黄土高填方地基沉降规律及排气条件影响
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摘要
为了探知黄土高填方地基的沉降规律及影响因素,对某黄土高填方原地基沉降、孔隙水压力以及填筑体内部分层沉降的长期监测结果进行了对比分析。分析结果显示:饱和黄土原地基的沉降与孔隙水压力基本同步趋于稳定,未发生明显的蠕变变形,沉降主要是上覆填土荷载作用下的瞬时沉降和固结沉降;排气条件是影响非饱和填筑体沉降发展的关键因素,排气条件较好土层的工后初期沉降量甚至是排气条件较差土层沉降量的2倍以上,离心模型试验揭示的沉降发展规律同实测规律之间存在差异的主要原因之一就是排气条件不同。适当减缓施工速度以及合理布设排气通道有利于缩短工后沉降稳定时间,为工后建设赢取宝贵时间。
The settlement behaviors of high loess-filled foundation usually plays a critical role in later construction planning. In order to investigate the settlement behaviors and affecting factors of high loess-filled foundation, a long-term in-situ monitoring was carried out to monitor the settlement of a high loess-filled foundation, pore water pressure and internal sedimentation of the filling body. Monitoring results show that instant settlement and consolidation settlement caused by the overlying soil loading are the main components of the settlement of the original saturated loess foundation. Moreover, the settlement and the pore water pressure tend to be stable at the same time, while no obvious creep deformation occurs during this process. On the other hand, the settlement of unsaturated filled foundation is largely dependent on the exhaust conditions. For example, the initial post-construction settlement of the soil with better exhaust condition is even more than 2 times of the soil settlement under non-ideal exhaust condition. Thus, variation of exhaust conditions is one of the main reasons for the soil settlement difference between the centrifugal model test and the in-situ monitoring. Properly slowing down construction speed and reasonably arranging exhaust passages are helpful to shorten the time of post-construction settlement stabilization and save time for subsequent construction.
The settlement behaviors of high loess-filled foundation usually plays a critical role in later construction planning. In order to investigate the settlement behaviors and affecting factors of high loess-filled foundation, a long-term in-situ monitoring was carried out to monitor the settlement of a high loess-filled foundation, pore water pressure and internal sedimentation of the filling body. Monitoring results show that instant settlement and consolidation settlement caused by the overlying soil loading are the main components of the settlement of the original saturated loess foundation. Moreover, the settlement and the pore water pressure tend to be stable at the same time, while no obvious creep deformation occurs during this process. On the other hand, the settlement of unsaturated filled foundation is largely dependent on the exhaust conditions. For example, the initial post-construction settlement of the soil with better exhaust condition is even more than 2 times of the soil settlement under non-ideal exhaust condition. Thus, variation of exhaust conditions is one of the main reasons for the soil settlement difference between the centrifugal model test and the in-situ monitoring. Properly slowing down construction speed and reasonably arranging exhaust passages are helpful to shorten the time of post-construction settlement stabilization and save time for subsequent construction.
引文
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[14]朱才辉,李宁,刘明振,等.吕梁机场黄土高填方地基工后沉降时空规律分析[J].岩土工程学报,2013,35(2):293-301.ZHU Cai-hui,LI Ning,LIU Ming-zhen,et al.Spatiotemporal laws of post-construction settlement of loess-filled foundation of Lüliang airport[J].Chinese Journal of Geotechnical Engineering,2013,35(2):293-301.
[2]王奎华,谢康和,曾国熙.双面半透水边界的一维黏弹性固结理论[J].岩石力学与工程学报,1998,20(2):34-36.WANG Kui-hua,XIE Kang-he,ZENG Guo-xi.A study on 1-D consolidation of soils exhibiting rheological characteristics with impeded boundaries[J].Chinese Journal of Rock Mechanics and Engineering,1998,20(2):34-36.
[3]汤斌,陈晓平,张伟.考虑流变性状的软土地基固结有限元分析[J].岩土力学,2004,25(4):583-589.TANG Bin,CHEN Xiao-ping,ZHANG Wei.Finite element analysis for consolidation of soft clay ground considering its rheological behaviors[J].Rock and Soil Mechanics,2004,25(4):583-589.
