Y型沉管灌注桩截面形式复杂,截面几何特性存在4个独立控制变量、8个积分区间.Y型桩桩端均布荷载在地基内部任意点产生附加应力系数的解析表达式求解困难,目前尚无得出简单的解析表达式.借助数学分析软件Mathematica的NIntegrate数值积分功能,以及Geddes推导应力解的思想,得出了Y型桩桩端均布荷载作用在地基内部任意点竖向附加应力系数的数值计算方法,经校核有很高精度.分析了Y型截面4个独立变量外包圆半径R、模板弧度θ、开弧间距s、夹角度数δ对附加应力系数的影响及采用Geddes应力解计算产生的误差.分析了随荷载作用面积变化、计算深度变化Y型、三角形、矩形、方形、圆形、圆环、H形、T形截面桩端均布荷载作用在地基内部时截面中心点下附加应力系数的差异及变化规律.将考虑Y型桩截面形状的附加应力计算方法应用于Y型桩单桩的沉降计算,计算结果与静载荷试验数据吻合较好.Abstract：The section of Y-shaped vibro-pile is complicated; its geometric characteristics has four independent variables and eight integral zones. It is difficult to achieve the expression of analytical solutions for additional stress coefficient at random point in the ground when the uniform tip load of the Y-shaped section acting in the ground; therefore, so far simple analytical solution hasn't been solved yet. Using the integral function NIntegrate of Mathematica software and referencing the idea from Geddes stress solution, the numerical computational method for vertical additional stress coefficient at random point in the ground under the uniform tip load of Y-shaped vibro-pile was achieved; and it is accurate according to the verification. The influences of four independent variables, R, θ, s,δ of Y-shaped section on vertical additional stress coefficient due to uniform tip load and errors produced by Geddes stress solution were analysed. The difference and regular in vertical additional stress coefficient at section center in the ground under the uniform tip load of Y-shaped, triangular, rectangular, quadrate, circular, annular, H, and T-shaped section were analyzed along with the change of acreage and calculation deepness. The additional stress calculation method in which the section shape of Y-shaped vibro-pile is considered was used in settlement calculation of single pile. The calculation result is consistent with the data of static loading test.
