Abstract: Twenty-one field explosive enlargement tests were carried out on six different soil test sites. The embedded charge were 0.05-51 kg and their embedded depths were 1.20-12.5 cm. Five explosively formed cavities were employed for the soil mechanical test on the variation patterns of natural density, pore-solids ratio, saturation degree, compressibility, compression modulus, internal friction angle and cohesive strength. The test results show that the radii of soil mass affected by explosion are four to six times larger than radii of explosively formed cavities. Soil performance indices such as natural density, dry density, saturation degree, compression modulus, cohesive strength are decreased with the increasing of distance to the center of charge. The indices such as pore-solids ratio, compressibility, coefficient of permeability are increased with the increasing of distance to the center of charge. No low-density region where density is lower than undisturbed soil is found around the caves. The variation pattern of internal friction angle of soil by explosive shock is not clear

Key words: explosive enlargement, soil, physico-mechanical performance, field test