Hangzhou, China
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Shen L.-C.,Hangzhou Metro Group Co. | Zhong X.-C.,Hohai University | Qin J.-S.,Hangzhou Metro Group Co. | Min F.-L.,Hohai University
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

It is of common occurrence that the flood scours the riverbed and the back-silting takes place immediately by turn, which inevitably influences the safety of shield tunnel through the Qiantang River. Hence, how to determine the thickness of covering layers reasonably is an urgent problem to be solved to ensure the safety of tunnel and the construction cost under control. According to the completed study that the riverbed thickness decreases extremely by nearly 16 m after the heaviest flood in 300 years, two embedding schemes of subway line are selected initially. That is, the minimum overburden layer thickness of tunnel is 3.5 m or 4.0 m. The results show that the two schemes are both safe for the tunnel considering the shearing effect of the soil around the tunnel and the one of the bolts between rings. However, in construction, the possibility of floating upward for shield tunnel increases greatly under the buoyant force action of back-filled grouting. More attention should be paid to construction management to minimize the disturbance of soil around the tunnel.

Zhong X.-C.,Hohai University | Zhang J.-R.,Hangzhou Metro Group Co. | Qin J.-S.,Hangzhou Metro Group Co. | Zhu W.,Hohai University
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

As shield tunnelling method is applied widely, the longitudinal uneven settlement of shield tunnel has emerged because of the comparatively large settlement after construction, and the designing method has been emphasized gradually, which can consider the longitudinal structure characteristics of shield tunnel. For the purpose of determining the longitudinal equivalent bending stiffness, a 3D calculation model has been established, considering the longitudinal bolts' characteristics and the ring seams' true splaying states. The results show that some factors related to the ring seam, for example the amount of longitudinal bolts, the assembly pretightening force and segment ring width, influence the longitudinal bending stiffness largely, which increases linearly with the amount of longitudinal bolts and the segment ring width, and which nonlinearly increases with the assembly pretightening force. Other factors related to the longitudinal seam, for example the transverse effective rigidity ratio, influence it less. The results provide key parameters for the longitudinal design method of shield tunnel.

Wang Y.,City University of Hong Kong | Wang Q.,Hangzhou Metro Group CO. | Zhang K.Y.,Hohai University
Procedia Engineering | Year: 2011

The underground space in urban areas is frequently congested with utilities, including pipelines and conduits that are affected by underground construction, e.g., tunneling. This paper develops a Winkler-based pipe-soil-tunneling interaction model for estimating pipe responses to tunneling-induced ground movement. Efforts are focused on different pipe-soil interaction in relative uplift and downward pipe movements. Governing equations are derived, and their closed-form solutions are provided. The closed-form solutions are then validated against finite element simulations. Finally, the effects of different pipe-soil interactions in relative uplift and downward pipe movements are explored. The effect of different pipe-soil interaction is shown to be significant, and it should be properly accounted for in the analysis.

Hu Q.,Zhejiang University of Technology | Xu S.-F.,Zhejiang University of Technology | Chen R.-P.,Zhejiang University | Ran L.,Hangzhou Metro Group Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

According to the laboratory unit tests on typical soft clay and disturbed soils, the influence of disturbance on the soft clay is analyzed. The results show that the engineering properties of the soft clay are related to its structure and stress state. Due to the disturbance of construction, the yield stress of the soil structure is destroyed, resulting in an increase of its compressibility and a decrease of its strength. Deep excavation will result in disturbance of soft soil foundation, reduce the strength of foundation soils and increase the deformation and exacerbate the impact of construction on the surrounding environment. According to the finite element simulation, the influence of soft clay disturbance on the force-deformation of surrounding metro tunnel is analyzed, and some suggestions for reinforcement measures are proposed. When the base soils are disturbed, the force-deformation of building envelope and nearby metro tunnel structure will be accelerated until failure occurs.

