【摘要】 在相同围压下,对饱和粉砂质泥岩分别进行常规三轴压缩试验、三轴压缩蠕变试验以及三轴压缩应力松弛试验。基于试验结果,比较3种力学试验得出的岩石试样轴向强度大小以及轴向峰值应变大小,并从岩石破裂机制方面解释岩石强度以及变形差异产生的原因。采用Burgers模型描述粉砂质泥岩的蠕变与应力松弛特性,依据模型参数辨识结果,比较常规力学试验得出的剪切模量G与Burgers蠕变模型和应力松弛模型得出的瞬时剪切模量G1大小关系,并比较Burgers蠕变模型与应力松弛模型对应参数值之间的大小关系。研究结果表明:(1)粉砂质泥岩试样的瞬时强度最大,蠕变长期强度其次,松弛长期强度最小。(2)常规力学试验中试样的轴向峰值应变最大,应力松弛试验中试样的轴向峰值应变其次,蠕变试验中试样的轴向峰值应变最小。(3)常规力学参数G值与Burgers蠕变模型和应力松弛模型参数G1值相差较大,分别是蠕变模型和应力松弛模型参数G1值的64.5,86.8倍。(4)对于G1,G2,1,2这4个参数,蠕变模型辨识得出的参数值均较应力松弛模型辨识得出的参数值大。2种模型的G1参数值大小接近,而其他3种参数G2,1和2,采用2种模型辨识得出的参数值差别较大,相差1～2个数量级,其中G2参数值相差最小,1参数值相差最大。与剪切模量G1,G2参数值相比,2种模型的黏滞系数η1,η2参数值相差较大,表明1,2对岩石蠕变与应力松弛特性的影响较大。(5)粉砂质泥岩蠕变与应力松弛模型对应参数的比较结果,证明所得出的岩石蠕变与应力松弛模型参数的正确性,与线黏弹性材料不同,岩石的蠕变特性与应力松弛特性是不等同的,不能简单地由岩石的蠕变特性推导得出其应力松弛特性。更多还原

【Abstract】 The conventional mechanical,creep and stress relaxation tests of saturated silty mudstone are carried out under triaxial compression with same confining pressure.Based on the test results,the axial strengths of the specimens in three mechanical tests are compared;and the peak axial strains of the specimens are also compared.Then the differences of axial strengths and peak axial strains of the specimens among tests are explained from the view point of rock failure mechanism respectively.Burgers model is selected to describe the creep and stress relaxation properties of silty mudstone.According to the identification results,shear moduli G of the specimens obtained from the conventional mechanical test are compared respectively with instantaneous shear moduli G1 of the specimens identified by the creep model and the stress relaxation model,and the parameter values of the creep model are compared with those of the stress relaxation model.The analysis results show that:(1) The axial strength of the specimens in the conventional mechanical test is the highest,followed by the creep test,and that in the stress relaxation test is the lowest.(2) The peak axial strain of the specimens in the conventional mechanical test is the highest,followed by the stress relaxation test,and that in the creep test is the lowest.(3) Shear modulus G is 64.5 times larger than instantaneous shear modulus G1 of the creep model,and 86.8 times larger than instantaneous shear modulus G1 of the stress relaxation model.(4) Through comparing the values of G1,G2,?1 and ?2 between the creep model and the stress relaxation model,it is found that each of four parameter values of the creep model is larger than that of the stress relaxation model.It is also found that the values of G1of the two models are close,and that the differences among the orders of magnitude of the values of G2,?1 and ?2 of the two models are 1 to 2 series.The difference in the values of G2 is the largest and the difference in the values of ?1 is the smallest between the two models.Moreover,it is shown that the differences in the values of ?1 and ?2 are larger than those of G1 and G2 between the two models.The results indicate that ?1 and ?2 have a great effect on the creep and stress relaxation properties of silty mudstone.(5) The results of comparison between the two models verify the correctness of the creep and stress relaxation parameters.The results show that the creep properties of silty mudstone are not equivalent to its stress relaxation properties,the stress relaxation properties of silty mudstone can?t be deduced simply from its creep properties,which is different from linear viscoelastic materials.更多还原