A PYROTECHNIC METHOD FOR THE STABILISATION OF LOW BEARING CAPACITY SUBSOIL

摘要

A pyrotechnic method for stabilisation of low bearing capacity subsoil, that consists of determination of the parameters of the layer of soil to be stabilised, drilling non­tabulated, vertical shot-holes at the intersection points of a square or equilateral triangle grid, selection, preparation and firing the oblong charges, characterised by the fact that the shot-holes with a diameter from 0.02 to 1.5 m and a depth of up to 50 m, aredrilled with a water flush or a mud or clay suspension, at a spacing of 3 to 25 m, this spacing distance being inversely proportional to the thickness of the layer of soil that is to be stabilised. The charges, the total length of which cannot exceed the thickness of the layer to be consolidated, are composed of several small "sub-charges", spaced at distances from 1 to 10 m down the shot hole. The bottom end of each charge is blocked with a rod the diameter of which is greater than that of the shot hole. The sub-charges are fired successively from the top one to the bottom one, with a delay of between 0.05 to 10 milliseconds. The sequence of firing starts at one end of the area of soil to be consolidated. The charges are fired individually or in small groups at time intervals. Before the drilling of the shot holes a layer of loose soil, the thickness of which should vary from 0.5 to 20 m, is deposited on the area to be stabilized. After the explosions the non-cohesive soil fills the shot holes. The "sub-charges" are vertically fastened in the shot holes with wood, plastic or metal distance making rods.