螺旋群桩的桩端压力相互影响极限深度及其沉降计算

引入桩端压力相互影响极限深度判定条件，反映群桩-地基荷载传递状态．基于Mindlin理论，建立了半空间弹性体内部双集中力地基应力解，且引入土材料的应力扩散性质，推导了桩端压力相互影响极限深度近似解，提出了螺旋群桩基础沉降计算方法，分析了3种布桩形式的螺旋群桩基础的沉降计算值和实测值．结果表明，本研究计算方法得出的沉降计算值较等代墩式基础沉降法计算值更接近于螺旋群桩基础的实测沉降值，说明建立在Mindlin应力解基础上的桩端压力相互影响极限深度判定条件能较好地反映桩端地基应力叠加问题．

The interactive limit-depth by pressure of pile tip and settlement calculation for screw pile group

The conditional decision of the overlay subsidiary stress's depth of ground under the tip of group pile(OSDG) was adopted to reflect how the load was transferred in the pile-ground.On the Mindlin's stress solution and the character of stress dispersion,the ground stress of two-concentrated force was answered,and the approximate solution of OSDG was deduced,and the determinant conditions and the calculational method of settlement was advised.Compared with the calculation of settlement by the proposed method in this paper and the settlement value by the method of equivalent entity foundation with these observations of settlement by 6 times of 3 kinds of static loading tests on group screw pile foundation,the values of the proposed method were close to the tested observations,this shows that the question of OSDG could be reflected by the conditional decision of OSDG.