ANTI DISASTER STRATEGY OF ZERO WASTE THATCHED HOUSE

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1 ANTI DISASTER STRATEGY OF ZERO WASTE THATCHED HOUSE LI Xinxin, LV Huanyu, JIN Hong School of Architecture, Harbin Institute of Technology, Harbin , China Abstract:Under the global background of low carbon, there is wide development space and realistic significance in the researching of traditional zero waste thatched house. To solve problems of rain erosion resistance and uneven settlement of foundation resistance which exist in the traditional thatched house, it should be improved building materials and construction methods and settle the small volume and low-density design of single house on the basis of maintaining the ecological characters of the original thatched house. It will be achieved good social effects and ecological effects if we engage in promoting anti-disaster ability of old thatched and spreading it in rural areas which has a great amount of building demand to meet needs of socialism new rural construction. Keywords:Thatched house, Green, Ecology, Zero waste, Raw soil The thatched house which has existed for more than 3000 years is a natural system of zero waste construction, has good thermal performance and relativity low energy consumption. Moreover, its great economic advantage can meet needs of low-income groups. Its instructive significance of traditional residents green regeneration cannot be ignored. Moreover, thatched house has been a kind of living culture. However, because of the impact of industrialization, in developing areas it has been taken the place by homogeneous products of large-scale production. It should not be given up its development and interpretation in many other aspects just to inherit its suitable living sense of space, such as, thermal insulation, affinity natural material selection and no construction waste, etc. 1. BACKGROUND At present, our rural areas have one million people who live in immature soil buildings. After an investigation by the authors, in our rural areas of Hei Longjiang province, immature soil buildings reaches 30% (as show in table one), is the second-largest housing structural form that existed in rural areas. However, due to the long history of those buildings, the living conditions are very poor under the double functions of natural power and human reasons, different degrees of damage have appeared, and some even become dangerous houses. Therefore, the anti-disaster research about immature soil not only has the function of reinforcement and reconstruction, but also has important function to the further development of immature soil architectures. It will get rid of its backwardness and have new meanings in the new era. Table 1 The statistics of the main housing structure of Hei Longjiang province Raw soil Brick Masonry-timber Stone Block Other Timberwork structure structure structure structure structure structures 30% 16.65% 52% 0.08% 0.69% 0.12% 0.38% The immature soil architecture has the following advantages: Easy to use local materials, low cost, convenience construction, simple technology, diverse building types, advantageous heat-insulating property, superior heat-shielding performance, advanced fire performance; demolition wastes can serve as fertilizer that returns to land. Project supported by National Major Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China (2006BAJ04A03-02) 1

2 At the same time, because of restriction in building ontology and technology, it still exists the following weaknesses about the immature soil buildings: the thick walls, low intensity and brittle material, poor safety in seismic area, low power of resistance of rain impact, possibility of uneven settlement; limited structural layout of immature, small bay, insufficient sunshine, unventilated and the damp room. 2. SURVEYS OF RURAL RAW SOIL BUILDINGS IN HEI LONGJIANG PROVINCE Combining with the national construction department's development projects, "investigation of China's rural housing situation, our group is responsible for investigation the rural living conditions of Hei Longjiang province, and research the anti-disaster strategies of raw soil buildings. 2.1 Research method We start to work in 2010 August. Sampling principle is to choose three counties-huanan, JiDong and LanXi in Hei Longjiang province whose living conditions are in three different levels (fig.1) and then extract three villages from each country, including 2931 households, whose living conditions in different levels to study. (Table 2) We collected information through questionnaires and field photographed. The questionnaire involves structures of residence s family, housing situation (design, structure, construction and safety, etc.), and subjective desire, and then begin to explore it deeply. Fig.1 Figure of research sits in Heilongjiang province Table 2 Level chart of sample survey Heilongjiang Province Huanan County Jidong County Lanxi County Zhonghe Huafeng Qianhefa Sipai Hongxing Xiangyang Shenli Aimin Pingan 2.2 Result Statistics After the investigation and statistics, the main structure of the house is raw soil, which reaches about 30% (table 1). The main structure of the houses, which adopts the soil (no watts) and a thatched roof materials were accounted for as 25.15% (Table 3). Wall materials for adobe or rammer earth accounted for participants occupy 29.8% (Table 4), green building materials (generates, stone, wood, bamboo), including total 29.36% in which immature soil walls retains 99%. It is thus obvious that in China's rural areas used generates building in order to achieve ecology, green, low carbon that has good foundation and broad space for development. Table 3 Statistics of main material of roof Pure Tile Tile Tile covered Color Concrete Precast slab Couch Others soil (no covered by by roof plate board water with water grass tile) rush mat boarding proof layer proof layer 13.10% 35.15% 5.48% 4.15% 24.06% 0.32% 0.77% 12.05% 4.92% 2

