微型钢管砂浆复合桩在土体中稳定性计算

Stability calculation of micro steel tube mortar composite pile in soil

微型钢管砂浆复合桩因纠偏受力明确、施工简单、工期短且加固费用低,被广泛用于基础加固托换。但小直径、大长度的微型钢管砂浆复合桩在土体中失稳破坏缺乏理论研究。故以弹性地基梁理论为基础,依据桩与地基土共同工作时的受力关系,建立微分方程求解。给出了微型钢管砂浆复合桩失稳承载力具体表达式,并与实际工程原位试验相比较,理论与试验结果接近;给出了最小临界计算长度的表达式指导工程施工;并运用Matlab编写程序计算分析了土与桩在不同的刚度比下不同桩长的失稳荷载,反映出土对微型钢管砂浆复合桩失稳约束力的影响程度。

The micro steel tube mortar composite pile is widely used in foundation reinforcement and pile replacement because of its clear force mechanism,simple construction,short construction period and low cost.However,there is rare theoretical study on instability or failure of micro steel tube mortar composite piles with small diameter and large length in soil.Therefore,on the basement of the theory of elastic foundation beam,the differential equation is solved according to the force relationship between the pile and the foundation soil.The specific expression of the bearing capacity for instability of the micro steel tube mortar composite pile is given.By comparing with the actual engineering in situ test,it is found that the theoretical and experimental results are close.An expression calcuating the minimum critical length is given to guide the construction of the project.Through a program writen in Matlab,the instability load refering to different pile lengths is calculated and analyzed under different stiffness ratios between soil and pile,which reflects the influence degree of soil on the instability and restraint force of micro steel tube mortar composite piles.