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Wang G.-B.,Hubei Engineering University | Wang Y.-X.,Hubei Engineering University | Yu Y.-L.,Wuhan University of Technology | Chen B.,Ningbo Rail Transit Project Construction Headquarter
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2015

Focusing on the newly emergence of soil tunnel group interaction system, soil-tunnel group calculation model was established based on a practical adjacent multi-overlap shield tunnel engineering. The seismic response of the complicated interaction system was investigated and discussed by complete parameter analysis. The main influencing factors include the aspects of soil, which include the character of layered soil; the factors of tunnel, which contain tunnel radius, tunnel space distance and tunnel depth. And also, the soil nonlinear characteristic was considered by the equivalent linearization method. The results show that tunnel radius and space distance and depth have a significant influence on soil and tunnel seismic response. Much attention should be paid on soil vertical seismic response induced by input horizontal seismic wave for the complicate soil-tunnel group interaction system. ©, 2015, Xi'an Highway University. All right reserved.

Zhu Y.-H.,Ningbo Rail Transit Project Construction Headquarter | Zou Y.-S.,Ningbo Rail Transit Project Construction Headquarter | Geng J.,Zhejiang University | Wang F.-Z.,Wuhan University of Technology
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2012

In the present investigation, various methods such as accelerated chloride migration test, chloride penetration test, stray current test and color analysis were used to research the characters of chloride ion migrated in concrete with stray current existed and the effect of fly ash on this process. The results showed that the transport direction and speed of chloride ion were changed under the action of stray current. The average penetration depth (PD) was 7~8 times that without stray current existed. Otherwise, the permeable zone was parabolic dish, the PD values of chloride ion were max at the direction of against to rebar. In such condition, the anti-permeability of concrete could be improved significantly because of fly ash mixed, and this improvement could be more obvious with the increase of fly ash content in a certain dosage range.

Cao Q.-Q.,Ningbo University | Zheng R.-Y.,Ningbo University | Zhu Y.-H.,Ningbo Rail Transit Project Construction Headquarter | Lin P.,Ningbo Rail Transit Project Construction Headquarter
2011 International Conference on Electric Technology and Civil Engineering, ICETCE 2011 - Proceedings | Year: 2011

According to the construction characteristics of rail transit engineering and the features of safety culture, the paper illustrates the concept of safety culture. And on that basis, the development scheme of safety culture is set forth from the following four aspects: safety sense culture, safety system culture, safety behavior culture and safety material culture. Then take Ningbo Rail Transit Project for example, analyzing its status quo of safety culture construction and the present problems. And at last improving suggestions are put forward. © 2011 IEEE.

Cao Q.,Ningbo University | Zheng R.,Ningbo University | Zhu Y.,Ningbo Rail Transit Project Construction Headquarter | Huang Y.,Ningbo Rail Transit Project Construction Headquarter
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011 - Proceedings | Year: 2011

According to the field measured data of a deep foundation pit of subway station of Ningbo rail transit, the paper studies the varieties of deformation rate and cumulative deformation along with excavation time, and estimates the proportion of deformation under different construction phases based on 450 monitoring data of 4 deep foundation pits. The result shows that the main deformation of diaphragm wall due to deep foundation pit of subway station in Ningbo soft soil happens in the third and the forth phases, and these two conditions should be the key point of hierarchical control. © 2011 IEEE.

Chen R.,Zhejiang University | Chen R.,Hunan University | Meng F.,Zhejiang University | Li Z.,Zhejiang University | And 2 more authors.
Tunnelling and Underground Space Technology | Year: 2016

The inevitable influence of large excavation in soft soils on nearby tunnels is of great concern in practice. In this paper, the influence of a nearby large excavation on existing metro tunnels of the Ningbo Metro Line 1 in sensitive soft soils is investigated and presented. Considerable displacement in the left tunnel closer to the excavation induced by the nearby excavation was revealed by field monitoring. Visible cracks and leakages were observed in left tunnel linings. Three dimensional numerical simulations are conducted to investigate the responses of the ground and left tunnel due to the adjacent excavation. The development of bending moment and displacement of the left tunnel during different construction stages of the nearby excavation is obtained. Then the interaction mechanism between the nearby excavation, surrounding soils and existing twin tunnels is investigated, which is of significance to the interpretation of the influence of the nearby excavation on the existing twin tunnels. Several protective measures for alleviating the influence of adjacent excavation on left tunnel are studied, including divided excavation, soil improvement and a cut-off wall. It is found that the left tunnel is influenced to varying degrees during different construction stages and the time effect is distinct for this large excavation in soft soils, which would be suggestive to engineers to pay more attention to the protection of adjacent tunnel during the crucial construction stages. The bending moment and displacement of the left tunnel is strongly related to the unloading effects and displacement of surrounding soils, which can be alleviated by means of proper improvement of excavation sequence. Comparatively, longitudinally divided excavation is more effective in protecting the left tunnel than soil improvement or a cut-off wall. This study is of certain reference value for protecting metro tunnels adjacent excavation in soft soils. © 2016.

Ye J.-N.,Ningbo Rail Transit Project Construction Headquarter | Liu G.-B.,Ningbo University | Jia B.,Ningbo University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

Uplift piles are usually used in the anti-floating design of underground engineering in soft soil areas, but due to the complexity of the site conditions, the play of internal force after construction and the recovery of pore-water pressure are not yet clear. Therefore, the common reinforced meter and fibre grating reinforced meter are used to monitor the long-term internal forces of uplift piles at Fuming Road station, line 1 of Ningbo rail transit traffic, and the tests on the pore-water pressure are also performed. The measured results indicate that the fibre grating reinforced meter is reasonable for monitoring the internal forces of anti-pulled piles because it can remove the produced prestressed effect of temperature changes. The internal force in uplift piles performs as pulling force firstly, then displays as pressure later, and the uplift piles play its anti-pulled role in early, and later as a superstructure of compressive pile to resist pressure. In addition, the pore-water pressure increases with time at the end of the hole, but the rate of growth is slow, and the soil water pressure under all conditions is steady.

Chen R.,Zhejiang University | Meng F.,Zhejiang University | Li Z.,Zhejiang University | Ye Y.,Zhejiang University | Ye J.,Ningbo Rail Transit Project Construction Headquarter
15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability | Year: 2015

The inevitable influence of large excavation in soft soils on adjacent tunnel is greatly concerned in practice. A case in Ningbo Metro Line 1 in China is presented in this paper. The constructed metro line of which axes were at a depth of 12 m to 18 m was almost parallel to the excavation. The minimum horizontal distance between the metro line and the retaining structures was 7.2 m. Field montoring indicated that the left tunnel suffered considerable deformation during the 3rd excavation step of the adjacent excavation, and the maximum increment of horizontal displacement of left tunnel reached 33.5 mm. From the completion of left tunnel to the completion of the excavation, the maximum increments of settlement and convergence of left tunnel reached 33.6 mm and 28 mm, respectively. As a result, these deformations caused the appearance of visible cracks and leakages of linings and threatened left tunnel severely. Numerical simulation was conducted with Plaxis 3D. The performance of surrounding soils and structures due to the nearby excavation, especially of left tunnel, are investigated. It is found that displacement growth of left tunnel and surrounding soils caused by adjacent excavation has intense correlation. In addition, the effects of divided excavation on alleviating the displacements and internal forces of left tunnel during the 3rd excavation step are also discussed. The above problems and findings should be paid more attention to to ensure the safety of the nearby twin tunnels.

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