A STUDY ON THE EMBANKMENT CACULATION METHOD REINFORCED BY GEOTEXTILE IN THE CONSTRUCTION OF HIGHWAY IN VIETNAM

Transcription

1 - i - MINISTRY OF EDUCATION AND TRAINING UNIVERSITY OF TRANSPORT AND COMMUNICATION Hao Huynh Ngoc A STUDY ON THE EMBANKMENT CACULATION METHOD REINFORCED BY GEOTEXTILE IN THE CONSTRUCTION OF HIGHWAY IN VIETNAM Major: Construction of hightway and street Code: SUMMARY OF Ph.D THESIS Hanoi, June 2014

2 - ii - This thesis was completed at the university of transport and communication Supervisors: Prof. PhD Phung Vu Dinh PhD Sy Vu Duc Examiner 1: Prof, Dr.Sc Quang Nguyen Van Hanoi Architectural University Examiner 2: Prof, PhD Chuong Do Ba National University of Civil Engineering Examiner 3: Ass.Prof, Dr.Sc Can Nguyen Van Hanoi University of Mining and Geology This thesis is defended at the university of transport and communication on... h,..., Thesis can be found at: 1. National Library 2. Library of the university of transport and communication

3 Publications - iii - 1. Hao Huynh Ngoc MS, Phung Vu Dinh Prof.PhD (2009), Several designing measures using geotextiles in order to stabilize weak soil in the constructing of road and dam, dike. Bridge and Road Magazine, N o. Nov-2009, Page Quang Tran Dinh PhD, Hao Huynh Ngoc MS (2011), Study of the improvement for fabrication and construction of prestressed I beam l = 42m with continous thermo slad based on the construction of Hoa xuan brigde- Danang city, The Transport and communications magazine, N o. Aug-2011, ISSN , Page Hao Huynh Ngoc MS, Phung Vu Dinh Prof.PhD (2013), Probability of instability of backfill construction from design perspective, Bridge and Road Magazine, N o. Aug-2013, ISSN X, Page Hao Huynh Ngoc MS, Phung Vu Dinh Prof.PhD (2013), The stability caculation model of embankment (highways, dikes, dams) reinforced by geotextile thanks to the finite element method and mention pull behaviors of geotextile and relationship between stresses and strains of the contact elements between embankment and geotextile, Bridge and Road Magazine, N o. Nov-2013, ISSN X, Page Hao Huynh Ngoc MS, Vu Duc Sy PhD, Phung Vu Dinh Prof.PhD (2014), Slide curve analysis results of slope stabilization by finite element method (HNH_RESS software) in comparison with analytic method, Bridge and Road Magazine, N o. Jan and Feb-2014, ISSN X, Page

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5 - 1 - INTRODUCTION 1 - Introduction to the study: Along with the strong growth in the application of new materials technology in the world, Vietnam s also very interested in the study of materials using in geotextile reinforced embankment works roads, dikes and dams. So that, the research methods completing for calculating results for reliability problems embankment reinforced by geotextile in the construction of roads in Vietnam becomes necessary. Within the scope of this study, the author used the finite element method - numerical method has several advantages in the present time to apply the construction algorithm, based on the programming software suit Vietnam and the conditions for a number of research results stability problems, stress - state deformation embankment, proposed making calculations and charts used in utility design. 2 - Reasons for choosing topic : To complete calculation methodology for problem embankment using geotextiles in the construction of highways 3 - Purpose : Develop computational models roadbed embankment reinforced by geotextile, contribute to improve the calculation method actually worked closely with the material and the ability to predict an instability correctly in order to bring high efficiency, ensure technical requirements designed embankment geotextile reinforcement 4 - Research Subjects : The land cover using geotextile in road works background 5 - Scope of the Study : Selection, calculation model building problem embankment geotextile reinforcement. Construction algorithms and computer programs using the finite element method. Look at the problem embankment geotextile reinforcement. 6 - The meaning of scientific and practical subjects : geotextiles is a new material made from synthetic polymer materials or products related to the polymer through different manufacturing technologies together. Since the 70s of last century geotextile fabric was born in the western world. Due to the interesting properties of geotextile Vietnam should have quickly been used to enhance reinforcement load capacity and stability for the construction, especially the building embankments in road and bridge construction and irrigation... The early years of the '90s - last century, geotextiles are widely used in many countries such as France, the Netherlands, the U.S. and Japan, particularly in Southeast Asian countries like Thailand, Philippines, Indonesia, Malaysia,... in our country, geotextile be put to use building the road since 1993 and more using widely. According to a study by experts at home and abroad show geotextile used in the construction of high embankment of earth or embankments on soft soils are effective economic and technical, easy simple in construction, reduced costs from 15-20%, increase quality of use, the life of the facility. Thus the complete study methodology, embankment design using geotextile reinforcement is needed to serve the practical requirements in the integration and

