圆形压力隧洞限裂配筋设计方法研究  

Study of reinforcement design by crack width control for circular pressure tunnels

作　　者：汪基伟[1] 冷飞[1] 蒋勇[1] 

机构地区：[1]河海大学,江苏南京210098

出　　处：《土木工程学报》2011年第10期143-148,共6页China Civil Engineering Journal

基　　金：国家自然科学基金(50978083)

摘　　要：为研究圆形压力隧洞衬砌合理的限裂设计方法,采用钢筋混凝土有限单元法对隧洞衬砌的受力特性进行分析,指出隧洞衬砌具有内力值随衬砌开裂区域增加而减小、配筋取决于裂缝宽度的限制要求而非承载力、规范中的裂缝宽度计算公式不适用等特性。通过对厚壁圆筒承载力计算公式的重新推导,指出该方法没有引入裂缝处环向钢筋应变最大值与环向钢筋在整个圆周内平均应变的比值ψ',使得钢筋面积计算值过小。鉴于隧洞衬砌的受力特性及没有合适的ψ'计算方法,建议取消厚壁圆筒公式,而采用钢筋混凝土有限单元法进行隧洞衬砌的配筋计算。对能由有限元计算直接求得裂缝宽度的衬砌,以裂缝宽度限值要求确定钢筋用量与布置;对不能由有限元计算直接求得裂缝宽度的衬砌,以限制钢筋应力来控制裂缝宽度,即以钢筋应力限值要求确定钢筋用量与布置。最后,通过较多的算例给出隧洞衬砌的钢筋应力限值,当保护层厚度为50mm时钢筋应力限值可取120MPa,当保护层厚度为100mm时钢筋应力限值可取100MPa。For reasonable design of circular linings by crack width control, the behavior of tunnel lining is analyzed by using reinforced concrete finite element method （RCFEM） to obtain three characteristics of lining structures： l ） the internal bearing force of the lining decreases while the cracked zone becomes wider, 2） the reinforcement but not the ultimate capacity of the lining is determined by crack width control, and 3 ） the formula for crack width in the specification is not appropriate. The ultimate bearing capacity formula for thick cylinders is derived, and it is found that the ratio ~p＇ of the maximum hoop strain of steel bars at crack to the average strain of the bars in whole cycle is not used in the formula in the specification, which may cause the reinforcement underestimated. On the basis of the above, RCFEM is suggested instead of the thick cylinder formula. The reinforcement, including amount and distribution, can be designed by crack width control for those lining structures in which the crack width can be calculated. For structures in which crack width cannot be calculated directly, crack width can be controlled by restricting steel stress, i. e. , reinforcement can be determined by the limit stress of bars. The limit stress 120MPa of steel bars in linings is recommended for concrete cover of 50mm and IOOMPa for concrete cover of 100mm.

关 键 词：压力隧洞 衬砌配筋设计 钢筋混凝土有限单元法 裂缝宽度 限裂设计 

分 类 号：TV332.9[水利工程—水工结构工程] TV672.1