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为使无杆钻具能有效支撑在孔壁土体上,探讨了支护结构施加的预应力对孔壁土体稳定性的影响,提出了采用虚拟土柱模拟桩孔并结合广义Mindlin解的方法,推导了预应力作用下孔壁土体中任一点的附加应力向量.基于此附加应力向量,求取了最大预扭矩和最大预压力作用下支护板下方5 mm、宽50 mm处各点的剪切应力及其相对强度.结果表明:当预扭矩与预应力分别为120 k N·m和100 k N时,最大剪切应力为6.52 MPa;除了支护板两端部外,剪切应力相对强度均小于1,即总体上孔壁土体为稳定状态.与试验结果的对比验证了文中方法的正确性,文中方法比Boussinesq-Gerruti联合求解法和有限元法更加精确
In order to make the rodless drilling tool support the hole wall soil effectively, the influence of the prestressing force exerted by the supporting structure on the stability of the soil wall near the hole wall is discussed. The virtual soil column is used to simulate the pile hole and the generalized Mindlin solution Method, the additional stress vector at any point in the hole wall under the prestressing force is derived.According to the additional stress vector, the maximum pre-torque and the maximum pre-pressure under the support plate 5 mm, width 50 mm Point shear stress and its relative strength.The results show that the maximum shear stress is 6.52 MPa when the pre-stress and pre-stress are 120 kN · m and 100 kN respectively. The relative strength of shear stress is less than 1, that is to say, the overall stability of the soil on the wall is verified by comparison with the experimental results. The proposed method is more accurate than the Boussinesq-Gerruti method and the finite element method