关于房屋裂缝的调查与分析(英汉互译).doc

关于房屋裂缝的调查与分析

摘要： 本文通过对房屋裂缝的调查，结合工作实践，从设计、施工两方面分析了墙体裂缝的开裂原因，并提出了一些可以借鉴的处理方案。
关键字：房屋裂缝 裂缝分析 处理方案
前  言:
房屋的裂缝问题是普遍存在的现象。就裂缝轻重程度而然，轻者影响其美观，重者影响其安全使用，甚至会造成不良的社会影响，尤其是用户反映十分强烈。由于用户对房屋的结构情况不甚了解，房屋一旦出现裂缝，使用户产生不安全感或恐慌，有的裂缝造成屋面、墙面、地面渗漏、门窗变形、外墙抹面脱落等现象，给用户带来许多烦恼。就裂缝的性质而然，可分为温度裂缝、沉降裂缝、施工质量因素裂缝、使用不当及维护不及时而产生的裂缝等。无论由何种原因引起的裂缝，都应高度重视，认真分析，找准裂缝“病源”，消除隐患。
一 、房屋裂缝调查情况
由基建处、设计院、质量监督站及建设单位联合协同调查了反映较为强烈的部分房屋裂缝情况。在调查中主要发现以下几种现象：①.多数房屋的顶层裂缝最为突出，尤其是房屋顶层的两端最为严重，房屋中部及自上而下依次减轻；②.裂缝的形状多为“八”字斜裂缝，以窗台角尤为突出；③.门窗因变形使玻璃破碎，开启困难（某医院科技档案楼最为严重）；④.屋面、墙面、地下室出现不同程度的阴洗或渗漏现象；⑤.外墙抹面裂缝，出现空鼓或脱落；⑥.房屋抗震加固后产生裂缝（某公司职工宿舍楼、某住宅小住宅楼等较为严重）；⑦.使用不当及年久失修而产生裂缝（某中学实验室、某高中教学楼等）；⑧.用户反映强烈，尤其是住宅建筑，因出现裂缝，使用户产生严重的不安全感，以及因裂缝而产生渗漏，给住户带来烦恼，使住户对建设单位意见纷纷，甚至发生不愉快的纠纷。
二、裂缝原因分析
造成房屋开裂的因素很多，诸如施工质量、施工季节、材料性能、使用条件以及气温变化、工程地质条件等因素。归纳起来房屋裂缝的产生不外乎以下几种情况：①.温度产生的裂缝；②.沉降引起的裂缝；③.施工质量引起的裂缝。下面就上述裂缝的产生分别加以阐述。
1.温度产生的裂缝：在调查中发现有90％的房屋顶层墙体、屋面产生不同程度的裂缝均属于温度产生的裂缝。该地区夏季室外流通温度可高达39oC，夏季屋顶表面受太阳的直射作用，屋面表温度可在65oC左右，而冬季室外流通最低温度一般为-17oC以下，由此可见冬夏温差可达70oC∽80oC。房屋建筑一般由混凝土和砖砌体组成，而砖砌体的线膨胀系数仅为混凝土的一半。由于房屋结构之间的相互约束，加之温度的变化及两种不同材料的线膨胀系数的差异，使屋面与墙体产生温度内应力。因材料的线膨胀系数是不变，温差越大，产生的内应力也就越大，当建筑物某部位产生的内应力超过砖砌体所承受的抗拉、抗剪极限强度时，则该墙砌体必裂无疑—即出现温度裂缝。
温度裂缝虽然不直接影响结构的安全使用，但若不及时加以处理和维修将对正常使用产生一定的不利影响，甚至使裂缝转化为不安全因素。如在调查中发现，由于温度裂缝而使屋面、墙面严重渗漏，给用户造成许多烦恼，有的墙体因裂缝进水，导致墙体抹面脱落，危及周围行人的安全等等。
2.沉降引起的裂缝：由沉降引起的裂缝，仅占被调查房屋的1％左右，主要是由于地基不均匀下沉引起的。调查中发现沉降裂缝主要有以下特征：①.裂缝大多呈正反“八”字型，尤以底层窗子角部最为突出；②.部分纵墙或横墙出现水平裂缝。
被调查的房屋，均处于该地区，地貌属于黄河三角洲冲积平原，土层分布多为粉土、淤泥质粘土、粉质粘土，属于软弱地基，地基土的压缩系数a1-2均大于0.2MPa，属于中高压缩性土，许多地段还可能存在厚度不均的软弱下卧层，且大多建设单位在工程地质资料不详或没有进行钎探的情况下进行房屋建设，因此使房屋沉降的原因分析较困难。但房屋沉降的原因也不外乎下列几中情况：①.该房屋地基基础下存在软弱下卧层；②.实际使用荷载大于设计荷载；③.施工质量因素；④.房屋基础的设计与工程地质资料不符。
3.施工质量引起的裂缝： 工程施工阶段是使业主及工程设计意图最终实现并形成工程实体的阶段，也是最终形成产品质量和工程项目使用价值的最重要阶段。在调查中，普遍认为施工质量对裂缝的影响十分明显，尤其是住户，把所有的裂缝原因全归罪于施工质量，虽然这种言论具有片面性和不确切性，但这也反映了用户对施工质量的信任程度和对质量的要求。因此，施工质量不容忽视。由施工质量引起的裂缝是多种多样的。可以说任何房屋的裂缝都有可能与施工质量有关。如温度裂缝，由于屋面保温厚度、保温材料或墙体强度不满足设计要求等等都可能导致裂缝的发生或扩大；砌体的砂浆饱满度不满足要求，也能造成墙体裂缝或门窗变形。因为，当每皮砖砌筑的砂浆不饱满时，建成使用后，随着荷载不断增加使砌体压缩变形，当砌体压缩不均匀时，墙体就会产生裂缝，若砌体压缩均匀时，可导致门窗变形使玻璃破碎。施工质量问题也可能引起沉降裂缝，因为，当基槽开挖后，地基土扰动而形成橡皮土或基础的施工不满足设计要求等都可能引起地基基础的不均匀沉降。在调查中还发现，很多房屋的外墙、地面产生不规则的裂缝，用锒头敲打和凿开后，发现墙体、地面并没有裂缝。这种裂缝纯属施工质量形成空鼓现象而导致裂缝。综上所述，施工质量对房屋的使用价值是显而易见的。
三、裂缝的处理方法
造成房屋出现裂缝的原因是多方面的，但不管哪种原因造成的裂缝，都会对房屋产生不同程度的不利影响。首先破坏了房屋的整体性，改变了结构构件原有工作状态，降低了房屋的抗震能力和承载能力，降低了房屋结构的可靠度和内久性；其次是影响房屋的正常使用。因此，要针对裂缝出现的原因和开裂程度，对裂缝房屋进行必要的处理，具体措施如下：
1.加固法。这种方法旨在提高房屋的整体性和结构构件的承载能力。如锚杆拉结法、钢筋网片水泥砂浆抹面法、压力自动灌浆法或地基加固法。
2.卸载法。对房屋层数较多、地基变形较重、使用荷载较大且不易进行加固的情况，可采用降低使用荷载、拆除不必要的附属重物，甚至减少房屋层数。
3.结合维修进行功能改造法。对房屋开裂较重的顶层或端部转折处，在无加固价值的情况下，可将该处拆除重建，或改变原有房屋的使用功能。
以上处理措施根据具体情况可单独采用，也可综合采用，但总的原则是行之有效、措施得力、施工方便、经济美观。

