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Study on Temporal and Spatial Effect in Construction of Weak Surrounding Rock Tunnel

Author: YuZuo
Tutor: XiaYongXu
School: Chang'an University
Course: Bridge and Tunnel Engineering
Keywords: Tunnel construction Space Effect Rheological model Viscoelastic Elastoplastic Numerical Simulation
CLC: U451
Type: Master's thesis
Year: 2011
Downloads: 94
Quote: 0
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Abstract


Excavation of a tunnel in the rock, country rock by construction disturbance continues to release stress, which led to the development of the surrounding rock deformation, the supporting structure with the growth of surrounding rock deformation and more obvious inhibition . This paper introduces the geomaterials space-time effects of the status quo, the time characteristics of the rheological theory, and concrete supporting structure creep. Monitoring data, relying on engineering lofty mountain tunnel through inductive analysis of the load release rate corresponding to the given tunnel construction at different times of the surrounding rock, and then to use the elastic-plastic model of DP and linear viscoelastic generalized Kelvin model, using the finite element method. The spatial and temporal effects of soft rock tunnel the whole construction process numerical analysis. The first attempt to consider the surrounding rock the rheological and concrete supporting strength growth characteristics, dynamic simulation and analysis of tunnel surrounding rock in the construction process and the mechanical properties of the supporting structure. Mainly to the following conclusions: (1) relying on engineering tunnel monitoring data were analyzed and grade Ⅳ surrounding rock tunnel and the week convergence within 20 days basic stable. The analysis gives a different construction periods corresponding to the surrounding rock pressure release rate and by induction. (2) the use of the elastic-plastic constitutive model analysis does not consider the strength of surrounding rock rheology and supporting the growth process, the various characteristics of the surrounding rock parts calculated displacement values ??are small, the deviation of the actual monitoring results; consider the surrounding rock the rheological and different time supporting structure corresponding to different strength characteristics, results in good agreement with the measured data reflect the spatial effect of the time of the construction process. Therefore, during the soft rock tunnel design and construction simulation included in the structure of the time factor. (3) three-dimensional numerical analysis results show that the tunnel excavation tunnel face monitoring points near the large displacement convergence rate, but because of space near the supporting role of the excavation face, the stress values ??are smaller, near the excavation face surrounding rock time effect is not obvious; away from the tunnel face remote (1.5D), characterized parts greater stress values ??surrounding convergence rate is small, the excavation face the spatial effect is basically from the excavation face about 1.5D ~ 2.0D disappear. (4) In the early phase of construction of the tunnel, the tunnel feature point displacement value is more intense, the displacement of the maximum rate of change of the basic appear for the first 3 days, the deformation accumulated value accounted for about half of the total. The supporting structure of the first 3 to 4 days, the stress value growth is also faster. At this stage, the effective elastic modulus of shotcrete was less than the final value of 40%, apparently the most unfavorable section during support after the first three days. Therefore, it is proposed to strengthen the 0.5D ~ 1.0D section at the construction management and monitoring from the tunnel face.

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CLC: > Transportation > Road transport > Tunnel project > Tunnel structure theory
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