锚碇沉井基础下沉稳定性分析

基于可靠度理论,通过对基桩极限状态方程的分析,得到了基桩极限承载力影响因素。将这一理论运用到大型锚碇沉井下沉施工的稳定性之中,得到了衡量沉井下沉稳定性的三个指标,抗滑动稳定系数,抗倾覆稳定安全系数和下沉稳定系数。以鹦鹉洲长江大桥北锚碇沉井施工为例,通过对鹦鹉洲长江大桥北锚碇沉井不同工况,不同接高阶段、不同下沉阶段中下沉稳定系数的分析可知：同一工况、同一下沉周期内,随着接高次数的增加,稳定系数逐渐增大；同一工况下,稳定系数随着下沉次数的增多而逐渐减小；不同工况中,全截面稳定系数最低。在今后类似锚碇沉井的下沉施工中可采用下沉稳定系数对沉井下沉稳定性加以分析控制。

Stability Analysis of Sinking for Anchorage Caisson Foundation

On the basis of reliability theory, the factors affecting the ultimate bearing capacity of pile could be got through the analysis of its ultimate state equation. The three indicators to measure sinking stability for caisson were obtained due to the application of this theory in the sinking construction of large anchorage caisson, which were stability coefficient of anti-slide and anti-dump, sinking stability coefficient. The sinking stability coefficient under different working conditions, stage of caisson jointing and sinking were analyzed in the construction for north anchorage caisson foundation of Yingwuzhou Changjiang River Bridge in Wuhan. The results showed that in the same working condition and sinking cycle, the sinking stability coefficient gained gradually with the increase of caisson jointing, conversely decreases with the increase of sinking times in the same working condition. The sinking stability coefficient was lowest under that working condition of whole cross section. It can be used to control sinking stability for caisson in the sinking construction of similar anchorage caisson in the future.