Abstract：Based on a large number of experimental data，in-situ observations and mining engineering practice on a large-scale reduction for coal column protection in weathered zone，the distributed characteristics of the weathered zone of bedrock in covered coal field are studied. The weathered rocks have a series of variational characteristics such as the decreased intension，increased plasticity deformation，muddy tendency，easily combined fractures，greatly boosted water resistance，and strong hydrophilicity and so on. The characteristics of engineering geology，which mainly cover the new movement evolution characteristics of overburden damage mining in weathered zone such as fast movement，large deformation，quick contraction and compression，and great subsidence，are studied with some new understandings，such as the rocks in weathered zone mainly composed of argillaceous rocks that have the dual functions of water blockage and water flowing prevention in fractured zone from development with mining influence. The thickness and the weathered degree of coal column are the main factors affecting the height development of flowing fractured zone and so on. The mining mechanism of reduction for the coal column protection is studied. A series of new measures of key techniques are proposed to guarantee extraction safe for the first time such as lagged controlling water in exhausted workings，distribution of coal and water，the height increase of extraction，geophysical prediction，and pre-reinforcement of geological fractures and so on. It has important theoretical application for the reclamation and safe mining in shallow resources of similar coal mines.
