桩端炭质泥岩浸水前后动力变形特性模型试验  

Model Test on the Dynamic Deformation Characteristics of Pile-side Carbonaceous Mudstone before and after Soaking

作　　者：叶朝良[1] 薛飞招 冯怀平[1] 谢玉芳 YE Chaoliang;XUE Feizhao;FENG Huaiping;XIE Yufang(Shijiazhuang Tiedao University,Shijiazhuang,Hebei 050043,China)

机构地区：[1]石家庄铁道大学,石家庄050043

出　　处：《铁道工程学报》2020年第3期1-6,共6页Journal of Railway Engineering Society

基　　金：国家自然科学基金(51478279);河北自然科学基金(E2017210186)。

摘　　要：研究目的:近年来,在我国西南山区的公路、铁路建设中均出现了炭质泥岩这种特殊岩土,因其浸水后极易软化,而且发生膨胀变形,导致在荷载作用下经常发生承载力不足、沉降变形增大和边坡失稳等一系列工程地质灾害,对沉降控制标准极高的高速铁路后期运营带来极大危害。为评价桩端炭质泥岩在浸水和动荷载条件下对高铁路基沉降影响,本文通过动力模型试验研究了桩端炭质泥岩在浸水前后、动荷载作用下的变形特性。研究结论:(1)动荷载为200~400 N时,桩端炭质泥岩浸水前后的换算沉降分别在2.92~9.64 mm和36.74~63.48 mm之间,浸水后沉降变形显著增加;(2)浸水与列车动荷载是导致桩端炭质泥岩产生过大工后沉降的主要因素,水对炭质泥岩的沉降影响远大于动荷载作用;(3)荷载振动次数对滞回曲线的六项指标λ、k、d、S、ζ、η有显著影响;(4)炭质泥岩浸水后,强度、刚度明显降低,粘滞性显著增大,能量耗散能力增强,在动荷载下损伤程度明显增加,软化效应显著;(5)本研究结论可为类似工程地质条件下的公路与铁路路基设计与施工提供借鉴和参考。Research purposes:In recent years,special soils such as carbonaceous mudstone have appeared in the construction of highways and railways in the mountainous areas of southwest China.Because it is easily softened after immersion in water,and it undergoes expansion and deformation,they often cause a series of engineering geological disasters such as insufficient bearing capacity,increased deformation and slope instability,which have brought great harm to the later operation of high-speed railways with extremely high settlement control standards.In order to evaluate the influence of pile-side carbonaceous mudstone on settlement of high-speed railway foundation under the conditions of water immersion and dynamic load,the deformation characteristics of pile-side carbonaceous mudstone before and after water immersion and under dynamic load were studied by dynamic model tests.Research conclusions:(1)When the dynamic load is 200 N^400 N,the actual settlement of carbonaceous mudstone at pile tip before and after soaking is 2.92 mm^9.64 mm and 36.74 mm^63.48 mm respectively,meaning that settlement deformation increases significantly after soaking.(2)The two main factors leading to excessive post-construction settlement of carbonaceous mudstone at pile tip are soaking and train dynamic loads,and the effect of the former is far greater than that of the latter.(3)The number of load vibration has a significant impact on the six indexes of hysteretic loop curve,namely,λ,k,d,S,ζ,η.(4)The softening effect of the stone after soaking is remarkable,in other words,the strength and stiffness are obviously reduced,while the viscous property and the energy dissipation ability are increased.In addition,the damage degree is obviously increased under dynamic load.(5)The research conclusions can provide reference for highway and railway subgrade design and construction under similar engineering geological conditions.

关 键 词：炭质泥岩 动力模型试验 浸水 累积变形 滞回曲线 

分 类 号：U416[交通运输工程—道路与铁道工程]