砂雨法饱和模型制样相对密度控制要素与评价方法
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摘要
为满足动力离心液化试验相对密度(Dr)低的制样需求,实现砂雨法饱和模型制样相对密度的准确控制,建立了设备制模稳定性评价方法,通过自主研制一套适于饱和模型制样的鸭嘴式砂雨法装置,开展了三组干砂/饱和砂模型对比试验;通过分析出砂口尺寸、落距、移动速度等控制要素的影响,对新型装置制样性能进行了验证;采用微型动力触探仪测试饱和模型不同位置及深度的Dr空间分布,给出了模型均匀稳定性评价方法;建立描述砂雨法制样过程流速变化的数学模型和推导表达式,提出了控制稳态Dr的归一化标准.研究结果表明:3 mm为低密实度制样的最佳出砂口尺寸;饱和模型Dr随水中落距的变化率为空中落距变化率的3.5倍,水中落距是饱和制样密实度的主导控制要素;出砂口移动速度最高达到颗粒落速的31%,对低密实度制样影响不可忽略;设备移速与落距对颗粒流速及试样Dr大小具有决定作用.
Accurate control of relative density(Dr) in saturated pluviation method is the fundamental requirement for low relative density sample preparation of dynamic centrifuge liquefaction tests. To achieve an evaluation method on pluviation stability, a set of duckbill pluviator which fits saturated modeling was developed. Three groups of dry and saturated sand model contrast tests were carried out to identify the impacts of nozzle size, drop distance and movement velocity, aiming to assess the capability of the developed sampling device. A mini dynamic penetrometer facility was applied to measure the spatial distribution of the saturated model's Dr, giving a homogeneity evaluation of the models. A particle-flow-velocity model for pluviation was derived to give a normalize criteria for density stable control. The results show that the optimal size of nozzle is 3 mm which satisfies the requirements of low compactness modeling. The change rate of Dr with thickness of water is 3.5 times of that with air drop height, indicating that thickness of water layer is the dominant factor on Dr of saturated model. The nozzle movement velocity is up to 31% of particle velocity which is non-trivial on the low density sample preparation. The travelling speed and drop height play a decisive role in particle flow velocity and Dr.
Accurate control of relative density(Dr) in saturated pluviation method is the fundamental requirement for low relative density sample preparation of dynamic centrifuge liquefaction tests. To achieve an evaluation method on pluviation stability, a set of duckbill pluviator which fits saturated modeling was developed. Three groups of dry and saturated sand model contrast tests were carried out to identify the impacts of nozzle size, drop distance and movement velocity, aiming to assess the capability of the developed sampling device. A mini dynamic penetrometer facility was applied to measure the spatial distribution of the saturated model's Dr, giving a homogeneity evaluation of the models. A particle-flow-velocity model for pluviation was derived to give a normalize criteria for density stable control. The results show that the optimal size of nozzle is 3 mm which satisfies the requirements of low compactness modeling. The change rate of Dr with thickness of water is 3.5 times of that with air drop height, indicating that thickness of water layer is the dominant factor on Dr of saturated model. The nozzle movement velocity is up to 31% of particle velocity which is non-trivial on the low density sample preparation. The travelling speed and drop height play a decisive role in particle flow velocity and Dr.
引文
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[19]徐超,贾斌,罗玉珊,等.圬工与加筋土组合式挡墙离心模型试验[J].同济大学学报:自然科学版,2015,43(3):379-385.XU Chao,JIA Bin,LUO Yushan,et al.Centrifuge model tests of behavior of masonry and reinforced soil composite retaining wall[J].Journal of Tongji University:Natural Science,2015,43(3):379-385.
[20]蔡正银,张晨,黄英豪.冻土离心模拟技术研究进展[J].水利学报,2017,48(4):398-407.CAI Zhengyin,ZHANG Chen,HUANG Yinghao.Areview on the development of geotechnical centrifuge modeling technique on frozen ground engineering[J].Journal of Hydraulic Engineering,2017,48(4):398-407.
[21]郑健,李育超,陈云敏.底泥固结对污染物运移影响的超重力离心试验模拟[J].浙江大学学报(工学版),2016,50(1):8-15.ZHENG Jian,LI Yuchao,CHEN Yunmin.Centrifuge test modeling of impact of sediment consolidation on contaminant transportation[J].Journal of Zhejiang University(Engineering Science),2016,50(1):8-15.
