考虑卸荷作用的黄土湿陷性评价方法研究
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摘要
卸荷作用会导致湿陷性黄土部分湿陷量未发生,但目前黄土湿陷性评价方法中未考虑卸荷因素的影响。推导并建立了卸荷条件下黄土湿陷系数的表达式,并通过卸荷湿陷试验确定了表达式中的参数取值。首先定义湿陷完成比、卸荷应力比分别用来表征卸荷作用发生前黄土湿陷变形的完成程度及卸荷作用发生时卸荷量的大小。运用湿陷完成比及卸荷应力比推导出卸荷湿陷系数的计算公式。该公式揭示出卸荷湿陷系数是对湿陷系数一定程度的折减,而该折减与湿陷完成比及卸荷应力比有关。随后进行黄土在不同湿陷完成比和卸荷应力比下的卸荷湿陷试验,得到上述条件下黄土卸荷湿陷量的取值。对试验结果进行分析得到卸荷湿陷系数的具体表达式。该公式可用于计算在不同初始压力下,任意湿陷完成比及卸荷应力比下的卸荷湿陷系数。通过对比卸荷湿陷系数的试验值与计算值验证了所推公式的合理性及准确性。得到了考虑卸荷作用的黄土湿陷性影响系数的确定方法,进一步总结了卸荷作用对黄土湿陷性的影响规律。
The segmental collapse of loess will not occur because of unloading. But loess collapse potential is generally evaluated without considering the influence of unloading. The coefficient of unloading collapse is obtained by unloading collapse test. The completion ratio of collapse is defined to represent the degree of loess collapse before unloading. The unloading ratio is defined to represent the degree of unloading. The calculation formula of unloading collapse coefficient is derived by completion ratio of collapse and unloading ratio. Through unloading collapse test, the unloading collapse of loess is measured in different unloading and collapse conditions. The specific expression of the unloading collapse coefficient is obtained by analyzing test results. It is suitable to calculate unloading collapse coefficient in either initial pressure, unloading amount and collapse condition. The calculated results based on the proposed equation are in good agreement with the test results. The loess collapse deformation have been further summarized by defining coefficient of collapse potential under the condition of unloading.
The segmental collapse of loess will not occur because of unloading. But loess collapse potential is generally evaluated without considering the influence of unloading. The coefficient of unloading collapse is obtained by unloading collapse test. The completion ratio of collapse is defined to represent the degree of loess collapse before unloading. The unloading ratio is defined to represent the degree of unloading. The calculation formula of unloading collapse coefficient is derived by completion ratio of collapse and unloading ratio. Through unloading collapse test, the unloading collapse of loess is measured in different unloading and collapse conditions. The specific expression of the unloading collapse coefficient is obtained by analyzing test results. It is suitable to calculate unloading collapse coefficient in either initial pressure, unloading amount and collapse condition. The calculated results based on the proposed equation are in good agreement with the test results. The loess collapse deformation have been further summarized by defining coefficient of collapse potential under the condition of unloading.
引文
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[20]史小萌,刘保国,亓轶.水泥石膏胶结相似材料在固-流耦合试验中的适用性[J].岩土力学,2015,36(9):2624-2630.SHI Xiao-meng,LIU Bao-guo,QI Yi.Applicability of similar materials bonded by cement and plaster in solid-liquid coupling tests[J].Rock and Soil Mechanics,2015,36(9):2624-2630.
[2]邵生俊,李骏,李国良,等.大厚度自重湿陷黄土湿陷变形评价方法的研究[J].岩土工程学报,2015,37(6):965-978.SHAO Sheng-jun,LI Jun,LI Guo-liang,et al.Evaluation method for self-weight collapsible deformation of large thickness loess foundation[J].Chinese Journal of Geotechnical Engineering,2015,37(6):965-978.
[3]杨校辉,黄雪峰,朱彦鹏,等.大厚度自重湿陷性黄土地基处理深度和湿陷性评价试验研究[J].岩石力学与工程学报,2014,33(5):1063-1074.YANG Xiao-hui,HUANG Xue-feng,ZHU Yan-peng,et al.Experimental study on collapsibility evaluation and treatment depths of collapsible loess upon self weight with thick depth[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(5):1063-1074.
[4]黄雪峰,杨校辉.湿陷性黄土现场浸水试验研究进展[J].岩土力学,2013,34(增刊2):222-228.HUANG Xue-feng,YANG Xiao-hui.A study progress on in-situ soaking test on collapsible loess[J].Rock and Soil Mechanics,2013,34(Suppl.2):222-228.
[5]张爱军,邢义川,胡新丽,等.伊犁黄土强烈自重湿陷性的影响因素分析[J].岩土工程学报,2016,38(增刊2):117-122.ZAHNG Ai-jun,XING Yi-chuan,HU Xin-li,et al.Influence factors of strong self-weight collapsibility of Ili loess[J].Chinese Journal of Geotechnical Engineering,2016,38(Suppl.2):117-122.
[6]安鹏,张爱军,邢义川,等.伊犁深厚湿陷性黄土浸水入渗及沉降变形特征分析[J].岩土力学,2017,38(2):557-564.AN Peng,ZHANG Ai-jun,XING Yi-chuan,et al.Analysis of soak infiltration and deformation characteristics for thick collapsible loess in Ili region[J].Rock and Soil Mechanics,2017,38(2):557-564.
