MINISTRY OF EDUCATION AND TRAINING MINISTRY OF CONSTRUCTION VIET NAM INSTITUTE FOR BUILDING SCIENCE AND TECHNOLOGY *** NGUYEN CONG KIEN RESEARCH ON ASSESSMENT OF ENVIRONMENTAL GEOTECHNICAL CONDITIONS[.]
MINISTRY OF EDUCATION MINISTRY OF CONSTRUCTION AND TRAINING VIET NAM INSTITUTE FOR BUILDING SCIENCE AND TECHNOLOGY *** NGUYEN CONG KIEN RESEARCH ON ASSESSMENT OF ENVIRONMENTAL GEOTECHNICAL CONDITIONS AND ESTABLISHMENT OF MONITORING SYSTEM FOR HAZARD PREVENTION AND SUSTAINABLE DEVELOPMENT OF THE RED RIVER DYNAMIC ZONE IN HANOI SUMMARY OF PHDTHESIS IN ENGINEERING MAJOR: Code: Geological Engineering 9520501 Hanoi - Year 2023 The thesis is completed at VIET NAM INSTITUTE FOR BUILDING SCIENCE AND TECHNOLOGY SCIENCE INSTRUCTOR Prof TSKH Tran Manh Lieu University of Natural Sciences - Hanoi National University TS Dinh Quoc Dan Viet Nam Institute for Building Science and Technology Counterargument 1: Counterargument 2: The thesis was defended before the Junior Thesis Judging Committee at the Viet Nam Institute for Building Science and Technology, 81 Tran Cung, Nghia Tan, Cau Giay District, Hanoi, at 13:30 on July 10, 2023 The thesis can be found at: The National Library Viet Nam The Library of Viet Nam Institute for Building Science and Technology PUBLISHED WORKS [1] Nguyen Cong Kien, "Scientific basis for setting up a monitoring network for geotechnical environment for disaster prevention and sustainable development of Red River Dynamic zone in Hanoi", Proceeding of the 4th International Conference VietGeo 2018, Quang Binh, 21-22 September, 2018 (ISBN: 978-604-67-1141-4) [2] Nguyen Cong Kien, "Characteristics and status of geotechnical systems of Red River Dynamic zone in Hanoi," Journal of Construction Science and Technology, vol 1, 2019 [3] Nguyen Cong Kien, "Assessment of the risk of permeable deformation in the dyke bed of the Red River Dynamic zone in Hanoi," Journal of Construction Science and Technology, vol 4, 2020 [4] Nguyen Cong Kien, Dinh Quoc Dan, "Scientific basis for building a system for monitoring and monitoring environmental geotechnical hazards in the Red River dynamic zone in Hanoi", Journal of Construction Science and Technology, vol 4, 2021 PREAMBLE The urgency of the topic Hanoi is the Cultural - Economic - Socio-Economic capital of the country, where there has been a rapid urbanization development in the past decades and the following years The 37,000 hectares of land between the two Red River dykes has full potential in planning for effective use but also contains complexities in assessing geotechnical and environmental conditions and establishing a monitoring system for disaster prevention to be able to sustainably develop this area The proposed exploitation and use planning has been proposed such as: Red River Township Project in 1994, proposed by investors from Singapore In 2006, Hanoi leaders and the mayor of Seuol City (South Korea) signed a cooperation agreement on planning, renovation and development of the two banks of the Red River with a project called "City by the River" In 2018, three large domestic real estate companies continued to contribute their own funds for research and planning on both sides of the Red River, but so far these projects have only stopped at comments and recommendations In fact, this is a dynamic zone that is assessed to have many potential risks arising and developing environmental geotechnical hazards from diverse interaction activities in types, abnormal changes in characteristics over time and space associated with human exploitation activities, accompanying the transformation of the riverbed along with a heterogeneous geological structure, characterized by geological characteristics of the work that varies sharply in area and depth, leading to dynamism during use The terrain changes in an imbalanced state with intertwined accumulation and erosion processes, the Red River is becoming a "hanging" river that causes river bank instability and threatens the stability of the entire levee line (levee breakage) when floodwaters rise In addition, the study of the use of dynamic zones is still difficult in the provisions of the Law on Dikes, at the same time, the system of monitoring stations providing data is small and discrete, the measurement parameters for forecast calculation are still incomplete and synchronous Starting from the goal of sustainable exploitation and use of this area, it is necessary to study and assess the specific geotechnical and environmental conditions of the dynamic zone, and at the same time identify environmental geotechnical hazards that may arise and develop, causing risks to human economic dynamics An environmental geotechnical monitoring system to provide input parameters for models, calculation, forecasting and proposing measures to prevent environmental geotechnical hazards with sufficient scientific basis for sustainable development of dynamic zones is really necessary The thesis "Research on assessment of environmental geotechnical conditions and establishment of monitoring system for hazard prevention and sustainable development of the Red River dynamic zone in Hanoi" is set as an urgent need, from both scientific and practical perspectives Research objectives - Elucidating the geotechnical and environmental conditions of the Red River dynamic zone in Hanoi for sustainable exploitation