基坑喷锚与木桩组合支护中木桩的作用机理数值分析

Numerical analysis on mechanism of timber piles in composite support of shotcrete bolts and timber piles for foundation pits

通过Plaxis有限元程序对某软土基坑开挖支护工程进行模拟,对比分析了基坑支护中设置木桩和未设置木桩时的情况。模拟计算结果表明,木桩对软土层的水平位移起到明显的控制作用,对竖向位移也起到一定的控制作用。从塑性区看,未设置木桩时存在一定贯通趋势,设置木桩时由于木桩作用,塑性区未能向坡顶延伸。设置木桩与未设置木桩相比,前者安全系数明显大于后者。木桩支护效果好,造价低,工期短,施工方便,其与喷锚结合在软土基坑支护工程中具有可行性和优越性。

On the basis of Plaxis finite element program,the support of a foundation pit in soft soils is simulated to analyze the conditions when there are timber piles or no timber piles in the foundation pit.The results show that the timber piles play an obvious role in controlling the horizontal displacement of soft soil layer and have certain effect of controlling the vertical displacement.From the plastic zone,there is certain trend of continuity without timber piles.When there are timber piles,the plastic zone can not extend to the slope crest.Comparison between two conditions with and without timber piles indicates that the safety factor of the former is larger than that of the latter.The timber piles are characterized by good support effect,low cost,short construction period,convenient construction and so on.They have great feasibility and superiority when combining with the shotcrete bolts in supports of foundation pits in soft soils.