Housing cracks on the investigation and analysis of
Abstract : In this paper the cracks in the housing survey work, design, Construction of two cracks on the wall cracking, and some can draw on to handle the situation.

Keywords : Housing cracks cracks analysis program

Foreword： cracks housing problem is a widespread phenomenon. On the severity of cracks and natural, to a lesser extent, affect its appearance severe impact on the safe use, it may even cause adverse social impacts, particularly users reacted very strongly to this. As users of the structure housing may not understand that the Housing Once the cracks appeared, which give users a sense of insecurity or fear, Some cracks caused roof, walls, floors leakage, windows deformation, shedding external surface, such as paper, to bring users a lot of headaches. Cracks on the nature of course, the temperature can be divided into cracks, settlement cracks, cracks construction quality factors, improper use and maintenance in a timely manner and do not have the cracks. No matter what the cause of the cracks, should attach great importance to and conscientiously analysis, find cracks in the "source" and eliminate hidden dangers.
First, the Housing cracks
Investigation by the Infrastructure Department, the Design Institute, Quality Supervision Station and the construction units of the joint investigation synergies reflect more strongly the part of the cracks. In the survey found the following major phenomenon : ①. Most of the housing is most prominent in the top cracks, especially at the two ends of the top floor of the most serious, central and reduce top-down order; ②. Cracks in shape as "8" ramp cracks in the window angle is particularly conspicuous; ③. by the deformation of windows broken glass. Open difficulties (in a hospital Archives floor, the most serious); ④. Roof, walls, Basement with varying degrees of overcast washing or leakage; ⑤. wall cracks on the surface of the floor, there hollowing or lost. ⑥. seismic reinforcement after cracks (a company Zhigongqishelou, a small residential houses and other more serious); ⑦. and the improper use of disrepair and cracks (a secondary school laboratories, a high school teaching building, etc.); ⑧. Users reflect strong, particularly in residential construction, because of cracks, so that users have a serious sense of insecurity, and cracks caused by the leakage caused trouble for the residents, tenants in the building of units ideas, even unpleasant disputes.
Second, the causes of cracks caused housing cracking a number of factors, such as the quality of construction, the construction season, material properties, conditions of use and temperature changes, the geological conditions and other factors. Summed up in the cracks produced by none other than the following situations : ①. The temperature cracks; ②. Subsidence caused by cracks; ③. Construction Quality caused the cracks. Below these cracks were produced elaborate.
1. The temperature cracks : the survey found that 90% of housing top wall, Roof produce different degrees of temperature cracks belong to the cracks. The flow of summer outdoor temperature can be as high as 39 Perturbation-degree, the roof surface by the summer sun pounded, Roof surface temperature at about 65 Perturbation-degree, and outdoor winter minimum temperature general circulation of-17oC below So Dongxia temperature difference of up to 70 Perturbation-degree politics 80oC. Housing construction generally concrete and brick masonry, while the brick masonry linear expansion coefficient of only half of the concrete. As housing structure between the constraints, in addition to the temperature of the two different materials and the linear expansion coefficient of variance Roof and wall so that the effect of temperature stress. Due to the thermal expansion coefficient is unchanged, the greater the temperature difference, the greater stress, When a building site within the brick masonry stress over withstand the tensile strength, ultimate shear strength, then the masonry wall will undoubtedly split - that is, temperature cracks. Although the temperature cracks in the structure does not directly affect the safe use But without timely treatment and the use of normal maintenance will have certain adverse effects, even crack into insecurity. If the survey found that the temperature cracks so roof, walls serious leakage to the users a lot of headaches, Some cracks in the flooded by the wall, leading to the wall surface peeled off the floor, endangering the safety of pedestrians around, and so on.
2. Subsidence caused the cracks : caused by the settlement of the cracks were only investigating Housing 1% mainly due to the uneven subsidence caused. Survey found cracks in the main settlement of the following characteristics : ①. Cracks were mostly positive and negative "8" H, particularly the bottom corner windows and the most prominent; ②. Some vertical or horizontal wall horizontal wall cracks.