[22]安鹏,邢义川,张爱军,等.基于离心模型试验的深厚湿陷性黄土自重湿陷性评价研究[J].四川大学学报(工程科学版),2016,48(6):23-30.AN Peng,XING Yichuan,ZHANG Aijun,et al.Research on evaluation of self-weight collapsibility for large-thickness collapsible loess using centrifugal model test[J].Journal of Sichuan University(Engineering Science Edition),2016,48(6):23-30.
[23]TOBITA T,ASHINO T,REN J,et al.KyotoUniversity LEAP-GWU-2015 tests and the importance of curving the ground surface in centrifuge modelling[J].Soil Dynamics and Earthquake Engineering,2017,113:650-662.
[24]周燕国,李永刚,丁海军,等.砂土液化后再固结体变规律表征与离心模型试验验证[J].岩土工程学报,2014,36(10):1838-1845.ZHOU Yanguo,LI Yonggang,DING Haijun,et al.Characterization of reconsolidation volumetric strain of liquefied sand and validation by centrifuge model tests[J].Chinese Journal of Geotechnical Engineering,2014,36(10):1838-1845.
[25]MOHAMMADI S D,NIKOUDEL M R,RAHIMI H,et al.Application of the dynamic cone penetrometer(DCP)for determination of the engineering parameters of sandy soils[J].Engineering Geology,2008,101(3):195-203.
[2]马险峰,孔令刚,方薇,等.砂雨法试样制备平行试验研究[J].岩土工程学报,2014,36(10):1791-1801.MA Xianfeng,KONG Linggang,FANG Wei,et al.Parallel tests on preparation of samples with sand pourer[J].Chinese Journal of Geotechnical Engineering,2014,36(10):1791-1801.
[3]李浩,罗强,张正,等.砂雨法制备砂土地基模型控制要素试验研究[J].岩土工程学报,2014,36(10):1872-1878.LI Hao,LUO Qiang,ZHANG Zheng,et al.Experimental study on control element of sand pourer preparation of sand foundation model[J].Chinese Journal of Geotechnical Engineering,2014,36(10):1872-1878.
[4]KHARI M,KASSIM K,ADNAN A.Sand samples’preparation using mobile pluviator[J].Arabian Journal for Science and Engineering,2014,39(10):6825-6834.
[5]GADE V K,DASAKA S M.Development of a mechanized traveling pluviator to prepare reconstituted uniform sand specimens[J].Journal of Materials in Civil Engineering,2016,28(2):1-9.
[6]RAGHUNANDAN M,JUNEJA A,HSIUNG B.Preparation of reconstituted sand samples in the laboratory[J].International Journal of Geotechnical Engineering,2012,6(1):125-131.
[7]IQBAL W.Sand pluviation technique[M].[S.l.]:LAPLambert Academic Publishing,2012:1-10.
[8]袁晓铭,曹振中,孙锐,等.汶川8.0级地震液化特征初步研究[J].岩石力学与工程学报,2009,28(6):1288-1296.YUAN Xiaoming,CAO Zhenzhong,SUN Rui,et al.Preliminary research on liquefaction characteristics of Wenchuan 8.0 earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(6):1288-1296.
[9]徐锡伟,陈桂华,于贵华,等.芦山地震发震构造及其与汶川地震关系讨论[J].地学前缘,2013,20(3):11-20.XU Xiwei,CHEN Guihua,YU Guihua,et al.Seismogenic structure of Lushan earthquake and its relationship with Wenchuan earthquake[J].Earth Science Frontiers,2013,20(3):11-20.
[10]蒋关鲁,刘先峰,张建文,等.高速铁路液化土地基加固的振动台试验研究[J].西南交通大学学报,2006,41(2):190-196.JIANG Guanlu,LIU Xianfeng,ZHANG Jianwen,et al.Shaking table test of composite foundation reinforcement of saturated silty soil ground for high speed railway[J].Journal of Southwest Jiaotong University,2006,41(2):190-196.
[11]刘汉龙.土动力学与土工抗震研究进展综述[J].土木工程学报,2012,45(4):148-164.LIU Hanlong.A review of recent advances in soil dynamics and geotechnical earthquake engineering[J].China Civil Engineering Journal,2012,45(4):148-164.
[12]BOULANGER R W,MONTGOMERY J.Nonlinear deformation analyses of an embankment dam on a spatially variable liquefiable deposit[J].Soil Dynamics and Earthquake Engineering,2016,91:222-233.
[13]程新俊,景立平,崔杰,等.不同场地沉管隧道振动台模型试验研究[J].西南交通大学学报,2017,52(6):1113-1120.CHENG Xinjun,JING Liping,CUI Jie,et al.Research of shaking table model tests on immersed tunnels under different conitions[J].Journal of Southwest Jiaotong University,2017,52(6):1113-1120.
