宽级配珊瑚土落雨制模分层现象与控制方法  

Layered phenomena and control method of sand pluviation on wide-graded coral soil

作　　者：张旭东 王永志[1,2] 王体强 刘红帅 段雪锋 袁晓铭 ZHANG Xudong;WANG Yongzhi;WANG Tiqiang;LIU Hongshuai;DUAN Xuefeng;YUAN Xiaoming(Key Laboratory of Earthquake Engineering and Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,China;Key Laboratory of Earthquake Disaster Mitigation,Ministry of Emergency Management,Harbin150080,China;College of Civil Engineering and Architecture,Hebei University,Baoding 071002,China)

机构地区：[1]中国地震局工程力学研究所地震工程与工程振动重点实验室,黑龙江哈尔滨150080 [2]地震灾害防治应急管理部重点实验室,黑龙江哈尔滨150080 [3]河北大学建筑工程学院,河北保定071002

出　　处：《自然灾害学报》2024年第4期188-197,共10页Journal of Natural Disasters

基　　金：中国地震局工程力学研究所基本科研业务费专项项目(2023B14,2023C11);黑龙江省自然科学基金资助项目(LH2023E019)。

摘　　要：珊瑚土场地液化是港口工程和滨海设施及岛礁典型的地震灾害现象之一,而珊瑚土具有级配宽、细粒含量高和易破碎等特点。落雨法作为研究饱和模型场地与单元试验液化的重要制模手段,针对落雨法在制备珊瑚土地基模型时出现的分层问题,利用自主研制的大型落雨装置及高速摄像和PFC3D离散元模拟,分析细粒含量、流量大小、落距和出砂口移动速度等因素对分层现象的影响,揭示分层现象的产生机理,并建立相应控制方法。研究结果表明:相对于落距和出砂口移动速度,细粒含量和流量是影响颗粒分层的主要因素。随着细粒含量的增加,分层现象逐渐减弱;随着流量的增大,分层现象逐渐明显;当落距和出砂口移动速度达到一定范围时,分层现象不会再随之增大而出现明显变化。高速摄像分析表明,粗细颗粒在出砂口移动时会出现粗细颗粒的分离,二者之间有着明显的分离界限,其结果表明,分层现象是在重力、空气拖曳力以及出砂口侧向移动的综合作用下产生的。利用PFC3D离散元模拟落雨法制模的过程,模拟结果与试验结构及高速摄像分析结果高度契合,证明PFC3D数值模拟方法的可行性。结合流量、落距和出砂口移动速度等影响因素,提出一种可有效控制落雨法分层现象的方法,为制备大型宽级配珊瑚土模型提供指导依据。Liquefaction of coral soil sites is one of the typical earthquake disaster phenomena in port projects,coastal facilities,and islands.Coral soil has the characteristics of wide gradation,high fine particle content,and easy breakage.The sand pluviation method is an important modeling method for studying saturated site models and unit test liquefaction.In view of the delamination problem that occurs when the sand pluviation method is used to prepare coral soil foundation models,the independently developed large-scale sand pluviation device,high-speed camera and PFC 3D discrete element numerical simulation are used.By simulation,the effects of fine particle content,flow rate,drop distance and moving speed of sand outlet on layered phenomena were analyzed.The generation mechanism of the layered phenomena was revealed,and corresponding control methods were established.The test results show that compared to the drop distance and the moving speed of the sand outlet,the fine particle content and flow rate are the main factors affecting layered phenomena.As the fine particle content increases,the layered phenomena gradually weakens.As the flow rate increases,the layered phenomena gradually becomes obvious.When the drop distance and the moving speed of the sand outlet reach a certain range,the layered phenomena will no longer increase,and the changes were not obvious.High-speed camera analysis shows that the separation of coarse and fine particles occurs when the coarse and fine particles move at the sand outlet,and there is an obvious separation boundary.The results show that the layered phenomena is caused by gravity,air drag force,and the lateral movement of the sand outlet.The PFC 3D discrete element was used to simulate the process of sand pluviation molding.The simulation results were highly consistent with the results of photos taken by high-speed cameras,which proved the feasibility of the PFC 3D numerical simulation method.Finally,combined with influencing factors such as flow rate,falling distance,and sand outlet

关 键 词：珊瑚土 宽级配 落雨法 分层现象 影响因素 控制方法 

分 类 号：TU41[建筑科学—岩土工程] X43[建筑科学—土工工程]