Updated: Sep 7, 2020

What is Soil Mechanics?

Soil mechanics is a discipline of civil engineering that predicts the soil performance characteristics utilizing the engineering techniques of dynamics, fluid mechanics, and other technologies.

Soil mechanics includes the study of soil composition, strength, consolidation, and the use of hydraulic principles to deal with issues concerning sediments and other deposits. Soil mechanics is one of the major sciences for resolving problems related to geology and geophysical engineering. Soil mechanics studies are very important for civil engineers because based on the findings of soil mechanics studies, engineering structures are constructed.

The type of construction, type of equipment to be used, type of foundation, support material, and many other aspects of construction works are largely affected by the soil mechanics studies. Basically we study about soil formation modes, physical and chemical properties of soil, dynamic loading of soils, permeability, consolidation, etc. In the subsequent sections of this article, we will discuss in detail about major aspects of soil mechanics studies.


Formation of Soils Soil is a combination of minerals and organic elements that are in solid, gaseous, and aqueous form.

Soil consists of particle layers that are different from the original materials in their physical, mineralogical, and chemical properties because of the interactions between the atmosphere and hydrosphere and other reasons. The particles of the soil are created from broken rocks that have been changed due to the chemical and environmental effects, including weather and erosion.

Particles of soil are filled loosely, creating a soil formation that consists of pore spaces. Studying soil formation modes is important because it helps in determining properties of soil.

Cohesiveness, adhesiveness, acidity of soil, and other related factors can easily be determined by knowing about the type of soil w have to deal with. We cannot draw any concrete conclusions merely by conducting soil studies but we surely can narrow our research parameters by studying the basic characteristics of soil like color, texture, and nature of soil.

Basic Characteristics of Soils Soil consists of different phases of solid, liquid, and gas and its characteristics depend on the interacting behavior of these phases, and on the stress applied. The solid phase includes clay, non-clay minerals, and organic matter. These elements are categorized by their size as clay, sand, and gravel. The liquid phase is composed of water that contains organic compounds available from chemical spills, wastes, and ground water, while the gas phase is normally air. The size, form, chemical properties, compressibility, and load carrying capability of the soil particles are determined by soil mineralogy, which is a science related with the chemistry, structure, and physical properties of minerals. The structure of a soil depends upon the arrangement of particles, particle groups, pore spaces, and the composition. These basic characteristics determine the type of structure to be built and what external support measures, if any, has to be taken to make the structure last long and bear the effects of earthquake, water seepage, and other external factors.

Foundation engineering,

also known as geotechnical engineering, applies theoretical knowledge concerning the behavior of soils and rocks and the construction of load-bearing structures to the planning and construction of foundations for infrastructure.

At the most basic level, a foundation engineer would consider the kind of soil on which construction is to begin, allowing for the selection of the best material for the job, taking into account variables such as the manner in which such materials would need to be reinforced. This field of engineering not only establishes the physical qualities and quantities needed for the construction of foundations but establishes the necessary design parameters needed for such construction.

Such parameters are established by evaluating factors such as the bearing capacity of a particular soil, allowable soil pressure, and the influence of slopes and adjacent foundations, among others.

Foundation Engineering is critical in construction

An equally important facet of foundation engineering entails the maintenance and evaluation of existing foundations, which in practice involves pre-empting the degradation or failure of a foundation, and in some cases assessing the damage that has already occurred.

Such risk assessments require the foundation engineer to take into account factors such as the arrangement of physical features, or topography, of the area being assessed, seismic forces, and groundwater, all of which may play a part in the deterioration of existing foundations. This aspect of foundation engineering is particularly important in minimizing risks to human safety which may occur as a result of unsound foundations.

Extrapolating along the lines of risk assessment, site conditions which may have otherwise limited development potential may be mitigated through the improvement of the engineering properties of the soil and rock foundations in themselves.

Simply described, the foundation of a structure serves to transmit loads from the structure to the earth. As such, the design of a foundation requires an estimation of the magnitude and location of loads that need supporting, a plan for the evaluation of the subsurface, and the establishment of the required soil parameters through field testing. Once these factors have been taken into consideration, the foundation is designed such that construction is achieved in the most economic manner feasible, while also ensuring that any risks which may be present during, or subsequent to the construction of the foundation, are minimized.

Soil is key!

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