Liang R.,Zhejiang University | Xia T.,Zhejiang University | Lin C.,Ningbo University | Meng W.,Hangzhou Metro Group Co.
Modern Tunnelling Technology | Year: 2015

It is inevitable for a shield to deviate from the designed route during tunnelling in soft soils, which may result in the concentration of stress in segments, segment cracking and excessive ground settlement. Based on measured data from a shield tunnel of the Hangzhou metro project, this paper analyzes the shield's vertical attitude variation in a typical Hangzhou soft-soil layer and gives corresponding control measures. The results show that: 1) it is inevitable for the shield to be tilted with a negative pitch angle during segment erection; 2) during shield driving, an effective way of adjusting the pitch angle is to control the deviation correction moment since the pitch angle is sensitive to deviation correction moment variation; and 3) adjustment of the shield attitude is a dynamic process, so it needs to be planned in detail and implemented patiently. ©, 2015, Editorial Office of "Modern Tunnelling Technology". All right reserved.

Ran L.,Hangzhou Metro Group Co. | Yi T.H.,Dalian University of Technology | Ye X.W.,Hong Kong Polytechnic University | Dong X.B.,Hangzhou Metro Group Co.
International Journal of Distributed Sensor Networks | Year: 2012

The project of Hangzhou Metro Line 1 is the first metro line of the urban rapid rail transit system in Hangzhou, China, which is one of the largest municipal projects of Hangzhou and is being constructed commencing from March 28, 2007 and expected to be completed by October 1, 2012. This metro line has a total length of 48 km and 34 stations, connecting Hangzhou downtown with the suburban area of the city. Owing to the complex geological condition, harsh construction situation, and immature computational methodology, construction of metro systems is often subjected to considerable sources of uncertainties. To ensure the safety of the adjacent building structures, it is a vital necessity to monitor deep excavations of metro tunnels at their in-construction stage. This paper introduces the instrumentation system for settlement monitoring of a metro-tunnel airshaft of the project of Hangzhou Metro Line 1 during the construction of deep excavation. The long-term settlement data monitored by the measurement markers installed at the surface ground and in the depth direction of the airshaft excavation construction site are analyzed and presented in detail. The obtained results indicate that the settlements at the instrumented locations of the construction site during different construction steps vary steadily in an allowable variation range. © 2012 L. Ran et al.

Ye X.W.,Zhejiang University | Ran L.,Hangzhou Metro Group Co. | Yi T.H.,Dalian University of Technology | Dong X.B.,Hangzhou Metro Group Co.
Mathematical Problems in Engineering | Year: 2012

In recent years, China has been undergoing a metro railway construction boom in order to alleviate the urban traffic congestion problem resulting from the rapid urbanization and population growth in many metropolises. In the construction of metro systems, deep excavations and continuous dewatering for construction of the metro tunnels and stations remain a challenging and high risk task in densely populated urban areas. Intelligent computational methods and techniques have exhibited the exceptional talent in dealing with the complicated problems inherent in the deep excavation and dewatering practice. In this paper, an intelligent risk assessment system for deep excavation dewatering is developed and has been applied in the project of Hangzhou Metro Line 1 which is the first metro line of the urban rapid rail transit system in Hangzhou, China. The specific characteristics and great challenges in deep excavation dewatering of the metro-tunnel airshaft of Hangzhou Metro Line 1 are addressed. A novel design method based on the coupled three-dimensional flow theory for dewatering of the deep excavation is introduced. The modularly designed system for excavation dewatering risk assessment is described, and the field observations in dewatering risk assessment of the airshaft excavation of Hangzhou Metro Line 1 are also presented. © 2012 X. W. Ye et al.

