循环加载试验中岩石单轴抗压强度的影响及洄溯测算法  

Influence and Inverse Deriving Method of the Uniaxial Compressive Strength in Cyclic Loading Test of Rock

作　　者：肖建清[1] 张庆伟[1] 张士科[1] 

机构地区：[1]安阳师范学院建筑工程学院,河南安阳455000

出　　处：《防灾减灾工程学报》2016年第5期804-810,852,共8页Journal of Disaster Prevention and Mitigation Engineering

基　　金：国家自然科学基金项目(11002067);河南省高等学校青年骨干教师资助计划项目(2011GGJS-144);河南省教育厅科学技术研究重点项目(14A410002)资助

摘　　要：由于岩石疲劳分析中岩样间的个体差异较大,常导致上限应力比计算不准,S与lnN之间的定量关系难以确立,因此准确地估算出岩样强度对于疲劳分析至关重要。首先,基于岩石大样本单轴压缩试验数据及S—N方程,研究了误差传播规律,分析了岩样的个体差异对于疲劳寿命的影响。可知,误差从单轴抗压强度传播至上限应力比,再从上限应力比传播至疲劳寿命,其数值急剧膨胀,单轴抗压强度很小的标准差就会产生疲劳寿命的极度离散,所以疲劳分析中必须使用岩样的强度;其次,构造一个修正回归峰值本构模型,提出了以曲线拟合法估算岩样单轴抗压强度的思路。由静态加载试验数据的拟合结果可知,该本构模型的拟合效果好,估算得出的单轴抗压强度非常接近真实值。最后,基于循环加载试验静态加载段的数据,运用曲线拟合法,分析了4个岩样的等精度试验数据。可知,各试样的单轴抗压强度各不相同,单轴抗压强度越大,则上限应力比越小,疲劳寿命也越高,S与lnN之间具有明确的线性规律。因此,用修正回归峰值本构模型估算岩样真实强度,修正上限应力比的方法,克服了常规疲劳分析法的固有缺陷。Due to the large individual differences between rock samples, the upper stress ratio is unable to be determined and the quantitative relationship between S and lnN can not be estab- lished in rock fatigue analysis. Therefore, it is important to estimate the unconfined compressive strength （UCS） of rock sample. Firstly, the error propagation law and the influence of the indi- vidual differences of rock samples on fatigue life are studied on the basis of a large number of test data under uniaxial compression and S-N equation. The results show that the error increases dra- matically during spreading from UCS to upper stress ratio, then to fatigue life. A very small standard deviation in UCS may lead to great dispersion in fatigue life. So, the UCS of rock sam- ple instead of the statistical average UCS of rock should be used in fatigue analysis. Secondly, an idea applying curve fitting method to evaluate the UCS of rock sample based on a modified regres- sion peak constitutive model is put forward. And the test data under static loading is fitted with this model. The fitting result show that the evaluated UCS is very close to the true value. Final- ly, based on the tested data of the static loading segment in cyclic loading test, this curve fitting method is used to analyze the experimental data of four samples under the same test condition. The results show that the UCS of each sample is different and the greater the UCS, the smaller the upper stress ratio and the loger the fatigue life will be. Meanwhile, there is existing obvious linear law between S and lnN. Therefore, the method revising the upper stress ratio with the sample UCS evaluated by the modified regression peak constitutive model can overcome the in- herent defect of the conventional fatigue analysis method.

关 键 词：岩石力学 循环加载 疲劳寿命 曲线拟合 S-N曲线 

分 类 号：TD458[矿业工程—矿山机电]