组合锤置换墩极限承载力计算方法

为研究组合锤置换法加固软土地基的承载性能,需建立置换墩的极限承载力计算模型并验证该计算方法的可行性.首先,进行室内模型试验,研究置换墩墩体形态和墩体破坏模式.其次,在模型试验的基础上,根据能量法建立置换墩极限承载力的计算模型,代入模型相关参数,基于GA_PSO优化算法在Matlab平台研究各参数对墩体极限承载力的影响.试验和计算结果表明:置换墩典型的墩体形态为一轴对称的旋转体,纵向剖面为上大下小的梯形截面;极限状态下墩体的破坏模式为鼓胀破坏;墩径和墩周土体强度对提高墩体极限承载力影响显著,此与组合锤置换法设计理念相吻合.最后,通过一工程案例,验证了该计算方法应用于组合锤置换法初步设计是可行的.

Calculation of ultimate bearing capacity of replacement pier by dynamic replacement method with various hammers

To study the bearing capacity of soft soil reinforced by dynamic replacement method with various hammers, a calculation model was put forward for evaluating the soft soil''s ultimate bearing capacity. A series of model tests was conducted to investigate the shape characteristics and the failure mode of the replacement piers. Based on the model test, the ultimate bearing capacity of replacement pier was established using the energy method, which was calculated using the GA_PSO optimization algorithm on the Matlab platform, and a parametric study was conducted to investigate the factors that influence the ultimate bearing capacity of the replacement pier. The test and calculation results show that the replacement pier is typically formed as a cone with cross section of an inverted trapezoid and the pier usually has a mode of bulging failure in the ultimate state. The diameter of the pier and soil strength around the pier have significant effects on the ultimate bearing capacity, which is consistent with the design concept of the dynamic replacement method with various hammer. The proposed method was verified to be feasible through comparison between calculation results and field test results.