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No 6(31) 2016, Dec 2016 Scientific Journal Of Thu Dau Mot University GREENHOUSE GAS EMISSIONS FROM MUNICIPAL SOLID WASTE DISPOSAL SITES A CASE STUDY IN HOI AN CITY Pham Phu Song Toan, Tran Minh Thao, Tran Thi Ngoc Linh Danang College of Technology The University of Danang ABSTRACT Currently, climate change shows an increasingly high intensity and anthropogenic greenhouse gas emissions are shown as the main drive force of rapid climate change In 2015, Hoi An City emitted 8,855 tons of CO2-eq from municipal solid waste disposal sites, which treated 25,000 tons of solid waste from domestic and tourist activities The flow of solid waste in disposal sites was analyzed and the sources of greenhouse gas emissions were identified by the Life Cycle Assessment (LCA) and Nordtest methods In addition, IPCC-2006 was a main tool for calculating, estimating and forecasting amount of greenhouse gas The results of this study shown that some activities in Cam Ha Composting Facility emitted 5,522 tons of CO2-eq, in which activities of using electricity, combusting diesel fuel and composting process were 1.6%, 7.8% and 90.6% of total GHG, respectively Additionally, 3,344 tons of CO2-eq was emitted from decomposited of Landfill site Furthermore, this study was analyzed specifically the composition of GHG whereby three main components were calculated such as CH4 (67.7% - 6,004 tons of CO2-eq), N2O (26.6% - 2,357 tons of CO2-eq) and CO2 (5.7% - 505 tons) Keywords: municipal solid waste management, greenhouse gas emissions, composting process, dumping landfill, Hoi An City INTRODUCTION In recent years, anthropogenically induced climate change becomes an alarming problem of the whole world N.T Viet et al., shown that from 2004 to 2014 the shoreline of Cua Dai Beach in Hoi An City (HAC) had been eroded, slid and engrained 500 m along the coastline This erosion pulled down many hotels, buildings and threatened the lives of fishermen [1] The rise of greenhouse gases (GHG) in recent decades is known as one of the main drivers of climate change According to the 4th report of Intergovernmental Panel on Climate Change (IPCC), amount of GHG emitted from management of solid waste and wastewater was 3% of total amount of GHG from human activities, particularly methane (CH4) accounted for 90% [2] HAC is an ancient tourist city so the two main sources of solid waste are domestic and tourism activities According to the report of Building a Hoi An Ecological City Project, 80% of total solid waste in HAC was collected and treated Over 50% of municipal solid waste amount was composted, about 5% of solid waste was recycled and the remainder was treated by dumping on landfills [6] Composting is a friendly solution with environment However, it must be admitted that there are considerable amounts of GHG emitted from the composting 67 Pham Phu Song Toan Greenhouse gas emissions from municipal solid waste disposal sites process[3] Additionally, dumping on landfills is known as a main source of GHG emission from solid waste disposal All of them contribute to increasing the effects of global warming[4] MATERIALS AND METHODS 2.1 Accounting GHG emission from using electricity The electricity was used for operating equipment in composting facility is considered in this study The GHG emission from using electricity was determined by the following equation: [7] Where: MJ is electricity consumption (MJ Kwh = 3.6 MJ); E is equivalency factors 2.2 Accounting GHG emission from diesel combustion In this study, one truck (15 tones) was used to transport solid waste from separating point to the landfill and two scooping trucks were used for mixing, scooping and moving solid waste in composting process Thus, the estimation of GHG emissions bases on vehicle type, distance travelled and working time per day (8 hours) The emissions (CO2 equivalents) were determined using life cycle inventory data and the formula below: [7] Where: S is distance travelled (Km); E is equivalency factors 2.3 Accounting GHG emission from composting In composting process, a large fraction of the degradable organic carbon (DOC) in the waste material is converted into CO2, CH4 is formed in anaerobic sections of the compost and N2O also produced Poorly working composts are likely to produce more both of CH and N2O [7] The CH4 and N2O emissions of biological treatment can be estimated using the default method given in follow equations: ; [7] Where: M is mass of organic waste treated by composting (Gg); EF is emission factor for composting (g CH4 or N2O/kg waste treated); R is total amount of CH4 recovered in inventory year (Gg); i is composting 2.4 Accounting GHG emission from landfill site The greenhouse gases emissions related to landfilling are mainly due to CH4 and carbon dioxide CO2 present in the biogas produced by anaerobic bacteria The equation is as follows: [8] Where: MSWT is total MSW generated (Gg/yr); MSWF is fraction of MSW disposed to solid waste disposal sites; MCF is methane correction factor (fraction); DOC is degradable organic carbon (fraction) (kg C/kg SW); DOCF is fraction DOC dissimilated; F is fraction of CH4 in landfill gas (IPCC default is 0.5); 16/12 is conversion of C to CH4, R is recovered CH4 (Gg/yr) RESULTS AND DISCUSSION 1.1 Municipal solid waste management in Hoi An City On the land of 61.71 km2, HAC has wards and communes of administration, which form main featured areas such as the ancient town area in the center of the city, the residential area and rural area According to the statistics from Center of Population and 68 No 6(31) 2016, Dec 2016 Scientific Journal Of Thu Dau Mot University Family Planning, Center of Management and Tourism Development and Public Works Ltc., in recent years while the population of HAC has been relatively stable, number of tourists has increased significantly and the amount of municipal solid waste also respectively raise as the below Table Table Statistics of population, tourist and MSW in Hoi An city in recent years Year Population (people) Tourist (people) MSW (ton) 2009 2010 2011 2012 2013 2014 