3 Table 4: Statistics of main material of walls Red brick Sement block Concrete building block Stone Dressed stone Raw soil Wood Others 61.45% 4.19% 3.99% 0.2% 0.04% 29.8% 0.04% 0.28% Research question analysis Due to the structural form and construction materials restrictions, all of raw soil buildings only have one floor, so we will analyze the raw soil buildings from the aspects of three aspects--foundation, the main wall, and roof. (1) Foundation A. Unprocessed (a part): The wall foundation is scattered, and building produces the uneven settlement so that there is a bigger displacement in the wall horizontal direction and because of the severe damp of the part above ground, the wall has been corroded so seriously that the seriousness damage can be as high as one meter. This processing technique is the most destructive. (fig.2) B. Rammed earth (a general way): the wall footing is much drier, near the doors or windows, the horizontal distortion is larger and the damage degree is bigger. (fig.3) C. Oker foundation (a little part): holistic performance is good. It can uneven settlement without obvious distortion, so that prolongs the service life. It is the basic form of ideal one. (fig.4) Fig.2 unprocessed Fig.3 Rammed earth Fig.4 Rammed earth (2) The main wall A. Rammer earth wall: It adopts sandy clay in site and combines structural layer with the wall. The holistic performance is good, but the construction is complicate. (fig. 5) B. Mud brick wall: It is made of adobe and yellow mud using dry or wet method, such as refined mud (screening, add water mixing), compaction (dry process ), parting, dry process, it also can be mixed short grass to increase the intensity. According to the regional characteristics, it can be targeted to solve destructive problem with appropriate materials (fig. 6) Fig.5 The rammed earth main wall Fig.6 The adobe main wall 3

4 (3) Roof truss The building which supported by raw soil wall usually adopts triangular purline (fig.7). On gable is pulin roof (fig.8). Then put rafter on the puline which located on the gable and roof truss. At last, build tile roof on the rafter. The style of roof is often symmetrical. In the research of raw soil structure housing in villages, a few houses adopted reinforcement measures, such as putting a beam in the broken place and Fig.7 Roof structure Fig.8 Pulin roof on gable laying bricks on severe crack walls etc. While most practice and construction methods of raw soil house buildings exists some problems. In poorer areas, it has a high proportion of dangerous houses. We found that many households farmers have no reinforcement awareness on raw soil construction and have no more in-depth understanding on raw soil structure housing to anti-disaster performance requirements in the deep study. 3. INFLUENCES OF COMMON ELEMENTS ON RAW SOIL STRUCTURE BUILDINGS IN HEI LONGJIANG PROVINCE This investigation divides the rural residential 50.00% buildings into A, B, C and D, four security levels % Among them, C and D, two levels account for about 30.00% 32% (Table 5), and the vast majority of them are raw soil 20.00% construction. Thus, the existing raw soil structure 10.00% buildings have a great deal of safety problems. Therefore, to study how to improve its ability of disaster, 0.00% Level A Level B Level C Level D strengthening the safety of has realistic meanings % 45% 18% 14% Heilongjiang does not belong to the earthquake Table.5 Statistics of safety class of buildings zone, and more of the raw soil structural houses just have one floor, the effect is small when the earthquake occurs. The whole condition is better than multistory buildings. Therefore, we do not discuss the disaster of earthquake in detail in this paper. This article mainly discusses anti-disaster strategies about the raw soil architecture in the rainstorm disasters, wind disasters and mild geological disasters. (1) Rainstorm disasters For raw soil structure building, the most significant influence on the raw soil structure building is to meet the gable rain erosion. Owing to the large quantity of the rain water, soil will lost vegetation after the decline of its rapping, therefore, it will produce the serious erosion from the pieces to the building. It will reduce the thickness of gables, expose walls' internal structure, and produce flake form's destruction. For a long time, the whole houses will collapse. (2) Wind disasters It is mainly damage to the raw soil structure buildings' roof and roof structures. Because the wind blew over the roof, it will produce high-speed negative pressure, which is easy to suck away the materials of roof, making the roof leak. However, the majority of existed raw soil structures is build earlier, and lack of effective measures to anti-disaster, so the influence of wind disasters to raw soil architecture is especially remarkable. And the winds days always along with heavy rain, under the function of high wind and rainstorm, it is more serious to the damage of raw soil buildings! 4