6 - 2 - implementation of industrialization and modernization development of the country CHAPTER 1 OVERVIEW ABOUT USING AND CALCULATION METHODS OF GEOTEXTILE REINFORCEMENT EMBANKMENT 1.1. The study used calculations and embankment geotextile reinforcement at home and abroad Historical development and use of geotextile Introduction : geotextile appear first Bidium trade name in the 60s of the last century in France, but has not been noticed and used very little. Since 1975, the geotextile is more complete study of water from the development phase, calculation methods and construction technology. Geotextile is used for rapid reinforcement enhance the load capacity and stability of the construction work in general and especially the ground up for work in the construction of roads and irrigation. In the 80s of the last century geotextile is widely used in many countries such as France, the Netherlands, the U.S., Japan, China, India, South Korea, especially in Southeast Asia : Thailand, the Philippines, Indonesia, Malaysia,Brunei... In 1993 our country geotextile was first used in the project to upgrade Highway 5 (Ha Noi - Hai Phong ) by the Design Consultant Company KEI - Japanese design with over 500,000 m2 of geotextile is to effectively handle embankment on soft ground. And from 1995 till now, geotextiles have been used a lot with different functions in various projects such as road construction project to upgrade National Highway 1, QL10, QL18, NH3, highway 51, QL32, QL38, QL39 and in construction projects like highways : highways Ho Chi Minh City - Trung Luong, Thang Long Boulevard ( away from Lang Hoa Lac ), high speed Hanoi - Hai Phong Expressway Gie - Ninh Binh, Noi Bai - Lao Cai Highway Long Thanh - Dau Giay Expressway and Ben Luc - Long Thanh Classification of geotextile [14], [28], [29], [30] Based on the fabrication technology, geotextiles are classified into two types : woven geotextile and silk geotechical kind of non-woven. Some evaluation criteria geotextile : Appendix 1 : Table 1.3 introduces the main physical and mechanical by application of geotextiles ; Table 1.4 specifications polyfelt TS nonwovens ; Table 1.5 and Table 1.6 non-woven geotextile HD - Vietnam [ 50 ] The function of geotextile [13], [14], [27], [31], [34], [35], [36], [38], [44], [56], [58], [61], [62], [63], [66], [68]. 1. functional separation between the layers of material together ( separation ) Geotextile separation layer is made between the buffer layer of sand and mud below, separated between subgrade below ( subbase ) and the bottom layer of pavement covered with sand on top. 2. Functional soft soil reinforcement (reinforcement) For high embankments on soft ground, it reaches a certain height sliding platform will emerge - the whole

7 - 3 - block sliding, sliding local slope should therefore use geotextile TECHNICAL reinforcement. Geotextile can also be used in case of reinforced soil need not weak but the background causeway. 3. Geotextile reinforcement retaining wall (wall soft key) to increase the ability to land up tall retaining wall, or steep to 900 degrees, people use geotextile wall build certainly unsatisfactory medium height wall covering, durability and use landscaping aesthetics but cheaper from 25 % to half of the reinforced concrete wall [14], [19], [34], [44], [45]. 4. Function filtering, drainage behind the retaining wall ( drainage ) ( or a system of underground drainage embankment works on traffic, irrigation... ), was previously used as filter bed material particle counter - with a grading of certain materials. For the first time in Vietnam, the filtering function, drainage was used in the retaining wall of the path to the bridge on National Road 1, Tan Thinh, Hanoi - Lang Son. 5. Geotextile to function absorbent They lowered groundwater levels using geotextile wrap small aggregate materials for drainage, underground drainage pipe wrap before sanding, enveloping material macadam when no drainage tube, which take the form of crushed stone material cut trapezoidal openings no drainage pipe, make waterproof layer functions to lower groundwater levels. 6. Protection, erosion control embankment dykes and dams and roof slope erosion Geotextile is used for erosion control function [ 31 ], protecting eroded slopes not to damage the roadbed, the ditch along the road, slope erosion control line, dikes, dams, bottom of the canal, filling the polder areas, riverine lake embankment, slope areas upstream and downstream river, especially through space segment of river basin narrow bridge... eg erosion in the upper and downstream of the bridge : Phu Dong bridge ( over the river road), Nhu Nguyet bridge ( over the river bridge ), Suong Giang bridge ( over the River Trade) on National Highway 1, Hanoi - Lang Son. 7. Geotextile tubes geotechnical work (Geosolution SI) [35] Geotextile tubes used are diverse with many different forms : people unfortunately get into geotextile tubes and fill with sand, lined shore erosion protection levees, buildings along the coast sea The construction projects have used geotextiles in Vietnam 1. With geotextile separation layer functions as project to upgrade Highway 5 in the year , expanding the old road surface by 20 meters on the main embankment. It separates the function of geotextile, road systems in urban areas Trung Hoa - Nhan Chinh (Hanoi), before spreading the layer of macadam people to spread a layer of geotextile Specifications for separating the sand embankment that separates below the mixed layer between the sand and stone chips easily lead to unstable surface. With this function geotextile was also used in the upgrade of Highway 5, National Highway 1, QL10, QL18 and some highways such as

