高液限红黏土的压实特性与路基填筑方案
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摘要
红黏土由于水敏性一般不宜直接作为路基填料,工程中可通过加入碎石等粗骨料对其路用性能进行改良,但在实际工程应用中存在土石拌和不均的问题。基于此,为研究红黏土的压实特性,进行了标准击实和CBR强度试验。结果表明:红黏土的湿法击实结果更适用于指导工程实际,其击实曲线呈现双峰特性,分析认为第二个峰值是真正的最大干密度,其对应的含水率为最优含水率;探究了红黏土含水率与压实度、CBR强度之间的关系,压实度与强度并不呈正相关,最大CBR强度值对应的含水率比最优含水率高约5%,在适宜含水率和适当的击实功作用下,红黏土的CBR强度值和压实度都可以满足公路路基规范所需标准,这为红黏土用于路基填料提供了可能。因此,提出了"互层式"红黏土土石分层填筑方案,并运用Flac3D软件对几种不同工况下的路基填筑方式进行了数值模拟,其竖向沉降、数值模拟及工后沉降监测分析结果都表明,"互层式"红黏土土石分层填筑方式能满足高速公路路基沉降所要求的标准。
Red clay can not be used as embankment filler directly due to its water-sensitive property. In engineering, it can be improved by adding gravel and other coarse aggregates. However, it is difficult to mix soil and gravel uniform. In order to study the compaction characteristics of red clay, standard compaction and CBR strength tests were carried out in this paper. The test results showed that the wet compaction results of red clay were more suitable for guiding engineering practice, and its compaction curve showed double peak characteristics. The second peak was the real maximum dry density, and its corresponding moisture content was the optimal moisture content. The moisture content and compression of red clay were explored. The relationship between compactness and CBR strength was not positively correlated with strength. The moisture content corresponding to the maximum CBR strength was about 5% higher than the optimal moisture content. Under the effect of suitable moisture content and appropriate compaction work, the CBR strength and compactness of red clay can meet the requirements of highway roadbed specifications, which makes it possible for red clay to be used as roadbed filler. Therefore, the "sandwich form" red clay-gravel filling scheme was proposed. Flac3 D software was used to simulate several roadbed filling modes under different working conditions, and the vertical settlement was analyzed. The numerical simulation and post-construction settlement monitoring results showed that the "Sandwich form" red clay-gravel filling method can achieve the requirements of highway roadbed settlement standards.
Red clay can not be used as embankment filler directly due to its water-sensitive property. In engineering, it can be improved by adding gravel and other coarse aggregates. However, it is difficult to mix soil and gravel uniform. In order to study the compaction characteristics of red clay, standard compaction and CBR strength tests were carried out in this paper. The test results showed that the wet compaction results of red clay were more suitable for guiding engineering practice, and its compaction curve showed double peak characteristics. The second peak was the real maximum dry density, and its corresponding moisture content was the optimal moisture content. The moisture content and compression of red clay were explored. The relationship between compactness and CBR strength was not positively correlated with strength. The moisture content corresponding to the maximum CBR strength was about 5% higher than the optimal moisture content. Under the effect of suitable moisture content and appropriate compaction work, the CBR strength and compactness of red clay can meet the requirements of highway roadbed specifications, which makes it possible for red clay to be used as roadbed filler. Therefore, the "sandwich form" red clay-gravel filling scheme was proposed. Flac3 D software was used to simulate several roadbed filling modes under different working conditions, and the vertical settlement was analyzed. The numerical simulation and post-construction settlement monitoring results showed that the "Sandwich form" red clay-gravel filling method can achieve the requirements of highway roadbed settlement standards.
引文
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2 Wang Z W,Hong B N,Liu X,et al.Journal of Sichuan University(Engineering Science Edition),2011,43(1),17(in Chinese).王中文,洪宝宁,刘鑫,等.四川大学学报(工程科学版),2011,43(1),17.
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4 Liu L W,Yang H P,Kang S L,et al.Highway,2002(6),125(in Chinese).刘龙武,杨和平,康石磊,等.公路,2002(6),125.
5 Snethen D R,Miller G A,Cerato A B.Field Studies,2008,4(4),206.
6 Yang Z Q,Guo J Y.Rock And Soil Mechanics,1991,12(3),11(in Chinese).杨志强,郭见扬.岩土力学,1991,12(3),11.
7 Yang J,Zou L,Di X J,et al.Journal of Highway and Transportation Research and Development,2015,32(9),41(in Chinese).杨俊,邹林,狄先均,等.公路交通科技,2015,32(9),41.
8 Chen Y.Experimental analysis of settlement deformation characteristics of high embankment.Master’s Thesis,Southwest Jiaotong University,2008(in Chinese).陈云.高路堤沉降变形特性试验分析.硕士学位论文,西南交通大学,2008.
9 Li X D.Study on road performance and construction technique of Yunnan red clay.Master’s Thesis,Chang’an University,2016(in Chinese).李向东.云南红黏土路用性能及施工工艺研究.硕士学位论文,长安大学,2016.
10 Liu C Y,Dou Y M,Ron X.Journal of Hebei University of Technology,1999,28(4),64(in Chinese).刘春原,窦远明,戎贤.河北工业大学学报,1999,28(4),64.
11 Zhang Y T,Wang B T,Zhu B P.Science Technology and Engineering,2013,13(6),1676(in Chinese).张永婷,王保田,朱宝平.科学技术与工程,2013,13(6),1676.
12 Richard G,Cousin I,Sillon J F,et al.European Journal of Soil Science,2010,52(1),49.
13 Sivakumar V,Wheeler S J.Géotechnique,2000,50(4),359.
14 Naeini S A,Ziaie-Moayed R.International Journal of Civil Engineering,2009,7(2),124.
15 Cheng Y,Shi M L.Rock And Soil Mechanics,2011,32(4),979(in Chinese).程钰,石名磊.岩土力学,2011,32(4),979.
16 Zhang Y X.Journal of Wuhan Institute of Technology,2011,33(6),72(in Chinese).张宇旭.武汉工程大学学报,2011,33(6),72.
17 Zhou Y.Research on control of construction technology and prediction of settlement for high Embankment Filled.Master’s Thesis,Chongqing Jiaotong Universty,2013(in Chinese).周禹.高填方路基沉降预测与控制沉降施工技术的研究.硕士学位论文,重庆交通大学,2013.
18 Jones D,Rahim A,et al.Lancet,2010,371(9618),1050.