膨胀土硬质地层振动载荷沉桩的挤土效应

Soil squeezing effect of vibratory pile sinking in expansive soil layer

为研究膨胀土硬质地层振动载荷沉桩的挤土效应,基于膨胀土剪切膨胀、遇水软化的力学特性,提出“水冲法”辅助沉桩关键技术,通过现场试验和有限元模拟,得到H型、O型钢板桩沉桩时桩周土体深层水平位移、深层土压力的变化规律。研究表明:桩周土体的深层水平位移、深层土压力均与土层性质、土层深度密切相关,膨胀土的剪胀作用能够显著增强沉桩的挤土效应。与未采取辅助措施相比,采取“水冲法”辅助措施后,桩周土体的深层水平位移、深层土压力的最大值均可减小50%以上。“水冲法”辅助措施可显著削弱沉桩对周边环境的不利影响,为组合钢板桩支护技术的设计与施工提供重要的技术支撑。

In order to study the soil squeezing effect of pile sinking under vibration load in expansive soil layer,based on the mechanical properties of shear expansion and water softening of expansive soil,the key technology of"hydrodynamic method"assisted pile sinking is proposed.Through field test and finite element calculation,the changing rules of deep horizontal displacement and deep soil pressure of the soil around the H-type and O-type steel sheet piles during pile sinking are summarized.The results shows that the deep horizontal displacement and deep soil pressure around the pile are closely related to the properties and depth of soil layer,and the shear expansion of expanding soil can significantly enhance the soil squeezing effect of the pile sinking.Compared with the pile sinking without auxiliary measures,the maximum value of deep horizontal displacement and deep soil pressure around the pile can be reduced by more than 50%when the pile sinking is assisted by"hydrodynamic method".The auxiliary measures of"hydrodynamic method"can significantly reduce the adverse effects of pile sinking on the surrounding environment,which provides important technical support for the design and construction of combined steel sheet pile support technology.