海域岛礁桥梁地基岩体质量分级体系研究

RESEARCH ON ROCK MASS QUALITY CLASSIFICATION SYSTEM OF SEA REEFS AS BRIDGE FOUNDATION

跨海大桥由于受地形限制,桥基只能布设在单薄的海域岛礁上,而岛礁岩体质量及其边坡稳定将控制桥基型式及埋深。结合在建舟山大陆连岛工程西堠门大桥桥基所在的老虎山岛礁,针对其大跨度、高塔柱桥梁地基赋存的地质环境条件,综合考虑不同部位(即水上、水下及潮间带三个不同位置),提出以岩石力学性质、岩体结构类型、结构面发育特征(尤其是软弱结构面控制)、风化状况、地下水(受海水频繁潮涨潮落影响)等分级控制因素,并分别相应采用岩石单轴饱和抗压强度Rs、岩石质量指标RQD、岩体完整性系数Kv、风化程度系数KY及地下水影响修正系数U对上述分级控制因素进行量化,建立了反映海域岛礁岩体总体质量综合指数Z=Rs×RQD×Kv×KY+U,并相应得出不同级别岩体质量分级体系。

Due to the restriction of landform,bridge foundation can only be placed on thin and weak sea reefs,the type and embedded depth of the bridge foundation are controlled by the quality of the sea reefs.Associated with the Laohu Mountain of the practice of Xihoumen bridge in Zhoushan mainland link project,in allusion to its geological conditions of large span and high tower bridge foundation,based on an overall consideration of different parts（that is above,below the water and the intertidal zone）,propose using rock mechanical property,rock mass structure type,characteristics of discontinuities（especially controlled by weak discontinuities）,weathering conditions and groundwater conditions（affected by tidal action）as controlling factors,and use uniaxial saturated compressive strength Rs,rock quality designation index RQD,rock mass integrality coefficient Kv,weathering degree coefficient KY and groundwater correction coefficient U to quantify the classification factors mentioned above,and build up a composite index Z=Rs×RQD×Kv×KY＋U to reflect the quality of sea reefs,and establish the classification system of different grades of rock mass.