预切槽法开挖黄土隧道的切槽方式研究  

Study on Slot Cutting Pattern for Excavation of Loess Tunnel by Pre-Cutting Method

作　　者：王秀英 郑维翰 张隽玮 孟德鑫[1] 王新东 WANG Xiuying;ZHENG Weihan;ZHANG Junwei;MENG Dexin;WANG Xindong(Key Laboratory of Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University, Beijing 100044, China;China Railway First Survey Design Institute Group Co.,L td ., Xi’an Shaanxi 710043, China)

机构地区：[1]北京交通大学城市地下工程教育部重点实验室,北京100044 [2]铁道第一勘测设计院集团有限公司,陕西西安710043

出　　处：《中国铁道科学》2018年第3期49-56,共8页China Railway Science

基　　金：国家自然科学基金资助项目(51178026);中国铁路总公司科技研究开发计划项目(2013G011-C)

摘　　要：结合目前研制的中心轴式预切槽机械开展现场试验的需要,数值模拟研究顺序3段、5段、7段和跳跃7段切槽方式对于地层沉降、预筑拱变形及受力的影响,并在宝兰客专洪亮营黄土隧道现场进行了1环切槽及灌注混凝土试验,以测试预切槽机械的性能。结果表明:随着切槽分段数目的增加,地层沉降和预筑拱的收敛变形均逐渐减小,顺序7段切槽方式在控制地层和结构变形方面最为有利;预筑拱拱脚在4种切槽方式下均会承受较大拉应力,且超过了混凝土抗拉极限强度,其他部位拉应力均在安全范围内,因此应在拱脚处增加锁脚,并及时对预筑拱进行加固,以提高预筑拱的抗拉能力,防止其结构发生破坏;分段切槽灌注模式在黏质黄土中成槽的稳定性较好,而在砂质黄土中成槽的质量和灌注成型的预筑拱质量较差。Combined with the need of carrying out field test with the currently developed central-axis pre-cutting machine,the ground settlement,deformation and stress state of the pre-arching with different sequential and jumping slot cutting patterns were studied by numerical method,four slot cutting patterns were compared which were sequential slot cutting with three,five,seven segments and jumping slot cutting with seven segments.To test the mechanical properties of the newly developed pre-cutting machine,a ring cutting and pouring concrete test was carried out on the site of Hongliangying loess tunnel on Baoji-Lanzhou passenger dedicated line.Results show that with the increase of slot-cutting segments,the ground settlement and the convergence deformation of the pre-arching diminish gradually.The sequential slot-cutting pattern with seven segments is the most favorable in controlling ground settlement and structure deformation.It is worth noting that in all the four slot cutting patterns,the arch foots of the pre-arching are in unfavorable stress state where excessive tensile stress appears and exceeds the ultimate tensile strength of concrete,and the stress of other parts of the pre-arching are all in safe range.Therefore,locked springing should be added at arch foot.In addition,the pre-arching should be strengthened in time to improve its tensile strength and prevent the failure of tunnel structure.Field test also shows that it is applicable to cut slot by segments in viscous loess with good slot stability,but it is not applicable in sandy loess,the qualities of slot and the cast-in-place pre-arching are poor in unstable ground.

关 键 词：黄土隧道 预切槽法 切槽方式 地层沉降 预筑拱变形 预筑拱受力 

分 类 号：U456.3[建筑科学—桥梁与隧道工程]