An Analytical Solution of Shield Tunnel based on Force Method Xiaomin You Zixin Zhang Yongsheng Li Dept. of Geotechnical Engineering Tongji University 3nd Sino-Japan Joint Seminar for the Graduate Students
ITA ( 2000 ) Guidelines for the Design of Shield Tunnel Lining
Tunnel projects constructed in Shanghai in recent years ProjectD cal * (m)Thickness (m) Shanghai Subway Tunnels East Yanan Rd. Tunnel Dalian Rd. Tunnel East Fuxing Rd. Tunnel Xiangyin Rd. Tunnel Shangzhong Rd. Tunnel South Xizang Rd. Tunnel Shanghai Yangtse River Tunnel Large section → low ratio of thickness vs. diameter Large section → shallow embedded depth
Conventional Model
Soil resistant pressure. STEP 1 STEP 2 STEP 3 β1β1 β2β2
Deduction based on Force- Method 1st step: Force method equation
2nd step: to solve β 1 and β 2
3rd step: Internal force
Comparison Detailed information about cases adopted in analysis Cases Rrrwrw K0K0 Khwhw (m)(kN/m3) (m) Clay layer Sand layer Analysis of the parameters 1.Effect of horizontal soil pressure coefficient 2.Effect of soil resistance coefficient Comparison with different solutions
Effect of horizontal soil pressure coefficient
Effect of soil resistance coefficient
Comparison with different solutions R(m) Thickness( m) Embedded depth (m) r (kN/m 3 ) rw (kN/m 3 ) hw (m) (kN/m3)K0 Compression Modulus (kN/m 3 ) SPT-NC (kPa) Φ(º)Φ(º)
CONCLUSION For a given soil resistance coefficient and a shallow embedded depth, the distribution of soil resistant pressure is significantly effected by the value of horizontal soil pressure coefficient, and also the ratio of thickness versus diameter is a influencing factor. For a given horizontal soil pressure coefficient and a shallow embedded depth, the distribution of soil resistant pressure is significantly effected by the value of soil resistance coefficient, and also the ratio of thickness versus diameter is a influencing factor. The results predicted by the proposed analytical solution are compared with those of numerical simulation and the conventional model solution. The comparison indicates that the proposed solution agrees more reasonably, and it provides a new approach to better predict and make the preliminary design of shield tunnel lining
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