考虑土拱效应的小桩距抗滑桩侧向力计算

Calculation of lateral force of small pile anti-slide pile considering soil arching effect

在总结分析国内外抗滑桩极限侧向力确定公式及其适用范围的基础上,将散粒体极限应力状态平衡微分方程引入抗滑桩桩间距对桩后土拱效应影响规律分析中,发现小桩距下桩端土较桩间土先达到极限平衡状态,推力过大时桩端土产生塑性变形而非桩间土绕流,桩土荷载分担比极大.研究结果可以解释试验中发现的现象,即小桩距下可产生明显的土拱效应,在较大滑坡推力下拱脚优先于拱顶发生破坏.借鉴目前对桩后土拱效应的研究成果与极限侧向力研究思路,结合日本建设省土木研究所的“土研公式”,提出适用于小桩距下抗滑桩侧向力确定的新方法,可为抗滑桩设计计算提供参考.

On the basis of summarizing and analyzing the formulas for determining the ultimate lateral force of anti-slide piles at home and abroad and their applicable ranges,this paper analyzes the formulas for determining the ultimate lateral force of anti-slide piles,the equilibrium differential equation of the ultimate stress state of the granular body is introduced into the analysis of the influence law of the spacing of the anti-sliding pile on the soil arch effect after the pile.It is found that under the small pile spacing,the soil at the pile end first reaches the ultimate equilibrium state compared with the soil between piles.When the thrust is too large,the soil at the pile end will produce plastic deformation instead of soil around the pile.The results of the study can explain the phenomenon found in the test,that is,the soil arch effect can be obvious under the small pile spacing,and the arch foot takes precedence over the arch roof failure under the large landslide thrust.Referring to the current research results of soil arch effect after pile and the research ideas of limit lateral force,combined with the"soil-research formula"of the civil engineering research institute of the ministry of construction of Japan,a new method for determining the lateral force of anti-sliding piles with small pile spacing is proposed.It can provide reference for design and calculation of anti-slide pile.