土钉与复合土钉支护结构数值模拟对比分析
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摘要
近几年来,复合土钉支护结构广泛应用于深基坑支护中。本文对一工程实例用SnEpFem土钉墙有限元数值分析软件,对土钉和预应力锚杆+土钉、微型桩+土钉、微型桩+预应力锚杆+土钉3种复合土钉支护结构的工作机制进行数值模拟,对比分析4种支护结构的坡面水平位移、坡顶沉降和沉降范围、坑底隆起、张拉区和塑性区范围等特点,发现:(1)与单纯土钉支护相比,复合土钉支护可以有效控制边坡变形,缩小边坡张拉区和塑性区范围,对提高边坡的稳定有利。(2)设置微型桩对坡面水平位移的控制比施加预应力的效果更好。(3)设置微型桩可以有效控制坡顶沉降,而施加预应力对坡顶沉降的影响很小。(4)4种支护结构对坑底隆起的影响趋势是一致的,量值变化很小。经过对比分析,在这一工程地质和水文地质条件下,最可靠的复合土钉支护结构是微型桩+预应力锚杆+土钉支护结构,该支护结构的变形、沉降以及张拉区和塑性区范围都是最小的,是最优的设计结构。
Foundation pits.In this paper,the authors use SnEpFem software to evaluate several alternative soil nail reinforcement structures: soil nail along,pre-stressed anchor plus soil nail;miniature pile plus soil nail;and miniature pile,pre-stressed anchor plus soil nail.Comparison of all four alternatives is done for the characteristics of horizontal deflections,ground surface settlements and the range of settlement,pit bottom uplifts and the areas of tension and plastic zones.It was concluded that(1) Compared with simple soil nail reinforcement structure,composite soil nail reinforcement can control slope distortion in effect,and reduce the areas of tension and plastic zones.Consequently,composite soil nail reinforcement structures can improve slope stability.(2) Setting miniature pile controls horizontal deflections better than adding pre-stress.(3) Setting miniature pile can efficiently control ground surface settlements,however,adding pre-stress influences it a little.(4) The effect for pit bottom uplifts is consistent in all the reinforcement structures,and the values vary a bit.By comparison,under this engineering geologic condition, of all the composite soil nail reinforcement structures,the most dependable one is miniature pile + pre-stressed anchor + soil nail reinforcement structure.Its distortion,settlement and the areas of tension and plastic zones are least in the four structures,and it is the most excellent reinforcement structure.
Foundation pits.In this paper,the authors use SnEpFem software to evaluate several alternative soil nail reinforcement structures: soil nail along,pre-stressed anchor plus soil nail;miniature pile plus soil nail;and miniature pile,pre-stressed anchor plus soil nail.Comparison of all four alternatives is done for the characteristics of horizontal deflections,ground surface settlements and the range of settlement,pit bottom uplifts and the areas of tension and plastic zones.It was concluded that(1) Compared with simple soil nail reinforcement structure,composite soil nail reinforcement can control slope distortion in effect,and reduce the areas of tension and plastic zones.Consequently,composite soil nail reinforcement structures can improve slope stability.(2) Setting miniature pile controls horizontal deflections better than adding pre-stress.(3) Setting miniature pile can efficiently control ground surface settlements,however,adding pre-stress influences it a little.(4) The effect for pit bottom uplifts is consistent in all the reinforcement structures,and the values vary a bit.By comparison,under this engineering geologic condition, of all the composite soil nail reinforcement structures,the most dependable one is miniature pile + pre-stressed anchor + soil nail reinforcement structure.Its distortion,settlement and the areas of tension and plastic zones are least in the four structures,and it is the most excellent reinforcement structure.
引文
[1]陈肇元,崔京浩主编.土钉支护在基坑工程中的应用(第二版)[M].北京:中国建筑工业出版社,2000.Chen,Z.Y.,Cu i,J.H.,Applications of soil nail reinforcem ent infoundation p it engineering(2nd ed.).Beijing:Ch inese construc-tion industry press,2000.
[2]秦四清,万林海,贾金禄,等.深基坑工程优化设计[M].北京:地震出版社,1998.Q in,S.Q.,W an,L.H.,Jia,J.L.et al..Optimal design fordeep foundation p it engineering.Beijing:Seismological press,1998.
[3]秦四清,王建党,王清,等.土钉支护机理与优化设计[M].北京:地质出版社,1999.Q in,S.Q.,W ang,J.D.,W ang,Q.et al..Supporting m echa-n ism s and optimal design for soil nails.Beijing:Geological Press,1999.
