Static Sounding Resistance In Correlation With The Soil Shear Strength Than Penetration

With the acceleration of urbanization, the utilization of urban underground space has been continuously developed. The increase in deep foundation engineering, excavation depth, project size and engineering difficulty has been presenting new challenges to both scientific research and engineering technology. Among these challenges, effective determination of soil shear strength and accurate calculation of basis stability is one of the key issues. Especially for the deep foundation pit of saturated soft soil area, it is difficult to measure the pore water pressure during the construction, instead, the situ or indoor consolidation undrained shear test is adopted to determine the total shear strength under destruction for total stress analysis. Among the many in-situ tests, static penetrometer has been widely adopted in geotechnical survey and design which could be tested without disturbing the in-situ state of soil, with the advantages such as simple device, good continuity and reliable data. To research the interrelationship between specific penetration resistance of CPT and shear strength could enhance the settlement of above issues. Whereas, until now, there are few related researches at home and abroad. This paper is constructed through theory, regression, numerical methods and the correlations between, the research content and outcomes are as follows:First, cylindrical cavity expansion theory is used to derive the relationship between specific penetration resistance of CPT and shear strength in saturated soft soil. Based on saturated soft soil assumption and yield criterion, cavity expansion limit pressure is given by balancing equations, geometric equations, constitutive equations and boundary conditions, together with the plastic zone soil stress solution, displacement solution and plastic zone solution. The interrelationship between specific penetration resistance of CPT and shear strength is also been presented under cylindrical cavity expansion theory.Secondly, through13projects in Shanghai and33projects in Wuhan, a total of694sets of data have been researched according to different soil types. This paper analyzes the physical and mechanical characteristics of these three types of soil in two areas, in order to get the interrelationship between specific penetration resistance of CPT and shear strength on the grounds of different constructions areas and soil types.Thirdly, based on adaptive grid finite element method for large deformation a simulation study is adopted of the CPT penetration process. The soil displacement increases with the penetration depth, adding to the scope of penetration zone constantly spreading laterally and inferiorly. When the cone reaches a certain depth, the displacement-affected zone approaches the ring-like distribution package. Resistance increases with the increase of shear strength, and correlation relationship is given according to the ratio of the stress cone penetration resistance.Finally, taking Shanghai World Expo Performing Arts Center District as a typical engineering example, comparative analysis has been conducted of the following three methods to determine soil shear strength coherency. This paper identifies that the cavity expansion theory and finite element analysis derived idealized conditions as well as ignoring soil consolidation, anisotropy, friction and other characteristics. Regression analysis is performed using local engineering data with a combination of various soil properties to get a better coherent to the actual soil shear strength. Therefore, before a general formula has been established under multi-factor conditions, it is necessary and important to determine the interrelationship between specific penetration resistances of CPT and shear strength based on the engineering data, with great practical value.In addition, based on the survey data of52engineering works, this paper creates CPT relevant information databases, which carries out the preliminary research of engineering survey information databases work (digital, standardized database) in combination of current IT technology and software. In combination with the current IT technologies and software engineering survey information databases work (digital, standardized database) made a preliminary exploration and research.