考虑土拱效应的锚杆加固桩间土机理研究  

Study on Reinforcement Mechanisms for Soil between Cantilever Piles on Consideration of Soil Arching Effect

作　　者：董捷[1] 宋绪国[1] 许再良[1] 

机构地区：[1]铁道第三勘察设计院集团有限公司,天津300142

出　　处：《铁道工程学报》2013年第8期45-51,共7页Journal of Railway Engineering Society

基　　金：国家自然科学基金资助(No.51108313);中国博士后科学基金面上资助(No.20100470776);中国博士后科学基金特别资助(No.2012T50215);铁道第三勘察设计院集团有限公司科技开发项目(No.721245)

摘　　要：研究目的:桩板墙是一种常见的铁路边坡防护工程,桩间板在施工前需要先开挖桩前土。因此为保障桩间土的稳定性,桩间常常逆作法施工锚杆,但由于该支护方法的机理尚不明确,尤其是当悬臂高度较大时桩间土极易发生垮塌,给后期施工带来安全隐患,并增加桩板墙背侧土方回填的费用。因此,论文重点围绕桩间土拱效应与锚杆加固的机理进行研究,以期为类似工程的设计及施工提供帮助。研究结论:(1)通过在桩间施工一定数量的锚杆,可有效降低桩间土发生局部垮塌的风险,使得锚杆能够紧密地连接桩间欠稳定土体、土拱压密土体及后方的稳定土体,土拱拱圈附近的密实土体发挥了锚杆锚固段的作用;(2)数值分析结果表明,受桩间土拱效应分布的几何形态的影响,锚杆布置宜在相邻两根悬臂桩跨中位置适当加密,采取该类布置方式相比均匀布置能够起到更好的加固效果;(3)桩间锚杆的设计钻进深度可以采用上部较短,中下部适当加长的方案进行设计,且锚杆设计钻进深度不应超过1.5倍桩间净距。若中下部桩间土体较密实,可以考虑适当减小锚杆的钻进深度;(4)采用锚杆加固桩间土大多是应用于临时防护,为了进一步提高桩桩间土的稳定性,降低道路运营期间因桩间土局部滑塌或掉块带来的风险,或出于美化道路周边环境等因素考虑。Research purposes： The sheet -pile retaining wall is a common protection engineering for railway slope and it is necessary to dig the soil in front of the pile before building the plate between the piles. In order to ensure the stability of the soil between piles, the anchors are usually built from top to bottom on excavation face. There are many risks in construction of the sheet- pile retaining wall, especially when the cantilever is high, the soil between piles is easy to collapse because the reinforcement mechanism of anchors between piles is very complex. This may brings the hidden trouble to the construction and the increase of the cost for refilling soil to the back side of the sheet - pile wall. This paper mainly researches the soil arching effect between piles and the reinforcement mechanism of anchor arm to provide the help for design and construction of the similar projects. Research conclusions：（ 1 ） The collapse risk of the soil between piles can be effectively reduced by building a certain amount of anchor arms between the piles. The anchor arms can tightly connect the unstable soil between piles. The soil is compacted by soil arching for stabilizing the real soil. The compacted soil around the soil arching cycle plays a role of anchoring section. （2） The results of numerical analysis show that anchor should be arranged in the proper position with more density between the two adjacent cantilever piles because of the geometric influence of the soil arching effect between piles. This arrangement can produce a better reinforcement effect than the uniform arrangement. （3） The drilling depth of the pile anchor can be designed like this： the upper is shorter and the lower is properly longer, however, the drilling depth should not exceed 1.5 times of the spacing between piles. If the lower part of the soil between piles is rather compacted, reduction of the drilling depth of the small anchor arm can be considered.. （4） Most of reinforcing the soil between pile with anchor arm are used

关 键 词：土拱效应 锚杆 悬臂桩 桩间土 机理 

分 类 号：TU457[建筑科学—岩土工程]