of the dynamic zone - Establish a basis and build a monitoring system for forecasting, hazards prevention and sustainable development models Subjects and scope of research - The research object is the environmental geotechnical conditions of the Red River dynamic zone in Hanoi and the corresponding monitoring system - The scope of the study of the Red River dynamic zone in Hanoi includes the territory between the two dykes and the area of influence The research area covers an area of more than 37,000 hectares, stretching about 117 KM, from Thai Hoa commune, Ba Vi district to Km 117, Quang Lang commune, Phu Xuyen district with the depth of the Quaternary sedimentary area Research content In order to accomplish the above-mentioned tasks, the thesis focuses on the following main contents: 1) General study of Environmental Geoengineering, theoretical basis of technical-natural systems and monitoring systems for hazards prevention 2) Study on the characteristics of formation, structure, nature, operation and environmental geotechnical conditions of the technical-natural system of the Red River dynamic zone in Hanoi 3) Research, analyze, evaluate and establish hazard risk assessment maps as a basis for the establishment of a dynamic environmental geotechnical monitoring system 4) Rationalize and establish an environmental geotechnical monitoring system to predict, prevent and prevent hazards and sustainably develop the Red River Dynamic Zone in Hanoi Research approach and methods 5.1 Approach - System approach: Red River Dynamic Zone is considered as a unified interactive system between components: engineering system, geological environment and surroundings - Integrated approach (inheritance - development-application): Inheritance of norms, standards, technical instructions and basic research results available domestic and foreign relevance 5.2 Research methodology: To solve the tasks of the thesis, research methods include: Systems theoretical methods; Retrospective methods; Expert methods; Analytic and numerical methods (analysis, data processing, mapping, GIS, aircraft image analysis, satellite, Geoslope, ArcGIS, ENVI); Defense thesis The thesis focuses on defending the following theses: Thesis 1: Environmental geotechnical conditions of the Red River dynamic zone in Hanoi are complex, strongly changing with space and time, characterized by: The geological environment is heterogeneous (with 23 stratigraphic subdivisions), sensitive to types of impacts The impact factors from economic-construction activities and the surrounding environment to the geological environment are diverse and drastically transformed These are factors, conditions and causes arising from the development of environmental geotechnical hazards In which, the main accidents include: deformation of dike permeability; riverbank erosion; flooding off river banks; Uneven subsidence of dikes with very different hazard risk zones Thesis 2: The geotechnical environmental monitoring system of the Red River dynamic zone in Hanoi is built on the basis of hazards risk zoning maps and component maps of corresponding hazards The new point of the topic Environmental geotechnical conditions of the Red River dynamic zone in Hanoi vary with space and time, which shall be fully analyzed and evaluated on the basis of the theory of technical-natural systems The system of zoning maps to assess the hazards risk of Red River dynamic zone is built on the basis of a full analysis of factors, conditions and causes of hazards and is divided according to different risk levels The integrated environmental geotechnical monitoring system shall be established on the basis of integrating hazards risk zoning maps and component maps corresponding to full scientific and practical bases for hazard prevention and sustainable development of the Red River dynamic zone in Hanoi Scientific and practical significance Scientific significance: It complements the theoretical and methodological basis for the new research direction of environmental geoengineering Practical significance: The research results of the thesis can be implemented soon in fact, the system of environmental geotechnical monitoring of the Red River dynamic zone and applied to other areas Material Basis of the Thesis The thesis is built on the basis of the results of key topics in Hanoi cities that have been accepted in which the author is a direct participant [59,60] In addition, the thesis also uses documents of units such as: Documents of boreholes, geological survey of works and project results of the Viet Nam Institute for Building Science and Technology, Institute of Hydrocong - Vietnam Institute of Water Resources, Institute of Geology Vietnam Academy of Technology and Science, Institute of Geotechnology - Vietnam Union of Science and Technology Associations, University of Natural Sciences - Hanoi National University, University of Mines and Geology, National Center for Water Resources Planning and Investigation Structure of the Thesis The thesis consists of an Introduction, chapters of research results, conclusions and recommendations, references and appendices Chapter I: Overview of Red River Dynamic Zone, Environmental geoengineering, Theoretical Foundations of Technical-Natural Systems and Monitoring for Hazard Prevention Chapter II: Technical-Nature systems and