新型拉压复合型锚杆锚固性能研究Ⅲ:现场试验
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摘要
针对传统拉力型锚杆存在受力集中、锚固体与岩土体界面黏结强度发挥不充分、抗拔承载力偏低的问题,研发了一种新型拉压复合型锚杆。通过开展现场破坏性试验,对拉力型锚杆及拉压复合型锚杆的承载能力、荷载位移曲线及应变数据进行分析,结果表明:3组拉压复合型锚杆TC12-3、TC11-1、TC21锚杆的平均破坏荷载分别提高至拉力型锚杆的2.81,2.01,2.52倍;拉压复合型锚杆套管内的拉力传递损失率最大为20.5%,在自由段内的拉力传递损失率最大仅为6.8%,拉力传递损失主要发生在承压锚固段上;TC12-3锚杆的受拉锚固段长度最短,单位受拉锚固段长度分担荷载最高;TC21-1锚杆的承压锚固段最短,单位承压锚固段长度分担荷载最高;锚杆破坏时,TC12-3、TC11-1、TC21-1锚杆的受拉承载系数分别为0.398,0.470,0.600;且TC11-1锚杆表现为承压锚固段与受拉锚固段同时破坏,TC12-3、TC21-1锚杆表现为先后破坏;拉压复合型锚杆锚固性能显著提高主要是由于荷载分解作用,界面剪应力双向传递机制及短锚承载效应;从荷载位移曲线来看,拉压复合型锚杆具有较好的抗变形能力,在岩土锚固工程中,具有显著的优势和广阔的应用前景。
The new tension-compression composite anchor(TC-anchor) is developed to overcome the shortcomings of the traditional tension anchor(T-anchor), such as stress concentration, insufficient bonding strength between anchorage body and soil mass, and low uplift bearing capacity. The bearing capacity, load-displacement curves and strain data of T-anchor and TC-anchor are analyzed, based on the field destructive tests. The results show that the average destructive loads of three groups of TC-anchor, TC12-3, TC11-1 and TC21, increase to 2.81, 2.01, 2.52 times those of T-anchor, respectively. The maximum tension loss rate in the rebar hole is 20.5% and only 6.8% along the free anchorage length, and therefore the tension loss occurs mainly along the compression anchorage body(CAB). The tension anchorage body(TAB) length of TC12-3 anchor is the shortest, and therefore the bearing loads of unit TAB length are the highest. The CAB length of TC21-1 anchor is the shortest,and therefore the bearing loads of unit CAB length are the highest. When the anchor is destructed, the tension bearing coefficients of TC12-3, TC11-1, TC21-1 are 0.398, 0.470, 0.600, respectively, and the CAB and TAB of TC11-1 are destructed at the same time, while those of TC12-3 and TC21-1 are destructed successively. The significantly increased anchorage performance of TC-anchor is mainly due to the decomposition of the loads, the two-way transmission mechanisms of the interface shear stress and the bearing effect of short anchor. It can be seen from the load-displacement curves that the TC-anchor has better deformation-resisting capability.Therefore, it has significant advantages and broad application prospects in geotechnical anchorage engineering.
The new tension-compression composite anchor(TC-anchor) is developed to overcome the shortcomings of the traditional tension anchor(T-anchor), such as stress concentration, insufficient bonding strength between anchorage body and soil mass, and low uplift bearing capacity. The bearing capacity, load-displacement curves and strain data of T-anchor and TC-anchor are analyzed, based on the field destructive tests. The results show that the average destructive loads of three groups of TC-anchor, TC12-3, TC11-1 and TC21, increase to 2.81, 2.01, 2.52 times those of T-anchor, respectively. The maximum tension loss rate in the rebar hole is 20.5% and only 6.8% along the free anchorage length, and therefore the tension loss occurs mainly along the compression anchorage body(CAB). The tension anchorage body(TAB) length of TC12-3 anchor is the shortest, and therefore the bearing loads of unit TAB length are the highest. The CAB length of TC21-1 anchor is the shortest,and therefore the bearing loads of unit CAB length are the highest. When the anchor is destructed, the tension bearing coefficients of TC12-3, TC11-1, TC21-1 are 0.398, 0.470, 0.600, respectively, and the CAB and TAB of TC11-1 are destructed at the same time, while those of TC12-3 and TC21-1 are destructed successively. The significantly increased anchorage performance of TC-anchor is mainly due to the decomposition of the loads, the two-way transmission mechanisms of the interface shear stress and the bearing effect of short anchor. It can be seen from the load-displacement curves that the TC-anchor has better deformation-resisting capability.Therefore, it has significant advantages and broad application prospects in geotechnical anchorage engineering.
