| Shield tunnelling technology, especial Earth Pressure Balanced Shield (EPBS) tunnelling technique, with integrating characteristics and advantages of high adaptability to diverse strata, advanced intelligent information system, safe and speedy, other way, harmonious and unified to circumjacent environment around construction site, largely applied and popularized in field of large underground excavation items in our country. Based on the research and study of former and scholar, the paper combined study on technique of transforming used-shield machine and construction technology of EPBS in complex strata systematically with engineering practice. Meanwhile, difficulties, key points and countermeasures of EPBS tunnelling in complex strata were considered. Therefore, the paper has value of reference and instruction to shield tunnelling practical engineering in field of water conservancy and hydropower engineering, energy and transpotation, besides determinate academic value. The paper developed the following main works and researches in five fields:1. Geological characteristics of complex strata in Guangzhou was elaborated. On the basement of looking up and studying related literature, with combining with practical construction example, the paper analyzed the difficult and focal points in complex strata. The construction ways to deal with the situation was put forward.2. The technique of transforming the used-shield machine adapted to complex strata was studied. Multiple factors of selecting shield type had been put forward in this paper. In order to enhance utilizing efficiency of shield repeatedly and reduce the construction cost, the plan of transforming two used-EPBS machines adaptably to complex strata was made and carried out successfully in the course of tunnelling through whole route safely.3. Shield tunnelling construction key parameters were checked. Shield's key parameters, including shield's total thrust force, torgue, etc. were checked.4. Shield tunnelling course consists of three main phases, which are initial phase, normal phase, and arrival phase. According these phases, construction technology of EPBS in complex strata was researched systematically.5. Shield tunnelling technique of special geological section was studied in the paper, including the technique of shield tunnelling through Peral River bed, sand strata and a construction hollow.The conclusion were obtained through above works. Although the condition of complex strata is complicated and difficult, shield tunnelling can be well done in a regular pattern. By selecting shield model, transforming shield and taking other efficient excavating measures, the advantages of safety, speed and high efficiciency are obvious, notable benefits of economy and society are available. |
