Undisturbed box type sampler for sediment on water surface layers

An undisturbed box type sampler for sediment on water surface layers comprises a mud acquiring bucket, a mud acquiring bucket carrying handle, an expansion bracket, a counterweight and a traction rope. The mud acquiring bucket carrying handle consists of a carrying handle upright column and a carrying handle crossbeam, the carrying handle upright column is fixedly connected with the mud acquiring bucket, small holes are arranged on the carrying handle crossbeam, the expansion bracket comprises an expansion bracket upper plate and an expansion bracket lower plate, expansion bracket upright columns are fixedly connected with the expansion bracket upper plate and the expansion bracket lower plate and fixed onto the expansion bracket lower plate, an expansion bracket strut and the expansion bracket upright columns penetrate through the small holes on the carrying handle crossbeam, a compression spring is sleeved on the expansion bracket strut, the mud acquiring bucket is provided with a square box and two symmetric mud acquiring claws, shaft heads are disposed on two sides of the box, the mud acquiring claws are rotationally connected with the shaft heads, a tension spring is connected between the mud acquiring claws, the mud acquiring claws are connected with suspension plates, the traction rope penetrates through the expansion bracket upper plate to be connected with the carrying handle crossbeam, and the other end of the traction rope penetrates out from a hole on the counterweight. The sampler has the advantages that a sediment-water interface of acquired sediment on a surface layer is clear, layers of the sediment keep well, a sampling process is undisturbed, and the volume of the acquired sediment can be accurately computed.