The survey was housing, is in the area, the Yellow River delta landscape is the alluvial plain, multi-layer distribution of silt, Muddy clay, silty clay, the foundation is weak, soil compression coefficient a1-2 were greater than 0.2 MPa, belong to the high compression soil, many sites may also exist uneven thickness of the weak underlying stratum. mostly construction units in engineering geology or no information is available for drilling the conduct of housing construction. Thus, the reasons for the settlement housing analysis more difficult. Housing settlement because it will be nothing more than the following situation : ①. The housing foundation existed weak underlying stratum; ②. load greater than the actual use of the design load; ③. Construction Quality; ④. Housing based design and engineering geological data are inconsistent.
3. Construction Quality caused the cracks : Construction phase of the project so that the landlord and the ultimate realization of design intent and engineering entity formation stage, is the ultimate form of product quality and project value is the most important step. In the survey, it was generally felt that the quality of construction of cracks is very obvious, especially households, put all the blame all the causes of cracks in construction quality, though it is one-sided and inaccurate, But this also reflects the users of construction quality and the degree of trust on the quality requirements. Therefore, the quality of construction can not be ignored. Construction quality caused by the cracks were varied. It can be said that any housing may have the cracks and the quality of construction. If the temperature cracks, roof insulation thickness. Wall insulation material or strength is not met design requirements, etc. may cause cracks or expanded; Masonry Mortar fullness not satisfied, but also can cause cracks in walls or windows deformation. Because, every skin brick building is not full of mortar, built for use, along with the increasing load deformation make masonry, When compressed uneven brick, the wall will have cracks, if the masonry uniform compression, can lead to deformed glass windows broken. Construction quality problems can also be caused by subsidence cracks, because when excavating the foundation trench, soil disturbance and formed rubber soil or foundation construction is not met design requirements so may lead to the uneven foundation settlement . In the survey also found that many housing the walls, floors have irregular cracks, with ornament and the drilling of the first beating, Walls found, and no cracks in the ground. This construction quality is purely cracks formed hollowing phenomenon which led to the cracks. In summary, the construction quality of the housing value is obvious.
Third, fracture treatment caused cracks in the housing for many reasons, but no matter what caused the cracks, housing will have varying degrees of adverse effects. First undermine the integrity of the housing and change the structural component of the original working state, reducing the housing seismic capacity and load-carrying capacity and reduce the housing structure within the reliability and long; Second is the impact of housing for normal use. Therefore, we must focus on the causes of cracks and crack, crack of the necessary housing, concrete measures are as follows :
1. Reinforcement Act. This method is aimed at improving the overall housing and structural component of the carrying capacity. If Rachel Bolt, steel mesh mortar floor surface, automatic pressure grouting method or foundation reinforcement.
2. Unloading Act. Rise more on housing, ground deformation heavier, the use of larger load difficult to reinforce the situation, available to reduce the use of loading, and the removal of unnecessary leg weights, or even reduce housing floors.
3. Combining maintenance functional transformation method. Cracking the housing heavier top or end-point, in the absence of reinforcement value of the circumstances, the site of demolition and reconstruction. or changing existing housing functions. According to the above measures to deal with specific situations can be employed singly or in combination can be, but the general principle is a well-established and strong measures, Construction easy, economical beauty.
Fourth, concluding remark
Widespread cracks in the housing issue has attracted the units and leaders at all levels attach great importance to it. However, the survey also found that some units of the construction completion information is not complete, cracks on the analysis of the reasons for the cracks housing handling difficult. In short, the causes of cracks is more complicated, in order to accurately determine the cause cracks, Much more needs to be done and meticulous investigation and evidence gathering; taken by the technical measures have yet to be in the future engineering practice to further improve and perfect.