Underground diaphragm wall structure and construction method

The underground diaphragm wall structure comprises a first prefabricated wall body and a second prefabricated wall body, a connecting groove is formed in the right side of the first prefabricated wall body, a mounting groove is formed in the inner wall of the left side of the connecting groove, and a fixing groove is formed in the top of the first prefabricated wall body; connecting assemblies are arranged in the first prefabricated wall body and on the left side of the second prefabricated wall body, each connecting assembly comprises a threaded cylinder rotationally mounted on the inner bottom wall of the corresponding fixing groove, a moving block is mounted on the inner wall of each threaded cylinder in a threaded mode, and a movable rod extending into the corresponding mounting groove is fixedly mounted at the bottom of each moving block; a plurality of limiting grooves are formed in the right side of the movable rod, limiting blocks are fixedly installed between the inner walls of the front side and the