湿陷性黄土高贴坡变形模式和稳定性分析

DEFORMATION MODE AND STABILITY ANALYSIS OF HIGH STICKING SLOPE OF COLLAPSIBLE LOESS

采用原状黄土与重塑黄土联合制作模型,针对湿陷性黄土高贴坡在天然含水量及饱和状态时的稳定性和变形模式开展离心试验研究。结果表明:湿陷性黄土高贴坡在天然含水量状态下稳定性较好,贴坡体固结变形是高贴坡变形的主导因素,高贴坡工后变形量及变形速率前期较大,后期较小,且贴坡体厚度越大,工后沉降也越大,变形稳定所需的时间也越长,贴坡体厚度与工后沉降量呈现线性关系;当土体饱和时,贴坡体固结及黄土湿陷共同导致高贴坡沉降变形,若沉降变形过大,坡体可能沿水分浸入时形成的软弱带开裂破坏;湿陷性黄土层的强度决定湿陷性黄土高贴坡的稳定性,坡体破坏时滑裂面将通过湿陷性土层,其位置取决于湿陷性黄土层与其相邻土层的强度差异。当强度差异较大以致湿陷性黄土层与相邻土层的接触面形成软弱夹层时,则接触面必为滑裂面的一部分,且强度相对较小的接触面首先破坏,滑裂面上部土层表现出比较典型的平移滑动模式;反之,滑裂面近似圆弧,且与接触面之间存在一定厚度的过渡层。

Intact loess and remolded loess are combined for modeling.The centrifugal test is carried out to study the stability and deformation mode of the high sticking slope of collapsible loess in the states of natural moisture content and saturation.According to the results,in the state of natural moisture content,the stability of high sticking slope of collapsible loess is good;and consolidation deformation of sticking slope is the leading factor for high sticking slope deformation.The amount and rate of deformation after construction are large at early stage yet small at later stage;and the thicker the sticking slope thickness,the larger the settlement after construction and the longer the demand time of deformation completion.The thickness of sticking slope has a linear relation with settlement after construction.In the state of saturation,sticking slope consolidation and loess collapse cause the settlement of high sticking slope.If the settlement deformation is too large,the slope may crack along the weak zone formed by water penetration.The intensity of collapsible loess decides the stability of high sticking slope.The slide surface from soil damage passes through collapsible soil;and its location depends on the intensity difference between collapsible soil and its adjacent soil.When the interface between collapsible soil and its adjacent soil forms a weak layer caused by large intensity difference;the interface is definitely a part of slide surface;and the interface with lower intensity is firstly damaged.Moreover,the soil at the top of slide surface is in a typical translation sliding mode.On the contrary,the slide surface is approximately in circular arc;and there is a filter layer with a certain thickness between slide surface and interface.