考虑基岩层面影响的水平受荷嵌岩桩模型试验研究
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摘要
西南地区常见碎石土-基岩斜坡地基,在此类地基上的嵌岩桩基础,其上覆土层、嵌固段基岩多为倾斜。然而岩石试样中结构面倾角改变时,岩石试样的强度也随之发生变化。故当嵌固段基岩存在层面且层面具有倾角时,往往对桩基的水平承载特性影响很大,所以基岩层面是影响嵌岩桩水平承载性能的主要因素之一。本文采用物理模型试验,通过改变嵌固段基岩层面倾角,得出嵌固段基岩不同层面倾角对于桩顶位移,桩身内力的发展规律,进而研究其对水平受荷嵌岩桩承载性能的影响。试验结果表明:在碎石土-层状基岩斜坡地基场地中,嵌固段基岩存在层面会降低嵌岩桩水平承载性能。相对于完整基岩,嵌固段层状基岩存在水平层面时,临界荷载下降了17%、最大弯矩值下降了23%、最大剪力值下降了37.5%;而嵌固段基层层面为倾斜时,嵌岩桩水平承载性能下降的更多,且层面倾角为逆向30°时比顺向30°更加不利于嵌岩桩的水平受荷;桩身最大弯矩点与最大剪力点位置随嵌固段层状基岩倾角变化影响比较小,最大弯矩点位置几乎没有变化,最大剪力点位置在嵌固段基岩层面为顺向30°与逆向30°时下降了1倍桩径。该项研究可为在不同层面倾角下的层状岩体斜坡地基上受水平荷载的嵌岩桩设计作一定的指导。。
Stratum structure of gravel soil-bedrock slope foundation is common in southwest China. The upper layer is slightly crushed stone and the lower bedrock is mainly weathered-slightly weathered thick quartz sandstone. The weak interlayer is black phyllite. Rock quality is good. For a rock-socketed pile foundation built on slopes and subjected to horizontal loads,the bedrock of the overlying soil and embankment is often inclined. If structural inclination of the rock changes,the strength of the rock specimen would also change. If the bedrock of embeddedsection exists and the bedding plane has inclination angle,it often affects the horizontal bearing property of pile foundation greatly. Therefore,the bedrock level is one of the main factors affecting the horizontal bearing capacity of rock-socketed pile. At present,there is little research on the horizontal bearing capacity of piles for the level inclination of embedded section. This article digs deeper into this aspect of theory. The physical model test is carried out at Physical Simulation Laboratory,Chengdu University of Technology. It uses a single pile water static load test.It uses small blocks of masonry and polyethylene film to simulate the structural plane of the rock formation. Loading method maintains load slowly. Jack is placed at the back of the pile to apply horizontal load. Each level load is0. 3 k N. The rock-socketed piles under four conditions are simulated by changing the inclination of bedrock of the embedded section. Model pile length is 1 meter. The embedded depth of the model pile is three times of the pile diameter. The exposed pile top length is equal to the pile diameter. The top soil and bedrock slope are 30 degrees in gravel soil-bedrock slope foundation site. Bedrock is complete bedrock and bedding inclination respectively horizontal,forward 30 degrees,reverse 30 degrees. The test data are obtained as follows. The top displacement of pile top,the maximum value of bending moment of pile body and the maximum position of bending moment,the position of maximum shear force and the maximum shear value of pile body are obtained with the variation of loads.Then the bearing capacity of pile foundation under different inclinations is analyzed. The critical load,ultimate load,pile foundation horizontal bearing capacity characteristic value and the maximum pile bending moment value and the maximum pile shear force value of the piles at different grass-root levels are compared. Finally,the effect on the bearing capacity of horizontal loaded rock-socketed pile is studied. The results show that in the slope site,the existence of bedrock in embedded section can reduce the horizontal bearing capacity of rock-socketed pile.Compared with the intact bedrock,when the bedded bedrock in horizontal section exists,the critical load decreases by 17%,the maximum bending moment decreases by 23% and the maximum shear force decreases by 37. 5%.However,the horizontal bearing capacity of rockfill piles drops more when the base level of the embankment is inclined. The influence of the maximum bending moment point and the position of the maximum shear point on the inclination change of bedrock inclination in the embedded section is relatively small. The location of the maximum bending moment is almost unchanged. The position of the maximum shear point is reduced by 1 times of pile diameter when the bedrock of the embedded section is forward 30 degrees and reverse 30 degrees. This study can be used as a reference for the design of rock-fill piles bearing horizontal loads on layered and slope rock mass foundations with different dip angles.
