later on that the failure occurred when the foundationÂ pressure at the base was about equal to the calculated ultimate bearing capacity of an underlaying layer of plastic clay (Peck and Byrant,1953), and was essentially a shearing failure. Full Article…

# Bearing Capacity of Rocks

Bearing capacities of rocks are often determined by crushing a core sample in a testing machine. Samples used for testing must be free from cracks and defects. In the rock formation where bedding planes, joints and other planes of weakness exist, the practice that is normally followed is to classify the rock according to RQD Full Article…