基于可靠度的高速公路准临界坡长

Pre-critical grade length of expressway based on reliability

为了防止对规范的恶意透支使用,提出了一种基于概率设计的方法来计算准临界坡长.采用结构工程中极限状态设计理念,考虑供给与需求之间的关系,构建系统可靠度与失效概率的数学模型.基于10年事故数据分析及现场追踪采集的381辆爬坡车辆速度变化特征,构建爬坡极限状态方程.利用一阶可靠度方法和蒙特卡罗仿真法分别进行数值计算和抽样仿真,对结果做敏感性分析.研究表明,当前我国《公路路线设计规范》中最大坡长值能够满足轻型车和中型车的爬坡需求,但对于重型车比例较大的高速公路,规范中设计坡长值显得较为严格或苛刻,从而降低了高速公路的运行速度,减少了交通通行能力.利用可靠度理论可以量化对坡长值的选用,获取连续可靠的计算值.

To prevent malicious overdraft use of the specifications,a probabilistic method was presented to calculate the pre-critical grade length. According to the limit state design concept of structural engineering and considering the relationship between supply and demand,the models of the reliability index and the failure probability of the system were established. Based on a set of 10 year crash data and the speed variation of 381 climbing vehicles tracked in site,the equation of the climbing limit state was put forward. The first-order reliability method and the M onte Carlo simulation were used for numerical calculation and sampling simulation,respectively. The sensitivity analysis was applied to evaluate the calculation results. The results show that the maximum slope length in the current China Design Specification for Highw ay Alignment can meet the climbing demand of light and middle-sized vehicles,but the design values of the slope length in the specification are strict or demanding for expressw ays with high percentage heavy vehicle,which reduces the vehicle speed and decreases the traffic capacity. The reliability theory can be used to quantify the selection of the slope length and obtain continuous and reliable calculation values.