非均质围岩压力隧洞混凝土衬砌的初裂间距  

THE INITIAL CRACK SPACE OF PRESSURE TUNNEL CONCRETE LININGS IN NON-HOMOGENEOUS ROCK MASS

作　　者：彭守拙[1] 钟建文[1] 

机构地区：[1]清华大学水沙科学与水利水电工程国家重点实验室,北京100084

出　　处：《工程力学》2013年第1期205-214,共10页Engineering Mechanics

摘　　要：非均质围岩中,水工压力隧洞混凝土衬砌间距不等,裂缝位置未知。建议一个能够确定初裂裂缝位置的数值计算方法,并利用现场试验结果验证了其可行性。阐明了典型地质条件对衬砌最大应力位置,即第一条裂缝位置的影响。通过大量计算,分析了混凝土开裂所引起的释放应力的特性,从而得出压力隧洞混凝土衬砌有关初裂间距的某些概念:相同围岩条件下,大直径压力隧洞混凝土衬砌的初裂裂缝条数少于小直径隧洞;洞径相同条件下,非均质围岩中混凝土衬砌的初裂裂缝条数少于均质围岩隧洞;各计算情况下,混凝土的初裂裂缝条数为1条4条,裂缝条数较少的主要原因是开裂时,围岩对衬砌的平均切向抗力较小(约为0.05MPa)和应力松弛范围较大,约90°。It is generally found that the spaces between initial cracks in the concrete linings of pressure tunnels are not the same in non-homogeneous rock mass, and the positions of these cracks can be distributed in a random manner. A numerical method is presented which is capable of determining the locations of the initial cracks under critical inner water pressure, the feasibility of which is verified through a comparison analysis of a prototype test. The Influence of typical geological conditions upon the location of the first crack has been analyzed. Parametric analyses have been conducted to investigate the characteristics of the space between initial cracks in the linings of pressure tunnel taking into account the influence of cracking induced stress release. It is found that under same rock mass conditions, the number of initial cracks in linings decreases as the tunnel diameter grows larger, while the tunnel diameter remains the same, the number of initial cracks in linings would be relatively small in the situation of non-homogeneous rock mass in comparison with the case under a homogeneous rock mass condition. Also it is found that the number of initial cracks in concrete linings for all the conditions considered in this paper ranges from 1 to 4, which is relatively small and can be attributed to the low value of average tangential stress between the lining and surrounding rock, about 0.05MPa, as well as the effect of a large stress release region induced by the cracking within the lining.

关 键 词：地下工程 围岩 水工压力隧洞 混凝土衬砌 初裂裂缝间距 释放应力 

分 类 号：TV554.14[水利工程—水利水电工程]