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 may contain an admixture of organic … Read more
As civil engineer, we built everything on the surface of earth. So it is important to know the structure of earth. Our planet earth was formed some 4500 million years ago. During this time period it has gone through many changes. Previously it was a ball of molten mass and gradually as the time elapsed, … Read more
Prior to construction of a structure, soil investigation is done in order to get the idea of subsurface condition. The scope of a soils investigation is generally depends on many factor, such as Type, size & importance of the structure The client Engineer’s familiarity with the soils at site Local building code Economy If an … Read more
As per IS-2911-Part1/sec2, the ultimate load carrying capacity of pile, Qu, consists of two parts. One part is due to friction, called skin friction or shaft friction or side shear, Qs and the other is due to end bearing at the base or tip of the pile toe, Qb. The equation given below is used … Read more
On Site Identification of Silt & Clay The distinction between silt & clay cannot be based on particle size because the significant physical properties of the two materials are related only indirectly to the size of particles. Furthermore, since both are microscopic, physical properties other than particle size must be used as criteria for field … Read more
Soil in an engineering sense is a relatively loose agglomerate of mineral and organic materials and sediments found above bedrock. Texturally the soil is divided into two primary groups. Coarse grained soil Fine grained soil The behavior of coarse grained soil is different from fine grained soil. The method of describing coarse grained soil is … Read more
Blow counts are affected by operational procedures, by the presence of gravel, or cementation. They do not reflect fractures or slickensides in clay, which may be very important to strength characteristics. The standard penetration test results (N values) are influenced by operational procedures as given in the following table. No. Procedure Its Affect 1. Inadequate … Read more
Even though plate load tests are very commonly used, they do not represent the behavior of prototype foundations totally for the following reasons: The zone of influence for prototype foundation is larger and deeper than for small size plate. Thus, in stratified soil deposits the soils at greater depths will have a significant influence on … Read more
There are many pitfalls associated with the standard penetration test. If these are not carefully avoided, the N-values collected from SPT are mere numbers rather than being useful indicators of soil parameters. Some of the precautions to be taken are: Results of standard penetration test are not reproducible in cohesion less soil below water level … Read more
The N-value observed during testing is not utilized directly in assessing soil properties. These values are corrected to account for The overburden pressure Dilatancy in saturated fine sands and silts Correction for overburden pressure The penetration resistance of soil depends on the over burden pressure. At deeper depth in-situ soil will have higher overburden pressure … Read more