Content 1 Overview of energy use in construction works MINISTRY OF EDUCATION AND TRAINING MINISTRY OF CONSTRUCTION VIET NAM INSTITUTE FOR BUILDING SCIENCE AND TECHNOLOGY *** NGUYEN CONG KIEN RESEARCH[.]
Trang 1-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: Geological Engineering
Hanoi - Year 2023
Trang 2PUBLISHED WORKS
[1] Nguyen Cong Kien, "Scientific basis for setting up a monitoring
network for geotechnical environment for disaster prevention andsustainable development of Red River Dynamic zone in Hanoi",Proceeding of the 4th International Conference VietGeo 2018, QuangBinh, 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 ofConstruction 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 inHanoi," 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 geotechnicalhazards in the Red River dynamic zone in Hanoi", Journal ofConstruction Science and Technology, vol 4, 2021
The thesis is completed at
VIET NAM INSTITUTE FOR BUILDING SCIENCE
AND TECHNOLOGY
SCIENCE INSTRUCTOR
1 Prof TSKH Tran Manh Lieu
University of Natural Sciences - Hanoi National University
2 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, 81Tran 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
Trang 31 The urgency of the topic
Hanoi is the Cultural - Economic - Socio-Economic capital of thecountry, where there has been a rapid urbanization development in the pastdecades and the following years The 37,000 hectares of land between thetwo Red River dykes has full potential in planning for effective use butalso contains complexities in assessing geotechnical and environmentalconditions and establishing a monitoring system for disaster prevention to
be able to sustainably develop this area The proposed exploitation and useplanning has been proposed such as: Red River Township Project in 1994,proposed by investors from Singapore In 2006, Hanoi leaders and themayor of Seuol City (South Korea) signed a cooperation agreement onplanning, renovation and development of the two banks of the Red Riverwith a project called "City by the River" In 2018, three large domestic realestate companies continued to contribute their own funds for research andplanning on both sides of the Red River, but so far these projects have onlystopped at comments and recommendations
In fact, this is a dynamic zone that is assessed to have many potentialrisks arising and developing environmental geotechnical hazards fromdiverse interaction activities in types, abnormal changes in characteristicsover time and space associated with human exploitation activities,accompanying the transformation of the riverbed along with aheterogeneous geological structure, characterized by geologicalcharacteristics of the work that varies sharply in area and depth, leading todynamism during use The terrain changes in an imbalanced state withintertwined accumulation and erosion processes, the Red River isbecoming a "hanging" river that causes river bank instability and threatensthe 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 theprovisions of the Law on Dikes, at the same time, the system ofmonitoring stations providing data is small and discrete, the measurementparameters 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 andenvironmental conditions of the dynamic zone, and at the same timeidentify environmental geotechnical hazards that may arise and develop,causing risks to human economic dynamics An environmentalgeotechnical monitoring system to provide input parameters for models,
Trang 4calculation, forecasting and proposing measures to prevent environmentalgeotechnical hazards with sufficient scientific basis for sustainabledevelopment 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
2 Research objectives
- Elucidating the geotechnical and environmental conditions of the RedRiver dynamic zone in Hanoi for sustainable exploitation of the dynamiczone
- Establish a basis and build a monitoring system for forecasting, hazardsprevention and sustainable development models
3 Subjects and scope of research
- The research object is the environmental geotechnical conditions of theRed River dynamic zone in Hanoi and the corresponding monitoringsystem
- The scope of the study of the Red River dynamic zone in Hanoi includesthe territory between the two dykes and the area of influence The researcharea covers an area of more than 37,000 hectares, stretching about 117
KM, from Thai Hoa commune, Ba Vi district to Km 117, Quang Langcommune, Phu Xuyen district with the depth of the Quaternarysedimentary area
4 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 oftechnical-natural systems and monitoring systems for hazards prevention 2) Study on the characteristics of formation, structure, nature, operationand 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 geotechnicalmonitoring system
4) Rationalize and establish an environmental geotechnical monitoringsystem to predict, prevent and prevent hazards and sustainably develop theRed River Dynamic Zone in Hanoi
Trang 55 Research approach and methods
5.1 Approach
- System approach: Red River Dynamic Zone is considered as a unifiedinteractive system between 3 components: engineering system, geologicalenvironment and surroundings
- Integrated approach (inheritance - development-application): Inheritance
of norms, standards, technical instructions and basic research resultsavailable domestic and foreign relevance
5.2 Research methodology:
To solve the tasks of the thesis, research methods include: Systemstheoretical methods; Retrospective methods; Expert methods; Analyticand numerical methods (analysis, data processing, mapping, GIS, aircraftimage analysis, satellite, Geoslope, ArcGIS, ENVI);
6 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 andtime, characterized by: The geological environment is heterogeneous (with
23 stratigraphic subdivisions), sensitive to types of impacts The impactfactors from economic-construction activities and the surroundingenvironment to the geological environment are diverse and drasticallytransformed These are factors, conditions and causes arising from thedevelopment of environmental geotechnical hazards In which, the mainaccidents include: deformation of dike permeability; riverbank erosion;flooding off river banks; Uneven subsidence of dikes with very differenthazard 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 zoningmaps and component maps of 4 corresponding hazards
7 The new point of the topic
1 Environmental geotechnical conditions of the Red River dynamic zone
in Hanoi vary with space and time, which shall be fully analyzed andevaluated on the basis of the theory of technical-natural systems
2 The system of zoning maps to assess the hazards risk of Red Riverdynamic zone is built on the basis of a full analysis of factors, conditionsand causes of hazards and is divided according to different risk levels
3 The integrated environmental geotechnical monitoring system shall beestablished on the basis of integrating 4 hazards risk zoning maps and
Trang 6component maps corresponding to full scientific and practical bases forhazard prevention and sustainable development of the Red River dynamiczone in Hanoi.
