中文摘要：

根据岩溶区桥梁基桩的工程特点，并考虑桩身转动时桩尖断面与基底岩接触面上产生的反力矩等对基桩的影响，提出了岩溶区桥梁基桩嵌岩深度的计算方法；在溶洞顶板抗冲切、抗剪验算中分别引入格里菲斯判据和莫尔判据，推导了岩溶区基桩下伏溶洞顶板稳定性计算新方法，并由此得出最小顶板安全厚度的确定方法。在此基础上，提出了如何根据地质钻探资料，确定岩溶区桥梁基桩桩长的计算流程，并应用于湖南省宁道高速公路，获得了较好的经济效益。

英文摘要：

Fiestly, according to the engineering character of bridge piles in In Karst Area, and considering some useful effects, such as the moment on pile tip formed by pile rolling motion, the calculation of socketed length is proposed ; then, Griffith Criterion and Mohr Criterion are introduced into the checking computations of cave roof＇ s anti-punch-shearing and anti-shearing capacity, so the new methods of cave roof stability is deduced, and so the detemination progress of pile length of bridge pile in karst area is presented in the paper based on the geological material, and the method is applied in hunan ningdao expressway.