云南龙江特大悬索桥锚碇稳定性分析

重力式是悬索桥安全的关键结构之一,其支墩的偏移量对悬索桥的稳定性至关重要。拟建的云南龙江特大悬索桥保山岸地层复杂,岩性软弱,地基土力学参数较低。在工程设计中,需预测在施工运行过程中的锚碇支墩偏移量,以合理确定地基是否需要加固处理以及设定加固参数。为此,本文利用FLAC3D按照锚碇基坑开挖、锚碇主体施工、回填及二期构件完成、主缆索连接的施工步骤,依次建立较为精细的数值模型来模拟实际工况。数值分析结果表明:云南龙江特大斜拉桥锚碇保山岸锚碇支墩在回填压重和最大缆力工况下的水平偏移量小于5cm,在允许范围15cm内,锚碇基坑底部沉降量顺桥轴线方向自锚后到锚前逐渐减少,但梯度不大,锚碇略微后倾0.05,不会发生倾倒翻转,也不需对地基加固。数值计算中发现,岩土参数的取值对计算结果影响有较大影响,为此,作者对变形模量、泊松比、黏聚力、内摩擦角、密度等5个参数进行了敏感性分析。结果表明,在研究区的岩土参数取值范围内,变形模量E敏感度较大,在工程勘察中通过足够的试验合理地确定其值十分重要。

STABILITY ANALYSIS OF ANCHORAGE FOR SUPER SUSPENSION BRIDGE OVER LONGJIANG RIVER IN YUNNAN PROVINCE

As a style of anchoring the cable of suspension bridge,the gravity anchor is one of the most important elements for the safe of the bridge.The displacement of the anchorage buttress is the key factor for the stability.This paper examines the stability of the anchorage for a Super Cable-stayed Bridge planned to be built over Longjiang river in Yunnan Province.It is located in the place with complex stratum condition.The soil strength and modulus parameters are very small at the construction site.Therefore,predicting the displacement of anchorage buttresses under various conditions is very important to design the proposal of foundation treatment and determine treatment parameters reasonably.This paper presents the large-scale numerical models with FLAC3D-fast lagranian analysis of continua in three-dimensions.The models are developed in strict accordance with the construction steps.They include foundation pit excavation,main body of anchorage construction,backfill and weights construction,and cable connection.The results indicate that the displacement of the anchorage buttress in the last two steps is about 5cm,lower than the allowable value 15cm.The settlement of foundation pit is in the allowable limits,too.The soil needn't to be strengthened.Because the displacement is largely dependent on the soil parameters,we also conduct the parameters sensitivity analysis.Results indicate that the deformation modulus E is ought to be assured through enough tests for its big sensitivity value.