The Design And Implementation Of Equipment For In Site Permeability Measurements

The method of combining the soil gas permeability and the soil radon concentration for radon risk mapping is developed rapidly. The work of radon risk mapping in china is still at the early stage, and the study of soil gas permeability is still on blank. Based on Darcy’s law and small-diameter probe tube technology, we have designed a set of on-site soil permeability measurement system and completed a prototype of the instrument. The instrument consists of three parts: the probe tube, compressor and automatic triggered timing system. The principle is use the compressed air device to drive a constant pressure air to the probe, which the specially designed probe tube punch to a certain depth into the soil with a fixed size cavity on the head of probe, As soon as the compressor devices start to work, the automatic triggered timing system will measure the time spent. According to measurements of time, combined with the geometric factor of the probe and compressor system factor, we can calculate the soil gas permeability parameters.To compare the prototype with the same type of equipment Radon-Jok, The laboratory simulation and field test results are in agreement, the relative error is less than 5%. But the prototype is more convenient、efficient and economical.