Sri Ramakrishna Mission Vidyalaya Polytechnic College, Coimbatore - 641 020

  What are the Methods of Compaction? In earlier times construction and embankment design were not given enough attention, resulting in embankments being left for compaction naturally. Because the older versions do not support heavier axle loads, it is necessary to now use a high degree of sub-grade support to create heavy and fast compaction. This form of compaction must be performed by suitable compacting equipment. Compaction or the densification of soil creates an all-around improvement of soil properties and how it performs as a pavement support bed. This process increases the density of the soil through mechanical means when packing the soil particles closer together and reducing air voids. The reduction of air voids through packing obtains a homogeneous soil mass that has much better properties. So what are the methods of compaction? Methods of Compaction There are different methods and machinery used in the process of compaction. Smooth Wheeled Roller The smooth-wheel rolle...

  Deep Foundations Unlike shallow foundations, which are placed closer to the surface, deep foundations are used when the depth from the ground surface to the underside of the foundation exceeds five times the width of the foundation. They are suitable for heavy structures or when the soil near the surface is not strong enough. Pile foundations, pier foundations and caisson foundations are the primary types of deep foundations. Pile Foundations These foundations are made up of long, slender structural elements called piles. Piles are driven deep into the ground to transfer the load of the structure to stronger, more stable soil or rock layers. Pier Foundations Similar to pile foundations, pier foundations consist of cylindrical or rectangular columns that are drilled or driven deep into the ground to bear the load of the structure. Caisson Foundations Caisson foundations are used when the load of the structure needs to be transferred to lower layers of soil or rock. They are constr...

Types of Shallow Foundations   1. Individual Footing or Isolated Footing The individual or isolated footing is the simplest and most common type of foundation. They are constructed to support a single column. They are also known as a pad foundation, and their shape is typically square or rectangular, calculated based on column load and soil bearing capacity.   Advantages: ·         Economical and straightforward in design ·         Ideal for supporting structures with a clear load path and predictable loads   Disadvantages ·         Not suitable for heavy structures or when soil conditions are variable ·         Supports only a single column.   2. Combined Footing When columns are closely spaced such that their footings overlap, a combined footing is constructed. It shares attributes with isolated footings b...

  Pore pressure (or pore water pressure,  𝑢 ) Soil is the pressure exerted by the fluid (usually water) within the spaces (pores) between soil particles, acting equally in all directions. It's crucial in geotechnical engineering because it reduces the effective stress (the force carried by the soil skeleton, between particles, impacting soil strength, stability, and deformation, governed by the principle   (Total Stress - Pore Pressure). This pressure can be positive (below the water table, hydrostatic), zero (dry soil), or negative/tension (unsaturated soil, known as suction).  Three-Phase System : Soil has solids, water, and air; pore pressure relates to the fluid phase. Neutral Stress : Pore water pressure is also called neutral stress because it acts equally in all directions, like hydrostatic pressure. Effective Stress : The actual stress carried by the solid particles, calculated as Total Stress minus Pore Pr...

  Any soil when depositing contains some voids in them.  The property of the soil which permits the water or any liquid to flow through it through its voids is called permeability.  Permeability is the ease with which water can flow through the soils.  There are numerous methods through which we can measure the permeability of a soil in the field or of a representative sample in the laboratory.  In the laboratory we employ two methods 1. Constant Head Permeability Test 2. Variable Head or Falling Head Permeability Test These tests measure the amount of water that goes through a soil sample in a fixed time interval.  Constant head method is suitable for coarse grained soils which are relatively more pervious because of their larger voids. While variable head is more suitable for small grained soils which are relatively less pervious because of their poorly connected void structure. For this test to perform we use an instrument which is called constant head p...