Ran L.,Hangzhou Metro Group Co. | Ye X.W.,Hong Kong Polytechnic University | Zhu H.H.,Nanjing University
Procedia Engineering | Year: 2011

The subway systems play a vital role in alleviating the urban traffic congestion problem. Recently, lots of underground railway transportation networks have been opened to operation or are being constructed in major cities of China. Due to the complexity and uncertainty inherent in excavation activities, metro station excavations brings a challenge to civil engineering communities and poses threat to the public safety in metropolitan regions. The stability of deep excavation and adjacent buildings has gained highlighted concerns during metro station construction. A viable and practical way to ensure the construction safety is by executing real-time monitoring strategy with the aid of advanced sensing and signal processing technologies. In this paper, the design and implementation of a long-term monitoring and safety evaluation system for the deep excavation of a metro station has been addressed. A software platform has been developed for analyzing and processing monitoring data based on the concept of dynamic construction inverse analysis, which includes the database system, the dynamic construction feedback system, and the deformation forecasting system. Field monitoring results in various categories during deep excavation are presented. After examining the field measurement results, the following conclusions are drawn: (i) the deformation of the diaphragm wall and ground surface settlements increased with the excavation depth; (ii) the location of the maximum horizontal displacement moved downward to the excavation face during excavation; (iii) the axial forces of struts transferred from the first row to the others during excavation; and (iv) the monitoring results indicate that the braced excavation remained overall stable at the construction stage.

PubMed | Hangzhou Metro Group Co. and Zhejiang University
Type: | Journal: TheScientificWorldJournal | Year: 2014

Shield tunneling construction of metro infrastructure will continuously disturb the soils. The ground surface will be subjected to uplift or subsidence due to the deep excavation and the extrusion and consolidation of the soils. Implementation of the simultaneous monitoring with the shield tunnel construction will provide an effective reference in controlling the shield driving, while how to design and implement a safe, economic, and effective structural monitoring system for metro infrastructure is of great importance and necessity. This paper presents the general architecture of the shield construction of metro tunnels as well as the procedure of the artificial ground freezing construction of the metro-tunnel cross-passages. The design principles for metro infrastructure monitoring of the shield tunnel intervals in the Hangzhou Metro Line 1 are introduced. The detailed monitoring items and the specified alarming indices for construction monitoring of the shield tunneling are addressed, and the measured settlement variations at different monitoring locations are also presented.

Zhu C.-L.,Hangzhou Metro Group Co.
Journal of Railway Engineering Society | Year: 2014

Research purposes: The complicated hydrogeological condition is a great challenge confronted in the construction of Hangzhou subway. Especially, the construction risk caused by the high pressure aquifer along the Qiantang River cannot be ignored. This paper summarizes the features of high pressure aquifer in Hangzhou which has great impacts on the subway construction. The problems of high pressure aquifer in the projects of cross-river tunnel and riverside deep foundation of Hangzhou Metro Line 1, and the corresponding control measures, are particularly introduced. Additionally, the practical implementation effects are also analyzed. This paper aims to provide the reference to the construction of Hangzhou subway.Research conclusions: Technical solutions to the problem of high pressure aquifer in the construction of Hangzhou subway are proposed as below: (1)The brine freezing method in conjunction with the mode of tunneling shield reaching the shaft underwater is used to avoid the risk of quicksand and water gushing. (2)The preventive measures against water gushing based on the structure optimization of shield are set, including two inverted one-way restrictors installed in the conveyer and two rings of wire brush seal appended a ring of steel plate brush seal; and the EPDM rubber gasket with water pressure resistance of 0.9MPa is determined to use as waterproof measures of segment joint. (3)The connected aisle under the river is constructed by the subsurface excavation technology and reinforced by a new freezing method, the frost heave and thaw collapse of which is controlled by the deformation of tunnel linings. (4) Combined with the foundation engineering of Jiangling Road station, a complex pressure reduction and dewatering technology is developed, which is to form a complete shut-off waterproof curtain by overlapping a grouting curtain with a certain depth beneath the toe of diaphragm wall. (5)The technical solutions to the problem of high pressure aquifer encountered in the subway construction mentioned in this paper guarantee the successful engineering implementation of Hangzhou Metro Line 1, which can provide valuable experience to the subsequent construction of Hangzhou subway.

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