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通过离心机模型试验，研究了砂质土为相对软粘土的两种层状土的承载力和变形特性。通过量纲分析，得出了可能直接影响这些现象的无量纲参数。离心机试验分为两个系列。一种是采用条形和圆形基础在恒定加载速率下进行的承载力试验，另一种是通过圆形基础承受小于其承载能力的恒定荷载的固结试验。结果表明：(1)归一化承载力2QF/GammaB是H/B的函数，而Po/GammaB是有效容重，与下伏粘土的不排水抗剪强度、Cu/GammaB归一化承载力和Po/Gb归一化覆盖层压力有关。在恒定的H/B下，2qf/GammaB与Cu/GammaB和Po/GammaB呈线性关系。(2)两层土的承载能力随H/B的增大而增大，直至达到均匀无限大砂层的承载能力。(3)两层土的破坏机理可分为两类，一类是砂层的一般破坏，(H/B)**；另一类是冲压破坏，当H/B小于(H/B)**时，在基础下形成一块沙子。(4)两层土在恒定荷载作用下的固结强度随强度的增加而增加。在H/B为1.0~2.0的地基中，荷载强度与承载能力的比值与固结沉降量之间存在着一元一次的关系。

Centrifuge model tests were carried out to investigate bearing capacities and deformations of two layred soil in whicha sand oelies a relatively soft clay. Non-dimensional parameters which might directy influence on these phenomena were derived from dimensional analysis. Centrifuge tests were divided into two series. One is bearing capacity tests which were conducted under constant loading rate by using strip and circular footing, and the other is consolidation tests in which model grounds were subjected to a constant load less than its bearing capacity through a circular footing. All test were conducted under 100g and constant thickness of clay laer varying with ratios of the thickness of sand to the footing width, H/B.Following conclusions are derived from this study.(1) Normalized bearing capacity, 2qf/ gammaB, is found to be a function of H/B, and pO/ gammaB, where gamma is effective unit weight, cu the undrained shear strength f underlying clay, cu/ gamma B normalized bearing capacity of clay and pO/gB normalized overburden resssure. The 2qf/ gammaB increases linearly with cu/ gammaB and pO/ gammaB under constant H/B.(2) The bearing capacity of the two layred soil increases with H/B until it becomes the bearing capacity of the uniform infinite sand layr. The value of H/B over which the bearing capacity is constant in that of the infinite sand, (H/B)**, is about 1.5 to 2 for circular footing and 4 for strip footing.(3) Failure mechanisms of the two layred soil can be classified into two categories ; one is general faiure in sand layr which occurred for (H/B)** and the other is punching failure forming a block of sand beneath the footing for H/B smaller than (H/B)**.(4) Consolidation of the two layred soil under constant load increases with its intensity. A single uique relationship was found between the ratios of applied load intensities to beaing capacities and consolidation settlements in the grounds with H/B of 1.0 to 2.0.