引文
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[9]刘钟,郭钢,张义,等.囊式扩体锚杆施工技术与工程应用[J].岩土工程学报,2014,36(增刊2):205-211.(LIU Zhong,GUO Gang,ZHANG Yi,et al.Construction technology and engineering applications of capsule-type under-reamed ground anchor[J].Chinese Journal of Geotechnical Engineering,2014,36(S2):205-211.(in Chinese))
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[11]涂兵雄,刘士雨,俞缙,等.新型拉压复合型锚杆锚固性能研究Ⅰ:简化理论[J].岩土工程学报,2018,40(12):2289-2295.(TU Bing-xiong,LIU Shi-yu,YU Jin,et al.Analysis of anchorage performance on new tensioncompression anchor:Ⅰsimplified theory[J].Chinese Journal of Geotechnical Engineering,2018,40(12):2289-2295.(in Chinese))
[12]涂兵雄,俞缙,何锦芳,等.新型拉压复合型锚杆锚固性能研究Ⅱ:模型试验[J].岩土工程学报,2019,41(3):475-483.(TU Bing-xiong,YU Jin,HE Jin-fang,et al.Analysis of anchorage performance on new tension-compression anchor:Ⅱmodel test[J].Chinese Journal of Geotechnical Engineering,2019,41(3):475-483.(in Chinese))
[13]刘永权,刘新荣,杨忠平,等.不同类型预应力锚索锚固性能现场试验对比研究[J].岩石力学与工程学报,2016,35(2):275-283.(LIU Yong-quan,LIU Xin-rong,YANGZhong-ping,et al.Field test on anchorage performance of different types of prestressed cables[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(2):275-283.(in Chinese))
[14]尤春安,战玉宝.预应力锚索锚固段界面滑移的细观力学分析[J].岩石力学与工程学报,2009,28(10):1976-1985.(YOU Chun-an,ZHANG Yu-bao.Analysis of interfacial slip mesomechanics in anchorage section of prestressed anchor cable[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(10):1976-1985.(in Chinese))
[15]GB 50086-2015岩土锚杆与喷射混凝土支护工程技术规范[S].2015.(GB 50086-2015 Technical code for engineering of ground anchoring and shotcrete support[S].2015.(in Chinese))
[2]张季如,唐保付.锚杆荷载传递机理分析的双曲函数模型[J].岩土工程学报,2002,23(2):188-192.(ZHANG Ji-ru,TANG Bao-fu.Hyperbolic function model to analyze load transfer mechanism on bolts[J].Chinese Journal of Geotechnical Engineering,2002,23(2):188-192.(in Chinese))
[3]何思明,田金昌,周建庭.胶结式预应力锚索锚固段荷载传递特性研究[J].岩石力学与工程学报,2006,25(1):117-121.(HE Si-ming,TIAN Jin-chang,ZHOU Jian-ting.Study on load transfer of bond prestressed anchor rope[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(1):117-121.(in Chinese))
[4]胡建林,张培文.扩体型锚杆的研制及其抗拔试验研究[J].岩土力学,2009,30(6):1615-1619.(HU Jian-lin,ZHANGPei-wen.Development of underreamed anchor and experimental study of uplift resistance[J].Rock and Soil Mechanics,2009,30(6):1615-1619.(in Chinese))
[5]郭钢,刘钟,邓益兵,等.砂土中扩体锚杆承载特性模型试验研究[J].岩土力学,2012,33(12):3645-3652.(GUO Gang,LIU Zhong,DENG Yi-bing,et al.Model test research on bearing capacity characteristics of underreamed ground anchor in sand[J].Rock and Soil Mechanics,2012,33(12):3645-3652.(in Chinese))
