Combined Support of Segmental Lining and Compressible Layer of Coal Mine Shafts

In order to study the influence of the compressible layer parameters on the mechanical properties of the segmental lining in the combined support system of the inclined shaft constructed by shield, a numerical model considering the contact effect between the segmental lining and the compressible layer and the stiffness reduction of the segment ring was established based on the Main Inclined Shaft Project of Shenhua Xinjie Taigemiao Coal Mine Area, and the distribution characteristics and variation laws of the internal force and deformation of the segmental lining are analyzed under different factors such as the presence or absence, the stiffness and the thickness of compressible layer. Similar model tests were carried out to further investigate the above problems. The ultimate bearing capacity and the form of destruction are also discussed. The results show that the greater the compressible layer stiffness, the greater the and the more uneven distribution of the surrounding rock pressure on the segment, at the same time, the bending moment of the segment decreases and the axial force increases. It is more obvious when the ratio of compressible layer modulus to surrounding rock modulus varies from 0.1 to 0.5. With the increase of the compressible layer thickness, the surrounding rock pressure on the segment varies according to the trend of uneven to uniform and then again to uneven. When the ratio of the compressible layer thickness to the segment thickness is 1.7, the pressure of the surrounding rock is the smallest. The axial force decreases with the increase of compressible layer thickness. The existence of compressible layer has little effect on the deformation of segmental lining. The model test results further show that the compressible layer can absorb the surrounding rock pressure and cause stress redistribution through its own compaction, so as to reduce and homogenize the load transferred to the segment, so that the internal force of the segment grows more smoothly with the external load smaller and more evenly distributed; and increased the ultimate bearing capacity of the segments by 40%. In the presence or absence of the compressible layer, the failure of the segment has experienced the processes of elliptic, elliptical exacerbation, the occurrence and expansion of the crack and instability.Moreover, the damage of the segment is more serious when the compressible layer is present. The research results of this paper can provide some reference for the design and construction of similar projects.