为量化分析预制桩帷幕一体化支护齿墙减载作用特性,基于预制桩帷幕一体化支护齿墙减载机理,假定滑裂面为旋轮线型,采用水平薄层微分理论,提出墙后土体滑动条件下齿墙减载作用计算方法,在算例验证的基础上,进一步分析齿墙结构参数、土体强度参数、墙土界面强度参数的变化对土压力减载作用的影响。结果表明:提出的计算方法能有效解决预制桩帷幕一体化支护齿墙减载作用量化分析问题。齿墙在减小墙后滑动土体土压力方面效果显著,其减载比例可达50%;增大齿墙宽度可显著提升减载作用,减小齿墙间距亦有助于减载作用的发挥,而增加齿墙厚度的改善效果有限;土体强度较高时,增设齿墙对支护性能的提升更有利;墙土间作用强度增加也有助于增大齿墙的减载比例,但墙土间黏聚力的增大影响更为显著。研究成果可为该类新型复合支护技术的设计提供理论参考。

[Objective] The integrated support structure of precast piles with dentiform curtains can effectively reduce the earth pressure acting on the support structure and enhance its overall performance. This study aims to quantitatively analyze the load-reduction characteristics of the dentiform walls in this structure, reveal the key mechanisms of load reduction, and provide a theoretical reference for the design and calculation of this novel composite support technology. [Methods] Based on the load-reduction mechanisms of the dentiform walls in an integrated support system of precast piles with curtains, a cycloidal slip surface conforming to the actual sliding failure mode of the soil behind the walls was introduced. A calculation method for the load-reduction effect of the dentiform walls under soil sliding conditions was developed using the horizontal thin-layer differential theory. Based on the validation through calculation examples, the impact of key parameters—including dentiform wall structural parameters (spacing, width, thickness), soil strength parameters (cohesion, internal friction angle), and soil-wall interface strength parameters (soil-wall cohesion, soil-wall external friction angle)—on the load-reduction effect of earth pressure was further analyzed. [Results] When the dentiform wall spacing decreased from 3 m to 1.2 m, the load-reduction ratio increased from 23.77% to 44.02%. When the dentiform wall width increased from 0.5 m to 3 m, the load-reduction ratio increased from 17.16% to 46.34%. When the dentiform wall thickness increased from 0.4 m to 1.0 m, the load-reduction ratio only increased from 32.66% to 36.66%. When soil cohesion (c) increased from 1 kPa to 16 kPa, the load-reduction ratio increased from 28.14% to 59.86%. When the soil internal friction angle increased from 16° to 31°, the load-reduction ratio increased from 20.43% to 42.68%. When the soil-wall interface cohesion (c₁) increased from 0.6 kPa to 9.6 kPa, the load-reduction ratio increased from 27.41% to 50.41%. When the soil-wall interface external friction angle increased from 9.6° to 18.6°, the load-reduction ratio increased from 30.33% to 36.21%, with the rate of increase gradually slowing down. [Conclusion] The developed calculation method effectively solves the problem that earth pressure is difficult to quantitatively analyze when the integrated support system of precast piles with curtains has dentiform walls. The dentiform walls exhibit a significant load-reduction effect, with the load-reduction ratio of earth pressure from the sliding soil behind the walls reaching over 50%. Decreasing the dentiform wall spacing and increasing its width can both significantly enhance the load-reduction effect. Since the walls have a certain width, the contact area between the back of the dentiform walls and the sliding soil mass is limited, and increasing the wall thickness does not lead to a notable improvement in the load-reduction effect. Increases in both the cohesion and internal friction angle of the soil behind the walls can significantly raise the load-reduction ratio of the dentiform walls. Therefore, on sites with better soil conditions, adding dentiform walls is more beneficial for improving the performance of integrated support of precast piles with curtains. The increase in the strength of the soil-wall interface also contributes to a higher load-reduction ratio of the dentiform walls, but the increase in soil-wall cohesion has a relatively more significant impact.