支护参数对基坑潜在滑移模式与稳定性的影响研究

Research on the influence of supporting parameters on the potential slip mode and stability of foundation pit

为了确定土钉在基坑防护中合理的支护参数,以济南汉峪B9地块深基坑为例,根据基坑不同区域特点有针对性地制定了支护方案,计算验证了方案的合理性并提出可优化方案,分析了土钉的支护倾角、支护位置、土钉长度等参数变化对表征基坑稳定性的安全系数与潜在滑移面的影响。结果表明:当土钉长度小于有效支护长度时,基坑安全系数随着土钉长度的增加而逐渐增大,近似呈指数函数规律,土钉长度超出潜在滑移面1.28 m时支护效果最优;随着土钉支护位置的降低,基坑安全系数先增高后减小,安全系数在达到峰值安全系数前,安全系数与土钉位置呈一次函数规律,最优的支护位置为距基坑底部1/4坡面高度;随着土钉支护角度的增加,基坑坡面安全系数逐渐降低,呈一次函数关系,考虑施工便利性,土钉支护角度可定为5°~20°。

In order to determine the reasonable support parameters of soil nails in the protection of foundation pits,taking the deep foundation pit of Jinan Hanyu B9 block as an example,a targeted support plan was formulated according to the characteristics of different areas of the foundation pit,and the calculation verified the reasonableness of the plan.It also proposed an optimized scheme,and analyzes the influence of changes in the inclination angle of soil nail support,support position,soil nail length and other parameters on the safety factor that characterizes the stability of the foundation pit and the potential slip surface.The results showed that when the length of soil nails was less than the effective supporting length,the safety factor of the foundation pit gradually increased with the increase of the length of soil nails,which was approximately an exponential function.The supporting effect was when the length of soil nails exceeded the potential slip surface by 1.28 m optimal;as the position of the soil nail support decreased,the safety factor of the foundation pit increased first and then decreased.Before the safety factor reaches the peak safety factor,the safety factor and the position of the soil nails were linear functions.The optimal support position was its 1/4 of the height of the slope from the bottom of the foundation pit;with the increased of the angle of soil nailing,the safety factor of the slope of the foundation pit gradually decreased,showing a linear function relationship.Considering the convenience of construction,the angle of soil nailing could be set as 5°~20°.