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堤(坝)基中往往存在局部浅层强透水层,其削减水头能力较弱,易发生管涌等侵蚀破坏,其破坏机理仍需深入探究。文中采用砂槽模拟堤(坝)基中浅层强透水层上覆砂层侵蚀情况,通过改变水位来观测堤(坝)基中砂土细颗粒流失现象,获取渗流量、渗透坡降、土体颗粒级配、锥头阻力等参数。试验表明,水位增至48 cm时浅层强透水层上覆砂层被“击穿”发生管涌破坏,破坏过程分为稳定渗流阶段、细颗粒流失阶段、较细颗粒流失阶段、管涌破坏扩大阶段。此外还发现,随着砂土中细颗粒砂土的流失,堤(坝)基的锥头阻力降低而发生沉降;细颗粒砂土流失导致其孔隙率和渗透系数增大,渗流场和应力场发生较大变化,研究成果能为堤(坝)基中浅层强透水层情况提供理论支撑。
The local shallow aquitard often exists in the embankment (dam) foundation, and its ability to reduce head is weak and prone to erosion and damage such as piping. The failure mechanism still needs to be further explored. In this paper, the sand tank is used to simulate the erosion of the overlying sand layer in the shallow permeable layer of the dike (dam) base. The change of water level is used to observe the loss of fine particles of sand and soil in the foundation of embankment (dam), and the seepage flux, seepage gradient, Body size grading, cone head resistance and other parameters. Experiments show that when the water level is increased to 48 cm, the overlying sand layer in the shallow aquitard permeable layer is damaged by “breakdown ”, and the failure process is divided into stable seepage stage, fine grain runoff stage, fine grain runoff stage and pipe breakage Expand phase. In addition, it is also found that with the loss of fine sand and sand in the sand, the resistance of the foundation of the dyke (dam) decreases and the settlement will occur. The loss of fine sand and sand leads to the increase of porosity and permeability coefficient, and the seepage and stress fields Great changes have taken place, and the research results can provide theoretical support for the situation of shallow permeable layer in embankment (dam) foundation.