Stratum structure of gravel soil-bedrock slope foundation is common in southwest China. The upper layer is slightly crushed stone and the lower bedrock is mainly weathered-slightly weathered thick quartz sandstone. The weak interlayer is black phyllite. Rock quality is good. For a rock-socketed pile foundation built on slopes and subjected to horizontal loads,the bedrock of the overlying soil and embankment is often inclined. If structural inclination of the rock changes,the strength of the rock specimen would also change. If the bedrock of embeddedsection exists and the bedding plane has inclination angle,it often affects the horizontal bearing property of pile foundation greatly. Therefore,the bedrock level is one of the main factors affecting the horizontal bearing capacity of rock-socketed pile. At present,there is little research on the horizontal bearing capacity of piles for the level inclination of embedded section. This article digs deeper into this aspect of theory. The physical model test is carried out at Physical Simulation Laboratory,Chengdu University of Technology. It uses a single pile water static load test.It uses small blocks of masonry and polyethylene film to simulate the structural plane of the rock formation. Loading method maintains load slowly. Jack is placed at the back of the pile to apply horizontal load. Each level load is0. 3 k N. The rock-socketed piles under four conditions are simulated by changing the inclination of bedrock of the embedded section. Model pile length is 1 meter. The embedded depth of the model pile is three times of the pile diameter. The exposed pile top length is equal to the pile diameter. The top soil and bedrock slope are 30 degrees in gravel soil-bedrock slope foundation site. Bedrock is complete bedrock and bedding inclination respectively horizontal,forward 30 degrees,reverse 30 degrees. The test data are obtained as follows. The top displacement of pile top,the maximum value of bending moment of pile body and the maximum position of bending moment,the position of maximum shear force and the maximum shear value of pile body are obtained with the variation of loads.Then the bearing capacity of pile foundation under different inclinations is analyzed. The critical load,ultimate load,pile foundation horizontal bearing capacity characteristic value and the maximum pile bending moment value and the maximum pile shear force value of the piles at different grass-root levels are compared. Finally,the effect on the bearing capacity of horizontal loaded rock-socketed pile is studied. The results show that in the slope site,the existence of bedrock in embedded section can reduce the horizontal bearing capacity of rock-socketed pile.Compared with the intact bedrock,when the bedded bedrock in horizontal section exists,the critical load decreases by 17%,the maximum bending moment decreases by 23% and the maximum shear force decreases by 37. 5%.However,the horizontal bearing capacity of rockfill piles drops more when the base level of the embankment is inclined. The influence of the maximum bending moment point and the position of the maximum shear point on the inclination change of bedrock inclination in the embedded section is relatively small. The location of the maximum bending moment is almost unchanged. The position of the maximum shear point is reduced by 1 times of pile diameter when the bedrock of the embedded section is forward 30 degrees and reverse 30 degrees. This study can be used as a reference for the design of rock-fill piles bearing horizontal loads on layered and slope rock mass foundations with different dip angles.
引文
Chen X,Liao Z H,Li D J.2011.Experimental study of effects of joint inclination angle and connectivity rate on strength and deformation properties of rock masses under uniaxial compression[J].Chinese Journal of Rock Mechnics and Engineering,30(4):781-789.
Geng D X,Yang L D.2003.Mechanical properties and numerical simulation of sandwich rock[J].Underground Space,23(4):380-383-455.
Guo S F,Qi S W,Li X X,et al.2016.Strength and deformation characteristics of rock sample with discontinuities under numercial uniaxial compression simulation tests[J].Journal of Engineering Geology,24(5):891-898.
Huang J Y,Wang D Y,Wang C Z.2008.On the lateral bearing behavior of large-diameter rock-socketed cast-in-place piles at river port[J].Port and Waterway Engineering,(3):59-63.
Liu K D,Zhang Y J.2002.Influence factors on shear failure orientation of layered rocks[J].Chinese Journal of Rock Mechanics and Engineering,21(3):335-339.
Liu Y Q,Li H B,Li J R,et al.2009.Study on strength characteristics of slates based on Hoek-Brown criterion[J].Chinese Journal of Rock Mechanics and Engineering,28(S2):3452-3457.
Liu Z S,Zhuo Y,Shi B L,et al.2010.Horizontal bearing capacity of pile foundation in high-piled wharf with inclined ground surface[J].Chinese Journal of Geotechnical Engineering,32(12):1861-1867.
