Abstract:

Shengyingxian tunnel, being 1230m long, is located in the busy Shengjiamen urban area in Zhoushan. The geological conditions of the north entrance section and south entrance section of the tunnel are very poor, where most of the ground is fullyweathered～heavilyweathered cohesive soil containing gravels. The surrounding ground of the tunnel has poor selfsupport ability. On basis of theoretical calculations and the requirements of the construction progress and construction convenience, excavation technology suitable for the portal sections of the tunnel is determined. Furthermore, the article also presents the actual construction scheme and construction results of the shallowburied portal sections.

Key words: large spansmall spacing, twin tunnel, excavation technology, selection