对岩溶隧道防突岩层安全厚度的发展现状作了全面综述，分析比较了定性分析法、半定量分析法和定量分析法3类研究方法的优劣及相互关系，结合有关研究成果，深入探讨了当前岩溶隧道防突岩层安全厚度的研究特点、不足之处及发展趋势。考虑到目前所用方法的复杂性与局限性，提出了裂隙密度影响指数概念，并给出其取值标准，在此基础上对防突安全岩层岩体的等效弹性模量和等效泊松比进行估算，得到可依据勘察数据资料进行适当估算的岩溶隧道防突岩层安全厚度估算公式，并结合实例进行具体计算分析，验证了估算公式的合理性、有效性和可行性。

The stateofart of the researches on the againstinrush safe thickness of rock strata in karst tunnels is summarized. The advantages/disadvantages of and the relationship among the qualitative analysis method, the semiquantitative analysis method and the quantitative analysis method are analyzed and compared. The characteristics, inadequacy and development trend of the researches on the againstinrush safe thickness of rock strata in karst tunnels are discussed on basis of relevant research results. Due to the complexity and limitation of the analysis method used at present, the concept of fissure concentration influence factor is proposed and the standard for the value taking of the fissure concentration influence factor is provided. The equivalent elastic modulus and the equivalent Poisson’s ratio of the againstinrush safe thickness of rock mass are evaluated on basis of the proposed concept. Finally, a formula to estimate the againstinrush safe thickness of rock strata of karst tunnels on basis of the geological investigation data is obtained. The formula has been used in engineering cases and the rationality, effectiveness and feasibility of the formula has been verified. 