environmental geotechnical conditions of the Red River Dynamic Zone in Hanoi Chapter III: Assessment of risk zoning of environmental geotechnical hazards in the Red River Dynamic Zone in Hanoi Chapter IV: Basic evidence and establishment of environmental geotechnical monitoring system for hazards prevention and sustainable development of the Red River Dynamic Zone in Hanoi CHAPTER 1: OVERVIEW OF THE RED RIVER DYNAMIC ZONE,ENVIRONMENTAL GEOENGINEERING, THEORETICAL FOUNDATIONS OF TECHNICAL-NATURAL SYSTEMS AND SERVICE MONITORING FOR HAZARD PREVENTION 1.1 Red River Dynamic Zone formation and Development The Red River was formed on the main fault and many secondary faults extending from Weixi, Yunnan, China running along the Red River valley to the Gulf of Tonkin, during the Quaternary period, went through cycles of sea advancement and sea recession The Red River Dynamic Zone is a Quaternary sedimentary zone that is continuously altered due to the flow modification effect of the Red River, whereby the dynamic zone has a depth to the end of the Quaternary sedimentary depth In order to exploit and use the Red River cave zone, people have built a dike system to control floods, from which the Red River system has been formed Over more than 1000 years, the Red River has caused the flow of the Red River to change and be controlled, forming a new formation that is constantly changing The terrain elevation, geomorphology are seriously imbalanced and the Red River gradually becomes the "Hanging River" This has led to the development of processes and hazards with different characteristics of this zone, which is the reason for the formation of the "Red River Dynamic Zone in Hanoi: is the land between the two dykes and its influence zone in Hanoi, where frequent and continuous environmental geotechnical processes and environmental geotechnical hazards affect the socioeconomic development of the area", which needs to be studied for the purpose of sustainable development Since the last decades of the 20th century, there have been many published research results on geology and sediments of the Quaternary, typically with the works of authors Hoang Ngoc Ky, Ngo Quang Toan, on flow hydrodynamics by Nguyen Van Cu, Assoc Dr Nguyen Thi Kim Thoa, Tran Xuan Thai, Assoc TS Nguyen Huy Phuong Before 2008, the Red River cave zone in the former territory of Hanoi was studied on the conditions of the General CCP After 2008, there were studies on assessing EIA conditions conducted only in specific locations such as: studying the dyke system in Van Coc, Co Do, Phuc Tho, Vinh Phuc and Hung Yen by author Nghiem Huu Hanh Incident studies along the Red River dyke route in Hanoi by Dr Tran Van Tu, 2012 Environmental geotechnical studies ofMr Hong's dynamic zone authored by Assoc TS Doan The Tuong, Assoc Dr Tran Manh Lieu, 2011 1.2 Environmental geotechnical and environmental geotechnical conditions Environmental geoengineering is the study of the structure, nature and operation of the technical - natural system, forecasting and prevention of environmental geotechnical hazards, ensuring the sustainable development of the technical - natural system Environmental geotechnical conditions are a combination of factors on the structure, nature and movement of the technical - natural system, corresponding processes and environmental geotechnical hazards affecting the sustainable development of the system In general, environmental geotechnical conditions of a naturaltechnical system include geology engineering conditions of sub-systems of geological environment systems, impact conditions of sub-technical systems, impact conditions of sub-environmental systems and interactions between environmental geotechnical conditions to guide development directions, the environmental geotechnical status of the the technical natural system under study G.K.'s new researchdirections for environmental geoengineering, some new theories of physical-natural geography Bondarik, Iarg L.A [80], Trophimov V.T.'s theory of environmental ecology, Osipov V.I [81] Thenew research on geological environment monitoring of Korolev B.A., the monitoring of geological accidents by Seko A.I, the construction of the urban geological environment information system of Osipov.V.I have really come into play in the problems of planning and efficient use of land, proactively prevent accidents, mitigate damages, and develop sustainably in territories in Russia and CIS countries As well as a series of developed industrial countries: USA, Canada, Sweden, Norway, Japan, etc But the outstanding issues remain: environmental assessment of construction works such as the BREEAM method, the EcoHome rating method, or the Ecopoints system is an environmental assessment tool in the UK [71,74] Design and construction of new waste storage structures, such as landfills used to treat municipal solid waste and hazardous waste; In Vietnam, the proposal of rational use of territory towards sustainable development in the stages of planning, design, construction and economic development on the basis of research on environmental geotechnical conditions in our country has begun to be concerned, although methodologically limited Several individual studies have been conducted by Tran Manh Lieu [21, 23, 25, 26, 27, 28, 29], Doan The Tuong [58, 59, 60], Nguyen Huy Phuong [38, 39], Prof Pham