高边坡对邻近基坑稳定性的影响研究

深圳地铁5号线上水径车站倚靠城市山地,山地边坡形成的偏压作用对基坑的稳定性存在着不可忽视的影响。为认识这种影响,并考察基坑与边坡之间合理的设计间距,运用FLAC3D软件,对基坑与边坡不同距离下基坑的桩变形、桩弯矩、边坡沉降以及地表沉降等进行了计算分析。研究结果表明：1）高边坡下基坑施工过程中,近坡桩的最大位移与基坑距边坡距离呈指数衰减关系;远坡桩最大位移与距离呈指数递增关系;当距离为24 m以上时,两侧桩的最大位移将趋于稳定。2）当距边坡距离大于2 m时,远坡侧地表最大沉降值y与基坑距边坡距离d大致成指数递增关系,当距离为24 m以上时,地表沉降最大值将保持不变。3）边坡最大沉降值y与d呈指数衰减关系,当距离达到16 m以上时,基坑开挖对边坡的影响可忽略不计。4）基坑整体稳定性系数y与距边坡距离d大致成指数增长关系,当基坑距边坡距离为0 m,基坑的整体稳定安全系数最小,为1.80。

Numerical Analysis on Stability of Foundation Pit at Foot of High Slope

Shangshuijing Station on Line 5 of Shenzhen Metro is located close to a high slope,therefore,the influence of the distance between the high slope and the foundation pit on the foundation pit stability can not be neglected.In order to understand such influence and to determine the rational distance between the foundation pit and the high slope,FLAC3D software is used to analyze the displacement of the piles,the bending moment of the piles,the settlement of the slope and the ground surface settlement under the condition of different distances from the foundation pit to the high slope.The results show that： 1） In the construction of the foundation pit at the foot of the high slope,the maximum displacement of the piles close to the slope and the distance between the foundation pit and the slope have an exponentially-decreasing correlation;the maximum displacement of the piles far from the slope and the distance between the foundation pit and the slope have an exponentially-increasing correlation;when the distance between the slope and the foundation pit is more than 24 m,the maximum displacement of the piles becomes stable;2） When the distance between the slope and the foundation pit is more than 2 m,the maximum ground surface settlement on the side far from the slope ＂y＂ and the distance between the foundation pit and the slope ＂d ＂ have an exponentially-increasing correlation;when the distance is more than 24 m,the maximum ground surface settlement becomes stable;3） The maximum settlement of the slope ＂y＂ and the distance between the foundation pit and the slope ＂d＂ have an exponentially-decreasing correlation;when the distance between the slope and the foundation pit is more than 16 m,the influence of the foundation pit excavation on the slope can be neglected;4） The overall stability coefficient of the foundation pit ＂y＂ and the distance between the foundation pit and the slope have an exponentially-increasing correlation;when the distance between the slope and the foundation pit is 0 m,the overall stability coefficient of the foundation pit is the least,being 1.80.