Soil Mechanics, history of

Alfreds Richards Jumikis 

Part of the Encyclopedia of Earth Sciences Series book series (EESS,volume 3)

Jumikis, A.R. (1984). Soil Mechanics, history of . In: Finkl, C. (eds) Applied Geology. Encyclopedia of Earth Sciences Series, vol 3. Springer, Boston, MA. https://doi.org/10.1007/0-387-30842-3_66

Soil mechanics, also known by the term géotechnique or geotechnics , is one of the younger basic civil engineering disciplines (see Geotechnical Engineering ). The twentieth century—and particularly the years since 1925—has witnessed an enormous impetus in the development of soil mechanics throughout the world. Our present-day knowledge of soil mechanics (q.v.) is, however, an accumulated heritage of the past.

Soil mechanics may be defined as the discipline of engineering science that studies soils, from theoretical and practical points of view, by means that influence the way engineers build structures. Thus the soil mechanics discipline treats soil and its properties as a construction material associated with engineering (see Vol. XII, Pt. 1: Soil). Soil mechanics studies, both theoretically and experimentally, the effect of forces on the equilibrium and/or performance of soil-foundation systems (see Foundation Engineering ) under static and dynamic loading conditions, as well as under the influence of water and nonfreezing and freezing temperatures.

The practice of engineering that applies the principles of soil mechanics to the design of engineering structures is called Soil Engineering (see Vol. XIV: Engineering Soil Science). Soil mechanics has developed from practical necessity and hence is of national importance.

In the more prehistoric civilizations, soil was used as a construction material for structures themselves: huge earth mounds for refuge during flood periods, caves to live in (e.g., loess dwellings in China), canals and ditches, and fortifications. Prehistoric man’s progress in managing soils was very slow indeed.

As time progressed, soil was used in the construction of roads, canals, bridges, foundations, and fortifications, and was also used for impounding water and in building dikes and levees. Earth retaining walls supported the terraces of the famous “hanging gardens” of King Nebuchadnezzar of Babylon (from 604 to 562 B.C.).

At the peak of the Roman Empire’s glory, engineers built heavy structures such as breakwaters, aqueducts, bridges, large edifices, and a great network of good roads (Vitruvius, 1914). This required considerable understanding of the performance of soil under the action of load, water, and temperature. A solid foundation and good drainage of roads were the basis of Roman engineering—principles that are still honored in modern road construction. It is known that the Romans studied soil to determine its firmness to support aqueducts and theaters.

In the Middle Ages, soil engineering extended beyond the building of roads and canals to the construction of heavy city walls with flanking towers, castles enclosed by heavy earthworks, large cathedrals, and campaniles (bell towers). The most famous example of a medieval soil mechanics problem is the Leaning Tower of Pisa, which tilts because of differential settlement. Begun in 1174 A.D., this Campanile, 54.56 m (approximately 179 ft) tall, was completed in 1350. In 1910, the tower had a visible slant, and its top was 5.03 m (approximately 16.5 ft) out of plumb. From 1174 to 1933 the settlement of the center of the footing of the tower was 80 cm (approximately 2.62 ft), the lowest point of the footing settled 320 cm (approximately 10.5 ft), and the highest point settled about 160 cm (approximately 5.25 ft).

In the latter part of the seventeenth century, French military engineers contributed some empirical and analytical data pertaining to earth pressure on retaining walls for the design of revetments of fortifications. In 1661, France undertook an extensive public works program, which included the improvement of highways and the building of canals. The construction of the great fortification system along the border of France was begun in 1667 under Marquis Sebastian le Prestre de Vauban (1633–1707), who was commissary general of fortifications and Louis XIV’s chief engineer, and who in 1703 became marshal of France. Vauban is regarded as one of the greatest military engineers of all times (Vauban, 1686, 1740).

It is known that at that time Vauban gave some rules for gauging the thickness of retaining walls. It is not known for sure, however, whether he based these rules on theoretical considerations or his own experience. In this respect thoughts were later expressed in France that Vauban’s empirical rules appeared to be so complete that it almost seemed as if they were based on an earth-pressure theory now unknown to us.

During the times of French mercantilism (17th century), soil problems were encountered in the terrain through which the canals were dug. Also, earth retaining walls of the great fortification system along the borders of France presented earth-pressure problems in connection with their stability. France established a corps of military engineers to train, among others, experts in fortification, and in 1745 the famous École des Ponts et Chaussées was established, where engineers were educated in sound principles of physics, mechanics, and mathematics for the construction of canals, highways, and bridges.

The first theoretical contributions to soil mechanics were made by C. A. Coulomb in 1773 with his Classical Earth-pressure theory —calculations of earth pressure against a retaining wall. In this analysis, Coulomb applied the laws of friction and cohesion, and determined the earth pressure on a retaining wall from the “Wedge Of Maximum Pressure”. The importance of Coulomb’s theory may be recognized best by the fact that his ideas on earth pressure are recognized and still used (with a few exceptions) even today.

Later Français (1820), Navier (1821), Poncelet (1840), and Culmann (1866) further developed Coulomb’s theory for practical applications by engineers. Alexandre Collin (1846) dealt with slides on slopes of canals and dams made in and of clays, and studied the forms of sliding surfaces. In 1857 W. J. M. Rankine published his theory on earth pressure and equilibrium of earth masses. Thus the impetus for the development of early soil mechanics was given by the increased activities in bridge design and construction for highways and railways. Contributions to earth-pressure theories and thus to soil mechanics were also made by Müller-Breslau (1906), Franzius, (1927), Krey (1936), Terzaghi (1925), and Fröhlich (1934).

Pioneering in practical soil mechanics must be credited to the Swedish Geotechnical Commission of the State Railways in Sweden, and the Foundations Committee of the American Society of Civil Engineers (ASCE), both established in 1913. The year of birth of modern soil mechanics, however, is now generally recognized as 1925, when Karl Terzaghi published his book Erdbaumechanik auf bodenphysikalischer Grundlage. Another important step in the development of this new discipline was taken with the publication of the settlement theory of clays, coauthored by Terzaghi and Fröhlich (1936).

The basic concept of the Effective Stress in soil mechanics, though, is to be credited to Terzaghi (1936). Terzaghi’s publications, and the work in soil mechanics done by other authorities in this field, were a great stimulus to soil mechanics studies and contributed a considerable amount of knowledge on engineering properties of soils in the United States, as well as abroad. The objectives of soil mechanics are (1) to study the physical and mechanical properties of soil, (2) to apply this knowledge for the solution of practical engineering problems, and (3) to replace by scientific methods the empirical ones of design used in foundation and soil engineering in the past.

Some typical problems encountered in soil mechanics involve the bearing capacity of soil (see Figs. 1, 2, and 3); stress distribution in soil; stability of soil foundation systems; tolerable settlement of soil and structure; effect of frost on soil and foundations; effect of vibration on soil; soil stabilization; and laying of foundations in permafrost. The combined efforts of engineers and researchers from all over the world in this discipline contributed to what may be called modern soil mechanics.