Development and application of double-ring infiltrometer

In order to overcome the deficiency of the existing double-ring infiltrometer (DRI) for the soils with high permeability, a new DRI is developed. The device is composed of water injection system and water supply system. It only requires two sets of mariotte reservoirs for both the inner and outer cylinders to which, water can be added to the empty mariotte reservoirs from the external water tank when needed without affecting the measurements. The method keeps accurate constant head for high permeability and consecutive water supply during the testing process. The new DRI is used to test the permeability coefficient of Angola brown-red Quelo sand, and satisfactory results are achieved. The test results show that the permeability coefficient of Quelo sand in the natural state is 10^-3~10^-2 cm/s orders of magnitude, and after compaction (heavy compaction standard, compacting factor λ≥0.95) 1~3 orders of magnitude are reduced. The result of the in-situ double-ring water infiltration test is about 0.5 orders of magnitude higher than that of the indoor variable-head permeability test under the same void ratio.