砂卵石层上大直径扩底短墩竖向承载性状

根据同一场地砂卵石层中一组土的深层静载荷试验、一组纯摩擦桩和两组原型扩底墩的竖向承载力静载试验，分析了埋深在6.20～6.75 m处的扩底短墩的荷载传递性状。结果表明，可用直接试验法和间接试验法确定扩底墩的竖向承载力。以卵石层为持力层的S3试验墩的极限承载力为7 250 kN，其中端阻力达6 890 kN，占95 %；以砂层为持力层的S2墩的极限承载力为2 330 kN，端阻力占85 %。当墩顶仅沉降1.46 mm左右时，S3、S2墩侧摩阻力已充分发挥；在端阻力充分发挥时，S3、S2墩顶沉降则分别达92.64 mm和21.07 mm。直径相同时，扩底桩的竖向承载力远大于纯摩擦桩和直身墩。

Vertical bearing behavior of large diameter short-belled pier in sand-cobble layer

This paper presented the test results of two large diameter short-belled piers, a deep loading test and a friction pile in sand-cobble layer at the same test site, and accordingly gives a study on the belled piers (embedded depth of 6.20 m-6.75 m) load transfer behavior. The analysis shows that the pier ultimate bearing capacity can be confirmed by direct test method and indirect test method. S3 pier (bearing layer is cobble layer) ultimate bearing capacity is 7 250 kN, end resistance is 6 890 kN, taking up 95 % of the ultimate bearing capacity, and S2 pier (bearing layer is sand layer) ultimate bearing capacity is merely 2 330 kN, end resistance taking up 85 %. When the settlement of loading pier is about 1.46 mm, the skin frictions of pier S3 and S2 have achieved ultimate state; but when the end resistance in ultimate state, the settlement of pier S3 and S2 are 92.64 mm and 21.07 mm; respectively. The vertical bearing capacity of belled pile is greater than the pure friction pile and shaft as their diameters are equal.