【作者】 陈伟；

【导师】 俞晓；

【作者基本信息】 武汉科技大学 ， 结构工程， 2013， 硕士

【摘要】 碎石桩极限承载力的理论及计算方法多样，常用的有Braun（s1978）法、Hughes和Withers（1974）法和Wong H.Y.（1975）、被动土压力法、圆筒形孔扩张理论法等。其中Brauns计算法具有思路清晰、计算简单等优点。虽然Brauns法在工程中运用广泛，但该法未考虑桩身及桩周土自重的影响且桩周土破坏面形式还未完善，使得计算结果与实际工程存在较大误差。因此很有必要对Brauns计算法进行自重及破坏面的修正，以在工程实践中获取更加良好的经济效益和社会效益。在Brauns计算法的基础上，通过理论分析及计算推导对其作出了相应的修正：①考虑桩周土及桩身自重的影响，推导出了相应的Brauns理论计算公式；②通过数据分析得出了碎石桩极限承载力与桩身半径、桩间土不排水抗剪强度的关系，并提出相应的近似计算公式；③将修正的Brauns理论计算公式与工程实践做出对比得出，该计算法对不排水抗剪强度较小的地基有着更加良好的适用性；④在Brauns计算法的基础上，假设破坏面为对数螺旋面，推导得出了相应的极限承载力的理论计算公式；更多还原

【Abstract】 The theories and methods of calculation of the ultimate bearing capacity of gravelpile are varied. The calculation methods of the ultimate bearing capacity of gravel pileinclude the calculation methods of Brauns(1978), Hughes&Withers(1974), WongH.Y.(1975),passive earth pressure, the cylindrical cavity expansion theory and so on.Among those, the Brauns is simple in calculations, clear in ideas.Although the calculation method of Brauns is used by the most designers,It is on the safe side which disregards the self-weight of the pile and the soil aroundand of which the form of failure surface is not perfect. So it’s necessary to take theself-weight of the pile and the soil into consideration and modified the form of failuresurface as to get more economic and social benefits in engineering constructions.On the base of Brauns, the issue makes some relative modifications throughanalysis and calculation:①Deriving the theoretical formula of the ultimate bearing capacity of gravel pilewhich considers the self-weight of both soil and pile;②Deriving the relationship between the ultimate bearing capacity of gravel pileand the radius of the pile, the undrained shear strength, and the approximate formulaas well;③Making comparison between the theoretical formula which is modified and thedata of engineering construction, and concludes that the modified Brauns method isbetter in the conditions that the soil has a smaller undrained shear strength;④Changing the plane of rupture into logarithmic spiral surface and derives therelative theoretical calculation formula.更多还原