Half-cover excavation cover plate supporting structure and stability early warning method

The invention relates to a half-cover excavation cover plate supporting structure which comprises a half-range cover plate, a foundation pit concrete support, a middle stand column, a linkage beam, a limiting block, a stand column jacking, a fixing bolt, a connecting rod, an external steel plate, a buffer spring, a vertical connecting rod, a cushion block and a telescopic steel wedge. The external steel plate is connected with the foundation pit concrete support, so that the supporting strength of the horizontal support is guaranteed; buffer spring supporting devices are installed on the lower sides of the limiting blocks and the stand column jacking supports, it is guaranteed that the whole structure can vertically move within a certain safety range, and the influence of vertical displacement of the middle stand column on the foundation pit concrete supporting structure is reduced. The telescopic steel wedges are arranged at the top ends of the external steel plates and the stand columns, so that the support