civil engineer who founded the branch of civil engineering science known as soil mechanics, the study of the properties of soil under stresses and under the action of flowing water.

He studied mechanical engineering at the Technical University in Graz, graduating in 1904, then worked as an engineer for several years; he was awarded a doctorate in engineering by the same institution in 1911. After visiting the United States, he served in the Austrian Air Force during World War I, but in 1916 he accepted a position with the Imperial School of Engineers, Istanbul. When the war was over, he took a post (1918–25) with Robert College, a U.S. institution, also in Istanbul. Much research had been done on foundations, earth pressure, and stability of slopes, but Terzaghi set out to organize the results and, through research, to provide unifying concepts. The results were published in his most noted work, Erdbaumechanik (1925; Introduction to Soil Mechanics, 1943–44).

In 1925 he went to the United States, where—as a member of the faculty of the Massachusetts Institute of Technology, Cambridge—he worked unceasingly for the acceptance of his ideas, serving also as consulting engineer for many construction projects.

In 1929 he accepted the newly created chair of soil mechanics at Vienna Technical University. He returned to the United States in 1938 and served as professor of civil engineering at Harvard University from 1946 until his retirement in 1956. His consulting practice grew to encompass the world, including the chairmanship of the Board of Consultants of Egypt's Aswān High Dam project until 1959.