Design Of Anti-subsidence Terrace In Subsided Lands Resulted From Coal Mining In Mountainous Area

Coal mining activities lead to multiple subsidence of arable land in hilly and mountainous areas,and it is very critical to study the main factors which affect the stability of terraces,and explore the damage patterns of ridges.In this paper,a total of 37.43 hm2 cultivated land in the southwest of Wanghushan Village and the east of Cheguozhuang Village,Zezhou County,Jincheng City,Shanxi Province,was chosen as a typical subsided demonstration area.On the basis of analyzing the factors that affect the stability of terraces,FLAC3 D numerical simulation software was introduced,the cross-sectional dimensions of the anti-subsidence terraces were designed,and the damage mechanism inside the terraced soil was revealed.Finally,comprehensive planning for anti-collapse terraces was carried out.The results indicated that:i)Based on the single factor sensitivity analysis and the multi-factor orthogonal experiment design,it was found that the unit weight of soils,cohesion,internal friction angle,ridge slope and height showed a significant level of stability to terraces.Cohesion was the most sensitive factor,followed by unit weight of soils,slope,height and internal friction angle.Among them,cohesion and internal friction angle were positively correlated with the stability of ridges,while unit weight of soils,slope and height were negatively correlated with them.ii)FLAC3D can objectively predict the shape and position of the potential sliding surface,reduce the subjectivity in the process of solving the safety factor,not only accurately evaluate the stability of the terraces,but also simulate the stress-strain relationship inside the ridges.Scientifically explain the damage patterns of terraces.iii)The size of the anti-subsidence terrace was proposed: when the topography slope is 5 °,the ridge slope is 75 °,and the height is 1.8 m;when the topography slope is 10 °,the slope of the ridge is 72 °,and the designed height is 2.2 m;when the slope is 15 °,the slope of the ridge is 70 °,and the designed height is 2.7 m;when the topography slope is 20 °,the slope of the ridge is 65 °,and the designed height is 3.0 m.After the anti-collapse design,the stability of the terraces were improved.iv)The results of numerical simulation of FLAC3 D showed that the tensile stress and compressive stress coexist inside the ridge,the compressive stress is very extensive,and however the tensile stress is merely concentrated at the top of the field.The distribution of the plastic zone showed that the main destruction pattern is shear damage.v)The maximum shear strain was the position of the potential sliding surface,and the maximum shear strain increment zone shows that the potential sliding surface of the ridge is circular,and the sliding surface position extends from the foot to the top of the ridge,and the sliding surface shear outlet is located on the slope above the toe of the slope.vi)Using ArcGIS platform,combined with the numerical simulation of FLAC3 D can be a scientific and reasonable approach to achieve comprehensive planning and design of terraced terrace.