MindMap Gallery 01Water conservancy and hydropower survey
First-level construction engineer, water conservancy and hydropower practice, mainly including the use of measuring instruments, water conservancy and hydropower construction measurement requirements, water conservancy and hydropower engineering geology and hydrogeological condition analysis, etc.
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Water conservancy and hydropower survey
1. Use of measuring instruments
1||| Level
Classification
By precision
Ordinary level: National third and fourth class ordinary level measurement
Precision level: National first and second class precision level measurement
Model: DS05, DS1, DS3, DS10. D means: geodetic survey; S means: level; The number indicates the accuracy of the instrument. For example, 3 indicates that the accidental error in the height difference measured per kilometer round trip is plus or minus 3mm.
by structure
Slight level
Automatic leveling instrument
laser level
Digital level (also known as electronic level)
Steps for usage
Set up instruments
rough leveling
Adjust the three foot screws to center the circular level bubble, which is called rough leveling
Focus and aim
Parallax must be eliminated by first adjusting the eyepiece focusing screw to see the crosshairs clearly, and then continue to carefully turn the objective lens focusing screw until the ruler image coincides with the crosshair plane.
Precise leveling
reading
When the bubble of the level tube is in the center, immediately read the level on the level stick according to the middle wire of the cross hair. Readings retain four digits
2||| Theodolite
Classification
By precision
DJ05, DJ1, DJ2, DJ6 and DJ10 D stands for: geodetic survey J stands for: theodolite The number indicates the accuracy of the instrument, and “05” indicates that the error in one measurement direction observation does not exceed ±0.5″ (seconds)
Dial scale and reading method
vernier theodolite
optical theodolite
Electronic theodolite
effect
Angle measurement: horizontal angle measurement and vertical angle measurement
Low precision measurement: sight distance measurement
Steps for usage
centering
Leveling
Sight
Steps: Focus the eyepiece; Aim roughly at the target; Focus the objective lens; Aim the target accurately.
reading
2. Requirements for water conservancy and hydropower construction surveying
1||| basic knowledge
Elevation: The 1985 national elevation datum is used as the unified datum for calculating elevation.
scale
Large scale: 1: 500, 1: 1000, 1: 2000, 1: 5000, 1: 10000 [ten thousand]
Medium scale: 1: 25,000, 1: 50,000, 1: 100,000 [one hundred thousand]
Small scale: 1: 250000, 1: 500000, 1: 1000000 [millions]
2||| Basic work of construction setting out
Preparation of stakeout data: Before stakeout, the stakeout data should be calculated based on the design drawings and relevant data and the control point results used.
Method of setting out the plane position
right angle intersection method
polar coordinate method
angle intersection method
distance intersection method
Elevation staking method
Leveling method: parts where the error is required to be no more than ±10mm
Photoelectric ranging trigonometric elevation method
Analytical Trigonometric Elevation Method
sight distance method
When using a theodolite instead of a level for engineering stakeout, the distance between the stakeout point and the elevation control point must not be greater than 50m.
3||| Excavation engineering survey
main content
Original topographic map and original section map measurement of the excavation area
Excavation contour point stakeout
Excavation completed topography, cross-section measurement and engineering quantity calculation
case point
Detailed stakeout of excavation work
Instructions
polar coordinate method
Angiometric forward intersection method
basic method
rear resection method
Distance measurement can be performed according to conditions and accuracy requirements
Measured by the sight distance method, the sight distance length should not be greater than 50m. For pre-splitting blasting stakeout, sight distance method should not be used.
Measured by the parallax method, the normal length of the endpoint should not be greater than 70m.
Section measurement and engineering quantity calculation
Drawing selection
Before starting the excavation project, the original cross-section or topographic map of the excavation area must be measured
During the excavation process, the receiving section or topographic map should be measured regularly
After the excavation project is completed, the completed cross-section or completed topographic map must be measured as the basis for settlement of project quantities.
Scale selection
The scale of cross-section and topographic maps can be between 1:200 and 1:1000 according to the purpose and project location.
For the completed excavation topographic map or cross-sectional view of the main buildings, 1:200 should be used;
The closing chart is preferably 1:500 or 1:200
For large-scale earth and rock cover excavation and collection, 1:1000 can be used
In the calculation of excavation engineering quantities, the area calculation method can be analytical method or graphical method (integrator).
When the difference between two independent measurements of the excavation work volume in the same area is less than 5% (rock) and 7% (earthwork), the middle value can be taken as the final value.
4||| Mold erection and architectural layout
main content
Measure and set the molding or filling outline points of various buildings
Check the shape and position of erected formwork and prefabricated (embedded) parts
Calculate the amount of filling work
Inspection requirements for building model setting out points
The difference between the setting out and checking points should not be greater than 1.4m (m is the error in the measurement and setting out of the contour points)
Measurement of filling project quantities
Calculate selection
The foundation location should be calculated based on the foundation excavation as-built drawing.
The parts above the foundation can be calculated directly based on the geometric dimensions of the hydraulic design drawings and the average elevation of the measured parts.
The amount of earth and stone filling should be calculated based on the actual measured dividing lines of various filling materials.
If the difference between two independent measurements of the same project is less than 3% of the volume, the middle value can be taken as the final value.
5||| External deformation monitoring during construction
main content
Landslide observation in construction areas
High slope excavation stability monitoring
Observation of Horizontal Displacement and Subsidence of Cofferdam
Temporary foundation settlement (rebound) and crack monitoring
The accuracy of the base point for deformation observation shall not be less than four decimal places.
Point selection and embedding
The base point must be established on stable bedrock outside the deformation zone.
At least one group of base points for vertical displacement must be laid out, with each group having no less than three fixed points.
The measuring point should be firmly combined with the deformation body.
Landslide measuring points should be located in the axis direction with large sliding amount and fast sliding speed and in the landslide front area.
Observation points for cracks in mountains or buildings should be buried on both sides of the crack.
Observation method selection
Landslide and high slope stability monitoring adopts intersection method
Horizontal displacement monitoring adopts sight line method (movable target method and small angle method)
For vertical displacement observation (settlement observation), the horizontal observation method should be used.
6||| As-built measurement
Completion survey
During the filling process of core wall, sloping wall and dam shell of earth and stone dam, every second layer of materials must be measured and the edge line measured and drawn into a chart for reference upon completion.
Cause of error
human reasons;
The reason for the instrument;
The influence of external environment.
Classification and characteristics of errors
System error: changes according to certain rules;
Accidental error: no regular changes;
Gross error: Carelessness or interference.
3. Analysis of water conservancy and hydropower engineering geology and hydrogeological conditions
1||| Geological structures and earthquakes
Geological structures are classified according to structural morphology
inclined structure
fold structure
anticline
syncline
fault structure
joints
split
fault
2||| Analysis of Engineering Geological Conditions of Slope
Classification of slope deformation and damage
relaxation crack
Creep
collapse
landslide
The most widely distributed and most harmful
3||| Analysis of engineering geological problems in soil foundation pits
Measures to prevent slope instability
Set a reasonable slope
Slope protection
Foundation pit support
lower water table
Foundation pit dewatering and drainage
Purpose
Increase slope stability
For slopes with fine sand and silt soil layers, prevent the occurrence of quicksand and piping.
For clay soil foundation pits with underlying pressurized aquifers, prevent the bottom of the foundation pit from rising
Keep the foundation pit soil dry to facilitate construction
method
Mingpao method
Artificial precipitation
Light well point
Suitable for small permeability coefficient
Tube well point precipitation