旋噴樁復合地基承載特性分析

孫夢杰

(重慶交通大學 河海學院，重慶 400041)

旋噴樁復合地基承載特性分析

孫夢杰

(重慶交通大學 河海學院，重慶 400041)

某邊坡主滑面為土巖交界面，整體穩定性不滿足規范要求，故需對邊坡進行處理。擬采用高壓旋噴樁對該邊坡進行地基處理。對旋噴樁樁體、樁間土及復合地基分別做單樁豎向抗壓靜載試驗、樁間土靜載試驗及單樁復合地基載荷試驗，分析其Q-s、P-s曲線圖,確定單樁豎向承載力特征值、樁間土及復合地基承載力特征值。結果表明：旋噴樁處理紅黏土形成復合地基，提高了土體的抗剪強度和地基承載力；對比分析了由樁體、樁間土的承載力特征值等參數確定復合地基承載力特征值的幾種方法；由樁土應力比n及折減系數λ計算復合地基承載力時，計算值與實測值基本一致。

高壓旋噴樁；復合地基；承載力

Abstract：The main sliding surface of a slope is the interface of soil rock, and the whole stability does not meet the requirement of specifications, so the slope should be treated. A high-pressure jet grouting pile is proposed to treat the slope with foundation treatment. The vertical compressive static load test of pile, soil and composite foundation of the jet grouting pile are carried out respectively. The static load test of pile and the load test of single pile composite foundation are analyzed, theQ-sandP-scurves are determined, the characteristic value of vertical bearing capacity of single pile, the bearing capacity of soil and composite foundation of pile are confirmed. The results show that the composite foundation is treated by the jet grouting pile, which improves the shear strength and the bearing capacity of the soil. Several methods of determining the bearing capacity eigenvalue of composite foundation by the parameters of the bearing capacity of pile and soil are compared and analyzed. When the bearing capacity of composite foundation is calculated by the stress rationand the reduction coefficientλof pile-soil, the calculated value is basically consistent with the measured value.

Keywords：high-pressure jet grouting pile; composite foundation; bearing capacity

在巖土工程中，對于淤泥、淤泥質土等其他高壓縮性土構成的軟土地基，一般不宜直接作為天然地基，須經過有效的地基處理才能使用[1-2]。常用的處理軟土地基的方法有：換填法、強夯法、高壓噴射注漿法、深層攪拌法等[3-4]。本文主要介紹旋噴樁在處理紅黏土地基時形成復合地基的應用。

高壓旋噴樁的基本原理：利用鉆機，把注漿管鉆進至預定土層深度，然后以20～40 MPa的壓力，把漿液或水從噴嘴中噴射出來，形成噴射流，使土體結構破壞，并與漿液混合，形成水泥土樁體[5-6]。宋興海等結合某地區旋噴樁復合地基現場載荷試驗對復合地基承載力的確定做了探討[7]；……