Van Ty Through the above points, it can be seen that the issue of sustainable development of a territory is only considered independently, not towards sustainable development While the sustainable transformation of a territory depends on a lot of interrelated factors Inorder to ensure that a territory is sustainable, studies from the point of view of environmental geoengineering are required, and the issues of interplay between the geological environment and related factors affecting the sustainable development of that territory are considered in a unified body called the technical-natural system on the basis of the system theory of G.K Bondarik is the foundation 1.2 Technical-natural systems theory G.K Bondarik proposed the concept of natural-technical systems as follows: The complex of natural and human interaction factors (considering all social, cultural-historical and technical perspectives) is considered as a unified system, called the technical-natural systems On an earth scale, the ICT is called aglobal natural-technical system The boundary is defined as the contour of the interaction zone between the subsystems (where there is a discontinuity in the interaction between the subsystems) Boundaries can be determined by calculation of processes, possibly by up-to-date information about the state of the system due to monitoring The technical-natural systems of course, in essence, physics has a hierarchical structure and is divided into levels depending on the purpose of the study The system has the following hierarchical structure: chamlet unit (no further division); localhamlets; regionalhamlets; nationalhamlets; globalhamlets The technical-natural systems has the following characteristic properties: adjustablesubstances; Dynamicsubstances; opensubstances; organizationalnature; self-organizingnature; tadaptogens Interactive activities of sub-systems that generate processes and environmental geotechnical hazards: geological processes and building dynamics (including pollution); and geological processes, exogenous dynamics, natural and semi-anthropomorphic, terrestrial manifestations of geological environment and environmental geotechnical hazards events 1.3 Monitoring system 1.3.1 Concept of environmental geotechnical monitoring Observation is a portmanteau of Chinese and tracing, in which observation is observation, surveying is surveying Therefore, to observe an object is to monitor the transformation of that object over time by To assess zoning to predict the risk of dynamic coastal erosion accidents, the thesis uses a variable integrated approach with an integrated index (IΣ) as the basis for dividing the study area into different erosion risk zones [27, 28] The formula for calculating the integrated index (IΣ) (formula 3.1) for zoning the risk of shore erosion of the study area [27, 28] n IΣ g i RiH 3.1 i 1 Where: IΣ is the indicator of integration of developmental factors g i is the density of the i-th factor, RiH is the geotechnical condition parameter of the i-th factor n: Number of factors I consider - Parameters included in the calculation are quantified without dimensions: + Heterogeneity of geological structure (E đc ) + Hof the dispersion number (Cd*) + The height of the terrain between the ground of the river bank and the river bottom (H*) + Riverbank slope angle (α *) + The highest water level difference value at the point calculated compared to the lowest water level in 2010 (h*) + River bottom slope (I*) + Distance from the shore erosion point to the nearest fault (F*) + River bending angle (*) + Density parameters of sand mining points and sand dumps (Sd*) - Results of calculations + The density of the parameters is as follows: gshoreline slope (α*)(g1= 0.21); gbend the river (ψ*)(g2=0.12); the elevation of the bank relative to the river bottom (ΔH*)(g3=0.13); soil composition (Cd)(g4=0.18); kdistance to fault (F*)(g5=0.08); sand mining density (Sd*)(g6=0.06); gwater level difference value (Δh*)(g7=0.10); entropy geological structure (G8=0.06); hydraulicslope (I*)( g9=0.06); R2 = 0.74 so R = 0.86 Thus, the parameters selected in the model are relatively suitable for the assessment and forecast of bank erosion in the Red River Dynamic Zone of Hanoi 13 - The multivariate integration criterion IΣ is determined by the following formula: IΣ = 0.21*(α*) + 0.12*(ψ*) + 0.13*(ΔH*) + 0.18*(C d) + 0.08* (F*) + 0.06* (S d*) + 0.10* (Δh*) + 0.06* (E) + 0.06* (I*) The principle of erosion zoning: the base grid calculates 500m per calculation point along both sides of the river, the calculation results of the integrated index I∑ are put on the background map (scale 1: 50 000) The data is converted into Vector form to conduct partitioning using the classification method in ArcGIS Using the Natural Break classification method, it is classified into value ranges (I∑ < 0.3; 0.3 < I∑ < 0.5; 0.5 < I∑ < 0.7; I∑ > 0.7) is presented in Table 3.1, corresponding to levels of erosion risk: weak, medium, strong and very strong shown on the zoning map assessing the risk of erosion on the banks of the Red River cave in Hanoi (Figure 3.1) Table Risk zones for shore erosion in the study area Risk of Red River bank erosion Area of erosion (m2/year) Integration criteria (I∑) The areas at low risk of erosion < 500 < 0.3 The areas at medium risk of erosion 500 - 1000 0.3 - 0.5 The