注气加载路径对增压式真空预压法加固吹填软土的效果分析  

Analysis of the effect of air injection loading path on strengthening soft dredger fill by air-booster vacuum preloading method

作　　者：雷华阳[1,2] 方庆峰 刘景锦[1,2] 王磊[1] LEI Huayang;FANG Qingfeng;LIU Jingjin;WANG Lei(Department of Civil Engineering,Tianjin University,Tianjin 300354,China;Key Laboratory of Coast Civil Structure Safety of Ministry of Education,Tianjin University,Tianjin 300354,China)

机构地区：[1]天津大学建筑工程学院,天津300354 [2]天津大学滨海土木工程结构与安全教育部重点实验室,天津300354

出　　处：《岩石力学与工程学报》2023年第8期2058-2067,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(52078334);国家自然科学基金青年项目(51908406)。

摘　　要：采用增压式真空预压法加固处理吹填软土时,其加固效果会受到注气压力和注气时间的影响。利用不同注气压力和注气时间组合条件的室内模型试验,研究注气加载路径对增压式真空预压法加固吹填软土的效果影响,试验中考虑恒压力–恒时间、恒压力–变时间、变压力–恒时间以及变压力–变时间4种注气加载路径。试验结果表明,增压式真空预压法对土体的加固效果总是优于常规真空预压法,且当采用变压力–变时间的注气加载路径时,土体的加固效果最佳。与恒压力–恒时间的注气加载路径相比,采用变压力–变时间的注气加载路径可使土体的表面沉降增大9.25%,排水量增大9.35%,平均含水率降低13.91%,平均十字板剪切强度增大20.59%。注气压力和注气时间的逐级递增可有效地防止黏粒向排水板处聚集,促使排水板与增压板之间土体孔隙数量的增多,增大土体的渗透性,提高深层土体的加固效果。When air-booster vacuum preloading method is used to reinforce soft dredger fill,the reinforcement effect will be affected by air injection pressure and air injection time.Indoor model tests with different combinations of injection pressure and injection time were used to investigate the effect of the air injection loading path on the reinforcement of soft dredger fill.Four air injection loading paths were considered:constant pressure-constant time,constant pressure-variable time,variable pressure-constant time and variable pressure-variable time.The test results show that the reinforcement effect of air-booster vacuum preloading method is always better than that of conventional vacuum preloading method.And when the air injection loading path of variable pressure-variable time is adopted,the soil reinforcement effect is the best.Compared with the air injection loading path of constant pressure-constant time,the air injection loading path of variable pressure-variable time can lead to an increase in soil surface settlement by 9.25%,an increase in drainage by 9.35%,a decrease in average water content by 13.91%and an increase in average vane-shear strength by 20.59%.The gradual increase of air injection pressure and air injection time can effectively prevent the accumulation of clay particles to the prefabricated vertical drains(PVDs),and increase the number of soil pores between PVDs and the booster board.The permeability of soil and the reinforcement effect of deep soil can be improved by using the loading path of variable pressure-variable time.

关 键 词：土力学 吹填软土 增压式真空预压 注气压力 注气时间 加固机制 

分 类 号：TU43[建筑科学—岩土工程]