土坯房屋基本力学和抗震性能的试验研究

发布时间：2018-01-18 12:26

本文关键词：土坯房屋基本力学和抗震性能的试验研究　出处：《大连理工大学》2013年博士论文　论文类型：学位论文

【摘要】：目前在我国大部分村镇地区,还存在着相当数量的土坯房屋。但这些房屋设计、施工等方面的规范、技术研究却严重滞后。很多土坯房屋主要由当地工匠根据经验建造,质量参差不齐,缺乏可靠性。这导致其在地震中往往受到较为严重的破坏,直接危害了当地居民的生命和财产安全。在国家“十一五”科技支撑计划重点项目2006BAJ06B03支持下,为研究和提高土坯房屋的基本力学和抗震性能,本文从单块土坯的制作及抗压强度、土坯砌体的力学性能、土坯墙体的抗震性能以及土坯房屋的整体抗震性能这四方面着手,分别通过试验研究、理论分析和数值计算等多种研究手段,得到了一些可供参考的研究成果,其主要内容概括如下： (1)土坯立面单轴抗压试验表明,细粒含量、干密度和试件高宽比对土坯的抗压强度有不同程度的影响。细粒含量的增加也会导致干燥后的土坯试件体积收缩率单调增加。收缩率过大时,收缩裂缝会降低其抗压强度。本文制作的土坯体积收缩率小且强度较高,这表明添加合理比例的建筑中砂对天然细粒土进行物理改性后得到的土料适宜制作生土土坯。 (2)土坯砌体的单调、反复抗压试验和单调抗剪试验表明,其破坏形态与普通砌体相似,受压时出现沿中部竖向裂缝的劈裂破坏,受剪时出现沿泥浆与土坯接触面的剪切粘结破坏。抗压试验表明,泥浆和土坯强度比对土坯砌体的强度和应力-应变关系有一定影响。与单调加载相比,反复受压试验结果的离散性明显降低,但卸载后的残余变形导致其峰值应变显著增加,与普通砌体差异明显。抗剪试验表明,土坯砌体抗剪强度随泥浆抗压强度的增加而单调增加；荷载-位移曲线的下降呈现脆性特征。 (3)通过平面内拟静力试验研究了实体土坯墙和不同开洞形式土坯墙的抗震性能。研究表明,土坯墙体试件的破坏形态与砌体墙相似,为剪压破坏和剪摩破坏。竖向应力和高宽比对极限荷载及刚度均有不同程度的影响。开洞后,土坯墙体的承载力、刚度及耗能能力均下降明显,但延性有所提高。建立了以剪摩公式为基础的土坯墙体承载力公式,计算结果与试验数据吻合良好。 (4)平面内拟静力试验研究表明,土坯墙的荷载-位移曲线及骨架曲线上升段呈一定线性特征,但卸载后却有较大残余变形,与砌体墙差异显著。考虑了初始竖向应力对残余变形的影响,对土坯砌体割线模量进行修正,建立了基于弹性深梁理论的土坯实体墙刚度计算公式。并对洞口两侧墙肢上下端节点的半刚性转动刚度系数进行修正,建立了土坯开洞墙刚度的计算公式。结果表明,该计算方法与试验结果吻合较好。 (5)通过振动台试验研究了土坯房屋模型在不同地震波及地震强度下的动力特性、破坏形态和抗震性能。研究表明,单层土坯模型的自振频率在15Hz-20Hz之间,阻尼比在4%-10%之间。土坯模型的破坏形态与砌体房屋相似,为沿墙体砌筑灰缝的阶梯、水平状裂缝和沿墙体交接处的竖向裂缝破坏。模型的整体变形能力较好,层间位移角在1/50以下时未见开裂；层间位移角为1/30-1/20时,模型开裂严重但仍未倒塌。基于土坯材料的塑性特征,提出了基于墙体罕遇地震作用下承载力的土坯房屋一阶段抗震设计方法。
[Abstract]:In most of the villages and towns in our country , there are quite a lot of green houses , but these houses are designed , constructed and so on , and the technical research has lagged behind . Many of the building houses are built mainly by local artisans to study and improve the basic mechanics and seismic behavior of local residents . ( 1 ) The uniaxial compressive test of the vertical single axis shows that the fine grain content , the dry density and the aspect ratio of the test piece have different influence on the compressive strength of the blank . When the shrinkage rate is too large , the shrinkage crack will decrease its compressive strength . ( 2 ) The monotonic , repeated compressive test and monotonic shear test of the earthwork masonry show that the failure mode is similar to that of the common masonry , and the shear bond between the mud and the earth billet is greatly influenced when the shear occurs . The compressive test shows that the strength ratio of the mud and the blank is obviously increased compared with the normal masonry . The shear test shows that the shear strength of the soil blank increases monotonically with the increase of the compressive strength of the slurry ; and the drop of the load - displacement curve presents the brittle feature . ( 3 ) The anti - seismic performance of the blank wall of solid and different openings is studied by means of quasi - static test in plane . The results show that the failure mode of the concrete blank is similar to that of masonry wall . The vertical stress and the aspect ratio have different influence on ultimate load and stiffness . After opening the tunnel , the bearing capacity , rigidity and energy consumption of the blank wall body are reduced obviously , but ductility is improved . The bearing capacity formula of the earth blank is established based on the shear - friction formula . The calculation results are in good agreement with the experimental data . ( 4 ) The study of quasi - static test in plane shows that the load - displacement curve and the rising section of skeleton curve are of certain linear characteristics , but after unloading , there is a large residual deformation , which is obviously different from the masonry wall . ( 5 ) The dynamic characteristics , failure modes and seismic behavior of the soil blank model under different seismic waves and seismic intensity are studied by shaking table test . The results show that the self - oscillation frequency of the single - layer soil blank model is between 15 Hz and 20 Hz , and the damping ratio is 4 % -10 % .

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU361

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