2015 93,806 1,474,098 19,282 91,368 1,504,478 20,147 94,531 1,753,228 22,164 92,389 1,679,262 23,915 94,246 1,911,000 24,548 94,367 1,756,916 26,101 89,755 1,899,000 25,339 3.2 Flow of solid waste and composition of MSW Life Cycle Assessment method was used to analyze the flow of solid waste in disposal sites and identify sampling points Nordtest methods (NT ENVIR 001 & 004) were used for sampling and measuring the composition of municipal solid waste which is showed in the Fig 175 samples were sampled continuously from positions of composting process in days of a week to calculate the average value and assess the stability of data between weekdays [9,10] The proportions of municipal solid waste components are shown in the Fig bellows Figure Flow of solid waste in disposals and composition of MSW The municipal solid waste is aggregated into the gathering point at the Cam Ha Composting Facility, where solid waste is classified for the next treatment stages The composition of solid waste in HAC was identified including 64% of organic, 15% of plastic, 11% of incombustible waste, 9% of glass, textile and card board and 1% of hazardous waste While the recycled waste is moved to the recycle companies in Da Nang City (DNC), small organic waste (89%) is collected for being the raw material of composting process, which has 11% of small size impurities such as plastic (4%), glass (2%), incombustible waste (2%), textile (1%) and card board (1%) However, the biodegradable process from the fermenting and composting process is reduced due to the significant impurities in the final product In addition, the bulky waste, which is transported to the landfill has 63% of organic (bulky bough, garden waste), 15% of plastic, 8% of incombustible waste, 10% of textile and glass and the remainders of card board, wood and ceramic Comparing to the characteristic of the municipal solid waste in DNC - a famous tourist city, which is one of the biggest cities in the central of Vietnam receives about 720 tons of solid waste every day with the component was identified by 66.71% organic waste 14% plastic, 9.7% incombustible waste and 9.59% of others [5] Although HAC is smaller than DNC (about urban scale and amount of solid waste generation), the composition of the municipal is relatively homologous 69 Pham Phu Song Toan Greenhouse gas emissions from municipal solid waste disposal sites 3.3 Activities of MSW disposals and sources of GHG emissions The municipal solid waste of HAC is collected and transported to Cam Ha Solid Waste Facility by trucks and is classified for the next treatment stages Composting and dumping landfill are two main disposal methods Several activities in Composting Facility and Landfill Site are shown and sources of GHG emissions from disposal sites are identified in the Fig In Composting Facility, GHG can emitted from three main activities such as burning diesel fuel from transportation by trucks and mixing waste by scooping trucks, using electricity for operating equipment and official activities and composting process Furthermore, using compost in agriculture is known as a way of saving carbon and nitrogen in soil that is the potential and long term emission In addition, at the dumping landfill, transportation and decomposition is two main processes can emit GHG [4] Fuel/Energy Activities GHG emissions Transportation Import raw materials and semi-processed Disposal Diesel Electricit y Recycle waste Transfer to storage Bulky Transfer to landfill waste Screen raw material GHG from burning diesel and using electricity Composting process Diesel Electricity Transferring and mixing by scooping trucks Composting process Operate equipments and official activities Decomposition process Dumping landfill site Composting facility Composting process Decomposition process Diesel GHG from burning diesel and decompositi on-on Transfer solid waste to landfill site Decomposition activities Note: GHG from burning diesel, using electricity and composting Sources of GHG emissions Figure Sources of GHG emissions from activities of municipal solid waste disposals 70 No 6(31) 2016, Dec 2016 Scientific Journal Of Thu Dau Mot University 3.4 GHG volume from disposal activities This bar chart in Fig.3 shows the amount of GHG emitted from four activities in both of disposals in HAC in 2015 In particular, the volume of GHG from composting process was the highest proportion with 5,017 tons of CO2-eq (equivalent to 56.6%), while decomposition activity from the landfill emitted about 3,343 tons of CO2-eq (equivalent to 37.7%) On the other hand, combusting diesel and using electricity activities emitted 429 tons and 76 tons CO2-eq (equivalent to 4.8% and 0.9%), respectively Comparing to GHG emission in DNC, 160,000 tons CO2-eq (equivalent to 7,573 tons CH4), which were emitted from Khanh Son Landfill site in Danang City were more than HACs 10 times of solid waste volume and 18 times of GHG emission volume [5] These data illustrate that aerobic and anaerobic decompositions is the main generation sources of GHG by 94.4% Thus, well controlling the processes of composting and landfilling, the amount of GHG emission will be reduced Particularly, oxygen should be supplied enough to restrict anaerobic space in composting piles The operating parameters such as moisture, temperature, the C/N ratio have to frequently check and control to reach optimum values Additionally, the recovery and reuse of CH4 should be improved to increase R coefficient and simultaneously reduce the amount of GHG from landfill Figure GHG volume from disposal activities in 2015 Figure The amount of GHG components in 2015 71 Pham Phu Song Toan Greenhouse gas emissions from municipal solid waste disposal sites The second chart in Fig.4 illustrates the emission of GHG components from disposal sites CH4 has always been a key component of GHG generation Total amount of CH4 which was emitted from disposal sites in 2015 was 286 tons (equivalent to 6,004 tons CO2eq), while there were 7.6 tons N2O (equivalent to 2,357 tons CO2-eq) and 505 tons CO2 were emitted, respectively Thereby, the municipal solid