Joint inference of multi-channel transient surface wave method and microtremor method to investigate the structure and thickness of the overburden layer in the typical area of karst collapse

In order to obtain the structure and thickness distribution of the overburden layer in the typical karst collapse area in large scale, multi-channel transient surface wave method and microtremor method were used to carry out field survey in the typical karst collapse area of Dongquan commune in Liucheng country, Liuzhou city.Based on the relationship between the characteristic frequency and the thickness of the formation extracted by the microtremor method, combined with the existing borehole data, the functional relationship between the thickness of the covering layer and the characteristic frequency is obtained and the thickness distribution of the overburden layer can be derived. The shear wave velocity distribution of the overburden layer was obtained from the dispersion characteristics of the surface wave, based on which the structural distribution of the overburden layer can be derived. With the structure and thickness distribution of cover layer, four local faults or dissolution trenches in the survey area were inferred. The study shows that the structure and thickness distribution of the overburden layer can be effectively deduced by using the characteristic frequency of microtremor and the dispersion characteristics of the surface wave.