邓肯模型的改进

邓肯(Duncan)等人用有限单元法对土石坝等土工建筑物中应变强化土料作非线性的应力应变分析,提出了一个简单实用的模型。该模型考虑了工程实践经验,运用常规试验技术,取得了近似的,但尚能令人满意的成果。它的主要缺点是不能反映中主应力、应力轨迹以及凝聚性土在拉压复合应力作用下的特性,这些问题对实际应用影响较大。本文做了某些改进,使模型能反映凝聚性土的抗张拉能力,并且能按试验成果准确反映无侧限压力作用情况下应力与应变的关系。

Method for calculating deformation pressure of surrounding rock of deep-buried tunnels

The pressure of surrounding rock is an important research content of tunnel engineering, and it includes deformation pressure. The study on the deformation pressure is of great significance to ensure the safety and economic construction of tunnels and underground engineering. The method of mathematical statistics is used to analyze the influence degrees and variation laws of grade of surrounding rock, tunnel span and tunnel depth on the deformation pressure through a large number of filed measured data. The formula for calculating the vertical deformation pressure is established by using the multivariate nonlinear regression analysis method. The deformation pressure is about 84%~92% times the value by the “Code for design of railway Tunnels” according to the analysis. As the grade of the surrounding rock increases, the ratio decreases continuously. The lateral pressure coefficient of deformation loads obeys the normal distribution. The lateral pressure coefficient of each surrounding rock condition has a certain increase compared with that in the “Code for design of railway tunnels”. The research achievements have certain reference guidance for the design of tunnels and underground supporting structures in China.