waste disposals in HAC emitted approximately 8,866 tons of CO2-eq into the atmosphere in 2015 Being born from the anaerobic digestion process, CH4 accounted for 67.72 % of total amount of CO2-eq This means that anaerobic decomposition was a significant part in composting process and the considerable leakage of CH4 from landfill site 3.5 Estimation of GHG emission from MSW disposal in HAC for the future According to the Building an Ecological City Plan of HAC, there are two scenarios for treating solid waste All of the municipal solid waste will be treated by composting and incinerator (S1) or will be burned by incineration (S2) However, to improve the effect of sustainable integrated MSWM, the 3rd scenario is proposed which integrates anaerobic digestion, recycling, composting and incineration methods The estimation of GHG generation in three scenarios from 2015 to 2030 is showed in figure Figure Estimation of GHG emission from municipal solid waste disposals in the future This chart shows clearly that the GHG emission from disposals in scenario (S1) and scenario (S2) will be higher than from scenario (S3) and go up slightly follow the growth of amount of municipal solid waste This is explained by plastic, flame retardants and wet materials have high CO2 emission factors from burning Thus, burning all of solid waste in S2 or a half without separation in S1 will emit more GHG Whereas, the municipal solid waste will be classified well in scenario Therefore, the recycle waste (plastic, paper, card board, metal, glass, ) will be reused, recycled; the organic waste with high moisture (chicken waste, market waste, sewage sludge, human waste, ) will be decomposed by anaerobic digestion method (AD) which is has low greenhouse gas emissions, produce liquid fertilizer and recover CH4 for cooking and power generation The bulky waste (garden waste) will be composted and the remaining fraction (household items) will be 72 No 6(31) 2016, Dec 2016 Scientific Journal Of Thu Dau Mot University burned The ash from incinerator will be landfilled Therefore, the municipal solid waste management (MSWM) in HAC should be integrated and handled according to scenario to reduce total GHG emissions from disposals and get more benefits from energy saving and fertilizer products as well CONCLUSIONS HAC generates about 2,000 tons of municipal solid waste every month which is separated by citizen and collected with distinct schedules However, all of solid waste is gathered to the same point and mixed together Thus, this makes the separation at the source lose the meaning and cause serious obstacles to the next treatment stage as well Composting and dumping landfill methods are used for treating all of municipal solid waste in HAC Cam Ha Composting Facility receives about 50% of total solid waste and the other half is dumped into Cam Ha dumping landfill site The composition of municipal solid waste was identified including 64% of organic, 15% of plastic, 11% of incombustible, 9% of glass, textile and card board and 1% of hazardous In 2015, 8,855 tons of CO2-eq was emitted from both of disposal sites in HAC, in which 5,522 tons of CO2-eq were generated from Cam Ha Composting Facility and 3,344 tons CO2-eq were generated from Cam Ha dumping landfill site, respectively In total GHG emitted, CH4 is a key component by 67.7% of total amount of CO2-eq (equivalent to 6,004 tons CO2-eq), while N2O and CO2 were 26.6% (equivalent to 2,357 tons CO2-eq) and 5.7% (equivalent to 505 tons CO2) This showed that these solid waste treatment disposals did not effectively operate Particularly, there were significantly anaerobic process in composting and considerably leakage of CH4 from landfill site The estimation of GHG generation for scenarios of MSWM proved that an integrated MSWM, which includes effect of separation and collection and integration of recycling, composting, anaerobic digestion, incineration and landfilling will emit fewer GHG This scenario will be the sustainable integrated MSWM model for HAC to build a Hoi An Low-Carbon City and bring numerous benefits for life Acknowledgements: The authors acknowledge the support of 13MTs students of Danang College of Technology The University of Danang and the financial support from GEGES Funding Research Program of Kyoto University, Japan REFERENCES [1] Viet N T, Hoang V.C., Hitoshi Tanaka, Morphological change on Cua Dai Beach, Vietnam: Part I image analysis, Research Gate, 2015 (http://www.researchgate.net/publication/271589428) [2] Charlotte Scheutz, et al., - Microbial methane oxidation processes and technologies for mitigation of landfill gas emissions, Journal of Waste Management & Research, International Solid Waste Association (SAGE published online), (2009), 409-455 [3] Antoni Sỏnchez, et al., -Greenhouse Gas from Organic Waste Composting: Emissions and Measurement, Springer, 2015, 33 42 73 Pham Phu Song Toan Greenhouse gas emissions from municipal solid waste disposal sites [4] Alessio Boldrin, et al., - Composting and compost utilization: accounting of greenhouse gases and global warming contributions, Waste Management & Research (2009), 1-13 [5] Vo Ngoc Diep Khoi, T.V Quang, H Hai, Greenhouse gas emissions from municipal solid waste in Danang City, Journal of Science and Technology, 53 (3A) (2015) pp 295-300 [6] People Committees of HAC, Building a Hoi An Ecological City Report, 2009, pp 11 [7] Recycled Organic Unit Greenhouse gas emissions from composting facility 2nd Edition, The University of New South Wale, 1466 Sydney, Australia, 2007, 25 34 [8] IPCC Chapter 4: Biological Treatment of Solid Waste, IPCC Guidelines for National Greenhouse Gas Inventories Vol Waste, 2006 [9] Nordtest method NT ENVIR 001 Solid Waste, Municipal: Sampling and Characterization, NORDTEST FINLAND, 1995 [10] Nordtest method NT ENVIR 004 - Solid Waste, Particulate Materials: Sampling, NORDTEST FINLAND, 1996 Article history: Received: Sep 8.2016 Accepted: Nov 30.2016 Email: ppstoan@dct.udn.vn / ppstoan@gmail.com 74 No 6(31) 2016, Dec 2016 Scientific Journal Of Thu Dau Mot University PRESERVATION OF ENVIRONMENTAL FUNCTIONS BY THE