超前支护的均一化横观各向同性弹性模型

超前支护（包括管棚和小导管注浆）是隧道开挖中保持地层稳定及控制其变形的重要手段，在隧道开挖模拟分析中需要妥善予以考虑。已有的分析模型一般是提高管棚和小导管注浆影响范围内的土体粘聚力和变形模量，或是分别模拟浆体和钢管。前者力图从整体效果上模拟超前支护对围岩的加强作用，但参数确定过于依赖经验，存在一定的随意性；后者如实模拟体系的构成，但大大增加了模型的复杂程度。如何采用既简单合理又能考虑其整体效应的模型是超前支护数值模拟的研究重点。为此，本文建议了一个均一化的横观各向同性弹性模型，研究了超前支护的平均弹性性质，并在此基础上提出了简化模型，该模型能够用来分析钢管的间距、管径、倾角等重要影响因素。最后，本文对某隧道开挖进行了三维有限元数值模拟，验证了所提模型的有效性。

Homogenization Transverse Isotropic Elastic Model of Pre-support

As an important means of stratum stabilization and deformation control in tunnel excavation, the pre-support, including pipe-roofing reinforcement and small pipe grouting, should be properly simulated and analyzed, and how to establish a simple and reasonable model considering the overall effect is the key issue in the numerical simulation. For this purpose, this paper presents a transverse-isotropic-elastic homogenization model of pre-support and establishes a simplified model based on the average elastic properties of pre-support, which can be used to analyze the influences of some important parameters such as pipe distance and diameter. The proposed model is then applied to the 3D finite element simulation of a tunnel excavation, with its effectiveness being finally verified.