[6]郭钢,刘钟,李永康,等.扩体锚杆拉拔破坏机制模型试验研究[J].岩石力学与工程学报,2013,32(8):1677-1684.(GUO Gang,LIU Zhong,LI Yong-kang,et al.Model test research on failure mechanism of underreamed ground anchor[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(8):1677-1684.(in Chinese))
[7]曹佳文,彭振斌,彭文祥,等.充气锚杆在砂土中的模型试验研究[J].岩土力学,2011,32(7):1957-1962.(CAOJia-wen,PENG Zhen-bin,PENG Wen-xiang,et al.Model test study of inflated anchors in sands[J].Rock and Soil Mechanics,2011,32(7):1957-1962.(in Chinese))
[8]彭文祥,张旭,曹佳文.充气锚杆极限承载力计算方法[J].岩土力学,2013,34(6):1696-1702.(PENG Wen-xiang,ZHANG Xu,CAO Jia-wen.Calculation method for ultimate bearing capacity of inflatable anchor[J].Rock and Soil Mechanics,2013,34(6):1696-1702.(in Chinese))
[9]刘钟,郭钢,张义,等.囊式扩体锚杆施工技术与工程应用[J].岩土工程学报,2014,36(增刊2):205-211.(LIU Zhong,GUO Gang,ZHANG Yi,et al.Construction technology and engineering applications of capsule-type under-reamed ground anchor[J].Chinese Journal of Geotechnical Engineering,2014,36(S2):205-211.(in Chinese))
[10]涂兵雄,贾金青,俞缙,等.一种拉压复合型锚杆[P].ZL201420450678.5,2014.(TU Bing-xiong,JIA Jin-qin,YUJin,et al.A Tension-compression composite anchor[P].ZL201420450678.5,2014.(in Chinese))
[11]涂兵雄,刘士雨,俞缙,等.新型拉压复合型锚杆锚固性能研究Ⅰ:简化理论[J].岩土工程学报,2018,40(12):2289-2295.(TU Bing-xiong,LIU Shi-yu,YU Jin,et al.Analysis of anchorage performance on new tensioncompression anchor:Ⅰsimplified theory[J].Chinese Journal of Geotechnical Engineering,2018,40(12):2289-2295.(in Chinese))
[12]涂兵雄,俞缙,何锦芳,等.新型拉压复合型锚杆锚固性能研究Ⅱ:模型试验[J].岩土工程学报,2019,41(3):475-483.(TU Bing-xiong,YU Jin,HE Jin-fang,et al.Analysis of anchorage performance on new tension-compression anchor:Ⅱmodel test[J].Chinese Journal of Geotechnical Engineering,2019,41(3):475-483.(in Chinese))
[13]刘永权,刘新荣,杨忠平,等.不同类型预应力锚索锚固性能现场试验对比研究[J].岩石力学与工程学报,2016,35(2):275-283.(LIU Yong-quan,LIU Xin-rong,YANGZhong-ping,et al.Field test on anchorage performance of different types of prestressed cables[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(2):275-283.(in Chinese))
[14]尤春安,战玉宝.预应力锚索锚固段界面滑移的细观力学分析[J].岩石力学与工程学报,2009,28(10):1976-1985.(YOU Chun-an,ZHANG Yu-bao.Analysis of interfacial slip mesomechanics in anchorage section of prestressed anchor cable[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(10):1976-1985.(in Chinese))
[15]GB 50086-2015岩土锚杆与喷射混凝土支护工程技术规范[S].2015.(GB 50086-2015 Technical code for engineering of ground anchoring and shotcrete support[S].2015.(in Chinese))