IMPLEMENTATION OF CORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENT IN WEST SUMATRA Rembrandt, SH MPd Andalas University (Indonesia) ABSTRACT Environmental issue is not only a matter of human physical environment nor human biological problem, but also a moral issue World Industries is often a major culprit in environmental degradation, since very greedy in exploiting natural resources When traced, perhaps one reason is the lack of concern and responsibility of management and owners of the company towards society and the environment at the company site Investors simply dredge and exploit the natural resources that exist in the area, regardless of environmental factors In addition, almost little or no corporate profits are returned to the community, especially intended for environment conservation Precisely that is the case, the community is marginalized even in its own area Keywords: Environmental Conservation, Corporate, Corporate Social Responsibility and the Environment INTRODUCTION Environmental issues are of most crucial in human life Consequently, the linkage between corporate responsibility and the enforcement of environmental law may serve as a guarantee on the sustainability of human life Environmental issues are not only in terms of human physical or biological issues, but also serve as moral issues The basic concept of such responsibility is still in the private domain and in development, is coming to a broader domain, i.e collective domain Maignan and Ferrel state that CSR as a business acts in socially eponible manner when its decision and action for balance divere stakeholder interests The Corporate Social Responsibility (CSR) has become a recent talk, triggered by the new provision in the Law No 40 of 2007 on Limited Corporation (Limited Corporation Act) which regulate such substance Basically, Article 74 of the Act mentions that each Limited Corporation in the field or related to natural resources is bound to conduct corporate social and environmental responsibility.[1] [1] There are two kinds of environmental issues, i.e environmental pollution and environmental destruction Article point 12 and 14 of Law No 32 of 2009 states that environmental pollution is the entry or the inclusion of living creatures, substances, energy and/or other components into an environment through human activities by which the quality of the environment degrades into a certain level that causes the environment to defunct from its allotment Meanwhile, environmental destruction is an act that may cause direct or indirect change towards the physical or biological treats that causes the environment fail to function in supporting sustainable development 75 Rembrandt, SH MPd Preservation of environmental functions by the implementation Law No 32 of 2004 contains the legal vision to accelerate the welfare of the people by means of improvement, services, empowerment, and participation of the society, and improvement of regional competitiveness by considering the principles of democracy, equality, justice, privileges, features and speciality of regions in the system of the Unitary State of Indonesia In achieving such goals, regional government needs to re-engineer the management of government and development to implement effective government Under the circurmstances, the province of West Sumatra attempts to accelerate the welfare by developing business opportunities especially for micro & small entrepreneurs, and cooperatives as this sector absorbs manpower Yet it is not easy to empower those entrepreneurs due to the limitation to access of capital Industries are often times deemed as the culprit in the environmental destruction due to their hunger in exploiting natural resources [2] Upon further in-depth observation, the cause of this is the lack attention and responsibility of the management and corporate owners towards the surrounding society and environment Investors harass and exploit the existing natural resources in an area disregarding the environmental factors Moreover, very little if any even none of the corporates profit are returned to the society It has been a common practices that locals are marginalized in their own area In West Sumatra, the area of protected forest covers 923,246 hectares, wildlife reserve area of 24,592 hectares, natural conservancy area of 36,624.93 ha, tourism natural park area of 861,802 hectares, and national park area of 554,280 hectares [3] Referring to the data of the Forestry Agency of West Sumatra, forest area of West Sumatra is 2,464,094 hectare with the following detail: conservation forest 773,343 hectare, protected forest 923,246 hectare, limited-production forest 216,223 hectare, production forest 429,281 hectare and convertible production forest 212,910 hectare [4] Today, the forest area is occupied by custom-based society (masyarakat hukum adat) and such occupation is passed hereditarily MATERIALS AND METHODS This Research is on the Preservation of Environmental Functions directly pertaining to the operation of corporations in the form of social and environmental responsibility, totally focused on the principles of social and environmental responsibility implemented by those corporations The social and environmental responsibility policy is related to the principles of justice for the society of West Sumatra that is known for its strong customs in the use of natural resources, and the concept of social and environmental responsibility that supports the preservation of environment in order to achieve the objectives of welfare state The methods that has been used for this menuscript juridical normative from the study of constitution law with sociologic juridical approach to cultivate the data from the field [2] [3] [4] AB Susanto, Corporate Social Responsibility; Pendekatan Strategic Management dalam TJSPL (Corporate Social Responsibility; The Approaches of Strategic Management in CSER); Jakarta; Erlangga, 2009, p Source: Forestry Agency of West Sumatra, 2011 Ibidem 76 Tp Khoa hc i hc Th Du Mt S 1(32)-2017 PHNG PHP PROPER GENERALIZED DECOMPOSITION CHO BI TON TM MNG CHU UN Lờ Quc