Research On Time Effects Of Surrounding Rock Strain During The Tunnel Construction

The stability of surrounding rock in tunnel is closely related with the safety of tunnel construction and operation. Recently, the elastic-plastic constitutive model is always applied to describe the tunnel surrounding rock in the tunnel design; However, the fact is that the tunnel surrounding rock is the material of evidently rheological character; Thus it is of great significance to take the time effect of Rock into consideration while doing the rock stability studies.Researches in this thesis are based on some highway tunnel of Henan Province; The actual monitoring and measurement are combined with the theoretical analysis, and then results are compared with the analysis of the three-dimensional model; During this process, the time characteristics on displacement and deformation and the mechanical properties of the surrounding rock in the process of tunnel construction are studied. The research process and results of the paper are list as follows:1.The current research domestic and international are contrasted to analyze the rheological properties of tunnel surrounding rock reflected in the construction process; and then the practical significance of the time effect in the stress and strain of the surrounding rock for the safety of tunnel construction and operation are discovered.2. The actual measured tunnel data are combined with the integral creep formula to do theoretical analysis on the time effect in the strain of tunnel surrounding rock; and then a conclusion has been drawn that the deformation on the assume face of the tunnel has already begun from some distance ahead of this face, what’s more, the pre-displacement occupies a relatively large proportion in the whole displacement of the tunnel construction process.3. The Matlab program language is applied together with the actual measured data in program calculation to get the parameters of integral-type creep model; and then these parameters are used to fit out the curve which shows the relationship between time and displacement of the pre-displacement and total displacement; the conclusion shows that the calculation curve has a good correlation with the actual measured curve.4. The finite element simulation software is employed to establish a three-dimensional model of the tunnel construction; and then the suitable elastic-plastic constitutive model is chosen for simulative analysis; the relationship between the deformation and the time during the construction process is achieved, together with the early and whole displacement of tunnel surrounding rock in the construction process, all of which could provide some guiding and necessary advices for practical engineering construction and design.