Study Of Creep Properties And Applications For Sueshige Sandstones Of Humaling Tunnel Zone

Based on construction project of the Humaling tunnel in the Lanzhou-Chongqing railway line, a study is carried out on creep properties for tertiary sandstones by a series of in-situ and laboratory tests. Meanwhile, by means of viscoelastic analytic method and FLAC3D simulation, this thesis does some research on the stability of the primary support in Humaling tunnel in sueshige sandstone zone. The main contents and conclusions of this thesis are as follows:1. The tertiary sueshige sandstone samples are taken from the No.3inclined shaft. The density p,specific gravity Gs,saturated water content ws, and uniaxial compressive strength σ0are obtained by laboratory test.In addition,the uniaxial compressive strength according to different water content was investigated,and the function relationship between σ0and water content was worked out.2. Uniaxial compression creep test of the sueshige sandstone was conducted according to different water content. The test result show that with the increase of water content,the viscous coefficient decreases sharply and the samples that in moisture state will take less time to reach the steady creep,and it’s initial creep deformation account for more proportion of the total creep deformation than the dry sandstone.By the result of the test above,the creep curve of the different water content creep test was fitted with the university Kelvin law by means of the Origin sofeware and the university Kelvin parameters was obtained.The result show that the parameters obtained by means of segmented function was more close to the test data than the parameters obtained from the regular fitting method.3. The time interation between the primary support structure and surrounding rock in the circular tunel is deduced through viscoelastic method.Then,the section of No.3inclined shaft is equivalent to round to adapt this method.The above result is applied to observe the surround rock deformation and the stability of the primary support.4.The three bench excavation method of the Humaling tunnel is simulated by means of FLAC3D sofeware under it’s creep model.The change of longitudinal displacement and displacement during the process of three bench excavation was illustrated and the total settlement of tunnel crown, indented side wall and the dome uplift displacement is calculated.The analysis show that the indented side wall and the dome uplift displacement is lager than the settlement of tunnel crown,and that the primary support can keep the stability of the surround rock.