Liu Z Y,Jiang X L,Lin H.2011.Numerical analysis for shear characteristic of soft structure plane with pile reinforcement[J].Journal of Central South University(Science and Technology),42(5):1461-1466.
Qin L K.2016.Study on the effect of deformation of embeded rock mass on the interaction of sliding pile and stratified rock mass under excavation[D].Chengdu:Southwest Petroleum University.
The Professional Stardards Complilation Group of People's Republic of China.1999.Soil test method standard(GB/T50123)[S].Beijing:China Planning Press.
The Professional Stardards Complilation Group of People's Republic of China.2014.Technical code for testing building foundation piles(JGJ 106-2014)[S].Beijing:China Architecture&Building Press.
Wang D W,Wang C M,Kuang S H.2016.Selection and optimization of the site of bridge piled foundation on the layered rock slope[J].Journal of Engineering Geology,24(S1):861-867.
Wang H J,Liu D A,Huang Z Q,et al.2017.Mechanical properties and brittleness evaluation of layered shale rock[J].Journal of Engineering Geology,25(6):1414-1423.
Wang J H,Chen J J,Ke X.2007.Characteristics of large diameter rocksocketed piles under lateral loads[J].Chinese Journal o Geotechnical Engineering,29(8):1194-1198.
Zhao M H,Lei Y,Liu X M.2009.Analysis of load transfer of rocksocketed piles based on characteristics of pile-rock structura plane[J].Chinese Journal of Rock Mechanics and Engineering,28(1):103-110.
陈新,廖志红,李德建.2011.节理倾角及连通率对岩体强度、变形影响的单轴压缩试验研究[J].岩石力学与工程学报,30(4):781-789.
耿大新,杨林德.2003.层状岩体的力学特性及数值模拟分析[J].地下空间,23(4):380-383,455.
郭松峰,祁生文,李星星,等.2016.含结构面岩体试样单轴强度与变形特征[J].工程地质学报,24(5):891-898.
黄建勇,王多垠,汪承志.2008.考虑节理分布的内河港口大直径嵌岩灌注桩横向承载性能研究[J].水运工程,(3):59-63.
刘卡丁,张玉军.2002.层状岩体剪切破坏面方向的影响因素[J].岩石力学与工程学报,21(3):335-339.
刘亚群,李海波,李俊如,等.2009.基于Hoek-Brown准则的板岩强度特征研究[J].岩石力学与工程学报,28(S2):3452-3457.
刘兹胜,卓杨,时蓓玲,等.2010.高桩码头桩基在倾斜泥面中的水平承载性能研究[J].岩土工程学报,32(12):1861-1867.
刘自由,江学良,林杭.2011.软弱结构面加桩剪切特性的数值分析[J].中南大学学报(自然科学版),42(5):1461-1466.
秦粮凯.2016.开挖条件下嵌固段岩体劣化对抗滑桩-层状岩体相互作用影响研究[D].成都:西南石油大学.
王东玮,王常明,匡少华.2016.层状岩质岸坡上桥桩位选择与优化[J].工程地质学报,24(S1):861-867.
王洪建,刘大安,黄志全,等.2017.层状页岩岩石力学特性及其脆性评价[J].工程地质学报,25(6):1414-1423.
王建华,陈锦剑,柯学.2007.水平荷载下大直径嵌岩桩的承载力特性研究[J].岩土工程学报,(08):1194-1198.
赵明华,雷勇,刘晓明.2009.基于桩-岩结构面特性的嵌岩桩荷载传递分析[J].岩石力学与工程学报,28(1):103-110.
中华人民共和国行业标准编写组.1999.土工试验方法标准(GB/T50123)[S].北京:中国计划出版社.
中华人民共和国行业标准编写组.2014.建筑基桩检测技术规范(JGJ 106-2014)[S].北京:中国建筑工业出版社.
Geng D X,Yang L D.2003.Mechanical properties and numerical simulation of sandwich rock[J].Underground Space,23(4):380-383-455.
Guo S F,Qi S W,Li X X,et al.2016.Strength and deformation characteristics of rock sample with discontinuities under numercial uniaxial compression simulation tests[J].Journal of Engineering Geology,24(5):891-898.
Huang J Y,Wang D Y,Wang C Z.2008.On the lateral bearing behavior of large-diameter rock-socketed cast-in-place piles at river port[J].Port and Waterway Engineering,(3):59-63.
