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GOVERNING EQUATIONS AND COMPLETE MATHEMATICAL PROOFS FOR COULOMB’S THEORY OF EARTH PRESSURE
GOVERNING EQUATIONS AND COMPLETE MATHEMATICAL PROOFS FOR COULOMB’S THEORY OF EARTH PRESSURE
Tse-Shan Hsu
President, Institute of Mitigation for Earthquake Shear Banding Disasters
Professor, Department of Civil Engineering, Feng-Chia University, Taiwan, R.O.C.
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Yi-Ju Chen
Ph.D. Student, Ph.D. Program of Mechanical and Aeronautical Engineering,
Feng-Chia University, Taiwan, R.O.C.
Zong-Lin Wu Tzu-Che Chao Ding-Yu Wei
Directors, Institute of Mitigation for Earthquake Shear Banding Disasters
Taiwan, R.O.C.
Jiann-Cherng Yang Yi-Min Huang
Associate and Assistant Professors, Feng-Chia University, Respectively,
Taiwan, R.O.C.
Abstract
Coulomb’s theory of earth pressure, proposed in 1776, has been widely used by engineers to design retaining walls for 245 years. However, because the earth pressure functions are very complicated, there is still no study providing governing equations and complete mathematical proofs. Therefore, this paper provides governing equations for solving Coulomb’s theory of earth pressure using the first-order differential equations of Coulomb’s earth pressure functions. Furthermore, the second-order differential equations of Coulomb’s earth pressure functions are used to mathematically prove that the active earth pressure is the maximum value and the passive earth pressure is the minimum value. This not only completes the mathematical proofs for Coulomb’s theory of earth pressures, but also enhances the physical understanding and mathematical basis of the calculation of Coulomb’s earth pressures.
Keywords: Coulomb’s theory, active and passive earth pressures, governing equation.