Cng(1), Nguyn Bỏ Duy(2) (1) Trng i hc S phm K thut TP.HCM; (2) Trng i hc Th Du Mt Ngy nhn 29/12/2016; Chp nhn ng 29/01/2017; Email: lecuong2109@gmail.com Túm tt Trong bi bỏo ny, chỳng tụi trỡnh by phng phỏp Proper Generalized Decomposition (PGD) gii quyt bi toỏn tm mng chu un khụng gian hai chiu Phng phỏp PGD c ỏp dng a bi toỏn hai chiu thnh chui cỏc bi toỏn mt chiu Sau ú, mi bi toỏn mt chiu c gii bng phng phỏp sai phõn hu hn Kt qu mụ phng s c ỏp dng cho bi toỏn tm mng chu un vi cỏc iu kin biờn khỏc Cỏc kt qu tớnh toỏn s c so sỏnh vi li gii gii tớch T khúa: gim bc mụ hỡnh, Proper Generalized Decomposition, tm mng chu un Abstract PROPER GENERALIZED DECOMPOSITION METHOD FOR THE THIN PLATE BENDING PROBLEM In this paper, we present Proper Generalized Decomposition (PGD) method to solve the problem of thin plate bending in two-dimensional space PGD method is applied to transform the two-dimensional problem into a series of one-dimensional problems Then, each onedimensional problem is solved by the finite difference method Numerical simulation results are applied to thin plate bending problem with different boundary conditions The calculation results are compared with analytical solutions Gii thiu Nhiu mụ hỡnh bi toỏn thng gp khoa hc v k thut thng c nh ngha khụng gian a chiu, iu ú lm cho chiu th nguyờn tr nờn cc k phc ỏp dng k thut chia li ri rc thụng thng Hn na cỏc mụ hỡnh theo tiờu chun cú th tr thnh a chiu cỏc thụng s thay i Vỡ vy vic phỏt trin mt phng phỏp mi nhm gii quyt bi toỏn mt cỏch nhanh chúng hn l rt cn thit Phng phỏp PGD ln u tiờn c gii thiu bi giỏo s Chinesta v cỏc cng s [1] S i ca phng phỏp PGD ó gúp phn h tr gii quyt bi toỏn cú s chiu khụng gian ln mt cỏch hiu qu vi thi gian x lý nhanh v chớnh xỏc cao Phng phỏp PGD ngy cng c m rng ng dng gii quyt cỏc bi toỏn a chiu cỏc lnh vc nh c lu cht [2], truyn nhit [3], vt liu composite [4] Phng phỏp PGD l phng phỏp gim bc mụ hỡnh da trờn c s tỏch bin, li gii ca bi toỏn c tỡm di dng tng ca cỏc tớch hm s trờn mi chiu khụng gian 63 Lờ Quc Cng Phng phỏp proper generalized decomposition cho bi toỏn Gi s trng u ph thuc N bin s x1 , x2 , , xN , ú giỏ tr u c vit di dng tỏch bin nh sau: Q u( x1 , x2 , , xN ) Fi ( x1 ) Fi ( x2 ) Fi ( xN ) (1) i ú xi i 1, 2, , N l bin s khụng gian, thi gian hay tham s m bi toỏn cn kho sỏt Bi toỏn phõn tớch tm mng chu un ó c thc hin thnh cụng vi nhiu phng phỏp s khỏc (phn t hu hn, sai phõn hu hn, phng phỏp ph, ) Trong bi bỏo ny, phng phỏp PGD c xut gii quyt bi toỏn tm mng chu un Phng phỏp PGD c ỏp dng a phng trỡnh vi phõn o hm riờng ca bi toỏn tm mng chu un khụng gian hai chiu thnh chui cỏc phng trỡnh vi phõn khụng gian mt chiu Sau ú, phng phỏp sai phõn hu hn da trờn s sai phõn trung tõm bc hai c ỏp dng gii cỏc phng trỡnh mt chiu Bi bỏo ny c t chc nh sau, phn trỡnh by phng trỡnh vi phõn ch o ca bi toỏn tm mng chu un Phn trỡnh by phng phỏp PGD cho phng trỡnh biharmonic khụng gian hai chiu Sau cựng, cỏc kt qu mụ phng c trỡnh by phn Phng trỡnh vi phõn ch o cho bi toỏn tm mng chu un Phng trỡnh vi phõn ch o ca bi toỏn tm mng chu un khụng gian hai chiu cú dng phng trỡnh biharmonic [7] nh sau 4w 4w w p , (2) õy w vừng ca tm, p lc tỏc dng lờn b mt tm x x 2y y D v D Eh 12 cng chu un ca tm Trong ú, E l mụ un n hi, h l chiu dy tm v l h s poisson Phng phỏp PGD cho phng trỡnh biharmonic Xột phng trỡnh biharmonic khụng gian hai chiu nh sau 4u 4u 4u f x, y x y (3) x x 2y y Mc tiờu ca chỳng ta l ỏp dng phng phỏp PGD tỡm nghim xp x ca phng trỡnh (3) Gi s nghim xp x ca phng trỡnh c vit di dng tỏch bin nh sau N u x, y X i x Yi y (4) i Gi s li gii bc lp th n ó bit, chỳng ta cn tỡm li gii bc lp th n u n n x, y X i x Yi y R x S y (5) õy: i Phng trỡnh (3) c a v dng yu nh sau 4u 4u * u u x x 2y y x y R x X n1 x v S y Yn1 y f dxdy , vi u* R* S R S * l hm trng s 64 (6) (7) Tp Khoa hc i hc Th Du Mt S 1(32)-2017 Thay (5) v (7) vo phng trỡnh (6), ta c R x y * d 4R d 2R d 2S d 4S S R S * S 2 R dxdy R * S R S * fdxdy dx dy dy dx x y R * x y R n d 4Xi S R S* Yi dxdy dx i * x y R x y * (8) n d X i d 2Yi S R S* dxdy dy i dx n d 4Y S R S * X i 4i dxdy dy i gii phng trỡnh (8) tỡm R x v S y , chỳng ta s dng gii thut lp c nh luõn phiờn gm cỏc bc sau: Bc 1: Tỡm hm R x Gi s S y ó bit, ú S * , thay vo phng trỡnh (8) ta c d 4R d 2R d 2S d 4S * R S S R dxdy R* S fdxdy 2 dx dx dy dy x y x y n d 4Xi * R S Yi dxdy i dx x y (9) n d X i d 2Yi * R S dxdy dy i dx x y n d 4Yi * R S X i dxdy dy i x y Vỡ tt c cỏc hm ph thuc y phng trỡnh (9) ó bit, chỳng ta cú th thc hin tớch phõn mt chiu trờn y a y S dy y b S d S dy y dy y d 4S c y S dy dy y f y x S fdy y i a y S Yi dy y byi S d Yi dy dy y i d 4Yi c S y dy dy y (10) 65 Lờ Quc Cng Phng phỏp proper generalized decomposition cho bi toỏn Khi ú phng trỡnh (9) tr thnh n d 4R d 2R * * * i d Xi R a b c R dx R f x dx R a y y y y y dx i1 dx dx dx x x x n R* byi x x i d 2Xi dx (11) dx n R* ciy X i dx i Phng trỡnh (11) l dng yu mt chiu c nh ngha trờn x Ngoi chỳng ta cú th a v dng mnh nh sau n n n d 4R d 2R i d Xi i d Xi a y 2by c y R f y x a y b ciy X i (12) y dx dx dx dx i i i Bc 2: Tỡm hm S y Vi R x va tớnh bc trờn, ú R* , tin hnh tng t nh bc tỡm hm R x , ta c phng trỡnh dng mnh ca hm S y nh sau n d 4S d 2S * * * i d Yi S a b c S dy S f y dy S a dy x x x dy x dy x dy i y y y n S * bxi y y i n S * cxi Yi dy i õy a x R dx x b R d R dx x dx x d 4R c R dx x dx x f x y R fdx x i a x R X i dx x d 2Xi bxi R dx dX x c i R d X i dx x dx x (14) 66 d 2Yi dy dY (13) Tp Khoa hc i hc Th Du Mt S 1(32)-2017 Phng trỡnh (13) cú th c a v dng mnh nh sau n n n d 4Yi d 4S d 2S i d Yi a x 2bx cx S f x y a xi b cxi Yi (15) x dy dy dy dy i i i Cỏc bc gii phng trỡnh (12) v phng trỡnh (15) tỡm R x v S y c lp q q cho n kt qu hi t Nu kớ hiu R x v R x l hm R x ó c tớnh q q bc lp hin ti v bc lp trc, tng t vi S y v S y , tiờu chun dng c chn nh sau e R q x S q y Rq1 x S q1 y RS (16) õy RS l hng s c chn m bo chớnh xỏc Sau cỏc bc lp tỡm R x v S y hi t, chỳng ta xỏc nh c X n1 x R x v Yn1 y S y Quỏ trỡnh tỡm cỏc cp hm X i x , Yi y phi c tip tc cho n t c s hi t ton cc ca bi toỏn bc lp th N , ú nghim xp x ca bi toỏn c tớnh nh sau N u x, y X i x Yi y (17) i iu kin dng ton cc ca bi toỏn c tớnh nh sau res E u (18) f x, y õy u l mt hng s c chn nh v res l hm thng d ca bi toỏn 4u 4u 4u res 2 f x, y (19) x x y y Chỳng ta thy rng phng trỡnh Biharmonic hai chiu ban u c nh ngha trờn x y ó c chuyn i thnh cỏc bi toỏn mt chiu trờn x v y vi phng phỏp PGD S sai phõn trung tõm bc hai c s dng gii cỏc phng trỡnh vi phõn mt chiu cú dng nh phng trỡnh (12) v (15) tỡm R x v S y tng ng S sai phõn bc hai cho o hm bc hai v bc ca mt hm f x bt k c tớnh nh sau: f x f x h f x f x h O h (20) x h2 f x 2h f x h f x f x h f x 2h f x x õy h l kớch thc bc li h2 O h (21) Kt qu mụ phng s Bi toỏn 1: Xột tm hỡnh ch nht x 1, y cú phng trỡnh vi phõn ch o nh phng trỡnh (2), vi v phi c cho nh sau: 67 Lờ Quc Cng Phng phỏp proper generalized decomposition cho bi toỏn q (22) sin x sin y D Trong trng hp tm vi iu kin biờn l gi ta n c bn cnh nh sau 2w 2w w 0, ti x v x (23), w 0, ti y v y (24) x y q ú li gii chớnh xỏc ca bi toỏn l w exact sin x sin y (25) 4 D Phng phỏp PGD c ỏp dng cho bi toỏn vi cỏc thụng s mụ phng nh sau: p , E 1092000 MPa , h 0.01 , 0.3 Min tớnh toỏn c ri rc vi li 100 cho mi chiu trc x v y Hỡnh trỡnh by li gii PGD cho vừng ca tm mng vi iu kin biờn gi ta n c bn cnh ca tm Sai s gia li gii PGD v li gii chớnh xỏc c trỡnh by hỡnh f x, y Hỡnh Li gii ca bi toỏn bng phng phỏp PGD cho tm mng vi iu kin biờn gi ta n bn cnh ca tm trờn li 100 100 Hỡnh Sai s wexact w gia li gii gii tớch v li gii PGD trờn li 100 100 Bi toỏn 2: Trong trng hp tm b ngm c bn cnh, ta cú iu kin biờn tng ng nh sau w (26) w 0, ti x v x , x w (27) w 0, ti y v y y Cỏc thụng s mụ phng c cho tng t nh trng hp bi toỏn 1, v phi ca phng trỡnh vi phõn ch o c cho nh sau: q 56400 a 10ax 15x b y y D q 18800x 6a 20ax 15 x y 6b2 20by 15 y D q 56400 a x x b2 10by 15 y D f x, y (28) Vi iu kin biờn b ngm bn cnh li gii chớnh xỏc ca bi toỏn l 68 Tp Khoa hc i hc Th Du Mt S 1(32)-2017 q 2 (29) 2350 x x a y y b D Hỡnh trỡnh by li gii PGD cho vừng ca tm vi iu kin biờn ngm cht c bn cnh ca tm Sai s gia li gii PGD v li gii chớnh xỏc c trỡnh by hỡnh wexact Hỡnh Li gii ca bi toỏn bng phng phỏp PGD cho tm mng vi iu kin biờn ngm bn cnh ca tm Hỡnh Sai s wexact w gia li gii gii tớch v li gii PGD trờn li 100 100 Kt lun Trong bi bỏo ny, chỳng tụi ó s dng phng phỏp PGD phõn tớch bi toỏn tm mng chu un vi cỏc iu kin biờn khỏc Cỏc kt qu mụ phng cho thy s ng thun khỏ tt ca phng phỏp xut vi li gii chớnh xỏc ca bi toỏn Vi vic a bi toỏn a chiu v cỏc bi toỏn mt chiu, phng phỏp PGD s giỳp lm gim chi phớ tớnh toỏn v tit kim b nh mỏy tớnh TI LIU THAM KHO [1] F Chinesta, A Ammar, E Cueto (2010), Proper generalized decomposition of multiscale models, Int J Numer Methods Eng, 83(89), pp 11141132 [2] A Dumon, C Allery, A Ammar (2011), Proper general decomposition (PGD) for the resolution of NavierStokes equations, Journal of Computational Physics, 230, pp 13871407 [3] E Pruliốre, F Chinesta, A Ammar, A Leygue, A Poitou (2013), On the solution of the heat equation in very thin tapes, International Journal of Thermal Sciences, 65, pp 148157 [4] P Vidal, L Gallimard, O Polit (2012), Composite beam finite element based on the Proper Generalized Decomposition, Computers and Structures, 102103, pp 7686 [5] A.J Chorin (1968), Numerical solution of the Navier-Stokes equations, Math Comput, 22, pp 745762 [6] U Ghia, K Ghia, C Shin (1982), High-re solutions for incompressible flow using the Navier Stokes equations and a multigrid method, Journal of Computational Physics, 48, pp 387411 [7] S P Timoshenko, S Woinowsky_Krieger (1970), Theory of Plates and Shells, McGraw-Hill, New York 69 Kim toỏn dao ng phng tin giao thụng gõy Lờ Thnh Trung KIM TON DAO NG DO PHNG TIN GIAO THễNG GY RA TRONG CễNG TC THIT K NN NG ễ Tễ TRấN T YU KHU VC NG BNG SễNG CU LONG Lờ Thnh Trung(1) (1) Trng i hc Th Du Mt Ngy nhn 29/12/2016; Chp nhn ng 29/01/2017; Email: lttrung@tdmu.edu.vn Túm tt Bi bỏo ny trỡnh by c s lý thuyt v kim toỏn dao ng cụng tỏc thit k nn ng ụ tụ trờn nn t yu theo tiờu chun ca Cng Hũa Liờn Bang Nga Trờn c s ú, ỏp dng vo cụng tỏc thit k nn ng ụ tụ iu kin t yu khu vc ng bng sụng Cu Long ng thi, kin ngh b sung iu kin kim toỏn dao ng trờn vo quy trỡnh kho sỏt thit k nn ng ụ tụ p trờn t yu 22TCN 262-2000 T khúa: kim toỏn dao dng nn ng, dao dng nn ng Abstract CALCULATING AND CHECKING THE VIBRATION CAUSED BY VEHICLES IN THE DESIGN OF HIGHWAY ROADBED ON SOFT SOILS IN THE AREA OF MEKONG DELTA This paper presents the theoretical basis of the calculating and checking the vibration of highway roadbed on soft soils using the standards of the Federal Republic of Russia The method is applied to the design of highway roadbed on soft soils in the area of the Mekong Delta Vibration checking conditions are proposed to be added into the actual guide of survey and design of highway roadbed on soft soils 22TCN - 262-2000 t Khi thit k xõy dng ng khu vc a cht nn t yu ngi ta thng c gng h chiu cao p xung cng nhiu thỡ cng tt nhm tng n nh trt, gim lỳn cho nn ng p Tuy nhiờn trờn nn t yu, nu nn ng p quỏ thp thỡ di nh hng ca ti trng ng xe chy, t yu di (c bit l khu vc tỏc dng ca nn ng) s xut hin cỏc dao ng n hi khụng cho phộp lm nh hng ti s n nh lõu di ca nn ng Ti mc IV.1.3 ca quy trỡnh kho sỏt thit k nn ng ụtụ p trờn t yu 22TCN 262-2000 ó khuyn cỏo: cn c gng gim chiu cao nn p to iu kin d m bo n nh v gim lỳn; nhiờn tr trng hp ng tm, chiu cao nn p ti thiu phi t 1,2 1,5m k t ch tip xỳc vi t yu, hoc phi l 0,8 1,0m k t b mt tng m cỏt (nu cú) m bo phm vi khu vc tỏc dng ca nn mt ng khụng bao gm vựng t yu Tr s ca chiu cao p ti thiu núi trờn c ỏp dng cho nn p ng cao tc v cỏc ng cú nhiu xe ti nng, tr s thp ỏp dng cho nn p cỏc ng khỏc 92 Tp Khoa hc i hc Th Du Mt S 1(32)-2017 Quy trỡnh 22TCN-262-2000 ch mi a c li khuyờn tng quỏt v chiu cao p ti thiu trờn t yu m khụng cú gii thớch v nh lng rừ rng Trong nc cng cha cú mt cụng trỡnh, mt ti liu no nghiờn cu c th v chiu cao ti thiu ny Vỡ vy, ni dung ca bi bỏo ny trỡnh by nhng nghiờn cu xỏc nh chiu cao ti thiu ca nn ng p thp nhm loi tr dao ng n hi khụng cho phộp ti trng ng gõy iu kin nn t yu khu vc ng bng song Cu Long nhm lm sỏng t ó nờu trờn C s lý thuyt tớnh toỏn ng lc hc nn t yu Hin nay, tiờu chun ca Cng hũa Liờn Bang Nga [1] tớnh toỏn n nh ca nn p trờn t yu