Vietnam: What are the details of National Standard TCVN 9363: 2012 on survey for construction - geotechnical investigation for high-rise buildings?
- What are the reference documents in National Standard TCVN 9363: 2012 on survey for construction - geotechnical investigation for high-rise buildings in Vietnam?
- What are the general regulations of National Standard TCVN 9363: 2012 on survey for construction - geotechnical investigation for high-rise buildings in Vietnam?
- What are the instructions on geotechnical monitoring for high-rise buildings in Vietnam?
What are the reference documents in National Standard TCVN 9363: 2012 on survey for construction - geotechnical investigation for high-rise buildings in Vietnam?
In Section 2 of National Standard TCVN 9363: 2012 on survey for construction - geotechnical investigation for high-rise buildings in Vietnam, the reference documents in National Standard TCVN 9363: 2012 are as follows:
The following references are necessary for the application of this National Standard. For reference documents with the year of publication, the version stated shall be applied. For reference documents without the year of publication, the latest version shall be applied, including amendments and supplements (if any).
- TCVN 4419:1987, Survey for construction - Basic principles.
- TCVN 9364: 2012, High-rise building - Technical guide for survey work during construction
What are the general regulations of National Standard TCVN 9363: 2012 on survey for construction - geotechnical investigation for high-rise buildings in Vietnam?
In Section 4 of National Standard TCVN 9363: 2012, the general regulations of National Standard TCVN 9363: 2012 on survey for construction - geotechnical investigation for high-rise buildings in Vietnam are as follows:
- Geotechnical investigation tasks for the design and construction of a high-rise foundation shall be set up by the design consulting contractor and approved by the investor. The geotechnical investigation plan shall be drafted by the survey contractor on the basis of geotechnical investigation tasks and approved by the investor.
- Geotechnical investigation for high-rise buildings shall be carried out in stages corresponding to the design phases: geotechnical investigation in the pre-basic design phase, geotechnical investigation in the basic design phase, geotechnical investigation in the technical design phase, and geotechnical investigation in the construction drawing design phase. Once the construction site has been determined, the pre-design survey phase can be skipped.
- Geotechnical investigation for high-rise buildings associated with general survey work for construction, according to TCVN 4419: 1987.
- Basis for formulating geotechnical investigation plans
+ Archival documents related to the proposed construction area: geological structure, topography, geomorphology, hydrogeology, problems of construction dynamics, mechanical and physical properties of soil and rock;
+ Geotechnical investigation tasks, data related to project characteristics such as premises, structure, and use.
- Major issues to be solved in geotechnical investigations for high-rise buildings
+ Elucidate geological conditions of construction areas, including geotectonic features (stratigraphy, geological structure, tectonics); Topography - geomorphology; Hydrogeology; Geodynamic geological processes and phenomena of buildings; Mechanical and physical properties of rocky soils; Natural building materials.
+ In all cases, specify the location and characteristics of the soil layer that can carry most or a significant part of the construction load (called the load-carrying layer).
+ When the load-bearing layer is relatively deep or deep, the pile foundation must be used to transmit the load down, it is necessary to provide information about the distribution range and mechanical and physical properties of each layer of soil that the pile penetrates, the coefficient of friction of the soil with the pile, the possibility of generating negative friction force on the pile in case of using friction piles and especially of The load-bearing soil layer under the tip of the pile in case of the use of stakes.
+ When the load carrier layer is rock, it is necessary to clarify the degree of weathering and cracking, the RQD index, the necessary physical properties, and the axial compression resistance of the rock core. In some cases, it is necessary to determine the shear resistance and separation resistance of the stone.
+ When there are one or several geological processes and phenomena of construction dynamics (earthquakes, flash floods, mudslides, landslides, karst,...), in addition to solving the above-mentioned problems, it is necessary to refer to the corresponding standards to carry out additional surveys.
+ When it is expected to apply background treatment solutions, it is necessary to conduct testing and monitoring before as well as after treatment.
+ When designing deep excavation pits, it is necessary to experiment and forecast the possibility of lowering the groundwater level, and the degree of impact on neighboring buildings, proposing treatment solutions if necessary.
What are the instructions on geotechnical monitoring for high-rise buildings in Vietnam?
In Section 6 of National Standard TCVN 9363: 2012, the instructions on geotechnical monitoring for high-rise buildings in Vietnam are clearly stated as follows:
- Geotechnical monitoring aims to monitor changes in the deformation and durability of soil and rock as well as of construction buildings during construction and exploitation. The location and duration of monitoring are determined depending on the characteristics of the construction work and the geotechnical conditions of the construction area.
- Geotechnical monitoring must reflect the scale and value of phenomena in space and time, and detect the development trend of adverse phenomena in order to plan effective prevention measures.
- For high-rise buildings, the main monitoring objects are houses and foundation pits dug deep.
- For houses, it shall focus on monitoring settlement, tilt, cracking, and damage. Monitoring equipment, monitoring methods, and measurement standards should comply with the requirements of TCVN 9364: 2012.
- For deep excavation pits, geotechnical monitoring mainly serves construction, including:
+ Subsidence of the soil surface around the excavation pit;
+ Transposition into a dug pit;
+ Groundwater level or hydrobromic level;
+ Flaring the bottom of the excavation pit;
+ Displacement of the top of the wall;
+ Soil pressure applied to the wall;
+ Displacement and stress in the struts of the support system;
+ Deformation of houses and nearby buildings.
- In case the buildings are built next to old buildings, experiments and observations should be carried out on neighboring buildings in order to take timely handling measures, including the following activities:
+ Observe the current status of neighboring foundations, types of foundations, and state of foundations; open excavation pits can be carried out to observe the shape, current condition, and size of nearby foundations;
+ Observe the current condition of the body of the project, existing cracks, and damages to propose necessary preventive measures during construction;
+ Set subsidence measurement landmarks and inclinometers at neighboring buildings for continuous monitoring during foundation construction.
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