一、工程及地质概况涤纶工程1号桥为单跨拱桥,每拱脚布置32根钻孔灌注桩,桩径1.2m,桩长根据地层不同必须伸入闪长岩中风化层1.5m以上。该桥拱脚地基土层分布为:上部是洪积的粘土夹有少量的姜固石及孤石,厚1.5～5.0m;其下为河流沉积的卵石层,卵石层上部有0.5～1.0m的钙质胶结砾岩,下部为较松散的卵石层,卵石含量在 I. Engineering and Geological Survey Polyester Project No. 1 Bridge is a single-span arch bridge, with 32 perforated cast-in-place piles arranged at each arch leg, with a pile diameter of 1.2m. The pile length must reach 1.5m above the weathered layer in the diorite rock depending on the formation. The distribution of the arch foundations of the bridge is as follows: The upper part is filled with clay with a small amount of Jiang Gushi and boulders, with a thickness of 1.5-5.0m; below it is a pebble layer deposited by rivers, and the upper part of the pebble layer is 0.5-1.0m. The calcareous cementitious conglomerate, the lower part is a looser pebble layer, the pebble content is