STUDY ON GEOENVIRONMENT AND GEOTECHNICAL PROBLEMS OF BADONG YANGTZE BRIDGE
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摘要: 巴东长江大桥是连接209国道的特大型公路大桥, 地处长江三峡地质条件最复杂的地区, 桥位区滑坡崩塌较发育. 为确保大桥安全稳定并为设计提供科学依据, 采用结构面网络模拟技术进行了岩体结构模拟, 应用弹塑性有限元法及块体极限平衡法, 对桥位存在的桥台斜坡和桥墩基础地基稳定性等岩土工程问题进行了系统的分析论述. 同时, 对断裂破碎岩体及风化岩体、滑坡对大桥的影响进行了分析. 在此基础上提出了桥墩基础形式、桩基深度、持力层及承载力和桥台斜坡治理的建议.Abstract: The Badong Yangtze Bridge is a large-sized road bridge across the Yangtze River, linking the No.209 national highway. It lies in middle part of the Three Gorges where geotechnical condition is the most complex. In the bridge area, the landform is cliffy; the valley incised sharply; and the geo-structure is complicated with the rock mass heavily cracked. While landslides and debris-flows are particularly common. By rock structure simulation, the rock discontinuity net and the RQD distributing figure were obtained. Moreover, the slope and groundsill stability about the bridge were analyzed systemically by the elastic-plastic finite element method and plot utmost balance way. At the same time, the influences of the aired and the fractured rockmass on the bridge were discussed. Based on the above, proposals have been made about the pier foundation style, the picket ground's depth and carrying strength. At last, more suggestions for the slope remedy have been put forward.
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Key words:
- bridge site /
- geoenvironment /
- geotechnical question /
- slope /
- pier foundation /
- stability
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图 1 岩体结构面等密度、网络图及RQD分布
a, b.T2b2, T2b3的等密度图; c, d.T2b2, T2b3的网络图; e, f.T2b2, T2b3的RQD (岩体质量指标) 分布图, 其中分类间距T=0.7, 0.5, 0.3, 0.1 m
图 4 斜坡应力、位移场及稳定性系数等值线(水位175 m骤降至145 m叠加地震及桥荷载)
Fig. 4. Slope stress, displacement and stability isolines
表 1 桥位区岩体力学计算参数建议值
Table 1. Rock mechanics parameters proposed
表 2 桥位区岩体承载力
Table 2. Rockmass capacity in bridge site
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[1] 刘佑荣, 唐辉明. 岩体力学[M]. 武汉: 中国地质大学出版社, 1999. [2] 李智毅, 唐辉明. 岩土工程勘察[M]. 武汉: 中国地质大学出版社, 2000. [3] GB50021-1994, 岩土工程勘察规范[S]. [4] JTJ024-1985, 公路桥涵地基与基础设计规范[S]. [5] GBT7-1989, 建筑地基基础设计规范[S]. -
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