## 1 Introduction  
The Shendong coalfield covers the southern part of Erdos City in Inner Mongolia Province, the northern part of Yulin City in Shaanxi Province and Baode County in Shanxi Province. This mining field is approximately 12,860 km\({}^{2}\) with an overall production capacity of more than 200 million tons, which was 67.7% of the national production in 2011 [1]. There are several large modern coal mines in this coalfield, including Bulianta Mine, Daliuta Mine and Bu'ertai Mine, with capacities of more than 20 million tons each; there are approximately a dozen other mines in the region with capacities that are more than 10 million tons each. The geological conditions of the coal seams in this region are characterized as being shallow, thick and horizontal [1; 2], which implies super-large coalfaces that can be mined with high-strength approaches. The definition of \"super-large\" is not strict, according to Refs. [1; 2; 3; 4; 5; 6; 7; 8], as a super-large coalface should at least have a length in the dip direction of 300 m, a length in the strike direction of 3000 m, a mining thickness of 5 m and a mining speed of 8 m/day. As the Shendong coalfield is a very important coal-producing region in China, the subsidence characteristics and the damages on the ground environment are both of high concern. Mining subsidence is a damage phenomenon that is induced from the exploitation of underground ore bodies. After excavation, the overlying strata first fractures and bends. By employing field data and physical and numerical experiments, the fracture theories and control methods of the overlying strata have been studied in the Shendong coalfield [6; 9; 10]. The subsidence phenomenon then develops from overlying strata to the ground surface. Observation stations are often used and reliable method to monitor ground subsidence. By the end of 2013, there were 17 coalfaces in 10 mines that were being monitored in the Shendong coalfield [5]. Other modern monitoring technologies, such as interferometric synthetic aperture radar (InSAR) [11; 12], have also been employed to obtain subsidence data. However, due to noise and other factors, InSAR monitoring results cannot easily reflect actual subsidence deformations of slopes and curvatures [12]. Numerical [13; 14; 15] and physical [6; 8] simulations are also usually used in ground subsidence research in this coalfield. Using all these aforementioned methods, the ground subsidence characteristics and subsidence parameters [13; 16] as well as their dynamics [11] have been studied. The super-large size of the coalface and high-strength mining cause the active period of the subsidence process to be short with the main subsidence values concentrated during this period [5]. Ground fissures are readily developed, and occasional discontinuous subsidence phenomena occur at the surface [8; 17; 18; 19]. Furthermore, some improved computation methods have been developed to better fit the ground subsidence for this coalfield, such as a prediction method based on the boundary value method [20], which can be used to more accurately compute the vertical subsidence on the ground. The ground environment is unavoidably influenced or damaged by the mining subsidence. In this region, the vegetation, crops, underground water, buildings, biodiversity and other ecological features are the primary concerned ground objects [4; 21; 22; 23; 24]. Due to the high-strength mining and the fact that the Shendong coalfield is a fragile-ecology region [25], the damage extent of the ground environment can be commonly considered to be serious [26]. However, it is fortunate that super-large coalfaces induce damage that has a certain \"self-repairing\" characteristic and damage mitigation ability [4; 27]. The existing assessment criteria of ground damage are not uniform [7; 28].