地下埋管可靠度校准分析

Reliability analysis of underground penstock

应用《水工统标》推荐的一次二阶矩法，对现行《水电站压力钢管设计规范（ＳＤ１４４ － ８５）》中的地下埋管进行了可靠度水平校准分析．介绍了地下埋管在正常工作情况下的荷载及荷载效应的统计特征、影响地下埋管抗力的因素和各因素的统计参数；分析计算了Ａ３ 和１６ Ｍｎ 钢管在不同荷载效应比和不同围岩承载率时的可靠指标β；讨论了现行规范地下埋管的可靠度水平；提出了地下埋管可靠度低于明管较多，在修订规范时宜适当提高的建议．可供地下埋管设计和修订规范时参考．

Based on the method of first order second moment recommended by 《Unified design standard for reliability of hydraulic engineering structures》, the reliability of underground penstock in 《Design Code for Penstock in hydropower plants (SD 144-85)》 are calibrated and analyzed. The statistics of load effects of underground penstock on normal condition and factors affecting the structural resistance are presented. The reliability indices β of penstock made of A3 steel and 16Mn steel, undergoing different raio of load effect and percentage of load carrying of surrounding rock, are calculated. The reliability level of underground penstock in current code is discussed. Because the reliability of underground penstocks are much lower than that of exposed penstocks, this paper suggests that it should be increased while evising code. These research achievements provide a scientific basis for the design of underground perstock and the revision of 《Design Code of Penstock》.