【作者】 刘伟；

【导师】 周福霖； 王社良；

【作者基本信息】 西安建筑科技大学 ， 防灾减灾工程及防护工程， 2020， 博士

【摘要】 砖石古塔是一种历史宗教建筑,也是我国古代“高层建筑”的典范。它为世人展现了古代建筑艺术、材料技术、营造能力等古匠人建造技艺,同时也反映了相应建造年代社会历史、宗教文化、经济水平等历史信息。砖石古塔作为我国古建筑历史代表,载誉了中国五千年文明史,但由于其建造年代较长,砖石结构古塔受自然侵蚀及灾害、人为损伤较为严重,结构本体抵抗灾害能力降幅较大,对砖石结构古塔本体亟需进行保护。但是,对于砖石结构古塔本体评估方法、保护理论、保护技术等方面的研究较少且不尽完善,在砖石结构古塔本体评估、保护方面还需进行更为深入的研究。本文基于对古灰浆和性能增强材料的相关试验研究,以小雁塔为研究对象,研究了砖石古塔无损性能增强技术,主要工作如下:(1)参照历史文献材料和制作工艺,选取古糯米灰浆、古麻刀灰浆和古混合灰浆为基材,改性环氧树脂、甲基丙烯酸甲脂和甲基硅酸钠为性能增强材料,通过相似性模拟分析与正交试验设计,模拟制作了24组共108块古糯米灰浆、古麻刀灰浆、古混合灰浆的立方体试块和棱柱体试块,其中基材立方体试块各3块(共9块)、棱柱体试块各6块(共18块),将各基材试块分别浸入改性环氧树脂、甲基丙烯酸甲脂或甲基硅酸钠性能增强材料的立方体试块各3块(共27块)、棱柱体试块各6块(共54块),并进行了相应的力学性能试验和分析。结果表明,3种基材古灰浆的立方体抗压强度、棱柱体峰值应力均较低,浸入改性环氧树脂、甲基丙烯酸甲脂和甲基硅酸钠性能增强材料后,性能增强古灰浆立方体抗压强度和棱柱体峰值应力、峰值应变、极限应变、弹性模量等均有明显改善,其中立方体抗压强度提高了约18.8-60.0%,棱柱体峰值应力提高了约17.5-40.7%,并且浸入改性环氧树脂和甲基丙烯酸甲脂提高的较为明显。(2)基于对古灰浆和性能修复古灰浆的试验和分析,选取古青砖和古糯米灰浆为基材,制作了9组共54件模拟古砌体轴心受压试件和9组共81件受剪试件。选用改性环氧树脂和甲基丙烯酸甲脂为性能增强材料,在已制作好的试件中取6组共36件古砌体轴心受压试件和6组共54件古砌体受剪试件,采用“浸渗法”对基材试件进行无损性能增强,并进行了相应的对比性能试验,研究了采用“浸渗法”浸入性能增强材料对古砌体基材无损性能增强的可行性。结果表明,上述2种性能增强材料均可明显提高古砌体基材的受压强度和受剪强度,提高值约为6.0-40.5%,同时拟合了古砌体基材、浸入改性环氧树脂或甲基丙烯酸甲脂砌体的应力-应变曲线,建立了相应的本构模型。此外,试验后对“浸渗法”无损修复砌体试件灰浆检查表明,无损修复性能增强材料可以充分浸入已固结的古灰浆中,浸入效果良好。(3)采用古青砖和古糯米灰浆为基材,改性环氧树脂和甲基丙烯酸甲脂为性能增强材料,模拟制作了8片厚度分别为240mm、370mm、490mm的古砌体墙体试件,其中对3片不同厚度(240mm、370mm、490mm)的墙体浸入改性环氧树脂,对2片不同厚度的墙体(240mm、490mm)浸入甲基丙烯酸甲脂,进行了古砌体墙体试件和性能增强墙体试件的低周反复拟静力试验,研究了古砌体墙体和性能增强古砌体墙体在地震作用下的破坏机理,分析了试件的开裂荷载、破坏荷载、恢复力特性和耗能性能,建立了相应的恢复力模型,确定了试件的等效阻尼比。结果表明:对于3种不同厚度的墙体试件,性能增强墙体试件比古砌体墙体试件的开裂荷载、破坏荷载、耗能能力等均有不同程度的提高,变形能力得到了比较明显的改善,抗侧移刚度也有一定程度的提高,说明浸入改性环氧树脂或甲基丙烯酸甲脂能够明显提高古砌体墙体的抗震性能,可用于砖石结构古塔的无损性能增强和抗震保护。此外,试验结果还表明,浸入改性环氧树脂增强墙体试件性能优于甲基丙烯酸甲酯。(4)综合考虑小雁塔的文物价值和保护意义,详细查阅了小雁塔的历史修缮档案,现场全面分析了小雁塔本体结构现状,对小雁塔本体结构砌筑材料强度、本体结构修复历史、本体结构现有损伤情况进行了相应的调查研究。现场对小雁塔结构进行了动力特性测试,对其结构动力特性及动力灾变特点进行了分析。建立了小雁塔本体结构有限单元分析模型,分析了本体结构动力特性及模拟地震加速度作用下的整体结构动力响应。综合现场测试及有限元分析结果,采用极限承载力、位移综合法对小雁塔本体结构现状的抗震性能进行了评估。(5)根据相似形理论对小雁塔本体进行了模型结构设计,制作了几何相似比为1/10的模型结构,采用“浸渗法”对模型结构浸入改性环氧树脂并进行局部结构修复,对基材模型和无损性能增强模型进行了26种工况下模拟地震振动台试验,对地震作用下基材模型和无损性能增强模型的塔体加速度、位移等动力响应参数进行了研究,探讨了小雁塔结构模型在地震作用下动力响应的特点以及变化规律。模拟试验结果表明,性能增强模型结构与原模型结构相比,在相应地震工况作用下,塔身高度方向结构动力位移响应均有不同程度的减小,位移响应降低较大位置位于塔身中部、顶部,平均位移响应可达约20%。同样工况和8度大震下,性能增强模型结构几乎无裂缝,而原模型结构在8度小震时已经开裂。(6)以小雁塔原型结构资料为基础,采用ANSYS有限元软件,对小雁塔本体结构建立有限单元分析模型,对模型结构在多工况作用下进行了有限元计算。分析了基材结构和采用“浸渗法”分别浸入改性环氧树脂、甲基丙烯酸甲脂材料性能增强小雁塔结构在8度大震下的抗震性能,讨论了小雁塔原型结构的无损性能增强效果。结果表明,浸入改性环氧树脂对小雁塔原型结构性能增强幅度较大,在8度大震下位移响应降低可达30%左右,同时结构各层层间位移角也相应减小,降低了地震作用下小雁塔塔身出现严重损坏或倒塌的可能性。综合以上研究内容及结果,本论文基于小雁塔本体结构地震动灾变保护提出了一种新的思路、方法,同时也是对砖石结构古塔无损性能增强保护的一种通用方法,具有一定的工程应用实践远景。更多还原

【Abstract】 Pagoda is not just a historical and religious architecture,and also is the ancient Chinese high-rise building model.It shows the history of ancient architecture materials,construction technology and other aspects of the history,also witnessed the history of the times,culture,art,religion,social and economic aspects of the development process.China’s existing Pagoda structure has a long history,and it has seriously influenced by natural disasters and man-made destruction.So it resists disaster’s ability is poor,and needs repaired and protected urgently.However,due to the particularity of the protection of masonry pagoda,the research on its protection theory and technology is still imperfect and needs more in-depth study.In this paper,we used the small wild goose pagoda as the research object,and studied the non-destructive performance enhancement technology of pagoda with the small wild goose pagoda,which is based on the related experimental study of ancient mortar and performance enhancement materials,.The main work is as follows:(1)With reference to historical literature