Liang R.,Zhejiang University |
Xia T.,Zhejiang University |
Lin C.,Ningbo University |
Meng W.,Hangzhou Metro Group Co.
Modern Tunnelling Technology
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. Source
Ran L.,Hangzhou Metro Group Co. |
Ye X.W.,Hong Kong Polytechnic University |
Zhu H.H.,Nanjing University
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. Source
Wang Y.,City University of Hong Kong |
Wang Q.,Hangzhou Metro Group Co. |
Zhang K.Y.,Hohai University
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. Source
Zhu C.-L.,Hangzhou Metro Group Co.
Journal of Railway Engineering Society
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. Source
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
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. Source