基于桩体加固密实度不同液化土变形特性分析  

Characteristics analysis of liquefied soilwith different densities reinforced by pile

作　　者：崔志平[1] 牛琪瑛[1] 赵军永 

机构地区：[1]太原理工大学建筑与土木工程学院,山西太原030024

出　　处：《广西大学学报（自然科学版）》2016年第1期156-162,共7页Journal of Guangxi University（Natural Science Edition）

基　　金：国家青年自然科学基金资助项目(51408393);山西省交通科学研究院开放基金资助项目(KLTLR-Y13-3)

摘　　要：为了进一步研究水泥土桩和碎石桩加固不同密实度液化土的机理,通过振动台模拟地震荷载,对水泥土桩、碎石桩加固不同密实度液化土进行一系列试验,得到密实度分别为1.5 g/cm3、1.6 g/cm3、1.7 g/cm3不同埋深处的超静孔隙水压力与沉降的时程曲线,分析水泥土桩和碎石桩加固液化土超静孔隙水压力、沉降量与埋深、密实度之间的变化规律。结果表明:随着振动荷载作用,不同埋深处超静孔隙水压力均急剧上升到峰值,随后碎石桩加固模型的孔隙水压力随着时间缓慢递减,表明土中水的排出,孔隙水压力得到充分消散,而水泥土桩加固模型以孔隙水压力峰值保持到试验结束,孔隙水压力几乎没有消散;孔隙水压力与密实度、埋深呈正相关,碎石柱加固模型相同埋深、相同密实度的孔隙水压力均小于水泥土桩加固模型的;沉降量与埋深、密实度呈负相关,相同密实度、相同埋深处碎石桩加固模型的沉降量峰值比水泥土桩加固模型的小,但随着振动荷载作用,碎石桩由下向上排水,使孔隙水压力消散,而水泥土桩刚性桩桩周摩阻力在振动过程中显现,桩体分割土体的格栅作用,使其土体沉降速率小于碎石桩柔性桩沉降速率;孔隙水压力、沉降量与埋深、干密度之间的关系式分别为U=U0+a Z-bγ,C=C0+mγ+n Z。In order to study reinforcement effect of gravel pile or cement-soil pileon liquefied soil,seismic load was simulated with a vibration table,and a series of tests were carried out on liquefied soil models reinforced by gravel pile or cement-soil pile. There were three dry densities of the models,1. 5 g / cm^3,1. 6 g /cm3 and 1. 7 g / cm^3. For each model,the water pressure of the settlement in different buried depth and the peak curve were analyzed. The relationship between water pressure and buried depth and the relationship between the settlement and buried depth were obtained. Conclusions are as follows. Under continuing vibration loadssuper static pore water pressure of the modelswith different buried depth sharply rises to the peak,and then the pore water pressure of the modelreinforced by gravel pile slowly declines,which shows the discharge of water in soil and the dissipation of pore water pressure. For the model reinforced by cement soil pilethe pore water pressure rises to the peak and keeps the value to test end,i. e.,the pore water pressure almost no dissipates. The pore water pressure are related to density and buried depth. For the same buried depth and density,the pore water pressure of the model reinforced by gravel pile is less than that of the model reinforced by cement soil pile. The settlement is negatively related to the buried depth and density. For the same density and buried depth,the settlement of the model reinforce by gravel pile isless than that of the model reinforce by cement soil pile. But,under continuing vibration loads,thegravel pile makes pore water pressure dissipate,and the friction resistance of cement soil pile appears,which makes the settlement rate less than that of gravel pile. The relationships of pore water pressure,settlement volume,buried deepand dry density are U=U0＋aZ-bγ,C=C0＋mγ＋nZ.

关 键 词：振动台试验 水泥土桩 碎石桩 密实度 孔隙水压力 沉降量 

分 类 号：TU473.1[建筑科学—结构工程]