and production technology,the ancient glutinous rice mortar,ancient mortar mortar and ancient mortar were selected as the substrate,modified epoxy resin,methyl methacrylate and methyl sodium silicate as the performance enhancing material.Through simulated analysis and orthogonal test design,we made a total of 24 groups of 108 ancient glutinous rice mortar,ancient Ma knife mortar,ancient mixed mortar cube test block and prism test block,which substrate cube test block 3(a total of 9),Each of the six pieces of prism test pieces(18 pieces in total)were immersed in each of the cubes of the modified epoxy resin,methacrylic acidmethyl ester or methyl silicate property enhancing material(Total of 27),prism test block of the six(a total of 54),and carried out the corresponding mechanical performance test and analysis.The results show that the cube compressive strength and prismatic peak stress of the three kinds of ancient mortar are low,and the properties of the modified mortar are improved after immersion in the modified epoxy resin,methyl methacrylate and methyl silicate.The compressive strength of the cube and the peak stress,peak strain,ultimate strain and elastic modulus of the prism are obviously improved.The compressive strength of the cube increases by about 18.8-60.0%,the peak stress of the prism is about17.5-40.7%.And the objects immersed in modified epoxy resin and methyl methacrylate are improved more obvious.(2)Based on the test and analysis of the ancient mortar and the performance of the ancient mortar,the ancient brick and the ancient glutinous rice mortar were selected as the base material,and 9 groups of 54 simulated masonry specimens were prepared as shear specimens.The modified epoxy resin and methacrylic acid methyl ester were used as the performance enhancing material,6 sets of 36 specimens of the ancient masonry were taken from the prepared test pieces and 6 groups of 54 ancient masonry.The non-destructive performance of the base material was enhanced by the infiltration method,and the corresponding performance test was carried out,and the feasibility of the infiltration method of the ancient masonry substrate was studied.The results show that the two kinds of performance enhancing materials can obviously improve the compressive strength and shear strength of the ancient masonry substrate,the improvement is about 6.0-40.5%,and stress-strain curve of the old masonry immersed in Oxygen resin or methacrylic acid methyl ester masonry were fitted,and the corresponding constitutive model was established.In addition,the examination of masonry specimen mortar showed that the non-destructive repair performance enhancement material could be fully immersed in the consolidated ancient mortar,and the immersion effect was good.(3)Eight ancient masonry wall specimens with thickness of 240 mm,370mm and490 mm were fabricated by using the ancient green brick and the ancient glutinous rice mortar as the substrate,and the modified epoxy resin and the methyl methacrylate wereused as the performance enhancing material.Among them,three different thicknesses walls(240mm,370 mm,490mm)were immersed in modified epoxy resin,and two different thickness walls(240mm,490mm)were immersed in methyl methacrylate.The failure mechanism of the ancient masonry walls was studied under low cyclic pseudo-static experiment,and crack load,failure load and the energy dissipation capacity are studied,and the corresponding restoring force model is established to determine the equivalent damping ratio of the specimen.The results show that the crack load,the failure load and