多级循环加卸载作用下砂岩变形规律试验研究  

Experimental Study on Deformation Law of Sandstone under Multi-stage Cyclic Loading and Unloading

作　　者：李洪亚 杨渝南[1,2] 刘杰[1,2] 张罗送 司马艳 Li Hongya;Yang Yunan;Liu Jie;Zhang Luosong;Si Mayan(Key laboratory of Geological Hazards on Three Gorges Reservoir Area,Ministry of Education,China Three Gorges University,Yichang,Hubei 443002,P.R.China;College of Civil Engineering&Architecture,China Three Gorges University,Yichang,Hubei 443002,P.R.China)

机构地区：[1]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002 [2]三峡大学土木与建筑学院,湖北宜昌443002

出　　处：《地下空间与工程学报》2020年第6期1636-1645,共10页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金(51439003,52079071);湖北省技术创新重点项目(2017ACA189);湖北省自然科学基金杰出青年人才计划(2018CFA065);湖北长江三峡滑坡国家野外科学观测研究站开放基金(2018KTL08);三峡大学硕士学位论文培优基金(2019SSPY026)。

摘　　要：以RMT-150C岩石力学试验机为试验平台,对砂岩岩样开展低频多级循环加卸载试验,研究得到了不同频率下当加载力峰值大于破坏荷载的28%时,表观弹性模量E(t)与即时载荷f(t)呈线性关系;同时对该关系中压密系数a、变形系数b进行拟合,得出随加载力峰值增大,a值递减、b值递增的变化规律。基于该规律,提出了一种通过有限加卸载循环下的试验数据预测任意屈服前加卸载峰值下的应力应变曲线的方法;并给出了变频变峰下岩样位移变形速率的预测公式,同时根据该公式对岩样位移速率峰值点时刻进行了预测。由该预测值与加载力峰值和实测位移变形速率峰值时刻值的对比,指出岩样循环加卸载中存在的"错峰"现象也是力位移存在不同步性的体现。Low-frequency multi-stage cyclic loading and unloading tests were carried out for sandstone rock samples on RMT-150 C rock mechanics testing machine.The study shows that the apparent elastic modulus is linear with the instantaneous load when the loading force peak is greater than 32 kN at different frequencies.At the same time,the compaction coefficient and the deformation coefficient b are fitted in the relationship.And the variation law of the a-value decreasing and the b-value increasing with the increase of the loading force peak is obtained.Based on this rule,a method for predicting the stress-strain curve at the peak of pre-yield loading and unloading is proposed by using the test data of finite loading and unloading cycle.And the prediction formula of the displacement deformation rate of the rock sample under the variable frequency peak is obtained,and this paper predicts the peak point moment of the rock sample displacement rate according to the formula.By comparing the predicted value with the peak value of loading force and the peak value of measured displacement and deformation rate,it is pointed out that the phenomenon of"peak dislocation"in the cyclic loading and unloading of rock samples is the embodiment of the nonsynchronism of force-displacement.

关 键 词：岩石卸载 变频变峰 表观弹性模量 位移变形速率 

分 类 号：TU458[建筑科学—岩土工程]