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Three-Dimensional Analytical Solution for Passive Limit Support
Pressure During Shield Tunnelling
(1 Department of Civil Engineering, Zhejiang University City College, Hangzhou, 310015;
2 Faculty of Civil Engineering and Mechanics, Kunming University of Science and Technology, Kunming, 650500)
Abstract Based on the Mohr-Coulomb yield criteria, the failure model of a wedge block + inverted truncated pyramid is improved by considering the influence of soil cohesion and optimizing the inclined angle of the wedge block, and a three-dimensional model is established to calculate limit support pressure when the excavation face is in the passive limit equilibrium state. Meanwhile, a corresponding formula is deduced to calculate the limit support pressure, and its solution is obtained by optimization analysis. Based on a calculation example, a comparison between the predicted results from the proposed model and the classic upper bound solution is made to verify its rationality. Finally, the relationship among the passive limit pressure, cohesion of the soil, friction angle of the soil, and thickness of the overburden is studied. Results show that there is a linear relationship between the cohesion of the soil and the passive limit support pressure, which means that the greater the cohesion of the soil, the greater the passive limit support pressure; the larger the friction angle of the soil, the greater the passive limit support pressure and the faster its rate of change is; and with an increase of the overburden of the tunnel, the passive limit support pressure increases gradually, and the rate of change becomes faster and faster, which presents an approximate exponential function relationship.
Abstract：
Based on the Mohr-Coulomb yield criteria, the failure model of a wedge block + inverted truncated pyramid is improved by considering the influence of soil cohesion and optimizing the inclined angle of the wedge block, and a three-dimensional model is established to calculate limit support pressure when the excavation face is in the passive limit equilibrium state. Meanwhile, a corresponding formula is deduced to calculate the limit support pressure, and its solution is obtained by optimization analysis. Based on a calculation example, a comparison between the predicted results from the proposed model and the classic upper bound solution is made to verify its rationality. Finally, the relationship among the passive limit pressure, cohesion of the soil, friction angle of the soil, and thickness of the overburden is studied. Results show that there is a linear relationship between the cohesion of the soil and the passive limit support pressure, which means that the greater the cohesion of the soil, the greater the passive limit support pressure; the larger the friction angle of the soil, the greater the passive limit support pressure and the faster its rate of change is; and with an increase of the overburden of the tunnel, the passive limit support pressure increases gradually, and the rate of change becomes faster and faster, which presents an approximate exponential function relationship.
SHEN Lin-Fang-1,
2 ,
WANG Zhi-Liang-1 etc
.Three-Dimensional Analytical Solution for Passive Limit Support
Pressure During Shield Tunnelling
[J] MODERN TUNNELLING TECHNOLOGY, 2014,V51(6): 35-40
2014, Vol. 51 