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Wang S.L.,Beijing University of Technology | Chen D.W.,China Construction Municipal Construction Corporation Ltd | Wang R.,Beijing Institute of Petrochemical Technology
Advanced Materials Research | Year: 2012

The behavior of a foundation built on normally consolidated soft soil reinforced with stone columns (SC) and deep mixing columns (DMC) is studied using a finite element analysis program, Phase2D. The numerical predictions are analyzed in terms of absolute vertical displacement, absolute horizontal displacement, mean stresses, volumetric strain, maximum shear strain and strength reduction factor. Firstly, the effectiveness of the use of stone columns, the first composite ground, is studied. Afterwards, because load bearing capacity is less than 160 kPa designed, the effectiveness analysis reinforced with DMC, the second composite ground, is performed to study the influence on the soil-columns system of the foundation and columns. © (2012) Trans Tech Publications, Switzerland.

Li Y.-S.,Central South University | Li Y.-S.,Hunan City University | Zhang K.-N.,Central South University | Huang C.-B.,China Construction Municipal Construction Corporation Ltd | And 2 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Underground station of Shenyang Metro line 2 is the first underground engineering built by pipe-roof pre-construction method (PPM). The surface subsidence caused by the construction was monitored; and revised Peck model was developed to predict the subsidence. Some conclusions are drawn as follows. (1) The predicted result is consistent well with the monitoring data. (2) Surface subsidence caused by tunnel construction with PPM is characterized by the whole subsidence; and the subsidence value is pretty equal to the one of underground structure foundation, and it is effective to control surface subsidence by controlling the the sink of foundation of tunnel structure with PPM. (3) The underground permanent structure built before constructing tunnel with PPM could obviously constraint the surrounding rock with 0.0005%-0.0020% of stratum loss rate and 0.5 of width coefficient of sinking tank. (4) Surface subsidence caused by PPM is much less than the normal construction method, which has significantly social and environmental benefits; and this method is suitable to construct the underground urban traffic hub and tunnel projects that crossing traffic trunk lines and is worth to be studied and promoted further.

Li Y.,Central South University | Li Y.,Hunan City University | Zhang K.,Central South University | Huang C.,China Construction Municipal Construction Corporation Ltd | And 2 more authors.
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011 - Proceedings | Year: 2011

Urban underground engineering construction may have bad influence on the environment and even cause disasters. Pipe-roof Pre-construction Method(PPM) had been used in building a metro station of line No.2 of Shenyang subway. It's very important to analyze and evaluate the deformation of the environment in order to ensure the safety of constructing procedure. So, based on the detailed study of geological conditions and PPM, Flac3D software combined with field monitoring data in stations earthwork phase is used. And then, research on the surface and vault settlement, arch feet headroom convergence and tunnel structure deformation law is presented. The results show that :(1)numerical simulation is close to the monitoring data, which ensures the large cross-section single arch tunnel construction safety, and provides guidance for the first successful application and research of this method in China mainland area. (2)The surface deformation and vault subsidence could be less by using PPM to build large sections tunnel, and in the whole PPM construction process of surface subsidence caused by the proportion is less too, which could meet the requirements of controlling the surface subsidence target. (3)It deserves further research and extension for the PPM to build underground space, because it has obviously social and environmental benefits, and can be used to build traversing urban traffic hub of the underground engineering. © 2011 IEEE.

Yang X.,Central South University | Zhang K.,Central South University | Li Z.,China Construction Municipal Construction Corporation Ltd | Deng M.,China Construction Municipal Construction Corporation Ltd
Zhongguo Tiedao Kexue/China Railway Science | Year: 2011

Based on soil arching effect theory, the soil arching effect model of jacking pipes in new pre-construction method is built. According to the force analysis of the arch axes in the model, the relation formula between the constraining counter-force of the arch axes support and the geometric parameters of the model is gotten. Combined the relation formula with the strength control conditions of the top and feet of arch simultaneously, the equation for calculating the maximal distance between jacking pipes is deduced. The integral stability of soil arch under the maximal distance between jacking pipes is checked, which can prove the rationality of the maximal distance between jacking pipes. Taken the jacking pipes at the top of No.1 air channel in Xinle Ruins Station of Shenyang Metro as example, the distance between jacking pipes is 3.28 m by calculation. The changes of cutting position on steel pipe and the diameter of steel pipe are suggested to optimize the design of the distance between jacking pipes. The optimal designs can reduce the quantities of steel pipes, save construction time, thereby reduce surface settlement.

Li Y.-S.,Hunan City University | Li Y.-S.,Central South University | Zhang K.-N.,Central South University | Huang C.-B.,China Construction Municipal Construction Corporation Ltd
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The mechanical response of the Chinese first tunnel project built by using the pipe-roof pre-construction method (PPM) during the process of large excavation is studied. The data of dynamic change regulation obtained and the accumulated field measurement can provide evidence to judge the safety and stability of the tunnel and ensure the application of PPM. The study shows: (1) the stress and deformation of the lining structure are very small, the pre-construction lining structure achieves good effectiveness to control the structural deformation and the stratum loss; (2) the greatest monitored value of lining structure is only 30% of the design value of stress, and the pre-construction lining structure improves the self-stabilized ability and reduces the pressure of tunnel surrounding rock; (3) the interval of the passive earth pressure is small, which means the interaction between lining structure and surrounding rock is not obvious; (4) because the settlement at the top of arch reaches 5 mm in the day when the top of the tunnel is penetrated, the structural and environmental effects during the penetration should be considered in the design, and monitoring and analysis need to be intensified during the construction; (5) the PPM technology for building underground space can control deformation in tunnel lining structure and ground settlement, and it has great social and environmental benefits and is worthy to be studied and promoted further.

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