Moderately differentiated mudstone and sandstone have high strength. The strength of moderately weathered mudstone is 5.40Mpa, and that of moderately weathered sandstone is 8.5MPa, so the strength of moderately differentiated mudstone and sandstone is high. Mudstone and sandstone are two kinds of common rocks on the surface. Peat has been squeezed and bonded together at high temperature after hundreds of millions of years of crustal activity. Mudstone is delicate, elastic and fragile. Sandstone is composed of sand, which is formed by high temperature extrusion for hundreds of millions of years. It is characterized by complex composition, hardness and great toughness.