湿地湖泊相软土加固方案及固结沉降离心模型试验研究
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摘要
为研究湿地湖泊相软土的软基加固方案及固结沉降规律,分别进行真空堆载联合预压和水泥土搅拌桩复合地基加固湿地湖泊相软土路基的离心模型试验,对比分析2种方案的沉降发展和土压力变化情况。试验结果表明:相同条件下,真空堆载联合预压固结沉降发展更快,第30天固结度达到80%以上,第90天达到90%以上,且各测点土压力值更小;真空堆载联合预压下路堤横断面沉降分布更均匀,但后期沉降差较大,真空堆载联合预压的工后沉降约为水泥土搅拌桩复合地基的一半,加固效果更好;由含水率测试可知,真空堆载联合预压的影响深度至埋深10 m以下;2个模型的沉降拟合公式都为指数型函数,与实际沉降拟合较好,可预测长期的固结沉降。真空堆载联合预压方案优于水泥土搅拌桩复合地基加固方案。
Centrifugal model tests are carried out on marshy and lacustrine soft soil embankments treated by vacuum combined with surcharge preloading and reinforced by composite foundation with cement deep mixed columns, respectively. The variations of settlement and earth pressures in two centrifugal models are compared. The reinforcement effects are analyzed in an attempt to determine a suitable reinforcement method for marshy and lacustrine soft soil. Results conclude that under the same condition, the consolidation settlement of embankment treated by vacuum combined with surcharge preloading increases more rapidly than that reinforced by cement deep mixed columns: the consolidation degree reaches over 80% on the 30~(th) day and more than 90% on the 90~(th) day, yet with smaller earth pressures at each monitoring point. Moreover, the sectional settlement distribution of embankment treated by vacuum combined with surcharge preloading is more even, but the differential settlement is large in the late test period. The reinforcement effect of vacuum combined with surcharge preloading is better than composite foundation with cement deep mixed columns because post-construction settlement of the former is half of the latter. In addition, measurement of moisture content before and after centrifugal test suggest that the reinforcement depth of vacuum combined with surcharge preloading extends over ten meters in marshy and lacustrine soft soil. The settlement fitting equations of the two centrifugal models are both exponential functions, which fit well with monitored settlement curves and can be used to predict the long-term consolidation settlement of embankment. In conclusion, vacuum combined with surcharge preloading is superior to composite foundation with cement deep mixed columns.
Centrifugal model tests are carried out on marshy and lacustrine soft soil embankments treated by vacuum combined with surcharge preloading and reinforced by composite foundation with cement deep mixed columns, respectively. The variations of settlement and earth pressures in two centrifugal models are compared. The reinforcement effects are analyzed in an attempt to determine a suitable reinforcement method for marshy and lacustrine soft soil. Results conclude that under the same condition, the consolidation settlement of embankment treated by vacuum combined with surcharge preloading increases more rapidly than that reinforced by cement deep mixed columns: the consolidation degree reaches over 80% on the 30~(th) day and more than 90% on the 90~(th) day, yet with smaller earth pressures at each monitoring point. Moreover, the sectional settlement distribution of embankment treated by vacuum combined with surcharge preloading is more even, but the differential settlement is large in the late test period. The reinforcement effect of vacuum combined with surcharge preloading is better than composite foundation with cement deep mixed columns because post-construction settlement of the former is half of the latter. In addition, measurement of moisture content before and after centrifugal test suggest that the reinforcement depth of vacuum combined with surcharge preloading extends over ten meters in marshy and lacustrine soft soil. The settlement fitting equations of the two centrifugal models are both exponential functions, which fit well with monitored settlement curves and can be used to predict the long-term consolidation settlement of embankment. In conclusion, vacuum combined with surcharge preloading is superior to composite foundation with cement deep mixed columns.
引文
[1] 刘春原, 王向会. 衡水湖湿地湖泊相软土研究[M]. 北京: 人民交通出版社, 2016.
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[11] 荆志东, 郭永春, 邱恩喜, 等. 新型桩板结构对高速铁路软基沉降控制作用离心试验[J]. 岩土力学, 2010, 31(8): 2565-2569,2574.
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[13] 蒋泽中, 肖宏, 蒋关鲁, 等. 桩网结构加固土质路基的离心机模型试验研究[J]. 铁道工程学报, 2013, (11): 18-22,56.
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[17] 陈志杰, 陈哲, 赵凤岐. 软基沉降拟合的Boltzmann曲线模型研究[J]. 煤炭工程, 2014, 46(12): 90-92,96.
[18] 朱志铎, 周礼红. 软土路基全过程沉降预测的Logistic模型应用研究[J]. 岩土工程学报, 2009, 31(6): 965-969.
[2] 马文栋, 岳建东, 朱建民. 膨胀加固土桩的工程应用[J]. 公路, 2014, (10): 94-97.
[3] 李志强. 钉形水泥土双向搅拌桩在邢衡高速公路的应用[J]. 交通世界(建养·机械), 2014, (7): 120-122.
[4] 岳建东. 刚柔性长短桩处理高速公路软土地基的应用研究[J]. 黑龙江交通科技, 2014, (7): 6-7.
[5] 包承纲. 我国岩土离心模拟技术的应用与发展[J]. 长江科学院院报, 2013, 30(11): 55-66,71.
[6] 卢国胜, 蒋昌贵, 王迅. 搅拌桩处理软土地基的离心机试验研究[J]. 岩土力学, 2007, 28(10): 2101-2104,2122.
[7] 张良, 罗强, 周成, 等. 基于离心模型试验的深厚层软基加固方案比较研究[J]. 岩土工程学报, 2007, 29(7): 982-987.
[8] 陈建峰, 俞松波, 叶铁锋, 等. 软土地基加筋石灰土路堤离心模型试验研究[J]. 岩石力学与工程学报, 2008, 27(2): 287-293.
[9] 崔溦, 闫澍旺. 水泥土桩联合土工格栅复合地基的离心模型试验研究[J]. 岩土力学, 2008, 29(5): 1315-1319.
[10] 陈桂香, 孙红亮, 肖昭然. CFG桩复合地基处理软弱地基的离心机实验研究[J]. 建筑科学, 2009, 25(3): 24-27.
[11] 荆志东, 郭永春, 邱恩喜, 等. 新型桩板结构对高速铁路软基沉降控制作用离心试验[J]. 岩土力学, 2010, 31(8): 2565-2569,2574.
[12] 张良, 罗强, 陈虎, 等. 基于离心模型试验的软基路堤基底压力和垫层筋带拉力分析[J]. 岩土力学, 2010, 31(9): 2772-2779.
[13] 蒋泽中, 肖宏, 蒋关鲁, 等. 桩网结构加固土质路基的离心机模型试验研究[J]. 铁道工程学报, 2013, (11): 18-22,56.
[14] 龚晓南. 地基处理手册[M]. 3 版. 北京: 中国建筑工业出版社, 2008.
[15] JGJ 79—2002, 建筑地基处理技术规范[S]. 北京: 中国建筑工业出版社, 2002.
[16] 赵常洲. 高速公路软基真空-堆载联合预压机理及数值模拟[D]. 北京: 中国地质大学, 2008.
[17] 陈志杰, 陈哲, 赵凤岐. 软基沉降拟合的Boltzmann曲线模型研究[J]. 煤炭工程, 2014, 46(12): 90-92,96.
[18] 朱志铎, 周礼红. 软土路基全过程沉降预测的Logistic模型应用研究[J]. 岩土工程学报, 2009, 31(6): 965-969.