areas at risk of strong erosion 1000 - 1500 0.5 - 0.7 The areas at risk of erosion very strong Figure > 1500 > 0.7 3.3 Nguy mechanical deformation permeable dike foundation 14 Dike permeable deformation is a combination of base processes (soil platform,soil extrusion, erosion underground, flowing sand ) development along the levee system during flooding rains The process of demolition of the foundation begins actually from the appearance of the phenomenon of the earth platform due to the insufficient thickness and strength of the protective coating and the formation of an active drainage zone through the earth platform window In order to develop a zoning map to assess the forecast of dyke permeability stability, it must be projected with the following maps: (1) Isometric waterproofing layer thickness map; (2) Isometric map of pulpit resistance (K), (3) Isoradient map of embossing (Ie), (4) Limit gradient value (Ilv = 0.4 taken by author Tran Manh Lieu); (5) Variable map of permeable pressure ΔH(x,t) - Permeable current pressure index at the dike base The permeability pressure value ΔH(x,t) was calculated according to V.A Mironenko and V.M Sextakov on the basis of the Buxinet equation [34] ΔH (x,t) = ΔHo erfe(λ) 3.2 With: λ = Where: The erfe(λ) function is determined by λ through a pre-spreadsheet (V.A.Mironenko and V.M.Sextakov); is the coefficient of conduction of the pressurized water level of the aqueous layer; - Ground platform resistance coefficient of the mantle layer (coefficient K) An earthen platform is a phenomenon of breaking through the surface water barrier downstream of the dike (located on the pine sand layer) when the pressure of the aquifer during flood immersion exceeds the supporting capacity of the mantle calculated by the formula (3.3) [22,23] according to the cutting destruction scheme tgm K 4C m d H That's it: K: ground platform resistance coefficient; m: waterproofing coating thickness (m); 15 3.3 ; ν: coefficient Possion (ν = 0.3 - 0.45 clay, ν = 0.2 - 0.45 sandy soil); C, , γd: adhesion force, internal friction angle and capacity of waterproofing strata; H: permeable aquifer pressure downstream of the dike since the bottom of the waterproofing aquifer; K = floor of waterproofing coating in a limited state against the ground platform; K1 floor of sustainable waterproofing coating against the ground platform; - Sand extrusion capability The sand extrusion capacity of the permeable aquifer is evaluated according to the floating repulsion gradient value (Igv) and the limit permeability pressure gradient of the sand when subjected to the action of upward permeability flow is determined (Igl) according to K Terzaghi, N.N Maxlov; 3.4 Igv = h L Igl= ( - 1) (1- n) - Calculation data: Geological data , river topography cross-sectional data and flood level measurement data in August 1996 with Trung Ha, Viet Tri, Son Tay, Hanoi, Thuong Cat and Hung Yen monitoring stations, the time to rise to the flood peak is 12 days as the basis for calculation with a calculation netof 500m/1 calculation point and mapping corresponding composition - Zoning, forecasting, stabilizing, permeable, foundation; BZoning Map Predicted Prediction of Permeability Stability of the Dike System Constructed on the Overlapping Basis of (1) Isometric Map of Waterproofing Overlay Layers; (2) Ground platform anti-podium isometric map (K), (3) Embossed push isoradient map (Igv), (4) Limit gradient value (Igl = 0.4); (5) Permeable pressure variable map ΔH(x,t), with the principle of division: Very unstable zone (Igv > Igl and KIgv and K>1); Stable zones (Igv< Igl and K>1) Astable zoning plan for the Red River dynamic dyke in Hanoi was established with a map scale of 1:50 000 (Figure 3.2) This map is the 16 basis for establishing a monitoring system for hazard prevention, deformation, permeability and sustainable development of dynamic zones Figure Dike permeable stability zoning map (scale 1: 50 000) 3.4 Risk of flooding hazards off river banks Flooding is a phenomenon in which river water rises during the rainy and flooding season, causing flooding and flooding of some mudflats between dykes in the cave zone This phenomenon occurs frequently with the scale (area and depth of flooding) depending on the meteorological hydrological conditions of the whole region and the regulation of the flow of hydropower plants and reservoirs upstream The impact of flooding caused by rising river water causes adverse geotechnical phenomena such as sedimentation to improve the topography of the area, increasing permeability pressure on the dyke, destabilizing the dike route Therefore, it is necessary to narrow the scope of flooding to the maximum, to this it is necessary to have a monitoring network tocontrol the factors that cause this phenomenon In order to so, it is necessary to develop maps of factors obstructing the flood escape process and flood forecast maps as the basis for establishing monitoring systems - Methodological basis: Flood zoning maps by alarm levels (levels I, II, III) are built on the basis of building density data, elevation numerical models and geomorphological maps - Calculation results: Map of dynamic zone flood zoning by alarm water level I to III is shown in Figure 3.5 17 Figure 3 Flood zoning map by alarm levels (scale 1: 50 000) 3.5 Risk of subsidence of the dike foundation To