基坑开挖变形的颗粒流数值模拟

Simulation of Soil Deformation Due to Pit Excavation with Particle Flow Code

摘要:

采用基于散体介质特性建立的颗粒流细观力学数值方法，通过二次开发对重力式搅拌桩围护基坑的开挖过程和宏细观力学响应进行了研究.结合具体工程，基于相似理论建立了基坑的数值模型，通过双轴试验确定了土的细观力学参数，将土体细观结构特征和宏观力学响应联系起来，重点分析了开挖过程中基坑外土体沉降、基坑内土体隆起及围护桩水平位移等变化规律，模拟结果与实测结果具有较好的一致性，初步验证了用颗粒流方法模拟基坑开挖的可行性，也为从微细观角度研究围护结构和土相互作用机理提供了新的途径.

Abstract:

Numerical simulations of macromeso mechanical behaviour of an excavation process supported by deep mixing piles were performed by secondary exploitation using the Particle Flow Code in 2 Dimensions(PFC2D code),which was developed based on the assemblies of particlular materials.The PFC2D model of a real pit was established according to similarity theory,and the mesoscale parameters of soils in the model were determined through a series of calibration biaxial tests in order to link the change of mesoscale fabric to macroscale response.Deformations of ground surface were analysized for all excavation steps,including heaves of pit bottom and horizontal displacements of mixing piles.The study verifies that PFC2D can be used to visualize the evolution of excavation process.Comparison between simulation results and the measured data proves the feasibility to explore the interaction mechanism of retaining structure and soils around from the prospect of the mesomechanics.