Abstract The overburden thickness is an important factor influencing the longitudinal stresses between the rings. The overburden thickness of shallow-covered receiving shield tunnel is small near the receiving end, which would lead to small longitudinal stresses. And so the water tightness of shield tunnel will be influenced. By establishing and solving the mathematical model, the distribution law of the longitudinal stresses is proposed. The difference between the longitudinal stresses distribution law of shallow-covered receiving tunnel and that of conventional receiving tunnel is discussed. Based on the longitudinal stresses distribution law of shallow-covered receiving tunnel, the structural measures and relevant design method which increase the longitudinal stresses are proposed. Taking a river-crossing tunnel under construction in Shanghai as the background, the practical application of the structural measures is discussed. The result shows that the longitudinal stress increases with the increase of the distance from the receiving end. At the shallow-covered receiving end the longitudinal stress is the smallest. The longitudinal pressure at the dividing point of variable overburden thickness area and constant overburden thickness area reaches about 70% of the limit value of longitudinal pressure. In the background project, the longitudinal pressure of the conventional receiving tunnel is about 1.21 times that of the shallow-covered receiving tunnel. Pre-tight? ened bolts can be set in the segments near the receiving end to increase the longitudinal stress. For the background project, pre-tightened bolts shall be set in about 24 ring segments near the receiving end.
Abstract：
The overburden thickness is an important factor influencing the longitudinal stresses between the rings. The overburden thickness of shallow-covered receiving shield tunnel is small near the receiving end, which would lead to small longitudinal stresses. And so the water tightness of shield tunnel will be influenced. By establishing and solving the mathematical model, the distribution law of the longitudinal stresses is proposed. The difference between the longitudinal stresses distribution law of shallow-covered receiving tunnel and that of conventional receiving tunnel is discussed. Based on the longitudinal stresses distribution law of shallow-covered receiving tunnel, the structural measures and relevant design method which increase the longitudinal stresses are proposed. Taking a river-crossing tunnel under construction in Shanghai as the background, the practical application of the structural measures is discussed. The result shows that the longitudinal stress increases with the increase of the distance from the receiving end. At the shallow-covered receiving end the longitudinal stress is the smallest. The longitudinal pressure at the dividing point of variable overburden thickness area and constant overburden thickness area reaches about 70% of the limit value of longitudinal pressure. In the background project, the longitudinal pressure of the conventional receiving tunnel is about 1.21 times that of the shallow-covered receiving tunnel. Pre-tight? ened bolts can be set in the segments near the receiving end to increase the longitudinal stress. For the background project, pre-tightened bolts shall be set in about 24 ring segments near the receiving end.
YANG Zhenhua
.Distribution Law of Longitudinal Stress of the Shallow-covered Receiving Shield Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(5): 18-26
2022, Vol. 59 