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PURPOSES OF SURVEYING
- The purpose of the geological surveying is to provide the parameters of geological conditions and other geological activities in area of construction to serves for design
- Defining clearly geotechnical cross sections basing on geologic data and physical mechanical properties of the soil at the surveying construction site.
- Defining the physical mechanical targets of soil layers that make up the geotechnical cross sections.
- Defining the depth of under-ground water level
- Assessing the feasibility of the project in terms of construction geology.
- Based on the surveying documents and testing, giving some comments on the construction geology conditions to provide necessary documents for the calculation of foundation of construction.
With a team of experienced geological engineers and high skilled workers, Polycons will certainly bring to customers the survey results with the most reliable precision
II.STANDARDS
- Floor, house and construction design standards, TCVN 45 – 1978.
- Viet Nam Standard TCVN 4419 : 1987 - Construction Surveying - Basic principles (Mandatory Standards)
- Construction Standard TCXD 160 : 1987. Surveying geotechnical serves design and construction of pile foundation.
- Construction Standard TCXD 194 : 1997. Building. Geotechnical Surveying.
- Construction soil – classified by TCVN 5747 – 1993.
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Construction soil – Testing soil methods in the lab includes standards, as follows:
- - Moisture content (TCVN 4196:1995)
- - Wet density (TCVN 4202:1995)
- - Specific Gravity (TCVN 4195:1995)
- - Liquid limit (TCVN 4197:1995)
- - Plastic limit (TCVN 4197:1995)
- - Hydrometer Analysis (TCVN 4198:1995)
- - Cohesion (TCVN 4199:1995)
- - Angle of friction (TCVN 4199:1995)
- - Compresive testing (TCVN 4200:1995)
- Standard Penetration Test at construction site method – Construction Standard TCXD 226-1999.
- Decision No. 65/BXD-KHCN dated on 02/03/1996 of Ministry of Construction on the issuing Vietnammese standards.
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SURVEYING SCOPE
Geological Surveying aims to provide all necessary documents of geotechnical in the expected construction area, as the basis for selecting the logical positions and design construction items.
Determining exactly the stratigraphy, drawing geological sections in the positions where is expected to construction.
Determining fully of physical and mechanical of land (soil) serves to design as-built drawings (cutting and compression 1 axis method).
III. SURVEYING METHODS
1. Geological surveying:
Drilling process must comply with the standard 22 TCN 259-2000 and the current regulations. With geological structure as above, we use drilling machines Koken, XY-1 (fixed drill) or drilling machines with similar features, with the twist drills method instillation by liquid clay. These are equipments that can work well in such geological conditions as above.
a. Drilling:
Carry out drilling by the method of twist drills instillation by liquid clay with half drilling from 1.5 - 2.0m. During drilling process, it is possible to carry out taking samples in the original form and performing testing SPT combines with taking soil samples which is not in the original form in boreholes.
b. Taking the testing samples
Samples in the original form were taken in boreholes at different depths that depending on stratigraphy and decision of construction site engineers. Soil samples were taken from boreholes, packaging and preservation in accordance with the applicable rules before bringing to the laboratory.
Observing under - ground water levels in boreholes and taking water specimen eroding concrete.
c. Standard Penetration Test SPT:
It was conducted in boreholes at different depths (usually immediately after taking samples in the original form) for the purpose of determining the density of soil layers and taking taking samples in the original form in the borehole. Equipments in SPT is the split pipe Ф 51 (2 "), casted weights 63,5kg (140lb) and the height of dropped weights 75cm (30").
d. In the Lab:
Testing of soil samples is conducted in the laboratory, that provide full specifications, serving for the preparation of construction geological surveying reports. Soil samples was tested in compliance with the current standards.
e. Readjusting documents and making report:
It was conducted in accordance with the current rules, aims to providing a full geological conditions, geological surveyings, as well as physical and mechanical indicators, soil layers to serve construction foundation design.
Reports:
- Explanations
- Exploration points’s ground Drawings
- Boring Logs
- Construction geotechnical soil sections drawings
- Synthesis table of testing results soil samples by layers
- Analysis results of water samples, soil samples.
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Equipments
Machines and equipments for surveying must be tested, ensuring the technical requirements for the geological surveying.
The dedicated equipments and machines serves geological drilling in construction site or testings in the lab (drilling machines, compactors, weight etc ...)