8 Scientific and practical significance
1 Scientific significance: It complements the theoretical andmethodological basis for the new research direction of environmentalgeoengineering
2 Practical significance: The research results of the thesis can beimplemented soon in fact, the system of environmental geotechnicalmonitoring of the Red River dynamic zone and applied to other areas
9 Material Basis of the Thesis
The thesis is built on the basis of the results of key topics in Hanoicities 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 ofthe Viet Nam Institute for Building Science and Technology, Institute ofHydrocong - Vietnam Institute of Water Resources, Institute of Geology -Vietnam Academy of Technology and Science, Institute ofGeotechnology - Vietnam Union of Science and Technology Associations,University of Natural Sciences - Hanoi National University, University ofMines and Geology, National Center for Water Resources Planning andInvestigation
9 Structure of the Thesis
The thesis consists of an Introduction, 4 chapters of research results,conclusions and recommendations, references and appendices
Chapter I: Overview of Red River Dynamic Zone, Environmentalgeoengineering, Theoretical Foundations of Technical-Natural Systemsand Monitoring for Hazard Prevention
Chapter II: Technical-Nature systems and environmental geotechnicalconditions of the Red River Dynamic Zone in Hanoi
Chapter III: Assessment of risk zoning of environmental geotechnicalhazards in the Red River Dynamic Zone in Hanoi
Chapter IV: Basic evidence and establishment of environmentalgeotechnical monitoring system for hazards prevention and sustainabledevelopment of the Red River Dynamic Zone in Hanoi
CHAPTER 1: OVERVIEW OF THE RED RIVER DYNAMIC ZONE,ENVIRONMENTAL GEOENGINEERING, THEORETICAL
Trang 7FOUNDATIONS 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 secondaryfaults extending from Weixi, Yunnan, China running along the Red Rivervalley to the Gulf of Tonkin, during the Quaternary period, went throughcycles of sea advancement and sea recession The Red River DynamicZone is a Quaternary sedimentary zone that is continuously altered due tothe flow modification effect of the Red River, whereby the dynamic zonehas a depth to the end of the Quaternary sedimentary depth In order toexploit 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 Overmore 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 constantlychanging The terrain elevation, geomorphology are seriously imbalancedand the Red River gradually becomes the "Hanging River" This has led tothe development of processes and hazards with different characteristics ofthis 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 geotechnicalprocesses and environmental geotechnical hazards affect the socio-economic development of the area", which needs to be studied for thepurpose of sustainable development
Since the last decades of the 20th century, there have been manypublished research results on geology and sediments of the Quaternary,typically with the works of authors Hoang Ngoc Ky, Ngo Quang Toan, onflow hydrodynamics by Nguyen Van Cu, Assoc Dr Nguyen Thi KimThoa, Tran Xuan Thai, Assoc TS Nguyen Huy Phuong Before 2008, theRed River cave zone in the former territory of Hanoi was studied on theconditions of the General CCP After 2008, there were studies on assessingEIA conditions conducted only in specific locations such as: studying thedyke system in Van Coc, Co Do, Phuc Tho, Vinh Phuc and Hung Yen byauthor Nghiem Huu Hanh Incident studies along the Red River dyke route
in Hanoi by Dr Tran Van Tu, 2012 Environmental geotechnical studiesofMr 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
Trang 8Environmental geoengineering is the study of the structure, nature
and operation of the technical - natural system, forecasting and prevention
of environmental geotechnical hazards, ensuring the sustainabledevelopment 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 affectingthe sustainable development of the system
In general, environmental geotechnical conditions of a technical system include geology engineering conditions of sub-systems
natural-of geological environment systems, impact conditions natural-of sub-technicalsystems, impact conditions of sub-environmental systems and interactionsbetween environmental geotechnical conditions to guide developmentdirections, 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 theurban geological environment information system of Osipov.V.I have reallycome 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 developedindustrial countries: USA, Canada, Sweden, Norway, Japan, etc But theoutstanding issues remain: environmental assessment of constructionworks such as the BREEAM method, the EcoHome rating method, or theEcopoints system is an environmental assessment tool in the UK [71,74].Design and construction of new waste storage structures, such as landfillsused to treat municipal solid waste and hazardous waste;
