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On Law of Ground Settlements and Its Prediction Method for the Shallowburied Tunnel under Asymmetrical Pressures
（1 Ningbo Communication Construction Engineering Testing Center Co., Ltd, Ningbo 315124；2 School of Architecture and Transportation, Ningbo University of Technology, Ningbo 315016；3 School of Civil Engineering, Qingdao University of Technology,Qingdao 266033; 4 Key Laboratory for Urban Underground Engineering of Ministry of Education，Beijing Jiaotong University，Beijing 100044; 5 Ningbo Traffic Engineering Quality and Safety Supervision Station, Ningbo 315040; 6 Hunan Mayang Highway Administration, Huaihua 419400）
Abstract Surface settlement is an important basis for judging stability of tunnel surrounding rock, and also the key
item in tunnel construction monitoring and measurement. The surface settlement law of shallow-buried tunnels under asymmetrical pressures is more complicated and more likely to induce safety accidents compared to the symmetrical loading tunnels, and so it is necessary to conduct in-depth study. Based on the maximum principal stress deflection theory, firstly a quantitative analysis on the asymmetrical loading degree of a tunnel was carried out, the concept and calculation method of tunnel unsymmetrical pressure coefficient were proposed; secondly an equivalent calculation model was established, and the surface settlement of a shallow-buried tunnel under asymmetrical pressure was regarded as superposition of asymmetrical loading terrain and pressure, a calculation method and procedures were given; finally the surface settlement law of shallow-buried tunnels under asymmetrical pressure was further analyzed by field measurement data, and the prediction results were verified. The results show the unsymmetrical pressure coefficient is related to surface bias angle, tunnel overburden and lateral pressure coefficient; surface settlement curve
will be twisted under effect of asymmetrical pressure, the maximum settlement area and influence range will be shifted towards the deep-buried side; if asymmetrical pressure is large, it′s easy to cause cracking of surface at deep buried side and staggering at the shallow-buried side.
Abstract：
Surface settlement is an important basis for judging stability of tunnel surrounding rock, and also the key
item in tunnel construction monitoring and measurement. The surface settlement law of shallow-buried tunnels under asymmetrical pressures is more complicated and more likely to induce safety accidents compared to the symmetrical loading tunnels, and so it is necessary to conduct in-depth study. Based on the maximum principal stress deflection theory, firstly a quantitative analysis on the asymmetrical loading degree of a tunnel was carried out, the concept and calculation method of tunnel unsymmetrical pressure coefficient were proposed; secondly an equivalent calculation model was established, and the surface settlement of a shallow-buried tunnel under asymmetrical pressure was regarded as superposition of asymmetrical loading terrain and pressure, a calculation method and procedures were given; finally the surface settlement law of shallow-buried tunnels under asymmetrical pressure was further analyzed by field measurement data, and the prediction results were verified. The results show the unsymmetrical pressure coefficient is related to surface bias angle, tunnel overburden and lateral pressure coefficient; surface settlement curve
will be twisted under effect of asymmetrical pressure, the maximum settlement area and influence range will be shifted towards the deep-buried side; if asymmetrical pressure is large, it′s easy to cause cracking of surface at deep buried side and staggering at the shallow-buried side.
GAN Xiaohong1 CHEN Liping2 ZHANG Sulei3,
4 YING Guogang5 LI Xiaoping
.On Law of Ground Settlements and Its Prediction Method for the Shallowburied Tunnel under Asymmetrical Pressures[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(2): 78-84
2019, Vol. 56 