| Full face rock tunnel boring machine(TBM)has been widely used in subway,water conservancy,municipal tunnels and other engineering fields in China.Related technologies and research achievements are abundant.Due to the complex geological and construction conditions of coal mine,there are few related researches on TBM construction of deep rock roadway at home and abroad.With the popularization and application of TBM in deep rock roadway driving in coal mine,bad strata have become the main factor affecting the safety and efficiency of TBM driving in coal mine roadway construction.In order to solve the problem that TBM is difficult to support roadway surrounding rock in bad strata of coal mine,a new assembled steel support structure of TBM driving coal mine roadway is proposed.The full-scale model of fabricated retaining structure was made,and the full-scale model tests under different lateral pressure coefficients were carried out in the large-scale mechanical test system of underground engineering,and the numerical tests of retaining structure were carried out.The main research contents and results are as follows:(1)The full-scale model test of indoor steel supporting structure with lateral pressure coefficient λ=1 and 1.5 was carried out.Systematically collect and analyze the load,displacement and strain of the steel support structure,and obtain more detailed deformation data of the support structure through photogrammetry.The analysis shows that the yield load of the supporting structure is 6132.4k N and the ultimate bearing capacity is 6454.1k N under the condition of λ=1 uniform load,and the supporting structure presents an asymmetric failure mode.Under the condition of λ=1.5 non-uniform load,the yield load of the supporting structure is 2505.8k N,and the ultimate bearing capacity is 3481.2k N.The supporting structure presents a symmetric failure mode.Compared with the uniform load test,the ultimate bearing capacity of the non-uniform load test is reduced by 46 %.(2)The numerical test research of steel support structure is carried out.The finite element software is used to carry out numerical analysis on the steel support structure,which is mutually verified and supplemented with the model test.Parameters such as structural axial force,structural bending moment and bolt axial force which are difficult to monitor in laboratory test are obtained and analyzed.The analysis shows that the stress of two vertical channel steels and one vertical mine-used I-beam in the segment is relatively small,and the stress of two circumferential mine-used I-beam in the segment is relatively large.The supporting structure is mainly borne by the circumferential mineused I-beam of the segment.The axial force of the supporting structure is large at the segment splicing,and the bending moment is large at the 1/2 section of the segment and the segment splicing.The local bending moment of the supporting structure is too large,resulting in local instability of the structure,and thus the overall instability of the structure.(3)The numerical test research of steel support structure under different influencing factors is carried out.The influence of different lateral pressure coefficient and steel grade on the mechanical properties of supporting structure is studied.The equations of lateral pressure coefficient,independent variable of steel grade factor and variable of ultimate bearing capacity are obtained by fitting.The results show that the lateral pressure coefficient increases by 1.1～1.5,and the ultimate bearing capacity of the supporting structure decreases by 17.79%～55.18%.With the increase of steel grade,the ultimate bearing capacity of supporting structure increases linearly.Figure 75 Table 4 Reference 76... |
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