Complex salt rock underground and water dissolution joint cavity construction method

The invention discloses a complex salt rock underground and water dissolution joint cavity construction method. The method comprises the following steps of: 1) selecting a site for a rock salt deposit; 2) enabling a water dissolution drilled well to drill through a target rock salt layer; 3) arranging an underground vertical shaft at the center of a regular hexagon; 4) excavating in the underground vertical shaft till the bottom of the target rock salt layer; 5) excavating a communicating laneway to the bottom of the water dissolution drilled well; 6) constructing a groove in the rock salt layer at the bottom of the water dissolution drilled well; 7) cutting off rock salt and transporting to the ground; 8) mounting a sealing valve at the vertical shaft end of the communicating laneway after the end of groove construction; 9) closing the valve and continuously constructing a cavern in rock salt; 10) opening the sealing valve of the communicating laneway and discharging insoluble matters at the bottom of the ca