the energy dissipation capacity of the wall specimen with different thickness are improved to some extent,the deformation ability and lateral resisting stiffness of the wall specimen with different thickness are also improved.The results show that the immersion of modified epoxy resin or methacrylic acid methyl ester can obviously improve the seismic performance of the ancient masonry wall,and it can be used for the enhanced performance and earthquake resistance of the masonry tower structure.In addition,the test results also show that performances of wall specimen immersed in modified epoxy resin are better than methyl methacrylate.(4)Considering comprehensively the cultural value and protection significance of Small wild goose pagoda,and detailed refer to the historical repair archives,and study on the strength characteristics of structural materials,repairing characteristics and damage status of Small wild goose pagoda.The dynamic characteristics of the Small wild goose pagoda structure were tested on site,and the dynamic characteristics and dynamic catastrophe characteristics of the structure were analyzed.And then,the finite element model of Small wild goose pagoda structure is established,and finite element analysis of dynamic characteristics and dynamic response of Small wild goose pagoda under different acceleration earthquakes.We also study on the combined method of ultimate bearing capacity and ultimate displacement is used to evaluate the seismic performance of Small wild goose pagoda structure.(5)According to the similarity theory of model structure design,a small geese model with geometric similarity ratio of 1/10 was designed and constructed.The impregnation method was used to immerse the modified epoxy resin and the local structure was modified.The base material model and the non-destructive performance model were used to simulate the seismic shaking table in 26 kinds of workingconditions.The relative acceleration and displacement response of the different models of the tower model and the non-destructive performance model under earthquake were studied,and the main Characteristics and Variation of Seismic Response of Model Structure.The results show that the displacement response of the performance enhancement model has a significant decrease in the tower under the earthquake,especially in the middle of the tower,and the displacement response at the top of the tower is generally about 20%.Under the same conditions and the 8 degree earthquake,the performance enhancement model has almost no cracks,but the original model structure has been cracked at 8 degree earthquake.(6)Based on the prototype structure data of small goose pagoda,the simulation model of the prototype structure of pagoda was established by ANSYS finite element software.The prototype structure of the pagoda was calculated under multiple operating conditions,analysed the effects of the structure of the substrate and the immersion method which Immersed separately in the modified epoxy resin and the methacrylic acid methyl ester enhanced material under the 8 degree earthquake,and discussed the effect of non-destructive performance of the prototype structure of the pagoda.The results show that the modified epoxy resin and methyl methacrylate can enhance the displacement response of the pagoda to about 30% under the 8 degree earthquake.The results of the study not only provide a new method for the earthquake protection of the pagoda,but also apply to the improvement of the performance of the masonry pagoda,which have a certain engineering application practice vision.更多还原