基于指数模型的岩石锚杆粘结强度统计研究

Statistical Study on Bond Strength of Rock Anchor Based on Exponential Model

对比研究了指数模型和双曲线模型拟合岩石锚杆P-S曲线的效果,选用指数数学模型对岩石锚杆抗拔试验数据进行统计分析。首先基于指数模型,由岩石锚杆抗拔验收试验P-S曲线预测得到岩石锚杆的极限承载力,然后根据岩石锚杆锚固长度反算出砂浆或混凝土与岩石间的粘结强度,并根据岩层软硬程度对统计结果分类,并取累积频率为90%对应处锚杆粘结强度作为最大参考值。结果表明,软岩和较软地质条件下,规范建议的砂浆与岩石的粘结强度值比统计值偏大20%,硬质岩地质条件下,规范建议值与统计值基本相符。

Comparisons between the hyperbolic model and exponential model prediction effects have been made and the exponential model is selected to analyze the P-S curve of rock anchor test data. The ultimate bearing capacity of anchor is predicted by the P-S curve of rock anchor test data based on the exponential model firstly,then the bond strength of rock anchor is back calculated according to the anchorage length and these results are classified according to the hardness degree of rock. Maximum reference values can be get at the 90% point in cumulative frequency distributing graph. It is shown that bond strength of rock anchor recommended in the code is larger by 20% than the statistic on the soft rock condition and both the recommended and statistic values are in agreement on the hard rock condition.