确定性计算方法将所有的计算参数用确定值表示和计算，结果有时与实际情况有所出入。针对岩土参数的特点，利用未确知有理数来表达计算参数的不确定性，将未确知数学的运算理论引入到确定性计算中，可避免传统方法对参数描述过于绝对化。笔者将未确知有理数应用于挡土墙的抗滑移验算中，使用确定性和不确定性两种方法进行了挡土墙抗滑安全系数的计算。结果表明：未确知有理数能更好地考虑参数的不确定性，与常规方法相比计算结果更翔实可靠，并可以推广到其他领域的分析计算。

All parameters are treated as definite numbers in deterministic computation, thus the result sometimes is inconsistent with the practical condition. Base on the character of geotechnical parameters, the uncertainty of the parameters is expressed by uncertainty rational number, and the theory of uncertainty mathematics is induced in the deterministic computation in order to avoid the shortage in the traditional methods. The uncertainty rational number is applied in the sliding computation of retaining wall, and the safe factor is calculated by certainty method and uncertainty method. The comparison of results indicates that uncertainty rational number can consider the uncertainty better of computation parameters, and the result is more detailed and reliable compared with routine methods, so it can be popularized to other fields.