中文摘要：

利用原位模型试验研究湛江组结构性黏土中桩基在竖向荷载作用下的承载性状。选取材质和桩径相同、入土深度不同的6组模型桩,采用慢速维持荷载法,在湛江组结构性黏土中进行单桩原位竖向承载模型试验,得到了单桩荷载-沉降曲线、单桩轴力沿桩身分布曲线、单桩侧摩阻力沿入土深度分布曲线。结果表明：在竖向荷载作用下,湛江组结构性黏土中模型单桩荷载-沉降曲线均存在显著陡降,极限状态拐点明显,竖向极限承载力随着长径比的增加而增大;在相同荷载作用下,随着长径比的增加,桩顶沉降逐渐减小且减小趋势逐渐变缓,在较大荷载作用下超长桩荷载-沉降曲线中桩顶沉降的减小速率几乎为零,存在有效桩长;在同级桩顶荷载作用下,单桩桩端阻力占总桩顶荷载的比例随着长径比的增加而逐渐变小,由最大29.8%减小为0.8%;不同入土深度的单桩在极限荷载作用下的桩侧极限摩阻力变化不大,均稳定在40 k Pa左右。

英文摘要：

The bearing capacity of a pile foundation in Zhanjiang group structural clay under vertical loads was studied based on in situ model tests. In single pile in situ model tests, six groups of pile models with the same material and diameter but different depths in soil were selected, and the slow maintained load method was used. The load-settlement curve, axial force distribution along the pile shaft, and side friction varying with the depth in soil of single piles were obtained. Under vertical loads, the load-settlement curves of all six groups of single pile models in the Zhanjiang group structural clay show sharply declining trends, with yielding points occurring at the ultimate limit state, and the vertical ultimate bearing capacity increases with the length-diameter ratio of the single piles;under constant loads, with the increase of the length-diameter ratio, the settlement at the pile top gradually decreases at a slowly decreasing rate; under large loads, the decreasing rate of resettlement at the top of super-long piles, according to the load-settlement curve, is almost zero, and there exists an effective pile length;and under a constant level of loads at the pile top, the proportion of the pile end resistance to the total load at the pile top gradually decreases with the increase of the length-to-diameter ratio, with the maximum value decreasing from 29. 8% to 0. 8%, while the side frictions of single piles with different depths in soil under ultimate loads change little, with a stable value of about 40 kPa.