考虑土体损伤的挤土效应计算探讨  

Discussion on the Calculation of Extrusion Effect Considering Soil Damage

作　　者：徐安全[1] 岳建伟[1] 岳婷婷[1] 

机构地区：[1]河南大学土木建筑学院,开封475001

出　　处：《固体力学学报》2016年第4期379-386,共8页Chinese Journal of Solid Mechanics

摘　　要：圆孔扩张理论应用于静压桩沉桩、搅拌桩成桩过程周围土体的应力和变形分析,取得了一定的成果,但其理论分析结果和实验结果仍存在一定的偏差,主要原因在于理论推导时未考虑桩周一定范围内的土体受施工因素影响而产生的损伤.为更有效地发挥圆孔扩张理论在指导桩基施工中的作用,论文通过构造桩周土体粘聚力变化的表达式来考虑施工造成的土体损伤,基于连续介质力学的原理,依据边界条件确定了表达式中的土体损伤因子,得到了能够反映造成土体损伤主要因素的土体粘聚力变化表达式.基于圆孔扩张理论,并引入土体损伤因子,通过平衡微分方程的迭代计算,分析了成桩过程中的土体塑性区半径及应力分布,发现考虑土体损伤时,塑性区范围相对较大且应力的变化会相对较缓.通过不考虑损伤和考虑损伤的分析结果与既有理论的计算结果对比分析,表明论文提出的考虑土体损伤的分析方法简单合理,为精细化分析桩基施工对地基的影响提供了新方法.The cylindrical cavity expansion theory is commonly used to analyze the stress and strain of soil during the construction of static pressure piles and mixing piles. Although some achievements have been made using this method, there still exist some deviations between the experimental results and the theoretical ones, because the soil damage resulting from the disturbance of soil around the pile during con- struction was not considered when the cylindrical cavity expansion theory of the pile was deduced. To ef- fectively apply the cylindrical cavity expansion theory to guide the pile construction practice, a changing cohesion formula is established considering the soil damage caused during the construction. Based on theo- ry of continuum mechanics and boundary conditions, the soil damage factor in the formula can be deter- mined, and the soil changing cohesion formula considering soil damage is obtained. The squeezing effect a- round the pile is analyzed in accordance with the theory and the formula. The cohesion formula is substitu- ted into the cylindrical cavity expansion theory, and the distribution of stress and radius of plastic zone a- round the pile during the construction can be analyzed by solving the differential equations of equilibrium. The computation results considering soil damage show a larger range of plastic zone and a slower stress variation around the pile than those from the elastic method. To verify the rationality of the presented method, comparisons are made between the results obtained with and without considering the soil damage, and against those obtained from the existing theory in literature. The comparison results show that the presented method considering soil damage is rational and effective in dealing with the extrusion effect dur- ing the construction of static pressure piles and mixing piles, and suitable for engineering practice. This analytical method considering soil damage can be helpful in the refined analysis of the effect of pile con- struction technology on different soi

关 键 词：圆孔扩张理论 土体损伤 粘聚力 挤土效应 

分 类 号：TU43[建筑科学—岩土工程]