5 (3) Mild geological disasters Mainly includes: the ground subsides, the ground oozes water slightly, yellow soil loses, soil expanses, sandy soil liquefies etc. The most remarkable feature is that building produces large uneven, the walls sediment, ground that inside house produces shear power, which makes the walls and house ground de damaged. However, shear damage belongs to brittle failure; it will cause extremely serious consequences. 4. ANTI-DISASTER STRATEGY OF RAW SOIL STRUCTURE For existing raw soil buildings, the main strategy to resist wind disasters, rainstorm disasters and mild geological disasters is reinforcing buildings. 4.1 Selection of reinforcing materials After analyzing to common reinforcing materials and combing the results of researching and survey, we decide to choose timber, steel and concrete to be our materials. The main reasons are the following: (1) Timber: Timber has a better mechanical property and excellent tensile properties. Compared with reinforced fibre material, it draws materials easily and has better resistance to pressure. Moreover, timber can also be biodegradable so it can be used in agricultural fertilizers after removal of the building. (2) Steel Because mechanical property of steel is very good, steel has superior tensile properties and resistance to pressure. Q235 steel has lower price and convenient transportation. The most important advantage is its damage characteristics. Aafter stress, steel still has a strengthen process. In this process, it is obviously that stress increases with the increase of strain. The stress-strain curve of the whole steel under the normal temperature indicates that the whole process, from stress to break, is plastoelastic. So it will not appear brittle fracture, in the other word, in the event of damage to the case, there will be a very long period of time during deformation so that resident has enough time to mend it. It is the most suitable materials to reinforce the existing raw soil. And it can be reused after the house is abandoned. Therefore, it can meet the standard of zero waste. (3) Concrete Concrete which is a common material because of its superior, it has been widely used in practical engineering. However, because it is difficult to treat after its waste, this thesis only is applied in the basic reinforcement grouting method. In this method, after rebuilding, the grouted foundation can be still used as foundation of the new building to achieve the purpose of environmental protection. 4.2 The strategies of reinforcement technique Rainstorm disaster (Fig. 9-11) The heavy rain easily erodes the frontispiece of the building, destroying the consolidation of it, especially causing the collapse of gable. It is adopted that mortar and gypsum can be used on the surface of the raw soil wall to protect it. Fig.9-11 Corrosion of storm to gable of raw soil buildings 5

6 Wind from the erosion of the rainstorm. Surface material can use local materials, such as usable lime mortar, cement mortar, modified course, gypsum etc, to improve the resistant ability of raw soil wall Disasters Winds mainly destroy the roof of the building. The negative pressure area caused by strong winds can even blow off the roof, which severely makes bad effect on the construction safety. The main method of consolidating the building to resist the destruction of strong wind is to increase anchorage force among the roof, the wall and the column of it. The specific measures are following: (1) Consolidating the structure of roof (Fig.13) The rafter is put on the purlin, however, when the connection between the rafter and purlin is not fixed, we can consolidate the connection among the rafter, the beam, and the wall body by using round nails, wire, wall ect. The flat iron or grilled nailing can be use to strengthen the connection and enhance structural integrity on the buttjoint position of the rafter, the beam, and the wall body. (2) The connection between the wool beam and the wall body: Focusing certain situations, like the rafter being put on the raw soil wall, no peam pad under the wool beam, and over small beam pad, we can adopt the support underpinning method to design the standard beam pat. Fixing the flat iron or grilled nailing to the connection parts of wool columns and beam or beam and beam pat can strengthen the integrity of the node iron Mild geological disasters The effect on the building from slight geological disasters is various, especially on its integrity. Fig.12 Roofing collapse caused by uneven settlement Fig.13 Damage of walls caused by uneven settlement The stress on building imposed by slight geological disasters is shear, which can easily makes the brittle failure happens and threats the house residents of life and property security. For the buildings under the influence of slight geological disasters, we increase houses integrity and make stiffness asymmetric treatment to reduce the possibility of brittle failure. Specific strategies are as follows: (1) Setting up the structural column of ring beam For the house with no structural column of ring beam, the plus type wood can be used. That is to use bolts to connect iron castings and wooden lintel firmly on the existing lintels of door and window, with plus steel complementing the absent of ring beam. When wood struts is cut off by wool beam, the flat iron or grilled nailing iron can conjunct them firmly. Connecting the Steel struts and wood beam, punch in the middle of steel web plate and reinforce ring beam, internal and external sides of wall body with reinforcing steel in equivalent strength. Set up vertical groove in the raw soil wall and bury the wool column in it the structural column is formed, connected by iron casting and struts. The column supporting the wall can be installed on the leaning wall. (2) Asymmetric rigidity treatment for house We can slot in the raw soil wall and add wood column, connecting the rafter with the top part of the wood and then set the vertical scissors supports, slant supports or energy dissipation supports, and also can add wood column, wood beam and slant supports in the outer side of the interior and exterior of the walls to form a wooden frame bearing that system. 6