[4]秦四清,贾洪,等.预应力对土钉支护结构变形和破坏影响的数值分析[J].岩土力学,2005,25(9):1356~1362.Q in,S.Q.,Jia,H.et al..Num erical simu lations of the deforma-tion and failure in the pre-stressed soil-nailed reinforcem entstructure,Rock and SoilM echan ics,2005,25(9):1356~1362.
[5]Goodman,R.E.,Taylor R/L/,and B rekke,T.L..A model forthe m echan ics of jointed rock〗[J].Journal of soil m echan ics andfoundation d ivision,ASCE,94,1968,1121~1129.
[6]D esai,C.S.,Zaman,M.M..Th in-layer elem ent for interfacesand joints[J].International Journal of num erical and analyticalm ethods in Geom echan ics,1984,8,1101~1110.
[7]李志刚,秦四清,张冰峰.土钉支护现场测试及三维数值模拟分析[J].工程地质学报,2003,12(1):69~73.[7]L i,Z.G.,Q in,S.Q.,Zhang,B.F.,In site test and three-d im ensional simu lation analysis of soil nailing support,Journalof Engineering Geology,2003,12(1):69~73.
[8]宋二详,陈肇元.土钉支护及其有限元分析[J].工程勘察,1996,(2):1~6.Song,E.X..,Chen,Z.Y.,Soil nail supporting and FEM analy-sis,Engineering investigation,1996,(2):1~6.
[9]娄国充,康中山,郭增强.土钉支护结构的施工监测与变形控制[J].工程地质学报,2004,12(3):323~327.Lou,G.C.,Kang,Z.S.,Guo,Z.Q.,Mon itoring the deforma-tion of the soil-nailing support structure and its control,Journalof Engineering Geology,2004,12(3):323~327.
[10]李志刚,秦四清,张冰峰.土钉支护现场测试及三维数值模拟分析[J].工程地质学报,2004,12(1):69~73.LI Zh igang,Q in S iq ing,Zhang B ingfeng.In situ test and three-d im ensional simu lation analysis of soil nailing support.Journal ofEngineering Geology,2004,12(1):69~73.
[2]秦四清,万林海,贾金禄,等.深基坑工程优化设计[M].北京:地震出版社,1998.Q in,S.Q.,W an,L.H.,Jia,J.L.et al..Optimal design fordeep foundation p it engineering.Beijing:Seismological press,1998.
[3]秦四清,王建党,王清,等.土钉支护机理与优化设计[M].北京:地质出版社,1999.Q in,S.Q.,W ang,J.D.,W ang,Q.et al..Supporting m echa-n ism s and optimal design for soil nails.Beijing:Geological Press,1999.
[4]秦四清,贾洪,等.预应力对土钉支护结构变形和破坏影响的数值分析[J].岩土力学,2005,25(9):1356~1362.Q in,S.Q.,Jia,H.et al..Num erical simu lations of the deforma-tion and failure in the pre-stressed soil-nailed reinforcem entstructure,Rock and SoilM echan ics,2005,25(9):1356~1362.
[5]Goodman,R.E.,Taylor R/L/,and B rekke,T.L..A model forthe m echan ics of jointed rock〗[J].Journal of soil m echan ics andfoundation d ivision,ASCE,94,1968,1121~1129.
[6]D esai,C.S.,Zaman,M.M..Th in-layer elem ent for interfacesand joints[J].International Journal of num erical and analyticalm ethods in Geom echan ics,1984,8,1101~1110.
[7]李志刚,秦四清,张冰峰.土钉支护现场测试及三维数值模拟分析[J].工程地质学报,2003,12(1):69~73.[7]L i,Z.G.,Q in,S.Q.,Zhang,B.F.,In site test and three-d im ensional simu lation analysis of soil nailing support,Journalof Engineering Geology,2003,12(1):69~73.
[8]宋二详,陈肇元.土钉支护及其有限元分析[J].工程勘察,1996,(2):1~6.Song,E.X..,Chen,Z.Y.,Soil nail supporting and FEM analy-sis,Engineering investigation,1996,(2):1~6.
[9]娄国充,康中山,郭增强.土钉支护结构的施工监测与变形控制[J].工程地质学报,2004,12(3):323~327.Lou,G.C.,Kang,Z.S.,Guo,Z.Q.,Mon itoring the deforma-tion of the soil-nailing support structure and its control,Journalof Engineering Geology,2004,12(3):323~327.
[10]李志刚,秦四清,张冰峰.土钉支护现场测试及三维数值模拟分析[J].工程地质学报,2004,12(1):69~73.LI Zh igang,Q in S iq ing,Zhang B ingfeng.In situ test and three-d im ensional simu lation analysis of soil nailing support.Journal ofEngineering Geology,2004,12(1):69~73.
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