It is challenging to represent the surface deformation characteristics and the rock mass failure modes caused by underground mining

since there are many uncontrolled factors such as variational orebody shapes

complex geological conditions

mostly subcritical excavation

different mining methods

conspicuous tectonic stress and obvious structure effect. In this study

the eastern area of Chengchao iron mine was selected as an example

and monitoring results were achieved by 3D laser scanning and GPS surveying based on the first-hand monitoring data of surface deformation from March 2010 to September 2015. Thus the surface deformation characteristics and rock mass failure mechanisms caused by underground mining were explored. The comparative analysis of surface deformation in the hanging wall and on the footwall of eastern area of Chengchao iron mine showed that: tubular caving continuously developed upwards at the beginning of the mining. Different sizes of funnel-shaped collapse pits appeared on the mined-out area surface after the rock mass caving propagated to the ground. The extension of surface deformation was consistent with the mining advance in the hanging wall. Furthermore

the surface deformation characteristics were mainly affected by horizontal stress which served as a main driving force of rock mass deformation. Additionally

the damage modes of rock mass were changed by the structural plane

which mainly slowed down and accelerated rock mass deformation in the hanging wall and footwall

respectively. Moreover

the total deformation and the vertical deformation rate were much greater in the downward direction due to the slope morphology.