7 Changing the raw soil walls bearing with wall body and mixed bearing system, we can reconstruct it into wooden thing as vertical bearing system, raw soil wall by main wall instead of peripheral wall to raw soil walls are severe damaged, or the material properties of soil's wall body. To the problems of narrow about walls between window, we can add double-sided reinforcement fabric or reinforcement fabric, and make cement mortar to the wall body. Under the condition that the stiffness is strengthened, we can choose to make a seam in vertical wall, so as to reduce its stiffness and reduce the difference between the wall body. At the same time, we can change the destruction form in seismic damage of shear failure. The earthquake-caused shear failure can also be changed into other failure forms. (3) Strengthening the foundation for house As for the raw building which has crack on the foundation, we can use basic reinforcement grouting treatment to deal it. These cracks may be caused by freezing, thawing and uneven settlement. At the same time, we should pay attention to select the suitable place to build houses, or we can build houses after processing foundation. As for the situation that shallow layer of foundation has the better soil which can be used as supporting course and has lower water level, we can deepen the original depth of foundation so that foundation can be supported on the better supporting course. 4.3 Housing energy conservation strategy Since the existed raw soil building has built for a long time, and does not get enough repairmen, and does not pay enough attention to the concept of energy-saving building, which leads to the existed raw soil building's energy-saving is very poor, phenomenon of waste energy is quite serious. My team has proposed some strategies to energy-saving about raw soil building by combining the research results with practical experience. Specific as follows: To handle the outside walls: we should add a layer of clay block, lined with benzene board, but the reconstruction must pay attention to the waste treatment., and reduce overall coefficient of heat conduction, at the same time, in laying process, we must strictly notice waterproof of bricks, moistureproof, and also a piece of waterproof material should be established. The treatment to roof: we should establish condole to support roof, lined with grass plate, and also must complete job of waterproof and moistureproof. The house's stiffness asymmetric processing: we should set roof ceiling under roof, and line with grass plate, at the same time, we should also treat waterproof well. 5. CONCLUSION Traditional materials of raw soil building is not as good as clay brick, no matter in the aspect of strengthen of itself or in the aspect of anti-erosion, so it difficult to satisfy the need of modern life style. That s why we use clay brick take the place of traditional materials of raw soil building in so long time. Today, people begin to pay attention to ecological crisis, energy crisis and environmental pollution. On the basis of sustainable development of living environment and social dimensions of ecological civilization, raw soil has become the green material of construction by its advantages which include find materials easily, good insulation property and fire protection and so on. References [1]SONG Fei, JIN Hong, Research of the local building development based on ecology, Journal Of Harbin Institute of Technolog [2]G.Roter,FAN Xue, Introduce a new adobe building [J]. Architectural Journal, 1986 [3]CHEN Xing-yi, LU Xiao-ming, WANG Wei-chao, Structure of the Earth Building in North Henan, CONSTRUCTION CONSERVES ENERGY, (6) 7

8 [4]Chang Weihua, Wang Jianwei, Xu Fuquan, Study on existing situation of adobe and rammed earth building construction in town and village, Journal of Building Structures, [5]JGJ foundation reinforcement of existing buildings technical specification [S]. Beijing: China Building Industry Press,