循环冲击荷载作用对土洞稳定性的影响分析  

Analysis of the Influence of Cyclic Impact Load on the Stability of Soil Hole

作　　者：刘宇 Liu Yu(Henan Fourth Geological and Mineral Survey Institute Co.Ltd.,Zhengzhou,Henan 450000)

机构地区：[1]河南省第四地质矿产调查院有限公司,河南郑州450000

出　　处：《江西建材》2024年第12期288-291,共4页

摘　　要：由于冲孔桩的施工,冲击荷载将会作用到岩溶地基中,可能加剧已有岩溶地面塌陷或引发新的岩溶地面塌陷,文中依据Flac3D完全非线性动力学分析的理论,把冲击荷载简化为三角形荷载模式,以覆盖层为“上黏下砂”的二元结构为研究对象,使冲击荷载作用于土洞顶板上地表处,监测不同时刻土洞顶板的位移,分析冲击荷载对土洞覆盖层稳定性的影响。结果可得,冲击荷载产生的冲击波以球面的形式向下传播,地表作用点位移有回弹现象,邻近土洞顶板处竖向位移最大,表明在冲击荷载作用下,地面塌陷机理为土洞周围塌陷破坏,覆盖层颗粒逐渐向土洞流失,最终引起地面塌陷。分析循环冲击荷载下土洞顶板竖向位移,可知其增幅相近且逐渐增大,随着冲击次数的增加,覆盖层顶板可能会产生瞬时冲切破坏。Due to the construction of perforated pile,the impact load will act on the karst foundation,which may aggravate the existing karst ground collapse or cause the new karst ground collapse.Based on the theory of complete nonlinear dynamic analysis in Flac3D,the impact load is simplified into a triangular load mode,and the binary structure with the cover layer as"sand on top"is taken as the research object.The impact load is applied to the surface of the soil tunnel roof plate,and the displacement of the soil tunnel roof plate at different times is monitored to analyze the influence of impact load on the stability of the soil tunnel roof layer.The results show that the shock wave generated by the impact load propagates downward in the form of a spherical surface,and the displacement of the surface application point has a rebound phenomenon,and the vertical displacement near the roof plate of the soil tunnel is the largest,which indicates that the ground collapse mechanism under the impact load is the collapse and destruction around the soil tunnel,and the particles of the covering layer gradually lose to the soil tunnel,and finally cause the ground collapse.In addition,through the analysis of vertical displacement of the roof plate under cyclic impact load,it can be seen that its increase rate is similar and gradually increases.Therefore,with the increase of impact times,the roof of the covering layer may produce instantaneous punching failure.

关 键 词：循环冲击荷载 土洞 稳定性 数值分析 

分 类 号：P642.25[天文地球—工程地质学]