花岗岩残积土的修正摩尔库伦模型参数取值研究

摘要

MIDAS GTS岩土分析软件中的修正摩尔库伦模型在基坑开挖分析中的应用非常广泛,其加载模量和卸载再加载模量分开定义,可适用于模拟包括软土在内不同类型的土体,其应用的关键是本构参数的选取.华南地区的花岗岩残积层分布广泛,对基坑变形以及邻近地铁隧道变位影响很大.在修正摩尔库伦模型参数中,加载曲线割线模量最为关键,其值可由未修正的标准贯入试验击数推算得到.本文通过反分析法确定割线模量的经验系数,并确定参考割线模量与参考切线模量、卸载再加载模量取值的比例关系.最后通过一基坑的应用实例验证了推荐参数取值方法的实用性和合理性.%In the Midas GTS geotechnical analysis software,the modified mohr-coulomb model is widely used in the analysis of foundation pit excavation,which is more suitable for the simulation of different types of soil including soft soil.Loading modulus and unloading-reloading modulus are defined separately.How to determine the appropriate soil parameter is the most important procedure during the whole process.Granite residual soil is widely distributed in South China,which has great influence on the deformation of the foundation pit and the adjacent tunnel.Among the relative parameters,the secant modulus of loading curve is the critical factor,which can be derived from unmodified standard penetration test blow count.The inverse analysis method was used to determine the empirical coefficient of the reference secant modulus and the proportion relationship between the reference secant modulus and the reference tangent modulus,unloading-reloading modulus in this paper.Finally,the method of parameter calculation provided in this paper was used into the application of a foundation pit to verify the practicability and rationality.