Method for detecting thickness of frozen soil curtain of urban underground large-scale freezing project

The invention discloses a method for detecting the thickness of a frozen soil curtain of an urban underground large-scale freezing project. The method is suitable for being used in the urban underground large-scale project. The current focusing principle is adopted, the current of an emitting electrode is compressed into a limited height range, a freezing pipe in the height range is insulated, and therefore it is guaranteed that the current is propagated in a nearly tubular mode, and the tubular current propagation equivalent area is calibrated through a model test; the apparent resistivity of a frozen soil-unfrozen soil-frozen soil system between an emitting electrode and a receiving electrode is calculated based on the voltage and current of the emitting electrode, the function relation between the frozen soil curtain thickness and the apparent resistivity on a current propagation path is established, and then the frozen curtain thickness detection method based on cross-hole resistivity measurement is achie