In Vietnam, the proposal of rational use of territory towardssustainable development in the stages of planning, design, constructionand economic development on the basis of research on environmentalgeotechnical conditions in our country has begun to be concerned,although methodologically limited Several individual studies have beenconducted by Tran Manh Lieu [21, 23, 25, 26, 27, 28, 29], Doan TheTuong [58, 59, 60], Nguyen Huy Phuong [38, 39], Prof Pham Van Ty
Trang 9Through the above points, it can be seen that the issue of sustainabledevelopment of a territory is only considered independently, not towardssustainable development While the sustainable transformation of aterritory depends on a lot of interrelated factors Inorder to ensure that aterritory is sustainable, studies from the point of view of environmentalgeoengineering are required, and the issues of interplay between thegeological environment and related factors affecting the sustainabledevelopment of that territory are considered in a unified body called thetechnical-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 asfollows:
The complex of natural and human interaction factors (considering allsocial, cultural-historical and technical perspectives) is considered as aunified system, called the technical-natural systems On an earth scale, theICT is called aglobal natural-technical system
The boundary is defined as the contour of the interaction zonebetween the subsystems (where there is a discontinuity in the interactionbetween the subsystems) Boundaries can be determined by calculation ofprocesses, possibly by up-to-date information about the state of the systemdue to monitoring
The technical-natural systems of course, in essence, physics has ahierarchical structure and is divided into levels depending on the purpose
of the study The system has the following hierarchical structure: chamletunit (no further division); localhamlets; regionalhamlets; nationalhamlets;globalhamlets
The technical-natural systems has the following characteristicproperties: adjustablesubstances; Dynamicsubstances; opensubstances;organizationalnature; self-organizingnature; tadaptogens
Interactive activities of sub-systems that generate processes andenvironmental geotechnical hazards: geological processes and buildingdynamics (including pollution); and geological processes, exogenousdynamics, natural and semi-anthropomorphic, terrestrial manifestations
of geological environment and environmental geotechnical hazards events
1.3 Monitoring system
Trang 101.3.1 Concept of environmental geotechnical monitoring
Observation is a portmanteau of Chinese and tracing, in whichobservation is observation, surveying is surveying Therefore, to observe
an object is to monitor the transformation of that object over time byobserving or measuring the peculiar indicators for that object at differentpredetermined points during monitoring
With the concept of environmental geotechnical from the theoreticalpoint of view of technical-natural systems, the environmental geotechnicalmonitoring system is a reasonable combination of different monitoringmethods, reasonably distributed spatially (area and depth) over the studiedterritory for the purpose of collecting and monitoring the variation ofgeotechnical parameters Various environmental terminology aims toassess the generation and development of environmental geotechnicalhazards The composition and characteristics of the monitoring systemselected vary depending on the geotechnical and environmental conditions
of the territory under study
1.3.2 Current status of monitoring and trends in application of new technologies
Monitoring has been carried out since the middle of the last century tomonitor geotechnical parameters assessing the stability of natural slideblocks, of large construction projects (hydroelectric dams,causeways onweak foundations, ) By 60-70 with the development of geotechnical andenvironmental geotechnical subjects, monitoring has progressed to forecastand assess the effects of natural disasters on human activities such asneotectonic activities (uplift, lowering locality), earthquakes, tsunamis,mud and rock floods have been studied by Mexico, the United States,Europe, China and Thailand Currently, in Japan, there is a stronglydeveloped monitoring system for disaster prevention with 6,726 waterlevel stations and 10,051 rainfall stations Geodetic and technicaltechniques of underground space environments in urban areas in Paris,Moscow, Saint-Petersburg, which are models for calculating andevaluating disaster forecasts on the basis of monitoring data and decision-making systems adjusting corresponding processing