calculate the maximum dike settlement under load, apply the formula of author Roy Whitlow below: Maximum settlement S: S = Si + Sc 3.5 Where: Si: Instantaneous settlement due to non-drainage transverse deformation Sc: Permeable coherent settlement due to effective stress increase Si = (m - 1) Sc 3.6 Where m is the coefficient of working conditions, m = 1.1 to 1.4 3.7 Parameters , and determined through hip non-expansion subsidence compression experiments for prototypes representing weak soil layer I - Calculation data: Geological cross-sections of works along the and across the; Mechanical and physical indicators of materials and foundations Subsidence is calculated with a distance of 500m with a cross-section along the two dykes Ta Hong and Huu Hong with the actual size of the dyke system, the width of the dike surface varies from 6m to 18 15m, the average dike height is m and the width of the dike foot varies from 45m to 55m - Calculation results: The grid calculates 500m per point along the two dykes of Ta Hong and Huu Hong The results show that the maximum settlement along the two dike routes is not large, mainly from 2cm to 8cm In areas with weak soil (grade 5, grade 9), the settlement of S is from 10cm - 15cm, even the settlement of S is >20cm, the reason is that the soil is weak in thickness; big - Dike subsidence hazard zoning map Principle of division: Auses the Natural Break method to classify into different subsidence value ranges including: Zone has S < 0.02m, Zone has S from 0.02 -0.05m, Zone has S from 0.05 - 0.10m, Zone has S from 0.10 - 0.15m, Zone has S from 0.15 - 0.20m and Zone has S>0.20m, corresponds to actual dike size and typical substrate structure with variation in thickness as well as number of weak soil layers Zones with settlement values are shown on a scale map of 1: 50 000 (Figure 3.7) Figure Map of maximum dike subsidence zoning (scale 1: 50 000) CHAPTER 4: BASIC EVIDENCE AND ESTABLISHMENT OF ENVIRONMENTTAL GEOTECHNICAL MONITORING SYSTEM FOR HAZARD PREVENTION AND SUSTAINABLE DEVELOPMENT OF THE RED RIVER DYNAMIC ZONE IN HANOI 19 4.1 Basis for setting up environmental geotechnical monitoring system 4.1.1 Monitoring objectives Comprehensively, systematically and synchronously collect parameters characterizing environmental geotechnical conditions and their changes over long-term time for efficient and sustainable exploitation of the territory 4.1.2 Requirements of the monitoring system The environmental geotechnical monitoring system must be automated from measuring, transmitting, storing to automating information exploitation for assessing the status of technical-natural systems including forecasting the risk of hazards 4.1.3 Design principles The monitoring system is established based on hazards risk forecast maps and corresponding component maps The monitoring route is designed in the direction of main changes of conditional factors, impact factors and concentrated in areas with high risk of hazards 4.1.4 Number of monitoring points The number of monitoring points is calculated according to the law of variation of the observed parameters if the transformation of the observed parameter is described by functions (order 1, 2, ), then the number of monitoring points is equal to the number of coefficients ofa polynomial representing that parameter, For example: Transformation according to a 1st order function is monitoring points, a 2nd order function is observation points 4.1.5 Monitoring parameters The monitoring information at the stations can be divided into two groups to meet two requirements: - Group of geotechnical and environmental monitoring parameters, providing data for zoning, assessment and forecasting of disaster risks for disaster prevention - The group of environmental geotechnical monitoring parameters for sustainable development of the Red River dynamic zone includes the background parameters of geological environment sub-systems, technical sub-systems, ambient environment (biological, gaseous, hydrological and deep parts of the lithosphere) 4.1.6 Monitoring cycles 20 The frequency (or cycle) of observation is determined by the mechanism of fluctuations of the accident process and the mechanism of action of causal factors 4.1.7 Monitoring equipment requirements - The monitoring and measuring equipment in the monitoring system must be updated modernly, automated at the highest possible level to increase accuracy and save time A set of software to control measuring equipment, store, analyze, document measurements, process measurement data in predefined directions The software is installed on a computer system at the central measuring station 4.2 Dike permeable deformation monitoring system The monitoring system is designed on the basis of the dike permeability stability partition map and the ΔH permeability pressure change map The dike permeability deformation monitoring system is set in the direction of perpendicular to the very permeable zone and in the descending direction of the permeability pressure ∆H (perpendicular to the dike and river) with the number of monitoring points on each line is points The number of 30 routes is shown in Figure 4.1 Monitoring parameters: (1) River level fluctuation parameters: chu measurement period: times/day (7h, 12h and 19h) during flood season from alarm I and exhaustion season