8 - 4 - Highway District. Ho Chi Minh City - Trung Luong ; Gie - Ninh Binh, Noi Bai - Lao Cai, Ha Noi - Hai Phong, Ha Noi - Thai Nguyen... Also geotextile is used in landfills to make division between land and the class rubbish such as landfill bottom liner Tam Tan (Cu Chi, Ho Chi Minh City, 2011), landfill Bo Trach district (Quang Binh), landfill Nhon district (Binh Dinh), Hung Yen city landfill Geotextile reinforcement function embankment on soft soil : In the years , before the construction of embankments online Troi - Vu Oai [ 40 ], grade III Delta (Quang Ninh), chaired set design was used 2, 3 layers of geotextile separation layer by doing medium duty reinforcement for embankment on soft soil. Also in 2002, on National Highway 1 bypass the city of Vinh [ 39 ] design chair used as geotextile separation layer between the soft soil at a depth of 80cm and digging up sand poured on. Then continue to use 3 more geotextile layers, each layer separated by 40cm to reinforcement training background ( 80cm ) and section 4 5 m high embankment. Two works have exploited so far ( 2013 ) is more than 10 years, very good quality. This is the process of using geotextiles to handle embankment on soft soil for the first time in Vietnam, simple construction, reduced construction costs. Two works make a good premise for the use of geotextiles for reinforcement of soft soil embankment on many other road construction projects such as highways, Ho Chi Minh City - Trung Luong, Gie - Ninh Binh, Ha Noi - Thai Nguyen, Noi Bai - Lao Cai,. 3. Geotextile for erosion control functions When slope embankment built to protect the coastline of Bai Chay - Quang Ninh, geotextiles are used to spread on the embankment slope surface, then place over the stones deck form concrete brick cement to prevent erosion of the dam due to heavy pressure waves. Also geotextile was also used to protect, reinforced slope reservoirs such as reservoir park Lao Cai city center ( designed in 2000 by the Department of Transportation as an investor in Lao Cai ), two lakes Regulators at the National Conference Center - Hanoi, designed by the German Advisory also used as geotextile layer of protection against erosion. National Highway 1 Improvement Project paragraph Hanoi - Lang Son PMU18 represented by the investor, in the period leading to the Phu Dong Bridge ( River road), As for the Moon ( The River ), Xuong Giang Bridge ( River Trade), one also used geotextile layer to protect against river erosion in the upper two side roofs - three downstream of the bridge. 4. Geotextile material is used instead of filter layer upside down on National Highway 1 bridge, Tan Thinh - town ( Lang Giang, Bac Giang ) section between Tan Thinh bridge and railway bridge ( the old National Road 1 ) length of 80m people built construction of reinforced concrete retaining walls with a height H = 7.2 m in At the bottom of the side walls of poured gravel embankment was then coated with a layer that geotextile before covering background material to replace the filter bed to the opposite wall at the foot drainage.