In Vietnam, the monitoring system is still a new job and is only aninitial step, the research and practical application of monitoring onlyrevolves around a specific type of work and project: large-scale leveling,causeways and foundation pits to deepen high-rise buildings Hanoi landsurface subsidence monitoring system is due to groundwater extraction
Trang 11with 8 measuring stations in the Hanoi area The Red River dynamic zonearea currently has 4 hydrological monitoring stations (Trung Ha, Son Tay,Hanoi, An Canh stations) besides Viet Tri station, Hung Yen station,stations with an average distance of about 35 Km In which, 2 stationsSon Tay and Hanoi from 1902 were built by the French In addition,there have been a series of open-type (PH), closed-type (PZ) pore waterpressure monitoring wells, which are no longer in operation
In short, the monitoring work has been implemented very early, inwhich specialized geotechnical observations are increasingly popular, allwill be the basis for inheriting the construction of the environmentalgeotechnical monitoring system in the Red River Dynamic Zone Thatshows that the construction of an environmental geotechnical monitoringsystem is completely feasible, especially in recent years, the application ofelectronic and informatics technology has become more and moreextensive
Conclusion of chapter 1
- The concept of environmental geoengineering and environmentalgeotechnical conditions based on the theory of technical-natural systems ofcourse is a new perspective, introduced to solve the problems ofsustainable development of technical - natural systems that are graduallydeveloping and perfecting, so there's a lot of debate Especially inVietnam, this perspective is still new, not studied much, still only locally
- Systems theory and specifically engineering-natural systems theoryproposed by Prof G.K Bondarik is a very good theoretical basis forenvironmental geoengineering research, supporting comprehensive andthorough solving of complex multi-data problems such as stabilityproblems of technical-natural systems of course
- The monitoring system is a basic characteristic and requirement inenvironmental geoengineering research from the point of view oftechnical-natural systems theory
CHAPTER 2: TECHNICAL - NATURAL SYSTEMS AND
ENVIRONMENTAL GEOTECHNICAL CONDITIONS OF THE
RED RIVER DYNAMIC ZONE IN HANOI 2.1 Technical and natural system of Red River caves in Hanoi
The technical-natural system of the Red River Dynamic Zone iscomposed of 3 sub-systems: sub-system of geological environment, sub-system of technical system (dykesystem plays the leading role) and sub-
Trang 12system of surrounding environment (hydrosphere plays the main role) areconsidered in a unified system
The operation of technical-natural systems of the Red River DynamicEconomic System is mainly determined by the interaction process betweenthe 3 sub-systems (Figure 2.1) The consequences of the above interactionsare the main environmental geotechnical hazards as follows: Deformation
of permeability; Riverbank erosion; Flooding of the strip of land beyondthe levee; Uneven subsidence of the dike foundation
Figure 2 1 Operation of technical - natural system of the Red River
Dynamic Industrial Park system
2.2 Sub- systems of geological environment conditions
- Topography - heterogeneous geomorphology, strong fragmentation andsevere imbalance The mudflats between the 2 dykes have an absoluteelevation of 10-12 m, 5 to 7 m higher than the ground level in the centralarea of Hanoi The topography of the Red River is also correspondinglyhigh and the Red River gradually becomes a "Hanging River"
- Modern tectonic movements and seismic activity are recorded along theexisting system of deep fault zones (Red River fault zone, flowing river,
Lo 1 River fault (Vinh Ninh fault), Lot 2 River fault (Dong Anh fault),
- Complex geological background structure (multiple origins and material
composition), unstable, sensitive to natural, technical and technical
-natural influences, divided into 23 layers of rocks (stratigraphicclassification) in order from top to bottom including: Sandy layers phase 1,2a, 2b, 3b; Sand layers include grades 7a, 7b, 13a, 13b; clay-type soillayers of 4, 4a, 6, 8, 10, 14; Soil layers containing plant remnantsbelonging to weak soils include grade Ta, grade 5, grade 9, grade 11
- Hydrogeological features: 9aquifers and 7 aquifers can be distinguished.
