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Lin C.,Ningbo University | Wu S.,Hangzhou Qing chun Road Cross river Tunnel Company Ltd | Xia T.,Zhejiang University
Tunnelling and Underground Space Technology | Year: 2015

Fluctuations of river stage are expected to induce changes in loads acting on the tunnel linings and cause readjustments of member forces in the segmental linings subsequently. Therefore, the evaluation of impacts of time-dependent river levels on the loads acting on the tunnel linings is of great importance in design of shield tunnel linings situated beneath the rivers. However, the loads acting the tunnel linings are generally considered as constant in most design methods available, taking no account of the influences of constantly changing river stage. In this study, the influences of river stage on design of shield tunnel linings are evaluated with respect to two common ground conditions: (a) impermeable overburden strata of low permeability and (b) permeable overburden strata of high permeability. Two earth pressure calculation models are correspondingly established. In addition, field observations in the Hangzhou Qiantang River Tunnel are described in detail to present the responses of tunnel linings to fluctuations in river stage and validate the established design model for the former case. © 2014 Elsevier Ltd.

Lin C.,Zhejiang University | Zhang Z.,Zhejiang University | Wu S.,Hangzhou Qing chun Road Cross river Tunnel Company Ltd
Advanced Materials Research | Year: 2011

The Qing-chun Road Cross-river Tunnel is the first road tunnel under the Qiantang River in Hangzhou, and it is also the first experiences of slurry shield tunnelling in Hangzhou soft ground. In order to ensure the safety of construction and reduction of environmental impacts while shield tunnelling, a comprehensive monitoring system was carried out during construction, which included ground settlements, displacements and deformations of installed linings and so on. In this paper, the long-term ground settlements induced by slurry shield tunnelling were described in detail, and careful analysis of monitoring ground settlements was made. This case study shows that: 1. The surface transverse consolidation settlements do not follow the Gaussian curve; usually the largest settlements exist above the centerline of the tunnel or nearby, from where settlements descend outwards. Due to consolidation, the surface settlement troughs widen with time.2. Shield tunneling in soft ground, the turning point in settlement-time curves or settlement rate-time curves can be chosen as the time divides the immediate and long-term consolidation settlements. © (2011) Trans Tech Publications.

Wu S.,Hangzhou Qing chun Road Cross river Tunnel Company Ltd | Lin C.,Zhejiang University | Zhang Z.,Zhejiang University | Wang N.,Zhejiang University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

It is inevitable for the slurry shield to under-pass the embankment in construction of under-river tunnels in urban areas. For the safety of both the embankment structure and construction, resources of risks when slurry shield under-passing the embankment are analyzed in detail, and their causes, impacts and mitigation measures are also studied accordingly. The case history of risk control for slurry shield under-passing the embankment in Hangzhou Qingchun road cross-river tunnel in China confirmed the rationality and feasibility of the suggested risk control measures. Through optimization of slurry shield driving parameters, avoidance of adverse external conditions, in-time monitoring, and setting of detailed emergency countermeasures, some of the risks encountered during slurry shield under-passing the embankment can be reduced or mitigated so as to insure safety of the embankment and construction.

Zhang Z.-M.,Zhejiang University | Lin C.-G.,Zhejiang University | Wu S.-M.,Hangzhou Qing chun Road Cross river Tunnel Company Ltd | Zou J.,Zhejiang University | Liu J.-W.,Zhejiang University
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2012

Extensive analysis of consolidation settlements induced by slurry shield tunnelling in construction of Hangzhou Qiantang River Tunnel was executed to explore their characteristics. A practical method to distinguish the consolidation settlements from immediate settlements was put forward. Formation mechanism, influencing factors, and control measures of consolidation settlements due to slurry shield tunnelling were summarized. This case study shows that: (1) Both immediate and settlement long-term ground surface settlement in the transverse direction can be fitted using Peck equation with great precision. (2) The transverse ground surface consolidation settlements usually do not conform to Gaussian curves. Maximum consolidation settlements develop at the ground surface above the tunnel centre or in the vicinity, from where they descend gradually with increasing distance. (3) Consolidation settlements contribute to widening the settlement trough width. (4) The time corresponding to the turning point in settlement-time curve or settlement rate-time curve is proposed to be chosen as boundary to divide the immediate and consolidation settlements. (5) Optimized control of slurry shield excavation parameters contributes to smaller disturbances to surrounding soils, consequently lowering consolidation settlements and their duration.

Lin C.,Zhejiang University | Zhang Z.,Zhejiang University | Wu S.,Hangzhou Qing chun Road Cross river Tunnel Company Ltd | Fang K.,Zhejiang University
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2012

Through analysis of shield driving parameters and ground settlements in the construction of the Qing-chun Road river-crossing tunnel, the influence of shield driving parameters on ground settlements induced by tunneling were studied. The studies show that: (1) Increasing the pressure of slurry and synchronized grouting appropriately can counterbalance some ground loss, so as to reduce the ground settlements. (2) The key to reducing shield tail ground loss is to fill the tail void immediately and effectively with synchronized grouting, but it should not be simply increasing the grouting volume. (3) With stabilization of the shield driving, higher advance rate leads to smaller ground settlements, whereas long time stop would lead to larger ground settlements. (4) Decreasing the torque of the cutter head while increasing the rotational speed can accelerate the shield driving and decrease the disturbance to surrounding soils and revolution of the shield. It can also decrease the size of the muck from working face, so as to avoid the blocking of the slurry pipelines. (5) Good control of the shield posture can decrease over-cut, friction and squeezing between the shield shell and the surrounding soils, so as to decrease the ground loss and consolidation. (6) The irregular ground heave movements caused the shape of transverse ground settlements deviate from Gaussian curve pattern.

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