This paper mainly introduced the design theory and method of Chinese tunnel and underground engineering, construction technique of drill blast method, the shield tunnel construction technique and TBM(tunnel boring machine) construction technique and so on,and pointed out the research direction of Chinese tunnel and underground engineering from now on, including: the long tunnel's construction technology of great burying depth, the urban underground space plan, dynamic design of the tunnel and underground engineering as well as methods to reduce the building cost of projects and so on.
Based on the designing technology of double-line large diameter(Ø11.6 m) shield tunnel of Beijing underground diameter wire, this article emphased on the selection of shield tunnel machine, the structural calculation of the lining, the segment lining design and the water resistant technology, also demonstrated the designing requirements of the shield tunnel construction. These would be valuable reference for the future similar projects.
Deformation forecast is proceeded for the structure of Beijing underground diameter side penetrating one station of metro line 2 by numerical value analysis. The comparative analysis and reasons of difference analysis is proceeded too between predicted value and measured value. Deformation prediction results have certain guiding role for engineering construction alike.
Through the detailed risk evaluation on underground diameter project from Beijing railway station to Beijing railway west station, the conditions of all the risk sources along were analyzed adequately. At last, effective control measures of risk prevention and reduction were proposed based on the evaluations results. The settlement of all the measuring points of metro line 2 was lower than 2 mm. Due to the tunnel excavation the settlement of Tianningsi Bridge was lower than 3 mm. The construction impact on surrounding building was very small.
According to the diameter of the tunnel and the geological conditions, considered factors of equipment selection and the choice of models of the large diameter tunnel of the Beijing underground diameter tunnel project were analysed, the main functions and geological suitability of shield type configure were described, and the main data of the structure and equipped capability were calculated and described. The issues and problems that need to be paid attention for selection and design of shield were proposed.
Based on the underground diameter line engineering experience from Beijing railway station to Beijing railway west station, through the application contrast of various cutter tool configurations under sandy gravel, a detailed comparative analysis of cutter tool adaptability was done focusing before and after transformation. The key issues were proposed about cutter tool configuration under sandy gravel, which can be reference to similar projects.
This paper gives a summary on application technology of slurry and water separation in condition of sandy-gravels layers in city's busiest street on base of underground diameter project from Beijing railway station to Beijing railway west station,with the hope of providing reference to the future similar project.
According to project experience in Beijing Railway underground project, the changing cutter and welding techniques with high pressure of slurry shield under deep water-rich sandy gravel stratum were summarized. There were two main technologies. One is to choose an appropriate position and an appropriate working pressure for making a good previous preparation to ensure the stability of tunnel face. The other is the replacement and grouting of high-concentration slurry, which avoided the gas escape effectively. During the repair welding, we successfully realized going into the excavation chamber with high pressure for more than 250 times, and the working pressure rose from 0.9 bar(1 bar=100 kPa) to 2.8 bar with no accident.
Based on the typical fault analysis of large diameter slurry shield of Beijing underground diameter, the corresponding treatment and preventive measures were proposed, these faults including cutter stuck, shield tail leakage, tail brush damage, segment erector failure, etc. Meanwhile, the shield was maintained in advance with predictability through the oil sample analysis, and the intact rate was guaranteed objectively. In the construction process, the "zero inventory" and a set of scientific equipment management methods like factory management were introduced, making the intact rate of shield machine grow from 60 % to 85 % and even higher, so the normal tunneling progress was ensured.
The only head driving distance of the engineering of Beijing underground diameter line is 5.2 km, thus controlling the precision of tunnel transfixion is difficult. Based on the analysis of the measuring accuracy, only through the wire line can not satisfy the design requirements of provisions error limit. Eventually, methods like wire directly orientation, adding the gyro in the tunnel and control net of wire of ground and underground in close connection are determined. These increased the lateral error precision of piercing,and achieved expected effect.
Based on the introduction of building launching shaft and the shield launching of Beijing Rail Transit which constructed with a slurry shield machine by Ø12.04 m, some key technologies of shield launching were summarized in the urban areas and the water-rich grit stone geological conditions.
A detailed test on tunnel machine excavation parameter was given, and then the relationship between cutter head torque and tools wear under different underground conditions was analyzed. Some measures for shield posture control and a brief introduction on synchronized grouting parameters and slurry cycle system were also given. In the end, a conclusion on the importance of excavation parameter and slurry density in machine excavation was made.
Based on the engineering example of underground diameter project replacing the cutter teeth inside with high pressure, the application of grouting reinforcement and pile foundation reinforcement in soil strengthening was discussed. The causes of gas leakage of inside with high pressure were analyzed, and the countermeasures were proposed for assuring the normal construction of shield.
Through the statistical analysis of the technical data which based on shield tunneling, comprehensively considering the information of water-rich sandy gravel stratum, such as the tunneling parameter of the slurry shield machine, slurry parameter, shield posture and stratum deformation mechanism information, the empirical formula of the main parameters of synchronized grouting technologies is determined while the slurry shield is tunneling in sandy gravel stratum. It can guide the similar project construction.
Aiming to the slurry shield construction of underground diameter project from Beijing railway station to Beijing railway west station, the optimum slurry ratio in the condition of sandy gravel was proposed through the proportional tests, which improved the forming quality and velocity of the slurry and ensuring the environmental requirements. It can supply some experience to the similar projects.
Through introducing the construction method of negative ring demolition during transforming cutter head and replacement technique of Beijing Rail Transit Line 2 bid section in detail, the experience of negative ring demolition and replacement techniques of large diameter slurry shield were summarized, which would provide reference to the implementation of the construction scheme.
In the paper, the segment assembling techniques of large-diameter shield were summarized, and the apparent damage reasons and repair technology of large-diameter shield reinforced concrete segment in the construction were preliminarily analyzed, based on research of the underground diameter project from Beijing railway station to Beijing railway west station. The different repair methods were proposed for the segments above hance and below hance, respectively, assuring the good strength and surface quality of large-diameter shield segment.
Beijing underground diameter project is located in the water-rich sandy gravel formation, which is through many structures .Through the analysis of actual monitoring results,the law of tunneling parameters to surface subsidence and deformation law of important buildings around were summarized. Deformation control was successful compared with similar projects.
The CRD(cross diaphragm) and hole pile method were adopted in the large section tunnel,aiming at poor geological stability, complex engineering environment and the higher control requirements of subsidence in water-rich sandy gravel stratum of Beijing,which controlled the deformation of engineering structure,surrounding buildings along and underground pipeline effectively and ensured the safety of surrounding environment.
Taking vertical shaft construction of the cutter transformation of the Beijing underground diameter shield for example, the design and construction of cutter structure transformation under complex boundary conditions for large-diameter shield shaft were discussed. Practice about how to ensure the structural safety of the shaft as well as well-coordinated shield construction was explored, and reliable solutions were provided successfully, which can provide reference for similar projects.
Taking the underground diameter shield construction of Beijing railway for example, the choosing principles of process parameters in different engineering geo-conditions and changing boundary conditions were introduced. The cost difference and change were analyzed according to the analysis of construction efficiency and machine material consuming when the process parameters were adjusted.[