Depth and Spacing of Trial Pits & Borings The depth and spacing of trial pits or exploratory borings should be such as to give a true picture of the underlying soil, with regard to any major changes in thickness, depth or properties of the strata over the base area of the structure and in its … Read more
Values of Safe Bearing Capacity The safe bearing capacity of soil should be determined on the basis of soil test data or by performing some field test such as Standard penetration test or Plate load test etc. However, in the absence of soil test data, the values of safe bearing capacity (S.B.C) as given in … Read more
Laboratory Vane Shear Test of Soil Aim To determine shear strength of clay soil using laboratory vane shear apparatus. Theory In soil, shear strength is contributed by the two properties. Cohesion, and Angle of internal friction In pure clays the shear resistance due to internal friction is negligible. Hence, the complete shear strength in clays … Read more
Boring Methods of Exploration The boring methods are used for exploration at greater depths where direct methods fail. These provide both disturbed as well as undisturbed samples depending upon the method of boring. In selecting the boring method for a particular job, consideration should be made for the following: The materials to be encountered … Read more
Types of Retaining Structure From the point of view of the source from which the retaining structure derives its stability, we have basically two types of retaining structures, viz., the gravity and the non-gravity types. The gravity type structures are normally ‘rigid’ and the non-gravity type, ‘flexible’. The gravity type of retaining structure derives its … Read more
Strength and Modulus of Weathered Rock from SPT Values In the weathered rock it is difficult to drive the split sampler to the full specified depth as in soil. Hence we may estimate the strength and elastic modulus values of weathered rock by driving the spt apparatus for a fixed number of blows and find … Read more
For economic consideration, the depth at which the foundation is located (i.e. Df) is kept as small as possible. Typically it is in the range of 0.5 to 1.5 m below the ground surface for buildings that do not have a basement. For those building having a basement, Df can be 3.5 m or more. … Read more
A pile is a slender, structural member installed in the ground to transfer the structural loads to soils at some significant depth below the base of the structure. Structural loads include axial loads, lateral loads, and moments. Another term commonly used in practice for pile foundations is deep foundations. Structures that cannot be supported economically … Read more
Types of Bearing Capacity Failures A bearing capacity failure is defined as a foundation failure that occurs when the shear stresses in the soil exceed the shear strength of the soil. Bearing capacity failures of foundations can be grouped into three categories, as follows: 1. General Shear Failure As shown in Fig-1, a general shear … Read more
On-Site Identification & Classification of Soil The principle terms used by civil engineers to describe soils are Gravel (particle size larger than 4.75 mm) Sand (particle size within 4.75 mm to 0.075mm) Silt & Clay (particle size less than 0.075mm) Most natural soils consist of a mixture of two or more of these constituents and … Read more