Study Of Deformation Characteristics Of Subway Deep Excavation And Control In Ningbo Deep Silt Region

With rapid development of the coastal cities, the increasing pressure of theresource, population and city life, the building in these cities are rising, so thedevelopment and exploitation of subbasement are more and more important, whichbring more and more deep excavation and geotechnical engineering problems becauseof the complex formation characteristics of coastal cities. In recent years, theaccidents of the excavation have brought different degrees of loss to people’s life andproperty, which caused negative effect to the society. In addition first protecting thedeformation of its structure and paying attention to the environment, there are twokeys to guarantee the safety and stability of the excavation foundation pit in soft soil.At present the rail traffic construction of Ningbo is just beginning, where deep silt isextensively distributed. The silt in this region has the characteristics of highcompressibility, high void ratio, low bearing capacity, and flow plastic or soft plastic.These characteristics have brought about many negative effects to various aspects offoundation pit construction. For example, they bring many technical problems to deepfoundation pit excavation of the subway. Therefore, it is necessary to offer theinformation to specialized research to design and learn according to the characteristics,provide a good reference to the similar projects from then on.To study the technical difficult of pit excavation of chick mud which have bigdeformation and hard to control. This article uses Ningbo subway line one station’sdeep foundation hole case study:1. By gathering a lot of testing and engineering material, with a statisticalanalysis of Ningbo stratigraphics physical and mechanical parameters, compared tothe soft soil of other areas in China, it analyzes the silt soft soil characteristic and rheology in Ningbo. Under different conditions of experiments, comparing thedifference between the strength parameters it provides the reference to theengineering design for calculating.2. Through the analysis of previous researches achievements, it summarized thefoundation pit deformation general mode, including protecting the deformation of thesettlement of the wall. Comparing the analysis of the designs and values of the alarmin different regions, it concludes that the index lines and number in different regionsare different because of the different regional characteristics of foundation pit.3. It makes a detailed analysis of the observation of the foundation pit-excavationof Shengmo Road station in Ningbo subway, which includes gap water pressure, soilpressure, wall thick walls inclined surface subsidence and strut axial forces. Theanalysis shows that the calculation of silt soil and water points should be adopted tocalculate because of the bigger pore pressure. The curve settles pit maximumdeformation of foundation pit excavation is not inclined near surface above, and in thefoundation pit bottom about4meters under, settlement and deformation of a groove,local triangle and parabolic mixed settlement distribution curve.4. By successfully adopting the K line theory into the monitoring analysis ofaxial force of foundation pit, image, intuitive, concise showed the characteristics ofthe foundation pit axial force change. For foundation pit of real-time monitoring andmass monitoring data processing provides a reliable solutions.5. On the basis of the research equivalent level resistance coefficient of theinfluence factors, this paper analyzes the construction process in the excavationparameters on the effect of deformation. And through the tested and reliableparameters analyze the main parameters of deformation control design. It concludesthat most of the design that the relationship between the value and deformation are notsingle, and the same design parameters on the effect of the inclined and subsidence isdifferent, the design considerations should be integrated.6. According to the engineering, this paper offers some advanced suggestions onthe design parameters and construction plan and provides reference to the project andthe subsequent project.