Technique And Application Study On Dewatering Of Deep Excavation In Two-layer Structure Strata Of Soft Soil Zone

Deep well dewatering of soft soil two-layer structure excavation is a kind of economical and effective dewatering method to ensure waterproof in deep excavation. Nevertheless its negative impact on is often unavoidable. Deep excavation dewatering often leads to the formation of a depressing cone, which may cause the cracking and even the breaking of surrounding buildings and utilities. On the one hand, the widely used design method is to calculate and predict the results of group-well dewatering by single-well well formulas. These formulas neglect the interactive interference, so the results inevitably cannot comply with the practical situation. On the other hand, the hydrogeology parameters, which are indefinite and difficult to measure accurately, are the main factors, which impact the dewatering calculation results. According to the intractable problems mentioned above, the author researches into the theories and applications of deep well dewatering for soft soil structure underground confined water. The basic theory of dewatering, the dewatering calculation methods, the impact of dewatering on the surrounding environment, the definition of hydrogeology parameters and the shape, area and depth of the deep foundation dominate over this dissertation. As a whole, the research work of this dissertation can be summarized as follows:(1) Based on the porous media elastic unstable theory, the interfering well flow model of soft soil two-layer structure underground confined water is inferred, and consequently, the basic dewatering calculation method of soft-soil two-layer deep excavation dewatering is inferred.(2) A simple calculation method for the soft soil two-layer deep excavation dewatering is put forward. Furthermore, the author analyses the regularities of the ground sedimentation, which was caused by deep excavation, with the combination of a practical construction project.(3) The hydrogeology parameters' acquisition and calculation principles of the deep well dewatering in theExcavation in Two-layer Structure Strata of Soft Soil Zone. The acquisition and calculation method of hydrogeology parameters are discussed distraughtly according to different deep foundations.(4) The author analyses the importance of the dewatering well's structure in deep excavation dewatering. The fundamental design rules, the technique requirements and the design methods are put forward. The calculation formulas of the depth and diameter of the dewatering well are deduced consequently.(5) The author researches the relationship between the deep foundation's shape, area and depth and the deep excavation dewatering. The formula, which calculates the minimum distance between foundation's bottom panel and the confined water layer's top panel, was put forward. The author also analyzed different deep well dewatering methods according to different foundations.