[4]张敏江,张丽萍.结构性软土微观结构参数及结构性流变模型[J].沈阳建筑大学学报(自然科学版),2006,22(2):177-180.ZHANG Min-jiang,ZHANG Li-ping.The study on the microstructure parameters and rheological constitutive relations of structural soft soils[J].Journal of Shenyang Jianzhu University(Natural Science),2006,22(2):177-180.
[5]殷宗泽,张海波,朱俊高,等.软土的次固结[J].岩土工程学报,2003,25(5):521-526.YIN Zong-ze,ZHANG Hai-bo,ZHU Jun-gao,et al.Secondary consolidation of soft soils[J].Chinese Journal of Geotechnical Engineering,2003,25(5):521-526.
[6]姚仰平,刘林,王琳,等.高填方地基的蠕变沉降计算方法[J].岩土力学,2015,36(增刊1):154-158.YAO Yang-ping,LIU Lin,WANG Lin,et al.Method of calculating creep deformation of high filled embankment[J].Rock and Soil Mechanics,2015,36(Supp.1):154-158.
[7]冯志刚,朱俊高.软土次固结变形特性试验研究[J].水利学报,2009,40(5):583-587.FENG Zhi-gang,ZHU Jun-gao.Experimental study on secondary consolidation behavior of soft soils[J].Journal of Hydraulic Engineering,2009,40(5):583-587.
[8]周秋娟,陈晓平.软土次固结特性试验研究[J].岩土力学,2006,27(3):404-408.ZHOU Qiu-juan,CHEN Xiao-ping.Test study on properties of secondary consolidation of soft soil[J].Rock and Soil Mechanics,2006,27(3):404-408.
[9]余湘娟,殷宗泽,董卫军.荷载对软土次固结影响的试验研究[J].岩土工程学报,2007,29(6):913-916.YU Zhi-gang,YIN Zong-ze,DONG Wei-jun.Influence of load on secondary consolidation deformation of soft soils[J].Chinese Journal of Geotechnical Engineering,2007,29(6):913-916.
[10]高彦斌,朱合华,叶观宝,等.饱和软黏土一维次压缩系数Ca值的试验研究[J].岩土工程学报,2004,26(4):459-463.GAO Yan-bin,ZHU He-hua,YE Guan-bao,et al.The investigation of the coefficient of secondary compression Ca in odometer tests[J].Chinese Journal of Geotechnical Engineering,2004,26(4):459-463.
[11]朱才辉,李宁.基于黄土变形时效试验的高填方工后沉降研究[J].岩土力学,2015,36(10):3023-3031.ZHU Cai-hui,LI Ning.Post-construction settlement analysis of loess-high filling based on time-dependent deformation experiments[J].Rock and Soil Mechanics,2015,36(10):3023-3031.
[12]葛苗苗,李宁,张炜,等.黄土高填方沉降规律分析及工后沉降反演预测[J].岩石力学与工程学报,2017,36(3):745-753.GE Miao-miao,LI Ning,ZHANG Wei,et al.Settlement behavior and inverse prediction of post-construction settlement of high filled loess embankment[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(3):745-753.
[13]朱才辉,李宁.基于修正FDA方法的黄土高填方地基工后沉降分析[J].岩石力学与工程学报,2015,34(增刊1):3408-3417.ZHU Cai-hui,LI Ning.Post-construction settlement analysis of loess-high filled foundation based on modified FDA approach[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(Supp.1):3408-3417.
[14]朱才辉,李宁,刘明振,等.吕梁机场黄土高填方地基工后沉降时空规律分析[J].岩土工程学报,2013,35(2):293-301.ZHU Cai-hui,LI Ning,LIU Ming-zhen,et al.Spatiotemporal laws of post-construction settlement of loess-filled foundation of Lüliang airport[J].Chinese Journal of Geotechnical Engineering,2013,35(2):293-301.