ó xột n dao ng phng tin giao thụng: m bo t yu di nn p thp khụng b phỏ v kt cu nh hng bi dao ng n hi t ti trng ng (xe chy) gõy thỡ tớnh toỏn ng lc hc nn p phi tha iu kin: att acf (1); ú: att (mm/sec2) gia tc dao ng tớnh toỏn ca nn p thit k trờn t yu, acf (mm/sec2) gia tc dao ng ca nn p cho phộp gii hn trờn t yu c xỏc nh ph thuc vo loi mt ng thit k v tn s dao ng ca nn p (hỡnh 1) Gia tc dao ng ca nn p thit k trờn t yu c tớnh toỏn theo cụng thc: att = A2 (2); ú: A (mm) biờn dao ng ca nn p trờn t yu xỏc nh theo cụng thc: A = l (K 1) (3) l vừng n hi ca nn t yu gõy nờn a (mm/sec ) 2000 1800 ti trng tnh t bỏnh xe ca xe tớnh toỏn 1600 1400 1200 K H s ng hc c trng s tng 1000 900 vừng hiu qu dch chuyn ca ti trng 800 700 -1 600 (sec ) - tn s dao ng riờng ca nn p, 500 450 xỏc nh theo cụng thc sau: 400 cf E qd g K (4) K K1 dy 3.K1 Trong ú: Eqd (kN/m2) mụun n hi quy i ca t yu c xem xột iu kin khụng cú dch chuyn hụng hdy E qd E dy 2. (Mpa) (5) Edy mụun n hi ca t yu c nộn di nn p, xỏc nh theo cỏc s liu thớ nghim nộn hay bng tm ộp Tr s Edy cng c xỏc nh theo mi quan h thc nghim Edy = f(d, n) c nờu trờn th hỡnh n Bin dng nộn tng i ca t yu c nộn di nn p - Tr s trung bỡnh ca h s Poisson i vi t yu, khụng cú s liu thc nghim cho phộp ly =0,35 Khi ú thỡ Eqd=1,41.Edy g - Gia tc trng trng (g=9,81m/s2) 93 350 300 250 200 180 150 140 120 III 100 90 80 70 60 II 50 45 40 35 30 25 I 20 18 16 14 12 10 20 40 60 80 100 sec-1) Hỡnh Toỏn xỏc nh gia tc dao ng (acf) ca Hỡnh nn p cho phộp giinh hngia trờn yu Ton xỏc tct dao ng nn cp p cao cho ch phộpyu gii hn cf) ca I: i vi(amt ng trờn t yu II: i vi mt ng cp cao th yu I: i vi mt ng cp cao ch yu, III: i vi mt ng cp thp II: i vi mt ng cp cao th yu, III i vi mt ng cp thp Kim toỏn dao ng phng tin giao thụng gõy Lờ Thnh Trung dy hd ; K2 (6) hdy d hd, d Chiu cao p tng cng v trng lng riờng ca nn p (s hỡnh 3), ú hd=h+S = Hỏo ng + hd (7) hdy, dy Chiu dy lp t yu di nn p (m) v trng lng riờng ca t yu (kN/m3) K1 n dy (g/cm3) 0.6 had bi 0.8 b 0.9 1.0 hd h'd hdy hhc 1.3 s 1.2 0.5 hdy h 1.1 1.4 1.5 H 1.6 0.4 1.7 1.8 1.9 0.3 2.0 2.1 Eqd3 Eqd hqd 0.1 h3e3 Edy2 2.2 0.2 h2e2 h1e1 1.0 2.0 3.0 4.0 5.0 6.0 7.0 edy (Mpa) Hỡnh Toỏn xỏc nh mụun n hi Edy Hỡnh S tớnh toỏn ca t yu vừng n hi ca t yu c tớnh theo cụng thc: l p.D K .n (m) Edy (8) Trong ú: D ng kớnh tớnh toỏn ca vt bỏnh xe tớnh toỏn (m); p ỏp lc bỏnh xe tớnh toỏn lờn mt ng (Mpa); K H s tng hp xột n cỏc kớch thc cui cựng ca t yu v kh nng phõn b ca nn p H s K xỏc nh theo th hỡnh 4a ph thuc vo t s hd/D v hdy/D; - H s thay i ng sut tip xỳc cỏc lp cú cng khỏc nhau, ph thuc ch yu vo t s cng c th hin bng cỏc mụun n hi Cỏc tr s tớnh h s nh l hm s ca t s Ed/Edy i vi hd 2.D v c xỏc nh theo th hỡnh 4b; Edy Mụun n hi ca t yu (Mpa); n - H s xỏc nh theo bng H s ng lc K bng t s gia vừng ng hc ln nht ca nn t yu gõy bi xe chy vi tr s vừng tnh v c xỏc nh theo th hỡnh ph thuc vo h s chng rung , h s chng rung bng 0,33/Edy Ni dung v kt qu nghiờn cu 3.1 Cỏc s liu tớnh toỏn Ni dung tớnh toỏn c thc hin theo cỏc s liu a cht c trng cho nn t yu khu cc ng bng sụng Cu Long [2] (bng 2) v tớnh cho hai trng hp i vi nn t yu cú 01 lp t yu v cú nhiu lp (s hỡnh v 10) Cp ng v b rng nn ng: c ly theo TCVN 4054-2005 kốm theo cỏc thụng s tc thit k v b rng ti thiu ca nn ng, xỏc nh theo bng Loi mt ng tớnh toỏn: c ỏp dng vi ba loi mt ng nh c quy nh TCN 211-06: Mt 94 Tp Khoa hc i hc Th Du Mt S 1(32)-2017 ng cp cao ch yu A1;mt ng cp cao th yu A2 v mt ng cp thp (B1, B2) Nn ng p: Vt liu p nn ng phi tuõn th cỏc quy nh ca cỏc tiờu chun k thut hin hnh Thụng thng vựng ng bng phớa Nam, nn ng c p bng cỏt, cú p bao bng t dớnh phớa ngoi Mt cỏch tng i cú th ly dung trng riờng ca nn p d=1,90 g/cm3, ng vi m tng i a = 0,60 ta c mụun n hi ca nn ng Ed = 45Mpa (bng B-3 tiờu chun 22TCN 211-06) i vi cụng trỡnh thc t cỏc tr s tham kho trờn cn c b sung chớnh xỏc Ti trng tớnh toỏn: ng kớnh vt bỏnh xe tớnh toỏn D=36cm (hoc D= 33cm tựy theo ti trng xe tớnh toỏn thc t), ỏp lc bỏnh xe trờn mt ng p=0,6Mpa, riờng i vi trng hp xe cú ti trng rt ln thỡ c tớnh toỏn c th theo 22TCN 251-98 Bng Xỏc nh h s n hd/D 2,5 3,5 4,5 5,0 n 1.5 1,3 K 0.13 0.9 hd/d =2 0.12 0.8 0.11 0.7 0.10 0.09 0.6 0.08 0.5 0.07 0.4 0.06 0.3 0.05 0.04 0.2 0.03 0.1 10 0.02 0.01 10 20 30 40 60 ed/edy 0 1.4 10 14 20 hdy/d Hỡnh 4b th xỏc nh h s Hỡnh 4a th xỏc nh h s tng hp K Bng S liu a cht c trng ca Nam c trng c lý Dung trng riờng m t nhiờn Gúc ma sỏt Lc dớnh H s rng p lc tin c kt Ch s nộn Ch s n Ký hiu (w) W C eo Pc Cc Cs n v g/cm3 % kG/cm2 T/m2 - kđ Giỏ tr 1,50 40 30 0.067 2,0 5,2 1,2 0.12 1.4 1.3 1.2 1.1 1.0 0.05 0.10 0.15 0.20 0.25 0.30 Hỡnh th xỏc nh h s ng hc K Bng Bng chi tit cp ng v b rng nn ng Cp thit k ca ng I II III IV V VI Tc thit k (km/h) 120 100 80 60 40 30 Chiu rng ti thiu ca nn ng (m) 32,5 22,5 12,0 9,0 7,5 6,5 95 Kim toỏn dao ng phng tin giao thụng gõy Lờ Thnh Trung 3.2 Cỏc kt qu tớnh toỏn Vic tớnh toỏn xỏc nh chiu sõu ti thiu cho phộp ca nn p trờn t yu loi tr nh hng ca dao ng c thc hin bng cỏch s dng phn mm Plaxis 2D version 8.6 v s húa cỏc biu tra (t hỡnh n hỡnh 5) lp cỏc bng tớnh chi tit (thay cho biu ) 3.2.1 Thay i chiu cao p thit k Vi Bnn = 12,0m, hp =1,0 ữ 3,2m chờnh lch h = 0,10m Kt qu cho thy chiu cao nn p cng ln thỡ tn s v gia tc dao ng ca nn p cng nh v vi phộp tớnh c th cho thy tha att< acf thỡ hdap cho phộp bng 1,8m (hỡnh 7) 140 2,5m Gia toc dao dong a (mm/s2) 12,0m 1/2 0,0 Bùn sét màu xám xanh, xám nâu g/cm3 'ckG/cm2, Pc=5,2T/m2, Cc=1,2 -6,0 120 100 att acf 80 60 40 20 Sét, màu xám vàng, trạng thái dẻo cứng g/cm3 'ckG/cm2 Chieu cao dat dap hd (m) Loi kt cu mt ng Chiu cao p ti thiu h dap acf-MD cap thap (m) Cp cao ch yu 1,8 Cp cao th yu 1,4 Cp thp 1,2 att Gia toc dao dong a (mm/s2) Hỡnh Mt ct c trng tớnh toỏn - trng Hỡnh Quan h chiu cao t p gia tc hp 01 lp t yu dao ng ca nn ng 3.2.2 Thay i loi kt cu mt ng xe chy Thay i ng vi 03 loi mt ng nh c quy nh TCN 211-06, kt qu cho cỏc chiu cao p ti thiu ng vi loi kt cu mt ng (th hin bng v hỡnh 8) Cp mt ng cng cao thỡ yờu cu v chiu cao p ti thiu loi tr dao ng n hi cng ln acf-MD cap 140.0 Bng Quan h chiu cao p cao chu yeu acf-MD cao loi kt cu mt ng 120.0 cao thu yeu 100.0 80.0 60.0 40.0 20.0 Hỡnh Quan h chiu cao t p gia tc