Chengshi guidao jiaotong yanjiu (Jun 2024)
Earth Pressure Calculation Method for Deep Foundation Pit Excavation in Chengdu Pebble Stratum Area
Abstract
Objective The existing theoretical calculation method of earth pressure does not take into account the discrete characteristics of pebble stratum such as large porosity and loose structure, and the calculated results are different from the actual earth pressure. Therefore, it is necessary to study the earth pressure calculation method suitable for pebble stratum in Chengdu area. Method Based on Chengdu Rail Transit Line 7, the differences between the earth pressure in deep foundation pit of pebble stratum and the theoretical Rankine value are analyzed, and an earth pressure calculation method for deep foundation pit excavation is established. Using discrete element numerical simulation and statistical data analysis, the distribution characteristics of static earth pressure, passive earth pressure and active earth pressure under the three basic displacement modes of the enclosure structure translation, rotation around the wall top and rotation around wall bottom are obtained. By comparing with the calculation results from Rankine earth pressure theory, the correction coefficient of the earth pressure under three different displacement modes are obtained, and the calculation method of earth pressure correction for deep foundation pit is established. The proposed earth pressure calculation method is verified by further comparison with the on-site measured data. Result & Conclusion The distribution of active earth pressure and passive earth pressure shows strong nonlinearity, which can be described by double fold lines, and the intersection points are located at the buried depth of 8m and 9m respectively. The static earth pressure correction coefficient is distributed between 0.91 and 0.96, not need for correction in use. The active earth pressure correction coefficient is distributed between 0.33 and 0.78, and the passive earth pressure correction coefficient is between 0.52 and 0.91, should be corrected in use. The calculated results of earth pressure in deep foundation pit of pebble stratum are in good agreement with the on-site measured results, providing a reference for similar rail transit projects.
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