基于模糊可靠度的缓和曲线最小长度计算方法研究

Research on Minimum Length Calculation Method of Spiral Transition Curve Based on Fuzzy Reliability

考虑缓和曲线最小长度计算参数的随机性与模糊性,以可靠度理论与三角模糊数为基础,利用模糊可靠度计算方法分析了缓和曲线最小长度的可靠性。研究结果表明:缓和曲线最小长度计算方法的选择受圆曲线半径取值的制约,当圆曲线半径取值较小时,宜采用按乘客感觉舒适所需最小长度计算公式来计算缓和曲线最小长度;当圆曲线半径取值较大时,采用按超高渐变率所需最小长度计算公式更佳。同传统可靠度计算方法相比,模糊可靠度计算得到的可靠指标大,失效概率小,计算精度高。将按乘客感觉舒适所需最小长度与按超高渐变率所需最小长度的计算公式应用于公路缓和曲线最小长度的计算,给出在缓和曲线最小长度失效概率为5%条件下的推荐值,可为缓和曲线长度设计提供参考。

Considering the randomness and fuzziness of the calculation parameters of the minimum length of transition curve,based on the reliability theory and triangular fuzzy number,the reliability of the minimum length of transition curve is analyzed by fuzzy reliability calculation method.The results show that the selection of the calculation method of the minimum length of transition curve is restricted by the radius of the circular curve.When the radius of the circular curve is small,the minimum length of the transition curve should be calculated by the formula of the minimum length required for passenger comfort.When the radius of the circular curve is large,it is better to use the formula for calculating the minimum length required for the ultra-high gradient rate.Compared with the traditional reliability calculation method,the fuzzy reliability calculation method has the advantages of large reliability index,low failure probability and high calculation accuracy.The formulae of the minimum length required for passenger comfort and the minimum length required for ultra-high gradient rate are applied to the calculation of the minimum length of highway transition curves,and the recommended values are given under the condition that the probability of failure of the minimum length of the transition curve is 5%,which can provide a reference for the design of the transition curve length.