dao ng ca nn ng v loi KCA 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Chieu cao nen dap hd (m) 3.2.3 Thay i b rng nn ng B rng ca nn ng v nguyờn tc cú th thay i tựy ý, nhng phự hp vi thc t, thay i b rng nn ng tng ng vi cỏc cp ng c th quy nh TCVN 96 Tp Khoa hc i hc Th Du Mt S 1(32)-2017 4054-2005 Kt qu tớnh toỏn th hin bng Cỏc s liu tớnh toỏn cho thy: B rng nn ng cng ln thỡ gia tc dao ng cng tng, nhiờn nh hng tng lờn ny l hu nh khụng ỏng k, b rng dự cú thay i Bnn =7,5mữ32,5m nhng chiu cao p ti thiu cho phộp l nh v bng hdap =1,8m iu ú cú ngha l chiu cao p ti thiu trờn t yu nhm loi tr nh hng ca dao ng ng hu nh khụng ph thuc vo b rng nn ng p thit k 3.2.4 Thay i b dy lp t yu Tớnh vi lp t yu cú b dy thay i hdy =5,0 ữ 9,0m v chiu cao nn p thay i t 1,0 ữ 3,2m, kt qu cỏc tr s hdap cho phộp c ghi bng v biu din trờn hỡnh cho thy b dy lp t yu cng ln thỡ gia tc dao ng tớnh toỏn (att) ca nn t yu cng nh, tc l chiu cao t p ti thiu nhm loi tr nh hng ca dao ng n hi cng nh 3.2.5 Thay i tớnh cht c lý ca t yu Tớnh yu ca t nn th hin nhiu ch tiờu c trng nh: h s rng e0, dung trng riờng ca t , ch s nộn Cc, ỏp lc tin c kt Pc Vỡ vy, chiu cao p ti thiu cho phộp c xỏc nh bng cỏch thay i cỏc tr s ca cỏc thụng s núi trờn v kt qu nờu bng di õy Ta d nhn thy t cng yu thỡ yờu cu v chiu cao t p ti thiu ( hdap ) loi tr nh hng ca dao ng xe chy phi cng ln Bng Chiu cao p ti thiu vi b dy lp t yu att < acf (mm/s2) 5,0 6,0 7,0 8,0 9,0 18.084 < 18.198 17.295 < 17.630 16.139 < 17.164 16.422 < 16.804 16.032 < 16.480 180 hdap 160 (m) Gia toc dao dong att (mm/s2) hdy (m) 2.50 2.10 1.90 1.70 1.60 att-1,0m att-1,5m 140 att-2,0m att-2,5m att-3,0m 120 100 acf-1,0 acf-1,5 acf-2,0 80 60 acf-3,0 40 20 Hỡnh Quan h chiu cao p- gia tc dao ng nn ng - chiu sõu t yu Chieu sau dat yeu (m) 10 Bng Quan h gia chiu cao p ti thiu b rng nn ng 1.00 Cp I: Bnd = 32,5m att acf mm/s2 mm/s2 119.421 18.684 1.20 74.749 18.569 74.606 18.567 73.757 18.559 72.327 18.546 Ko t 1.70 20.329 18.332 20.290 18.331 20.067 18.322 19.695 18.309 Ko t 1.80 17.398 18.294 17.366 18.293 17.179 18.284 16.870 18.271 t 1.90 16.071 18.257 16.042 18.256 15.874 18.248 15.596 18.234 t hd (m) Cp II: Bnd=22.5m att acf mm/s2 mm/s2 119.216 18.683 Cp III: Bnd = 12m att acf mm/s2 mm/s2 117.974 18.675 Cp V: Bnd = 7.5m att acf mm/s2 mm/s2 115.847 18.661 97 Kt lun Ko t Kim toỏn dao ng phng tin giao thụng gõy Lờ Thnh Trung Bng Quan h gia tớnh cht ca nn t yu v chiu cao p ti thiu (hd) trờn t yu Ch s nộn Cc hdap (m) H s rng e0 hdap (m) 1.20 2.10 1.50 2.00 1.50 2.30 2.00 2.10 1.80 2.60 2.50 2.40 3.2.6 Thay i ti trng xe lu thụng trờn ng Ti trng xe chy c quy nh bi hai thụng s l ng kớnh vt bỏnh xe tớnh toỏn (D) v ỏp lc bỏnh xe tớnh toỏn lờn mt ng (p) Tớnh toỏn vi ti trng thay i theo 22TCN21106 xỏc nh c chiu cao p ti thiu ph thuc vo ti trng xe thit k nh sau: Bng Quan h loi ti trng xe chy & chiu cao p ti thiu (hd) trờn t yu ng kớnh vt bỏnh xe D (m) hdap (m) p lc bỏnh xe tớnh toỏn p (Mpa) hdap (m) 0.36 2.10 0.5 1.90 0.33 1.90 0.6 2.10 - - 0.7 2.40 T bng ta thy ti trng xe chy trờn ng cng ln thỡ yờu cu v chiu cao t p ti thiu ( hdap ) loi tr nh hng dao ng ng ca xe phi cng ln 3.2.7 Trng hp nhiu lp t yu Trong trng hp di nn ng p cú nhiu lp t yu thỡ vic kim toỏn ng hc trờn c s qui i nhiu lp t yu v trng hp mt lp t yu [1] (Tng t nh tớnh toỏn kt cu ỏo ng mm) Khi ú tb - dung trng riờng trung bỡnh c xỏc nh da trờn biu hỡnh t giỏ tr Edytb v bin dng nộn tng i ca tng hai lp () Sau ó xỏc nh c Edytb v tb ca lp t quy i vic kim toỏn tip theo tin hnh nh vi trng hp mt lp t yu Di õy l mt vớ d tớnh toỏn xỏc nh chiu cao p ti thiu cho phộp i vi nn t yu cú 02 lp S v cỏc thụng s tớnh toỏn c trỡnh by trờn hỡnh 10 v kt qu th hin trờn hỡnh 11 ( hdap =1,7m tng ng vi 15,075=att < acf=17,622 (mm/s2) Bùn sét màu xám xanh, xám nâu -4,0 g/cm3 'ckG/cm2, Pc=5,2T/m2, Cc=1,2 Bùn sét màu xám nâu g/cm3 'ckG/cm2, Pc=5,5T/m2, Cc=0,8 hdy1 0,0 hdy2 2,5m 1/2 Gia toc dao dong a (mm/s2) 140.000 12,0m 120.000 100.000 80.000 40.000 20.000 0.000 0.00 -4,0 att acf 60.000 0.50 1.00 1.50 2.00 2.50 3.00 3.50 Chieu cao dat dap hd (m) Sét, màu xám vàng, trạng thái dẻo cứng g/cm3 'ckG/cm2 Hỡnh 10 Mt ct c trng tớnh toỏn (trng hp 02 lp t yu) Hỡnh 11 Quan h chiu cao t p gia tc dao ng ca nn p (trng hp lp t yu) 98 Tp Khoa hc i hc Th Du Mt S 1(32)-2017 3.3 Tng hp kt qu tớnh toỏn Tng hp ton b cỏc kt qu tớnh toỏn nghiờn cu trờn cho phộp xỏc nh c chiu cao t p ti thiu loi tr nh hng ca dao ng xe chy ph thuc vo chiu sõu t yu (hdy) v cp hng mt ng iu kin a cht yu c trng cho khu vc ng bng sụng Cu Long nc ta Kt lun v kin ngh Vn kim tra dao ng ca ti trng ụtụ lờn nn p thp trờn t yu l cn thit, c bit l i vi cỏc cụng trỡnh ng cú lu lng ln xe ti, xe ti nng nh cỏc ng vnh thnh ph, ng cng, ng chuyn ca kho bói Cỏc kt qu nghiờn cu tớnh toỏn chiu cao ti thiu ca nn ng p nhm loi tr dao ng n hi khụng cho phộp ti trng ng gõy cho thy õy s l mt iu kin na b sung vo tiờu thit k ng ca nn ng p trờn t yu Bng nhng kt qu tớnh toỏn nghiờn cu, nhng quy nh v chiu cao ti thiu quy trỡnh TCN262-2000 ó c lm rừ Tỏc gi kin ngh xem xột a cỏc s liu nghiờn cu ca bng vo ph lc ca quy trỡnh thit k nn ng trờn t yu, t ú xem xột quyt nh chiu cao nn p ti thiu trờn t yu cú cỏc c trng tng t Trong cỏc trng hp khụng th thc hin c cỏc yờu cu ca cụng thc att acf m bo dao ng cho phộp ca nn p trờn t yu di tỏc dng ca ti trng ng thỡ cn phi a cỏc gii phỏp k thut nhm lm gim dao ng (tng chiu cao nn p kt hp vi x lý nn t yu hoc o b cc b (mt phn) lp t yu hoc nõng cao trc dc ) Bng Bng tng hp chiu cao p ti thiu ca nn ng ụ tụ Chiu sõu t yu hdy (m) Chiu cao p ti thiu ng vi loi kt cu ỏo ng (m) Cp cao ch yu A1 Cp cao th yu A2 Cp thp (B1, B2) 2.2 1.6 1.3 2.0 1.5 1.3 1.8 1.4 1.2 1.7 1.4 1.1 1.6 1.3 - TI LIU THAM KHO [1] -1067- 03.12.2003 [2] Pierre Lareal, Nguyn Thnh Long, Nguyn Quang Chiờu, V c Lc, Lờ Bỏ Lng (1994), Cụng trỡnh trờn nn t yu iu kin Vit Nam, NXB Khoa hc K thut [3] B Giao thụng Vn ti (2006), o ng mm Cỏc yờu cu v ch dn thit k 22 TCN 211 -06 [4] B Giao thụng Vn ti (2000), Quy trỡnh kho sỏt thit k nn ng ụ tụ trờn t yu 22TCN 262 2000 [5] B Giao thụng Vn ti (2005), ng ụ tụ yờu cu thit k TCVN 4054:2005 [6] Dng Hc Hi, Nguyn Xuõn Trc, Thit k ng ụ tụ II, NXB Giỏo dc 99