Abstract:

Puli bridge is a large suspension bridge with a main span of 628 m and tunnel-type anchorage on one side. Rock mass unloading and karst problem are the key issues of engineering geology in the tunnel anchorage area. An exploration hole of 120 m long was excavated through the center of the anchorage, and in-situ rock mechanical test, sonic test and geological description were conducted in the exploration hole. The physical and mechanical parameters of rock masses and the classification of basic quality of rock masses were obtained. On this basis, the regularities of rock mass unloading and karst development varying with elevation and embedded depth were analyzed. Comprehensive investigation technologies and analysis methods involving ground surface geological survey, geological mapping, drilling, tunnel excavation, pitting, trenching, elastic wave testing, and in-situ testing are explored in view of the possible engineering geological problems of tunnel anchorage in karst region. These technologies provide fundamental data for the design of tunnel anchorage and the stability analysis, and are worth to be popularized in similar works.

Key words: Puli bridge, tunnel anchorage, rock mass unloading, karst, rock mass mechanics test