蠕变扰动效应下红砂岩强度极限邻域试验研究

Experimental study on range of strength limit neighborhood of red sandstone under effect of creep disturbance

为得到更合适的强度极限邻域及其划分依据,以红砂岩为研究对象,应用自主研发的RRTSIV型岩石蠕变扰动效应试验系统及动态测试分析系统,通过岩石蠕变及其扰动效应下单轴压缩试验,结合理论分析,开展红砂岩强度极限邻域及其划分依据相关研究。依据试验结果,首先从分级加载蠕变曲线和应力应变等时曲线2个方面分析了横向蠕变和轴向蠕变所确定长期强度的差异性;然后从瞬时扰动变形量和残余扰动变形量转化规律2个方面对岩石横向蠕变和轴向蠕变所确定的强度极限邻域进行了对比研究;最后通过综合分析得到合适的强度极限邻域及其划分依据。研究结果表明:相对于瞬时扰动变形量,以残余扰动变形量转化规律确定强度极限邻域更合适;相对于轴向蠕变残余扰动变形量转化规律,以横向蠕变残余扰动变形量转化规律确定强度极限邻域更合适,由此得出红砂岩的强度极限邻域阈值约为32.5 MPa;长期强度确定的强度极限邻域阈值与残余扰动变形量转化规律确定的强度极限邻域阈值相差约2.5 MPa,但作为简单的初步分析判定,以长期强度界定强度极限邻域仍有较高的参考价值。

In order to obtain more suitable range and division basis of strength limit neighborhood.Red sandstone is used as the research object.Using RRTS-IV rock creep disturbance effect test system developed by ourselves,and the dynamic test and analysis system.Through the test of uniaxial compression creep and its disturbance effect of rock,combined with theoretical analysis,the range and division basis of red sandstone"strength limit field"are studied.Firstly,the difference of long-term strength determined by transverse creep and axial creep is analyzed from two aspects:graded loading creep curve and stress-strain isochronous curve.Then a comparative study of the range of"neighborhood of strength limit"determined by lateral and axial creep of rock is carried out from two aspects:instantaneous dis⁃turbance deformation and transformation law of residual disturbance deformation.Finally,through comprehensive analysis,the suitable range and division basis of strength limit neighborhood is obtained.The results show that:compared with the transformation law of axial creep re⁃sidual disturbance deformation,it is more appropriate to determine the range of strength limit neighborhood by the transformation law of transverse creep residual disturbance deformation,so the threshold value of strength limit neighborhood range of red sandstone is about 32.5 MPa;the difference between the range threshold of strength limit neighborhood determined by long-term strength and the range threshold of strength limit neighborhood determined by transformation law of residual disturbance deformation is about 2.5 MPa.However,as a simple preliminary analysis,it is still of high reference value to define the range of strength limit neighborhood by long-term strength.