土工基础

›› 2016, Vol. 30 ›› Issue (2): 232-236.

• 工程实录 • 上一篇    下一篇

砂岩结构面法向加卸载本构模型研究

姜 黎1，范 雷2   

  1. (1.中国电力工程顾问集团中南电力设计院有限公司,武汉 430071;2.长江科学研究院水利部岩土力学与工程重点实验室,武汉 430010)
  • 收稿日期:2016-03-02 出版日期:2016-04-20 发布日期:2016-04-27
  • 作者简介:姜 黎（1980-），男，工程师，研究生，研究方向为方向岩土工程，工程地质。

Constitutive Model of Sandstone Discontinuities under Normal Loading and Unloading Conditions

JIANG Li1,  FAN Lei2   

  1. (1.Central Southern China Electric Power Design Institute, China Power Engineering Consulting Group, Wuhan 430071;
    2.Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, 
    Yangtze River Scientific Research Institute, Wuhan 430010)
  • Received:2016-03-02 Online:2016-04-20 Published:2016-04-27

摘要： 鄂西志留系罗惹坪组砂岩结构面法向循环加卸载试验结果表明，在中低法向应力范围内，结构面加载变形曲线呈上凸型，卸载变形曲线呈上凹型，结构面卸载后产生残余变形，形成明显的回滞环。目前已提出的结构面法向变形本构方程都是在试验的基础上总结出的经验方程，因结构面的初始法向刚度和最大闭合变形量难以确定，使模型的计算精度受到一定的限制。因此，针对浅表工程岩体应力状态较低的特性，提出了结构面法向变形的半对数-圆弧线联合本构模型，加载曲线采用半对数模型表征，卸载曲线则采用圆弧线模型表征。其中，半对数函数的模型参数可根据加载试验结果回归分析得出，圆弧线模型方程则由本级加载曲线的起点、终点与卸载曲线的终点三点坐标确定。通过模型计算结果与试验结果对比分析表明，半对数-圆弧线模型计算结果与试验结果相吻合，较好地体现了结构面法向加载曲线为上凸型与卸载曲线为上凹型的特征，重现了卸载-加载过程的回滞圈。新的模型回避了最大闭合变形量和初始刚度的确定难题，并且不需引入新的模型参数，便于实际应用。

关键词: 砂岩结构面, 法向加卸载, 本构模型, 法向刚度

Abstract: A normal loading/unloading test were conducted out on the Silurian Luoreping Formation sandstone samples with discontinuities. The results indicate that, under the low normal stress conditions, the discontinuities deformation curves are in convex, and a concave shape is obtained on the discontinuities with the residual deformation under the normal unloading. The obvious stress strain hysteresis loops can be observed in the result. Currently, the normal deformation constitutive models of discontinuities are all empirical relations from laboratory test results. However, due to the difficulties in the determination of both the initial normal stiffness and maximum closure deformation at the discontinuities, the accuracy of these models is limited. A semilogarithmcircular arc constitutive model for predicting the normal deformation at the discontinuities is proposed in this paper based on the characteristics of low confining stress of the shallow rock mass. The loading curve is described by the semi-logarithm model and can be obtained from the regression analysis of the loading test results. The circular arc is used to represent the unloading process and it can be determined from the coordinates of three points: initial loading, final loading and the end of unloading. The calculated results were consistent with the laboratory test results.

Key words: Sandstone Discontinuities, Normal Loading/Unloading, Constitutive Models, Normal Stiffness