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为了有效地描述软岩的软化特征,首先推导了以压为正统一强度理论表达式,该理论可以考虑材料拉压强度不等及中间主应力效应,适合岩土工程界以压为正的使用习惯以及岩土材料拉压强度不等的特性;其次推导了以压为正统一强度理论π平面的极限线;第三,基于推导的π平面的极限线,结合Yin-Graham模型,推导了软岩的三维统一弹黏塑性本构模型表达式。根据针对取自日本石川县能登半岛端部的硅藻质泥岩所进行的不同围压、不同加载速率条件下的应变控制式和应力控制式固结不排水三轴试验资料确定了模型参数,进行了弹黏塑性数值模拟分析。并与三轴试验结果进行了对比分析,结果表明:本文建立的软岩三维统一弹黏塑性软化本构模型的数值模拟结果与试验结果非常接近,可以很好地模拟软岩的应变软化特征。
In order to describe the softening characteristics of soft rock effectively, the theoretical expression of pressure as the orthodox strength is deduced first. The theory can consider the tensile strength and medium stress of the material and the effect of the intermediate principal stress, and is suitable for the geotechnical community to use positive pressure The habit and the tensile and compressive strength of geomaterials. Secondly, the limit line with pressure as the π plane of orthonormal intensity theory is deduced. Thirdly, based on the derived limit line of π-plane and Yin-Graham model, Three - dimensional unified elasto - plastic constitutive model expression of rock. The model parameters were determined according to the stress-controlled and stress-controlled undrained triaxial tests under different confining pressures and different loading rates for diatom mudstone taken from the end of the Denneng Peninsula in Ishikawa, Japan Elastic-plastic numerical simulation analysis. The results show that the numerical simulation results of the three-dimensional softening elastic constitutive model of soft rock in this paper are very close to the experimental results, which can well simulate the strain softening characteristics of soft rock.