9 The calculation method geotextile reinforcement embankment: The analytic methods reinforced embankment calculated to assess stability using limit equilibrium methods ( force or torque ) and is accompanied by is the use of partial coefficients, respectively [15], [63] Methods of analytical calculations have reinforced embankment on soft ground [ 2 ], [ 3 ], [ 7 ], [ 9 ], [ 15 ], [ 16 ], [ 17 ], [ 21 ], [ 32 ], [ 33 ], [ 35 ], [37] : Reinforcement is placed in the internal ground and even in body embankment, to prevent damage due to shear through the embankment itself or in shear zones soft soil. 1. Locally stable [7], [15], [32], [33] : Check the local stability of the embankment slope under the following inequality : (1.1) H : height embankment ; Ls : length of horizontal side slope (the slope foot width) ; φ'cv : friction angle of embankment materials at large deformation effective stress conditions ; fms : partial material factor applied to φ'cv tg ( fms = 1 ). 2. Stable circular slide (sliding surface analysis method) : analysis of sliding surface method is used most commonly in circular sliding stability calculations for embankment using reinforced embankment placed at the bottom. The torque caused by the land sliding and load M D as : (1.2) M RS torque by keeping the land : Torque remains enhanced by keeping M RR : (1.4) in which: ffs is the partial load factor of unit weight of soil ; wi : the weight of soil column i ; bi : the ith soil column width ; αi : angle tangential bottom soil column with the ith lateral Rd : radius circular slip ; fms : partial material factor applied to tgφ'cv ; φ'cv : friction angle at the base construction material in large deformation effective stress conditions ; ui : pore-water pressure effects on the ith sliding piece Troj traction required for 1 meter long embankment at each point along the bottom of the embankment j is defined as : (1.5) Among them : YJ arm is in the vertical direction of the torque to the dangerous sliding surface at the center point on the bottom of the embankment j ; MRRj : largest holding torque by strengthening core at point j on the bottom of embankment ; MDJ : maximum torque slip at the bottom of the embankment j (human factor has been) ; M RS j : keeping the largest torque generated by the soil at the bottom of the embankment point j (human factor has been) Method of computation analysis on reinforced soil embankment good natural 1. Where the external stability of one or more results to sabotage occurs, treatment options may ways, such as reducing roof slope embankment, increasing the width column layout, using quality packing material good quality, enhanced by the foundation soil reinforcement measures, counter pressure pad,

10 - 6 - packing material used is lightweight, reinforced combinations in various high level, more layout drainage system to reduce pressure pore water pressure, or combined treatment options in [15], [32]. 2. Internal stability [ 15], [32], [33], [35], [57], [53], [63] The method of calculating reinforced embankment on the basis of gender balance method and use the term partial coefficients corresponding to limit state are calculated. Includes : a. Method two wedge blocks ( slip surfaces kinked shape ) [12], [15] Driving forces synthesis ( synthetic human disturbance ) in the case of a slope no more subject to external load is calculated as : ( 1.7 ) Among them : the human R h disturbing synthesis of 1m length along the slope ; ffs is the partial factor applied to the unit weight of the soil, K is the ratio of stress ( pressure ) horizontal and vertical stress ; ɣ is the unit weight of the soil ; H is the height of embankment. To pull off being reinforced, reinforced distance vertically is determined from the expression: (1.8) Among them : Svj gap remains vertical in slope at j ; Tj is the greatest traction in the 1 m core length in slope at j ; ffs the partial load factor applied to the weight unit volume of soil, hj is the height of the embankment on the slope j ; f q is the partial load factor applied to the external load, ws is the external load due to static load ( evenly distributed on the surface at structure [ 15, p. 10 ] ). Paragraph anchor Lej not happen to slip reinforcement is determined from the limit state vandalism, anchor length remains satisfied [ 15, p. 118 ]. (1.9) Among them : L ej is reinforced anchor length minimum calculated at j ; fp : partial factor control remains pulled slip phenomenon, fn : partial coefficient control works damaged due cause ; fms : partial factor applied to tgφ'p and c ', ws : external load, α ' : interaction coefficient indicates the relationship between power and ground anchor reinforced with tgφ'p ; φ'p : corner resistance biggest cut of fill materials ; αbc ' : stickiness factor denotes an anchor link between soil health - reinforced with c ' c ' : effective cohesion of the packing material. Comment crease sliding surface method - The method of calculating " wedge block two " not consider the effects of horizontal thrust due to the inclination of the upper surface created ( only considering the vertical force is the weight soil ). " Block wedge two part " is a general form of the limit equilibrium method. This method has the advantage of simplicity, the present destructive potential can determine the approximate gradually in a wide range. In addition, this method is also easy to set up a loop calculation program on your computer. Crease sliding surface method is used in