time/day; (2) Groundwater level parameters in the affected area: cmeasurement period: times/year (1 time in flood season and time in dry season); (3) Pore water pressure in the permeable deformation affected area: measuringperiod: flood season time / day and exhaustion1 time/day; (4) Water samples determine the content of materials in the water exposed: chu measurement period: lsample times a day during flood season 4.3 Monitoring system for river bank erosion The monitoring system is designed on the basis of an erosion risk zoning map according to integrated indicator I∑ The shore erosion monitoring system is set up in a direction perpendicular to the very strong erosion risk zone with the number of monitoring points on each line is points The number of 46 routes is shown in Figure 4.2 Monitoring statistics include: (1) Topographic elevation of riverbeds and riverbanks: times/year (1 time in flood season and time in dry season); (2) Kgeometric dimensions of erosion points (length, width, depth and angle of bank slope): time per year in the dry season (3) Parameters dof river level fluctuation: measurement period: rushing flood 3times/day 21 (7h, 12h and 19h) from alarm I, rushing exhaustion time/day; (4) Flow parameters (flow velocity, flow rate, flow direction, amount of suspended sand silt and amount of bottom sandy silt): measurement period: times / year (1 time in flood season and time in dry season) 4.4 Dynamic Zone Flood Monitoring System The monitoring system is designed on the basis of construction density maps and flood maps at alarm levels 1, alarm 2, alarm and geomorphological maps The flood monitoring system is set up in a direction perpendicular to areas with high construction density from 70% to 90% towards the river side and the flooding characteristics of the study area with the number of monitoring points on each line is points The number of routes consists of 20 routes shown in Figure 4.3 Monitoring statistics include: (1) Topographic elevation of shoals, riverbeds and cross-sectional area of rivers: measurement period: times / year (1 time in flood season and time in dry season); (2) Parameters of river level fluctuation: measurement period: rushing flood times / day (7h, 12h and 19h) from alarm I, rushing exhaustion time /day; (3) Flow parameters (flow velocity, flow rate, flow direction, amount of suspended sand silt and amount of bottom sand silt): measurement period: times / year (1 time in flood season and time in dry season) 4.5 Subsidence monitoring system for dykes in dynamic zones The monitoring system is designed on the basis of a map of subsidence change under self-load and a map of the distribution of weak soil layers (class Ta, grade 5, grade and layer 11) The monitoring system for uneven subsidence deformation of the dike floor is set up along the direction of change of subsidence with the number of points arranged along the dike route with the distance of monitoring points from 100m to 500m and a minimum of points The number of 33 routes is shown above (Figure 4.4) Monitoring parameters include: (1) Groundwater level parameters in the affected area: measurement period: times/year (1 time in flood season and time in dry season); (2) Pore water pressure: measurement period: times / year (1 time in flood season and time in dry season); (3) Rate of subsidence of dikes and dikes: times / year (3 months/1 time) and more when subsidence occurs 22 Figure Location of dike permeability deformation monitoring route (scale 1: 50 000) Figure Location of riverbank erosion monitoring line (scale 1: 50 000) Figure Location of flood monitoring line (scale 1: 50 000) Figure 4 subsidence monitoring line (scale 1:50 000) 4.6 Integrated monitoring system of Red River dynamic zone in Hanoi The integrated monitoring system is designed on the basis of integrating partition maps to forecast the risk of hazards and 23 corresponding monitoring networks Integrated monitoring routes are established at the intersection locations of accidents including: Interference position of accidents, interference of accidents, interference of hazards and location of hazard For example: Route (T+NL) (Km90+500TT) (Route intersect of accidents: permeability deformation (T) and flooding (NL) at Km90+500 of Download Thao); Route 24 (T+X+L+NL) (Km10 Van Coc) (Route 24 intersects accidents: permeability deformation (T), bank erosion (X), flooding (NL) and dike subsidence (L), at Km 10 Van Coc dyke) Number ofroutes: 54 routes are shown in Figure 4.5 Monitoring parameters of the integrated monitoring system of Hanoi Red River dynamic zone include groups of parameters collected according to the map scale 1:50000 including: - Background parameters: data are collected, interpreted images (satellite, aviation) and field survey annually with a frequency of times / year (1 time in flood season and time in dry season) throughout the dynamic zone including: (1) New location parameters appear accidents (2) Fluctuation parameters of technical systems and socio-economic exploitation activities of humans include: density of houses, bridges, culverts, river management works, river embankments; upgrading the system; sand mining; drilling wells; excavation of waterproofing mantles; sources of pollution (if any) (3) Impact parameters from the surrounding environment: rainfall, storms, floods, temperature and