A long‐term field soil survey by acoustic techniques: Part II. Nonlinear acoustics

Abstract

Soils are complicated, multiphase granular materials; their behavior is determined by the discrete nature of these media, external and interparticle forces, interconnected porosity, and multiphase conditions. In a real world, the properties of field soils change ceaselessly due to seasonal and climate effects. It is generally difficult or impossible to simulate field soil conditions in the lab. To study and monitor the evolution process of soil properties, acoustic techniques are invoked for a long‐term field soil survey. In this study, an acoustic probe with five acoustic transducers is inserted into the ground with minimum disturbance of soils. At different depths, sound speed, temperature, moisture, soil suction, and rain precipitation are recorded continuously. It is found that temperature has a negligible effect on the sound speed, moisture plays a minor role, and soil suction is the predominant factor governing the sound speed of the shallow field soil. Terzaghi’s principle of effective stress is br...