【摘要】 坝基抗滑稳定问题中,软弱结构面概化为多滑动面的情况相当常见,而规范对此并未给出明确的校核方法。为了提出一整套具有普遍适用意义的坝基多滑面稳定校核公式以及配套参数,为设计提供参考依据,首先在滑楔法基础上提出一种新的适用于多滑面和双滑面的等K′法;然后通过安全系数直接构成的极限状态方程,对等K′法进行可靠度研究,并分析强度参数的互相关性对可靠指标的影响。最终明确给出该方法定量安全系数K′的设计验算式、安全允许指标以及配套的分项系数。多方案验算结果表明,强度参数f,c的互相关性对可靠指标的影响比较显著:随着相关性从完全独立变化到完全负相关,可靠指标β与ρf,c的关系基本呈现非线性的增长,涨幅最大达到48.7%。常规方法将f,c视为独立变量,计算结果是偏于安全的;对等K′法设计验算式中的结构系数γd1,提出分等级的推荐取值,I,Ⅱ,Ⅲ级大坝γd1分别为1.2,1.1,1.0。方案验算和实例应用证明,采用等K′法验算式以及配套的分项系数进行坝基抗滑设计是可行的,安全可靠度也更有保障。更多还原

【Abstract】 It is focused on the anti-sliding stability problem for multi-slide surfaces of dam foundation. Firstly,a new method called equal safety factor K ′ is presented for multi-slide surfaces or double-slide surfaces mode,which is obtained by modifying the wedge method. Subsequently,the reliability research is conducted by using the limited equation composed of safety factor;and the effects of the cross-correlation among strength parameters frictional coefficient f,cohesion c on the stability index are analyzed through calculations of several typical sections of gravity dam foundation. Finally,the safety check formula of K ′,its permitted index and the corresponding partial coefficients are proposed. The results indicate that the cross-correlation of strength parameters f and c affect the reliability index remarkably. The reliability index β increases nonlinearly with correlation coefficient ρ f,cwhen the two parameters change from independent to negative correlated ones;and the largest increment is 48.7%. The parameters f,c are usually treated as independent ones for traditional method,which results in reliable calculation result. A suit of corresponding partial coefficients is also proposed for the design check formula of K ′. The recommended values of structure coefficient γ d1are classified to three grades with 1.2,1.1 and 1.0 for concrete dams of grade-I,grade-Ⅱ and grade-Ⅲ,respectively. Compared with the traditional wedge method,the new method is stricter for bad foundation and high dams,but looser for good foundation and low dams. Using the approach of equal safety factor K ′ for design of dam foundation,the safety degree is equivalent or even more reliable to the traditional method;moreover,the distribution of reliability is more reasonable.更多还原