饱和黏土中考虑土塞效应的柱孔扩张分析  

Analysis of cylindrical cavity expansion considering plugging effect in saturated clay

作　　者：李雨浓[1,2] 曹锦楼 Li Yunong;Cao Jinlou(Key Laboratory of Geeen Construction and Intelligent Maintenance for Civil Engineering of Hebei Province,Yanshan University,066004,Qinhuangdao,China;Department of Civil Engineering and Mechanics,Yanshan University,066004,Qinhuangdao,China)

机构地区：[1]燕山大学河北省土木工程绿色建造与智能运维重点实验室,秦皇岛066004 [2]燕山大学建筑工程与力学学院,秦皇岛066004

出　　处：《应用力学学报》2020年第4期1549-1555,I0012,共8页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金青年基金(51408527);河北省自然科学基金青年基金(E2015203195)。

摘　　要：为研究静压开口管桩的挤土效应,在考虑土塞效应的前提下,采用柱孔扩张理论对管桩压入饱和软黏土时的扩孔过程进行了分析。基于可以合理描述黏性土强度特性的拓展Lade-Duncan屈服准则,对柱孔扩张过程中的桩周土体进行了弹塑性理论推导,得到了桩周土体应力场、位移场、塑性区半径、极限扩孔压力和塑性区外侧边界径向位移的解析解。在此基础上,通过室内模型实验获得了软土中开口管桩的土塞高度,且运用等效替代法验证了理论解答的合理性;并通过引入土塞长度比对参数进行了分析。结果表明:在沉桩过程中随着土塞长度比的增大,塑性区半径、极限扩孔压力和塑性区外侧边界径向位移均逐渐减小;土体的剪切模量和黏聚力对沉桩挤土效应有显著的影响,挤土效应始终随着土塞效应的增强而减弱。该研究成果对开口管桩工程的实际应用具有一定理论指导意义。To study the squeezing effect of open-ended pipe pile, the cylindrical cavity expansion theory is applied to study the expanding process of pipe pile sinking into saturated soft clay under the premise of considering the plugging effect. Based on the expanded Lade-Duncan failure criterion which can be used to describe the strength characteristics of the cohesive soil reasonably, the criterion is applied to the theoretical deduce of the elasto-plastic zone of cylindrical cavity expansion process, the analytical solutions of stress field and displacement field of the soil around the pile, the radius of plastic zone and limit expansion pressure are derived. Then, the pile installation is reconstructed to study the variation of soil plug height in saturated soft clay through laboratory model test, and the rationality of analytical solutions are verified by equivalent substitution method. By Introducing height ratio of soil plug to analyze parameters, results show that the radius of plastic zone, limit expansion pressure and radial displacement of plastic zone outside boundary is decreased with the enhanced of height ratio of soil plug during the pile driving process. The shear modulus and cohesion of the soil have a significant effect on the squeezing effect of the pile, and the squeezing effect is always weakened with the increase of the plugging effect. The research have certain theoretical guiding significance for the practical application of open-ended pipe pile.

关 键 词：静压桩 柱孔扩张理论 开口管桩 土塞效应 挤土效应 

分 类 号：TU473[建筑科学—结构工程]