Liu K D,Zhang Y J.2002.Influence factors on shear failure orientation of layered rocks[J].Chinese Journal of Rock Mechanics and Engineering,21(3):335-339.
Liu Y Q,Li H B,Li J R,et al.2009.Study on strength characteristics of slates based on Hoek-Brown criterion[J].Chinese Journal of Rock Mechanics and Engineering,28(S2):3452-3457.
Liu Z S,Zhuo Y,Shi B L,et al.2010.Horizontal bearing capacity of pile foundation in high-piled wharf with inclined ground surface[J].Chinese Journal of Geotechnical Engineering,32(12):1861-1867.
Liu Z Y,Jiang X L,Lin H.2011.Numerical analysis for shear characteristic of soft structure plane with pile reinforcement[J].Journal of Central South University(Science and Technology),42(5):1461-1466.
Qin L K.2016.Study on the effect of deformation of embeded rock mass on the interaction of sliding pile and stratified rock mass under excavation[D].Chengdu:Southwest Petroleum University.
The Professional Stardards Complilation Group of People's Republic of China.1999.Soil test method standard(GB/T50123)[S].Beijing:China Planning Press.
The Professional Stardards Complilation Group of People's Republic of China.2014.Technical code for testing building foundation piles(JGJ 106-2014)[S].Beijing:China Architecture&Building Press.
Wang D W,Wang C M,Kuang S H.2016.Selection and optimization of the site of bridge piled foundation on the layered rock slope[J].Journal of Engineering Geology,24(S1):861-867.
Wang H J,Liu D A,Huang Z Q,et al.2017.Mechanical properties and brittleness evaluation of layered shale rock[J].Journal of Engineering Geology,25(6):1414-1423.
Wang J H,Chen J J,Ke X.2007.Characteristics of large diameter rocksocketed piles under lateral loads[J].Chinese Journal o Geotechnical Engineering,29(8):1194-1198.
Zhao M H,Lei Y,Liu X M.2009.Analysis of load transfer of rocksocketed piles based on characteristics of pile-rock structura plane[J].Chinese Journal of Rock Mechanics and Engineering,28(1):103-110.
陈新,廖志红,李德建.2011.节理倾角及连通率对岩体强度、变形影响的单轴压缩试验研究[J].岩石力学与工程学报,30(4):781-789.
耿大新,杨林德.2003.层状岩体的力学特性及数值模拟分析[J].地下空间,23(4):380-383,455.
郭松峰,祁生文,李星星,等.2016.含结构面岩体试样单轴强度与变形特征[J].工程地质学报,24(5):891-898.
黄建勇,王多垠,汪承志.2008.考虑节理分布的内河港口大直径嵌岩灌注桩横向承载性能研究[J].水运工程,(3):59-63.
刘卡丁,张玉军.2002.层状岩体剪切破坏面方向的影响因素[J].岩石力学与工程学报,21(3):335-339.
刘亚群,李海波,李俊如,等.2009.基于Hoek-Brown准则的板岩强度特征研究[J].岩石力学与工程学报,28(S2):3452-3457.
刘兹胜,卓杨,时蓓玲,等.2010.高桩码头桩基在倾斜泥面中的水平承载性能研究[J].岩土工程学报,32(12):1861-1867.
刘自由,江学良,林杭.2011.软弱结构面加桩剪切特性的数值分析[J].中南大学学报(自然科学版),42(5):1461-1466.
秦粮凯.2016.开挖条件下嵌固段岩体劣化对抗滑桩-层状岩体相互作用影响研究[D].成都:西南石油大学.
王东玮,王常明,匡少华.2016.层状岩质岸坡上桥桩位选择与优化[J].工程地质学报,24(S1):861-867.
王洪建,刘大安,黄志全,等.2017.层状页岩岩石力学特性及其脆性评价[J].工程地质学报,25(6):1414-1423.
王建华,陈锦剑,柯学.2007.水平荷载下大直径嵌岩桩的承载力特性研究[J].岩土工程学报,(08):1194-1198.
赵明华,雷勇,刘晓明.2009.基于桩-岩结构面特性的嵌岩桩荷载传递分析[J].岩石力学与工程学报,28(1):103-110.
中华人民共和国行业标准编写组.1999.土工试验方法标准(GB/T50123)[S].北京:中国计划出版社.
中华人民共和国行业标准编写组.2014.建筑基桩检测技术规范(JGJ 106-2014)[S].北京:中国建筑工业出版社.