The most important and influential on the environmental geotechnical
Trang 13conditions of the Red River Dynamic Zone is the Holoxen aquifer of ThaiBinh sediment This floor is located directly on the surface subject to theeffects of hydrological, climatic conditions and technical impacts Inaddition, they are closely related to the aquifers beneath it, the mostimportant of which are the upper Pleixtoxen aquifer qp2 and thePleixtoxen aquifer below-above qp1 They are also directly related to RedRiver water and the dynamics of this stratum are influenced by river waterdynamics
The above characteristics of the geological environment are favorableconditions for the generation and development of geological hazardswithin the scope of the study
2.3 Sub- system technical dynamic zone
Sub-systems technical of diverse and rich dynamic zones include: dikesystem; constructionand technical infrastructure works; Rivercorrectionworks (roof embankments, welding torches, culverts)
+ The dyke system in Hanoi has a history of more than 1000 years fromthe time (Ly Dynasty) to the present, with the task of flood protection andraising and expanding through the periods The river is covered with on-site waterproofing material with mainly phase lightning, the current height
of the dike is 4-6m, many places are higher The surface of the dike is onaverage 5-1.8m wide, the width of the dike body is 30-50m The static load
of the dike body acting on the dike foundation averages 0.86 kg/cm2 [27].The process and associated geological accidents include: Material removaland formation of a dry fissure system in the body of the; Unevensubsidence of the dike foundation; Seepage through dike bodies, dikefoundations and earth platform processes, underground erosion, sandflowing downstream of the levee
+ Construction activities include housing construction activities inresidential areas and river crossing bridges that significantly prevent theflow and raise the water level during the rainy and flood season.According to annual statistics, the residential housing area increases by20% in 3 years and the number of permanent houses on two floorsincreases by about 40-50% annually and makes the water level about 15-
20 cm higher during the flood season
+ Activities of exploiting construction materials, mainly coastal sandmining with 201 exploitation points, imbalance the river flow, change thestream regime, sedimentation regime, increase the risk of coastal erosion.According to incomplete statistics, in the period of 2015 to 2020, it is
Trang 14about 37 million m3/year while the amount of additional sand mud in thisperiod is about 10 million m3/year, which leads to erosion and landslideswhen combined with unplanned sand mining
2.4 Sub-systems environmental
Sub-systems environmental (hydrosphere, biosphere, atmosphere anddeep part of the lithosphere) in which the hydrosphere plays an importantrole, especially giving rise to the development of environmentalgeotechnical hazards
+ The Red River drainage in the dynamic area is dominated by the DaRiver, Thao River, Lo River, so the strong kinks change directioncontinuously (meandering coefficient from 1.3 to 1.5, radius of curvaturevaries from 2000m to 6000m) and the width of the riverbed changessharply (corresponding to Hanoi water level 7.0m from 0.5 to 1.35Km,From the base of the dike, from 0.8 to 4.0 km) is one of the factors andconditions that form areas susceptibleto riverbank erosion
+ The water level, flow and direction of the Red River flow between thetwo fluctuate very strongly, especially at the time of rains and floods,different from the system of other river basins without Rising flood levels,increased levels, run off rates and material content are major causes ofbank erosion, flooding and permeability deformation
CHAPTER 3: RISK ZONING ASSESSMENT OF ENVIRONMENTAL GEOTECHNICAL HAZARDS
3.1 Environmental geotechnical hazards and hazard risk forecasting zoning
From the point of view of technical-natural systems theory,environmental geotechnical hazards are hazards that occur due tointeractions between sub-systems of technical-natural systems
Environmental geotechnical hazards fall into two groups: (1)Biochemical hazards: water pollution, air pollution, and soil pollution (2)Hazards resulting from geomechanical and hydromechanical processesinclude: whotransforms the permeable deformation of the dike foundation;twho turns riverbank erosion; off-bank flooding and dike subsidence.Within the framework of the thesis, the author only delves into theassessment of the zoning to predict the risk of accident groups formedfrom geomechanical and hydromechanical processes in the Red Riverdynamic zone in Hanoi
Disaster risk zoning is the division of the territory into areasaccording to some homogeneous criteria corresponding to the levels of
Trang 15disaster risk (stable, unstable, very unstable or low-risk, medium-risk,high-risk areas) for the purpose of disaster prevention for sustainableexploitation and use of the territory.
3.2 Risk of riverbank erosion hazards
To assess zoning to predict the risk of dynamic coastal erosionaccidents, the thesis uses a variable integrated approach with an integratedindex (IΣ) as the basis for dividing the study area into different erosion riskzones [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]
I Σ is the indicator of integration of developmental factors
g i is the density of the i-th factor,
R iH 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 theriver bottom (H*)
+ Riverbank slope angle (α *)
+ The highest water level difference value at the point calculatedcompared 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 tothe river bottom (ΔH*)(g3=0.13); soil composition H*)(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*)(g3=0.13); soil composition h*)(g7=0.10); entropy geological structure(G8=0.06); hydraulicslope (I*)( g9=0.06);