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Hoek-Brown准则作为应用最广的岩石强度准则之一,其主要有2个方面的局限性:1)在常规三轴高围压条件下,根据Hoek-Brown准则预测的强度与试验实测的强度数据偏差较大;2)在真三轴条件下,该准则忽略了中间主应力对岩石真三轴强度的影响。为了克服以上局限性,引入Barton提出的临界围压和Singh中间主应力处理办法对Hoek-Brown准则进行改进。通过大量完整岩石强度试验数据分析改进的Hoek-Brown准则对三轴强度预测的适用性,分析结果表明:在围压低于临界围压时改进前后2个准则预测的岩石强度基本一致,而在围压高于临界围压时改进的Hoek-Brown准则预测的结果与试验数据更吻合;真三轴试验条件下,考虑中间主应力的改进的Hoek-Brown强度准则与试验结果的平均误差最小。因此,改进的Hoek-Brown强度准则更适用于完整岩石的三轴强度的预测。
The Hoek-Brown criterion, as one of the most widely used rock strength criteria, has two main limitations: 1) Under the conventional triaxial high confining pressure conditions, the strength predicted by the Hoek-Brown criterion and the measured strength The data deviation is large; 2) Under true triaxial conditions, this criterion ignores the influence of intermediate principal stress on true triaxial strength of rock. In order to overcome the above limitations, Hoek-Brown criterion is improved by introducing Barton’s critical confining pressure and Singh intermediate principal stress treatment. The applicability of the improved Hoek-Brown criterion to triaxial strength prediction is analyzed by a large amount of complete rock strength test data. The analysis results show that the rock strength predicted by the two criteria before and after the improvement is basically the same when the confining pressure is lower than the critical confining pressure, The Hoek-Brown criterion predicted by improved Hoek-Brown criterion is more consistent with the experimental data when the pressure is higher than the critical confining pressure. Under the true triaxial test, the average Hoek-Brown strength criterion considering the intermediate principal stress has the smallest average error with the experimental result. Therefore, the improved Hoek-Brown strength criterion is more suitable for the prediction of triaxial strength of intact rocks.