顶管沉井施工引起的桩土变形之数值模拟  

Numerical Simulation of Soil-Caisson Interaction in the Caisson Installation in Pipe Jacking

作　　者：毛济民 杨雪强[1] 连继业 吴颖怡 张敏 杜可函 MAO Jimin;YANG Xueqiang;LIAN Jiye;WU Yingyi;ZHANG Min;DU Kehan(School of Civil and Traffic Engineering,Guangdong University of Technology,Guangzhou 510006;Guangdong Shunde Power Design Institute Co.Ltd.,Foshan 528000)

机构地区：[1]广东工业大学土木与交通工程学院,广州510006 [2]广东顺德电力设计院有限公司,广东佛山528000

出　　处：《土工基础》2023年第6期959-965,共7页Soil Engineering and Foundation

基　　金：国家自然基金青年基金项目(51809050)。

摘　　要：以广东省佛山市顺德区一处输变电工程为例,建立以加固旋喷桩作为沉井周围加固体的ABAQUS软件计算模型进行运算,并对小型顶管井在顶管施工前后旋喷桩体与周围土体内力变化与位移进行有限元计算分析。揭示小尺寸电力沉井在穿越分层土体并施加顶推力之后的墙体变形,以及土的三维破坏变形分布规律,结论如下:在不同顶进力作用下,主动区最大位移出现位置较为一致,而被动区土和桩位移变化较大,但在到达土体极限状态甚至超过土体极限状态时,土体和桩体在顶力施加范围位移很大,桩身容易受损破坏。当桩体穿越两层土体时,在两层交界面有应力突变,加载区的应力形成开口葫芦型。低顶推力时内力分布较为均匀,但随着顶推力不断增大,主要承力部分则变成被动区桩体;当顶推力达到一定限度后,被动沉降区稳定发展,向上位移区域扩张迅速,导致表层土体隆起严重。主动区由于有旋喷桩体支撑,受到顶力后土体拉裂程度小,说明旋喷桩的设置极大地改善了土体性能,能有效地防止主动区土体的开裂。The jet grouting improved soil surrounding the caisson for a pipe jacking for a power transmission project in Shunde District,Foshan City,Guangdong Province,is numerically simulated by using the ABAQUS software.The internal force variation and displacement of the jet grouting improved caisson and surrounding soil before and after pipe jacking construction of small diameter pipe jacking shaft are evaluated by the finite element method.The wall deformation and soil three-dimensional failure modes of the small diameter electric caisson after passing through layered soil and applying jacking force are evaluated.The following conclusions are made during the excavation,the surrounding soil is easy to cave into the excavated area due to the soil unloading effect,and the pile tends to be extruded by soil.Under different jacking forces,the locations where the maximum displacement in the active zone are consistent;the performance of both soil and pile are similar and no separation is observed.In the passive area,larger differences between soil and pile are observed.With the push force reaches the limit state,the displacements of the soil and pile are large,and the pile is likely to be damaged.When the pile passes through two different soil layers,the stress at the interface changes,and the stress in the loading region forms an open gourd shape.The shape of this gourd becomes obvious with the increase of the jacking force.The internal force distribution is uniform at the low jacking force,but the main bearing part becomes passive pile with increasing jacking force.When the thrust force reaches a certain limit,the passive settlement area develops stably,while the upward displacement area expands rapidly,resulting in serious uplift of surface soil.Due to the pile support in the active zone,the tensile cracking degree of soil under the jacking force is small,indicating that the installation of jet grouting pile can greatly improve the performance of soil and effectively prevent the cracking development in the active zone soil.

关 键 词：顶管沉井 顶推力 数值模拟 旋喷桩加固 土体变形 

分 类 号：TU473[建筑科学—结构工程]