[7]姚志华,黄雪峰,陈正汉,等.关于黄土湿陷性评价和卸荷减小湿陷量的新认识[J].岩土力学,2014,35(4):998-1006.YAO Zhi-hua,HUANG Xue-feng,CHEN Zheng-han,et al.New recognition of collapsibility evaluation and remnant collapse of loess[J].Rock and Soil Mechanics,2014,35(4):998-1006.
[8]叶为民,崔玉军,黄雨,等.黄土的湿陷性及其评价准侧[J].岩石力学与工程学报,2006,25(3):550-556.YE Wei-min,CUI Yu-jun,HUANG Yu,et al.Collapsibility of loess and its discrimination criteria[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(3):550-556.
[9]张茂花,谢永利,刘保健.增(减)湿时黄土的湿陷系数曲线特征[J].岩土力学,2005,26(9):1363-1368.ZHANG Mao-hua,XIE Yong-li,LIU Bao-jian.Characteristics of collapsibility coefficient curves of loess during moistening and demoistening process[J].Rock and Soil Mechanics,2005,26(9):1363-1368.
[10]文宝萍,余志山,黎志恒,等.灌溉条件下黑方台黄土湿陷特征及其内在机理[J].兰州大学学报(自然科学版),2015,51(6):777-785.WEN Bao-ping,YU Zhi-shan,LI Zhi-heng,et al.Collapsibility of the loess soils on Heifangtai tableland due to wetting by flooding irrigation and its mechanism[J].Journal of Lanzhou University(Natural Science),2015,51(6):777-785.
[11]张登飞,陈存礼,杨炯,等.侧限条件下增湿时湿陷性黄土的变形及持水特性[J].岩石力学与工程学报,2016,35(3):604-612.ZHANG Deng-fei,CHEN Cun-li,YANG Jiong,et al.Deformation and water retention behaviour of collapsible loess during wetting under lateral confinement[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(3):604-612.
[12]赵明华,何腊平,张玲.基于荷载传递法的CFG桩复合地基沉降计算[J].岩土力学,2010,31(3):839-844.ZHAO Ming-hua,HE La-ping,ZHANG Ling,et al.Settlement calculation of CFG pile composite foundation based on load transfer method[J].Rock and Soil Mechanics,2010,31(3):839-844.
[13]黄雪峰,杨校辉,殷鹤,等.湿陷性黄土场地湿陷下限深度与桩基中性点位置关系研究[J].岩土力学,2015,36(增刊2):296-302.HUANG Xue-feng,YANG Xiao-hui,YIN He,et al.Study of relationship between maximum collapsing depth and neutral point position of pile foundation in collapsible loess ground[J].Rock and Soil Mechanics,2015,36(Suppl.2):296-302.
[14]朱彦鹏,赵天时,陈长流.桩基负摩阻力沿桩长变化的试验研究[J].岩土力学,2013,34(增刊1):265-272.ZHU Yan-peng,ZHAO Tian-shi,CHEN Chang-liu.Field tests on changes of pile negative friction along its length[J].Rock and Soil Mechanics,2013,34(Suppl.1):265-272.
[15]魏进,李哲,郝忙利,等.自重湿陷性黄土场地的桩基浸水载荷试验[J].长安大学学报(自然科学版),2011,31(5):63-67.WEI Jin,LI Zhe,HAO Mang-li,et al.Submerged static load test of pile foundation in collapsible loess area[J].Journal of Chang’an University(Natural Science),2011,31(5):63-67.
[16]刘争宏,郑建国,张继文,等.湿陷性黄土地区桥梁桩基工后沉降计算方法研究[J].岩土工程学报,2014,36(2):320-326.LIU Zheng-hong,ZHENG Jian-guo,ZHANG Ji-wen,et al.Method for post-construction settlement of pile foundation of bridges in collapsible loess area[J].Chinese Journal of Geotechnical Engineering,2014,36(2):320-326.
[17]张玉伟,翁木生.大厚度湿陷性黄土地层浸水条件下承载桩基对近距隧道的影响研究[J].岩石力学与工程学报,2017,36(8):2040-2050.ZHANG Yu-wei,WENG Mu-sheng.Influence of pile foundation to adjacent tunnel with water immersion in collapsible loess layer of great thickness[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(8):2040-2050.
[18]南京水利科学研究院.GB/T50123-1999土工试验方法标准[S].北京:中国计划出版社,1999.Nanjing Hydraulic Research Institute.GB/T50123-1999Standard for soil test method[S].Beijing:China Planning Press,1999.
[19]陈正汉,许镇鸿,刘祖典.关于黄土湿陷的若干问题[J].土木工程学报,1986,19(3):86-94.CHEN Zheng-han,XüZhen-hong,LIU Zu-dian.Some problems about the collapse of loess[J].China Civil Engineering Journal,1986,19(3):86-94.
[20]史小萌,刘保国,亓轶.水泥石膏胶结相似材料在固-流耦合试验中的适用性[J].岩土力学,2015,36(9):2624-2630.SHI Xiao-meng,LIU Bao-guo,QI Yi.Applicability of similar materials bonded by cement and plaster in solid-liquid coupling tests[J].Rock and Soil Mechanics,2015,36(9):2624-2630.