摘要
通过室内砂槽模型试验模拟不同砂土土层厚度组合和不同水力条件,对上细下粗复合砂土地层渗透破坏的发生发展过程进行研究。结果表明:砂土发生渗透变形的过程中,存在一个渗透系数不变的阶段,此时砂土中还未形成渗流通道,处于稳定渗流阶段;同一水力条件下,下层粗砂渗透系数大,主要起供水作用,上层细砂渗透系数小,承担大部分的渗透压力,在粗砂层厚度越大、细砂层厚度越小的情况下,砂土颗粒流失越快,因此渗透破坏过程也越快;高水力条件下,渗流流量和流速迅速变大,破坏速度加快,此时砂土内部未形成渗流通道,土层的整体性未减弱,土体的临界水力梯度存在一个短暂的上升阶段,砂土发生渗透破坏后,砂土的颗粒流失加重,土层结构出现严重的水力筛分现象。
Indoor sandbox model test was used to simulate different thickness of sandy soil layers and hydraulic conditions,and then to study the occurrence and development of seepage failure in fine above and coarse below composite sandy soil stratum.The result shows that,during the seepage deformation of sandy soil,there has a phase with the coefficient of permeability not changed and,for the sandy soil in this period,there does not forms seepage channel and stays in the state of stable seepage;under the same hydraulic condition,the coarse sand below of large coefficient of permeability plays a role of water supply mainly,and the fine sand above of small coefficient of permeability withstands most of seepage pressure,therefore,the larger thickness of coarse sand layer and the smaller thickness of fine sand layer,the faster loss of sandy particles,as a result,the seepage failure will accelerate;under high hydraulic conditions,the seepage flow and velocity accelerate rapidly and then to accelerate the failure,at this time,no seepage channel forms inside the sandy soil and the integrity of soil stratum does not diminished,thus there is a brief upward phase in the critical hydraulic gradient of the soil body and,when seepage failure occurs,the sandy particle loss increases and serious hydraulic screening comes out in the stratum structure.
作者
向威
刘小军
XIANG Wei;LIU Xiaojun(School of Civil Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China)
出处
《路基工程》
2025年第4期87-92,共6页
Subgrade Engineering
关键词
复合砂层
渗透破坏
模型试验
水力筛分
水力条件
composite sandy stratum
seepage failure
model test
hydraulic screening
hydraulic condition
