吹填场区双层软黏土地基承载特性及破坏模式

针对天津滨海地区围海造陆工程所形成的上软、下硬双层软黏土地基，利用室内载荷试验和数值模拟开展了双层软黏土地基的承载特性及破坏模式研究。研究表明：由于下层沉积土的补强效应，双层软黏土地基的P-S曲线会出现明显的凹凸转折点，其出现的位置与宽厚比密切相关，宽厚比越小，转折点出现的时间越靠后，下层沉积土的补强效果越不明显。数值结果表明：双层软黏土地基破坏模式随着上覆土厚度的变化相差不大，均为整体剪切破坏。随着载荷板宽度的增加，双层软黏土地基以冲剪破坏模式过渡为局部剪切破坏，当载荷板宽度大于3.0 m时，表现为整体剪切破坏。

Bearing property and failure mode of double-layer soft clay grounds in a dredger fill site

This research focuses on the double-layer soft clay foundation with an upper soft layer and lower hard layer in Tianjin coastal area. The bearing property and failure mode of the double-layer soft clay grounds are studied by laboratory load test and numerical simulation. The results show that the P-S curves of double-layer soft clay foundation have an obvious concave-convex turning point due to the reinforcement effect of the underlying sedimentary soil, which is different from the reclaimed homogeneous ground. What’s more, the position of the turning point is closely related to the width-thickness ratio. The smaller the width-thickness is, the later the turning point appears, and the less significant reinforcing effect of underlying sedimentary soil is. Numerical results demonstrate that the failure modes of the double-layer soft clay grounds are trivially affected by the thickness of upper soft soil layer, all of them are general shear failure. The failure mode of the double-layer soft clay grounds varies from punch-shear failure mode to local shear failure mode with increasing the width of the load plate. When the width of the load plate is more than 3.0 m, the general shear failure mode occurs.