Strength and stiffness from in situ tests

The content: 1.1 Standard penetration tests (SPT) 1.1.1 Modification of raw SPT values Method A Method B 1.1.2 Relative density 1.1.3 Undrained soil strength vs. SPT N 1.1.4 Friction angle vs. SPT N, Dr, and Ip 1.1.5 Parameters affecting strength 1.2 Cone penetration tests 1.2.1 Undrained shear strength 1.2.2 SPT blow counts using qc 1.3 Soil stiffness 1.4

Uses of Piles

The major uses of piles are: 1. To carry vertical compression load. 2. To resist uplift load. 3. To resist horizontal or inclined loads. Normally vertical piles are used to carry vertical compression loads coming from superstructures such as buildings, bridges etc. The piles are used in groups joined together by pile caps. The loads carried by the piles are

Types of Piles According to the Method of Installation

According to the method of construction, there are three types of piles. They are 1. Driven piles, 2. Cast-in-situ piles and 3. Driven and cast-in-situ piles. Driven Piles Piles may be of timber, steel or concrete. When the piles are of concrete, they are to be precast. They may be driven either vertically or at an angle to the vertical.

Types of Piles According to Their Composition

Piles may be classified according to their composition as 1. Timber Piles, 2. Concrete Piles, 3. Steel Piles. Timber Piles: Timber piles are made of tree trunks with the branches trimmed off. Such piles shall be of sound quality and free of defects. The length of the pile may be 15 m or more. If greater lengths are required, they

Classification of Piles

Piles may be classified as long or short in accordance with the L/d ratio of the pile (where L = length, d = diameter of pile). A short pile behaves as a rigid body and rotates as a unit under lateral loads. The load transferred to the tip of the pile bears a significant proportion of the total vertical load

Floating Foundation

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 horizontal ground surface with a

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 reaction. The finite difference method

Design of Combined Footings by Elastic Line Method

The relationship between deflection, y, at any point on an elastic beam and the corresponding 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 an elastic foundation The classical

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 is as follows: 1. The

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 mat does not influence the pressure distribution, 2. The soil pressure is distributed in a straight line or a plane surface such that the centroid of the soil pressure coincides with the line of action of