基于简化力学模型的隧道锚极限承载力估值公式  

Estimation method of ultimate bearing capacity of tunnel-type anchorage based on simplified mechanical model

作　　者：王东英 汤华[3] 尹小涛[3] 杨光华[1,2,4] 姜燕[1,2] WANG Dong-ying;TANG Hua;YIN Xiao-tao;YANG Guang-hua;JIANG Yan(Guangdong Research Institute of Water Resources and Hydropower,Guangzhou,Guangdong 510610,China;Guangdong Technical Research Center of Geotechnical Engineering,Guangzhou,Guangdong 510640,China;State Key Laboratory of Geo-mechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;School of Civil Engineering&Transportation,South China University of Technology,Guangzhou,Guangdong 510640,China)

机构地区：[1]广东省水利水电科学研究院,广东广州510610 [2]广东省岩土工程技术研究中心,广东广州510640 [3]中国科学院武汉岩土力学研究所岩土力学与工程国家重点试验室,湖北武汉430071 [4]华南理工大学土木与交通学院,广东广州510640

出　　处：《岩土力学》2020年第10期3405-3414,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51778609,No.5177082703);中国博士后科学基金(No.2019M662827)。

摘　　要：悬索桥隧道式锚碇的设计理念为锚碇夹持岩体协同承载,因而承载能力远超同体积的重力式锚碇。但因目前对围岩协同作用认识尚不充分,在当前隧道式锚碇设计中仍保守地忽略锚碇和岩体间的挤压效应。为弄清锚碇-岩体协同承载的机制,揭示隧道锚承载能力提高的本质,通过分析隧道式锚碇建设至成桥全过程受力,建立隧道锚的简化力学模型,并引用Mindlin应力解分析了荷载沿锚碇轴向的传递规律以及荷载产生的作用于锚碇-岩体间的挤压应力分布,最终给出了隧道式锚碇极限承载力的简化估算方法,并通过伍家岗大桥隧道锚工程实例分析了结果的合理性。所得结论主要有:锚碇-岩体界面力主要由锚碇自重和锚碇-岩体相互挤压产生;锚碇-岩体界面附加应力自后锚面向前锚面呈先增后减的变化趋势,在距后锚面约1/3L处达到应力峰值;以容许抗剪强度为破坏判据解得的伍家岗长江大桥隧道式锚碇的极限承载力为3 504 MN,约为16倍的设计荷载,与室内试验值基本吻合。The design philosophy of suspension bridge tunnel-type anchorage is that anchorage and rock bear the bridge load together. As the cooperative bearing mechanism of anchorage and rock, its bearing capacity is much higher than that of gravity anchorage with the same volume. However, due to the insufficient understanding of the synergy of surrounding rock, the squeezing effect between the anchorage and rock mass is still conservatively ignored in the design of tunnel anchorage. In order to understand the mechanism of coordinated bearing between anchorage and rock mass, and reveal the essence of improving the bearing capacity of tunnel anchor, a simplified mechanical model of tunnel anchor was established by analyzing the whole process from construction to completion of the bridge. Mindlin stress solution was used to analyze the law of load transmission along the anchorage axis and the distribution of compressive stress between anchorage and rock mass caused by load. A simplified method for estimating the ultimate bearing capacity of tunnel type anchorage was proposed. Then the recommend estimation method was successfully applied to Wujiagang suspension bridge project. The main conclusions are as follows: the interface force between anchorage and rock mass is mainly produced by the self weight of anchorage and the mutual extrusion of anchorage and rock mass;the additional stress at the interface between anchorage and rock mass increases first and then decreases from the rear anchor face to the front, and reaches the peak stress at about 1/3 L away from the rear anchor surface;the ultimate bearing capacity of the tunnel anchorage of Wujiagang Yangtze River Bridge calculated by the allowable shear strength is 3 504 MN, about 16 times of the design load, which is basically consistent with the laboratory model test value.

关 键 词：隧道式锚碇 协同承载机制 MINDLIN应力解 附加挤压应力 极限承载力 

分 类 号：TU457[建筑科学—岩土工程]