摘要
采用离心试验手段研究浅埋大跨度土质隧道中软塑和硬可塑2种粉质黏土的特性,从土体的无侧限抗压强度、回弹量以及成拱能力等方面探讨土体的主要变形特征,分析其对隧道施工稳定性的影响,进而提出开挖和支护时应注意的问题。通过不同埋深、跨度的毛洞开挖试验对比,发现该黏土隧道中土体成拱与岩石存在着明显的不同,硬塑土具有成拱能力而软塑土不具有。土体的变形特性表明,浅埋黏性土中土压力不存在松动压力而是以变形压力为主,据此可确定作用在隧道支护上的荷载。试验还研究了不同软塑夹层位置对隧道开挖变形以及施工稳定性的影响,发现软弱夹层对隧道开挖稳定性有着较大的影响,尤其是位于洞顶时。测量不同埋深下随深度变化土体的水平和竖向变形特性,据此初步分析剪切带在该种土体中的存在与否以及剪切带内土体的变形性状。
The characteristics of two kinds of silty clays in shallow-buried large-span soil-layered tunnel, which are soft-plastic and hard-plastic soils, are studied using centrifugal model test; and the main deformation characteristics are discussed through the unconfined compression strength, rebound and arching capabilities. The effect on construction stability is also analyzed. By contrast of unsupported tunnel excavation with different soil covers, the great difference between soil and rock tunnels in arching is found, and the hard-plastic soil has arching ability while the soft-soil does not have. It is shown from the deformation characteristics that there isn＇t relaxed earth pressure in shallow clay but deformation pressure, then the load on the tunnel can be determined according to the deformation. Besides, the influence of soft-plastic interlayer with different locations to excavation deformation and construction stability is studied. It is found that the soft-plastic interlayer has a large effect on the excavation stability, especially for the interlayer at the crown. The layered horizontal and vertical deformations of soil with different covers are measured. Thus, whether the shear band exits or not, the deformation characteristics inside the shear band are analyzed.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第A02期3360-3366,共7页
Chinese Journal of Rock Mechanics and Engineering
关键词
土力学
土质隧道
粉质黏土
离心试验
成拱
剪切带
soil mechanics
soil tunnel
silty clay
centrifugal test
arching
shear band
