摘要
介绍钻井两个井壁破坏情况,分析破坏原因和今后设计设防办法。
When constructing main shaft and auxiliary shaft at Tongting colliery by means of shaft drilling, damages of shaft walls at shafts, the depth of 242.9m and 265m respectively,some 1 m above walling curbs, occur inner protective layers of shaft walls fall away, vertical reinforced bars bend and leave from their normal position to the centre of shaft.Strains occured at ring direction and vertical direction are compressing strains which are less than ultimate compressing strain of concrete.but stretching strain occurs at radial inner side, which strain comes up to or tops ultimate stretching strain under certain condition, results described above obtained by mechanical calculatioa and recognized as essential reasons causing shaft wall inner layer to fall off. When shaft wall falls down slowly, iron wedges are used to keep shaft wall at normal position, which causes concentric stress and shaft wall damage. Field investigation results show that there are additional forces in shaft wall vertical direction. Author assumes that filled materials are located between shaft wall and strata, friction force between depositing materials and bunker wall is calculated depended on deep bunker theory, which force is vertical additional force P_f = (γ_g,γ_os-γ_nρ/μk)ρ. Some suggestions for shaft wall design in the future include (1) to considerate all the loads loaded on shaft wall; (2) calculation of construction bearing force must includes calculation of section strain; (3) to adopt steel plate-reinforced concrete to built shaft wall near interface between overburden and basement rock.
出处
《煤炭科学技术》
CAS
北大核心
1992年第2期38-41,共4页
Coal Science and Technology
