| A lot of working shaft projects have appeared constantly as a result of the construction of building foundation pits, subways and underground pipelines. Circular diaphragm wall has become a common supporting measure of working well projects because of its advantages such as big rigidity, good water retaining effect, large construction space and etc. However, the problems of security, reliability and economy which are associated with the circular diaphragm wall remain an issue for us to explore.Based on the existing research results, the dissertation summarizes the design theory of circular working shaft envelop structure. According to the second phase project of Nan Tanhai shield tunnel for the natural gas pipeline network in Guangdong Province, a detailed monitoring system is established to observe the pressure of lining structure of working shaft, and to analyze the internal forces and deformation of the envelop structure and permanent lining structure of the working shaft. Three-dimensional finite difference software, FLAC3D, is applied to simulate the excavation process, analyze the mechanics characteristics of circular working shaft structure. The comparison between the calculated and actual measured results is given, and its results are in accordance with measured basically.The impacts of diaphragm wall thickness, embedment depth and the size of pressure circle spray reinforcement on structural mechanical behavior are synthetically analyzed according to the engineering geological conditions of Nan Tanhai shield tunnel. Through calculation and analysis, the reasonable optimization scheme of working shaft is proposed: the thickness of diaphragm wall is0.6m, the embedment depth is6m, the thickness of pressure circle spray reinforcement is6m. The paper provides a reference for the design and construction of cross-river tunnel working shaft under similar conditions in the future. |
PDF Full Text Request