季冻区公路路基低液限粉质黏土动强度指标的影响因素研究
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摘要
在季节性冻土区,公路路基土动强度特性的影响因素较为复杂。以探究冻融循环作用对季冻区公路路基强度和变形特性的影响为目的,通过冻融循环作用下的室内动三轴试验,得到动强度指标随冻融循环次数、压实度和振动频率的变化规律,并采用正交试验设计方法进行显著性分析,探究各影响因素的影响程度。结果表明:随着冻融循环次数的增加,动内摩擦角呈现出一定的衰减趋势,但动黏聚力下降明显;随着压实度的增加,动内摩擦角约增加10%左右,动黏聚力值基本呈线性上升趋势,约升高1倍左右;随着振动频率的增加,动内摩擦角无明显变化,其值在31°～35°范围内波动,动黏聚力值呈上升趋势,且经历冻融循环后,上升幅度减小;各因素及其交互作用对动黏聚力的影响从大到小依次为压实度B,冻融循环次数A,交互作用A×B,振动频率C,交互作用B×C,交互作用A×C。研究成果对季冻区公路路基冻胀和融沉的防治,以及公路的服役性能和维护具有参考价值。
Influence factors of dynamic strength characteristics of subgrade soil are complicated in seasonal frozen soil region. By taking the influence from the effect of freezing-thawing cycle on the strength and deformation characteristics of highway subgrade in the seasonal frozen region as the study objective,the changing law of the dynamic strength index depended on the number of freezing-thawing cycle,degree of compaction and vibration frequency is obtained through the relevant indoor dynamic tri-axial test under freezing-thawing cycle,and then the significance analysis is made with the design method of orthogonal test,while the influencing degrees of all the influencing factors are explored as well. The result shows that along with the increase of the number of freezing-thawing cycle,the dynamic internal friction angle exhibits a declining trend,while the dynamic cohesion is obviously declined. Along with the increase of the compaction degree,the dynamic internal friction angle is increased by about 10%,while the value of dynamic cohesion basically presents an increasing trend with the increasing amplitude of about 1 times. Along with the increase of vibration frequency,the dynamic internal friction angle is not obviously changed with the fluctuation of the value within the range of 31° ～ 35°,while the dynamic cohesion exhibits an increasing trend,of which the increasing amplitude is to be decreased after freezing-thawing cycle. The influences from all the factors and their interactions on the dynamic cohesion are compaction degree B,number of freezing-thawing cycle A,interaction A × B,vibration frequency C,interaction B × C,from large to small in turn. The study result has referential value for control and prevention of frost-heave and thaw-settlement of highway subgrade in seasonal frozen region as well as the service performance and maintenance of the road.
Influence factors of dynamic strength characteristics of subgrade soil are complicated in seasonal frozen soil region. By taking the influence from the effect of freezing-thawing cycle on the strength and deformation characteristics of highway subgrade in the seasonal frozen region as the study objective,the changing law of the dynamic strength index depended on the number of freezing-thawing cycle,degree of compaction and vibration frequency is obtained through the relevant indoor dynamic tri-axial test under freezing-thawing cycle,and then the significance analysis is made with the design method of orthogonal test,while the influencing degrees of all the influencing factors are explored as well. The result shows that along with the increase of the number of freezing-thawing cycle,the dynamic internal friction angle exhibits a declining trend,while the dynamic cohesion is obviously declined. Along with the increase of the compaction degree,the dynamic internal friction angle is increased by about 10%,while the value of dynamic cohesion basically presents an increasing trend with the increasing amplitude of about 1 times. Along with the increase of vibration frequency,the dynamic internal friction angle is not obviously changed with the fluctuation of the value within the range of 31° ～ 35°,while the dynamic cohesion exhibits an increasing trend,of which the increasing amplitude is to be decreased after freezing-thawing cycle. The influences from all the factors and their interactions on the dynamic cohesion are compaction degree B,number of freezing-thawing cycle A,interaction A × B,vibration frequency C,interaction B × C,from large to small in turn. The study result has referential value for control and prevention of frost-heave and thaw-settlement of highway subgrade in seasonal frozen region as well as the service performance and maintenance of the road.
引文
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[19]崔广芹,秦迪,尚志成,等.冻融循环作用下粉质砂土的压缩变形特性研究[J].水利水电技术,2017,48(11):174-178.
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[21]交通部公路科学研究院.公路土工试验规程:JTG E40—2007[S].北京:人民交通出版社,2007.
[2] CHEN J,SU Y H. Numerical simulation of dynamic performance ofhighway subgrade under traffic loads[J]. Journal of Highway andTransportation Research and Development,2011,28(5):44-48.
[3]王常晶,陈云敏.交通荷载引起的静偏应力对饱和软黏土不排水循环性状影响的试验研究[J].岩土工程学报,2007,29(11):1742-1747.
[4] FARHAD S,SIGURDUR E,ZAPATACLAUDIA E. Modelling re-silient modulus seasonal variation of silty sand subgrade[J]. Canadi-an Geotechnical Journal,2014,51(12):1413-1422.
[5]牛玺荣,韩萍,张晓燕.车轮荷载下路基和基底竖向应力计算[J].长安大学学报自然科学版,2011,31(1):26-30.
[6]武立波,祁伟,牛富俊,等.我国季节性冻土区公路路基冻害及其防治研究进展[J].冰川冻土,2015,37(5):1283-1293.
[7]王书娟,陈志国,秦卫军,等.季节性冰冻地区路基冻胀机理分析[J].公路交通科技,2012,29(7):20-24.
[8]王天亮.冻融条件下水泥及右灰路基改良土的动静力特性研究[D].北京:北京交通大学,2011.
[9]郑郧,马巍,邴慧.冻融循环对土结构性影响的机理与定量研究方法[J].冰川冻土,2015,37(1):132-137.
[10] KWEON G,HWANG T. Deformational characteristics of subgradesoils and subbase materials with freeze-thaw[J]. KSCE Journal ofCivil Engineering,2013,17(6):1317-1322.
[11]凌建明,陈声凯,曹长伟.路基土回弹模量影响因素分析[J].建筑材料学报,2007,10(4):446-451.
[12]李雪连,陈宇亮,周志刚,等.红砂岩路基土动态模量影响因素及预估模型研究[J].实验力学,2014,29(5):627-634.
[13]程培峰,陈景龙,韩春鹏,等.季冻区路基土回弹模量影响因素分析[J].公路,2013,58(10):174-178.
[14]荆儒鑫.冻融循环作用后压实粉质粘土的静动力学性能研究[D].哈尔滨:哈尔滨工业大学,2014.
[15]王静,刘寒冰,吴春利,等.冻融循环对不同塑性指数路基土动力特性影响[J].岩土工程学报,2014,36(4):633-639.
[16]刘寒冰,王静,魏海斌,等.冻融循环下路基土抗剪强度与塑性指数相关性[J].吉林大学学报(工学版),2011,41(s2):149-152.
[17]李琳.冻融循环对路基土剪切强度的影响研究[J].湖南交通科技,2015,41(2):28-30.
[18]王威娜,支喜兰,毛雪松,等.冻融循环作用下路基土回弹模量试验研究[J].冰川冻土,2010,32(5):954-959.
[19]崔广芹,秦迪,尚志成,等.冻融循环作用下粉质砂土的压缩变形特性研究[J].水利水电技术,2017,48(11):174-178.
[20]袁克阔,党进谦,卓莉.黄土路基CBR值影响因素研究[J].路基工程,2009(6):125-127.
[21]交通部公路科学研究院.公路土工试验规程:JTG E40—2007[S].北京:人民交通出版社,2007.