[14]苏雷,凌贤长,唐亮,等.可液化场地桥梁群桩基动力反应振动台试验研究[J].防灾减灾工程学报,2015,35(2):186-191.SU Lei,LING Xianzhang,TANG Liang,et al.Shaking table tests on dynamic responses of pile group foundations for bridge in liquefiable ground[J].Journal of Disaster Prevention and Mitigation Engineering,2015,35(2):186-191.
[15]冯研,蒋关鲁,陈伟志,等.离心模型试验预测复合地基沉降的精度[J].西南交通大学学报,2014,49(1):105-110.FENG Yan,JIANG Guanlu,CHEN Weizhi,et al.Accuracy of settlement prediction of composite foundation by centrifuge model tests[J].Journal of Southwest Jiaotong University,2014,49(1):105-110.
[16]涂杰文,刘红帅,汤爱平,等.基于离心振动台的堆积型滑坡加速度响应特征[J].岩石力学与工程学报,2015,34(7):1361-1369.TU Jiewen,LIU Hongshuai,TANG Aiping,et al.Acceleration response of colluvial landslide based on centrifugal shaking table test[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(7):1361-1369.
[17]王维早,许强,郑光,等.强降雨诱发缓倾堆积层边坡失稳离心模型试验研究[J].岩土力学,2016,37(1):87-95.WANG Weizao,XU Qiang,ZHENG Guang,et al.Centrifugal model tests on sliding failure of gentle debris slope under rainfall[J].Rock and Soil Mechanics,2016,37(1):87-95.
[18]王永志,WILSON D W,KHOSRAVI M,等.动力离心模型试验循环剪应力-剪应变反演方法对比[J].岩土工程学报,2016,38(2):271-277.WANG Yongzhi,WILSON D W,KHOSRAVI M,et al.Evaluation of cyclic shear stress-strain using inverse analysis techniques in dynamic centrifuge tests[J].Chinese Journal of Geotechnical Engineering,2016,38(2):271-277.
[19]徐超,贾斌,罗玉珊,等.圬工与加筋土组合式挡墙离心模型试验[J].同济大学学报:自然科学版,2015,43(3):379-385.XU Chao,JIA Bin,LUO Yushan,et al.Centrifuge model tests of behavior of masonry and reinforced soil composite retaining wall[J].Journal of Tongji University:Natural Science,2015,43(3):379-385.
[20]蔡正银,张晨,黄英豪.冻土离心模拟技术研究进展[J].水利学报,2017,48(4):398-407.CAI Zhengyin,ZHANG Chen,HUANG Yinghao.Areview on the development of geotechnical centrifuge modeling technique on frozen ground engineering[J].Journal of Hydraulic Engineering,2017,48(4):398-407.
[21]郑健,李育超,陈云敏.底泥固结对污染物运移影响的超重力离心试验模拟[J].浙江大学学报(工学版),2016,50(1):8-15.ZHENG Jian,LI Yuchao,CHEN Yunmin.Centrifuge test modeling of impact of sediment consolidation on contaminant transportation[J].Journal of Zhejiang University(Engineering Science),2016,50(1):8-15.
[22]安鹏,邢义川,张爱军,等.基于离心模型试验的深厚湿陷性黄土自重湿陷性评价研究[J].四川大学学报(工程科学版),2016,48(6):23-30.AN Peng,XING Yichuan,ZHANG Aijun,et al.Research on evaluation of self-weight collapsibility for large-thickness collapsible loess using centrifugal model test[J].Journal of Sichuan University(Engineering Science Edition),2016,48(6):23-30.
[23]TOBITA T,ASHINO T,REN J,et al.KyotoUniversity LEAP-GWU-2015 tests and the importance of curving the ground surface in centrifuge modelling[J].Soil Dynamics and Earthquake Engineering,2017,113:650-662.
[24]周燕国,李永刚,丁海军,等.砂土液化后再固结体变规律表征与离心模型试验验证[J].岩土工程学报,2014,36(10):1838-1845.ZHOU Yanguo,LI Yonggang,DING Haijun,et al.Characterization of reconsolidation volumetric strain of liquefied sand and validation by centrifuge model tests[J].Chinese Journal of Geotechnical Engineering,2014,36(10):1838-1845.
[25]MOHAMMADI S D,NIKOUDEL M R,RAHIMI H,et al.Application of the dynamic cone penetrometer(DCP)for determination of the engineering parameters of sandy soils[J].Engineering Geology,2008,101(3):195-203.
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