The Development Of The New Auto-Controlling Apparatus For Measuring Air-Water Movement And The Test Investigation Of Watering

The testing technique and experiment methods of unsaturated soils are the important means and tools to investigate the mechanic behavior of unsaturated soil. Due to it's difficult to measure the water and air permeability, many researchers put forward the various forms of permeability functions which calculate the water coefficient of permeability. However, neither any apparatus or function forms is popularized nor any of them can satisfy the request of the theory of unsaturated soil and the engineering.In this paper, in terms of the shortage of the current apparatus of permeability for unsaturated soils, the new permeameter for measurements of water and air coefficients of permeability of unsaturated soils has been developed based on improvement and amendment on original apparatus of measuring water-air movement. It is carried into effect to control the suction through setting the only air-penetrate and only water-penetrate material when saturation on top and bottom of specimens respectively. So it has multiple functions of measuring the air and water coefficient of permeability directly under watering , controlling the suction, loading as well as the coupling the loading and watering. Further more, this apparatus can also exert stress axially to reveal the change characteristic of suction on the condition of wetting and drying under pressing or the coupling of loading and watering.Another important achievement of this paper is to carry out a large number of infiltrating tests with the apparatus of measuring the air-water movement to investigate the permeability of unsaturated soil upon several dry density and the different degree of saturation. And it proves that the wetting, dry density and water content have influence on the coefficient of permeability.