drought - Thenumber of environmental geotechnical observations of conditions and impact factors causing accidents and changes in time cycles shall be measured on synthetic monitoring routes: (1) River level fluctuations: measurement period: flood rushing times/day (7h, 12h and 19h) from alarm I, mrushed time / day; (2) Groundwater level parameters in the affected area: measurement period: times / year (1 time in flood season and time in dry season); (3) Pore water pressure: times / year (1 time in flood season and time in dry season); (4) Topographic elevation of riverbeds and river banks: times / year (1 time in flood season and time in dry season); (5) Erosion point geometric dimensions (length, width, depth and bank slope angle): cmeasurement period: time per year in the exhaustion season; (6) Water samples determine the content of materials in the water exported: cmeasurement period: Sampling times / day in flood season; (7) Flow parameters (flow velocity, flow rate, flow direction, 24 amount of suspended sand silt and amount of bottom sandy silt): chu period: times / year (1 time in flood season and time in dry season) Inorder to adapt economic resources for the development of the capital in each phase, the monitoring system will be divided into levels of use according to priority to ensure the feasibility of practical application: Level 1: cmonitoring routes at the intersection locations of accidents and accidents with the occurrence of penetration accidents proposed to be implemented at priority level (with 12 routes) Level 2: The monitoring routes at the intersection locations of accidents, accidents and accidents with the occurrence of dike penetration accidents are proposed to be deployed at priority level (with 25 routes) Level 3: all54 routes of the integrated system are proposed at priority level Figure Composite monitoring route map (scale 1: 50 000) 25 CONCLUSIONS AND RECOMMENDATIONS Achievements of the Thesis: - A new direction of environmental geoengineering research and assessment of environmental geotechnical conditions from the point of view of technical-natural systems theory has the foundation of systems theory that has been approached by the thesis on a wide-area, comprehensive and long-term scope of hazard risks, thereby controlling the change to ensure the sustainable development of the territory This is a distinct view from traditional views of environmental geoengineering - Studying the natural conditions of the Red River dynamic zone for the purpose of efficient exploitation and ensuring sustainable development, assessing the environmental geotechnical conditions of the Red River dynamic zone from the point of view of technical-natural systems will give comprehensive results, most fully meets the requirements of the assessment of sustainable exploitation of the territory - Environmental geotechnical conditions of the Red River dynamic zone from the point of view of technical-natural systems have the following basic characteristics: + Sub-system geological environment has and the common distribution of Holocene sandy formations, they are constantly changing according to Red River flow cycles + Sub-system of technical with the basic characteristic of the constant existence of the dike system + Sub-system of the surrounding environment is characterized by the flow over time that changes according to the seasonal cycle (flood season and exhaustion season) - Environmental geotechnical hazards are very diverse In particular, the most notable are the most important disasters that determine the sustainable development of the dynamic technical - natural systems: (1) Deformation of permeability, (2) Riverbank erosion, (3) Flooding outside the river bank and (4) Subsidence of the foundation due to self-gravity The risk of these hazards varies across different areas, all indicated on zoning maps that predict the risk of hazards - The basis for evaluating interactions in technical - nature systems to consider hazards is the monitoring data obtained from the environmental geotechnical monitoring system Each technical - nature system has, of course, a definite monitoring system 26 - The environmental geotechnical monitoring system of the Red River dynamic zone from the theoretical point of view of technical systems naturallya set of flow observations, displacement, sub-deformation of technical systems and erosion, sedimentation, change of flow crosssection - The integrated geotechnical environmental monitoring system of the Red River dynamic zone in Hanoi is set up with 54 routes with full facilities, along with disaster risk assessment maps and corresponding component analysis maps Petition: - The research results of the thesis are a good reference source and a scientific basis for the planning and rational use of the Red River dynamic zone in Hanoi - The integrated geotechnical environmental monitoring system of the Red River dynamic zone in Hanoi proposed by the thesis has a full scientific and practical basis and will soon be deployed to Hanoi according to each priority level - Changing the structure and structure of the dyke body and the location of the dyke system will reduce the risk of accidents, increase the land fund for construction works, improve the efficiency of using water sources for domestic irrigation, stabilize the flow for navigation 27