Civil buildings are divided into single storey, low storey (2 ~ 3 storeys), multi storey (4 ~ 8 storeys) and high storey (above 9 storeys). Because of different building types, their lofting methods and accuracy requirements are different, but the lofting process is basically the same.

Civil building construction survey includes building positioning and setting out; Foundation engineering construction survey; Wall construction survey, etc. Before construction survey, besides checking the measuring instruments and tools used, the following preparations should be made.

1. Understand the design intent, be familiar with and proofread the design drawings.

Through the design disclosure, we can understand the whole picture of the project, the main design intent, and the accuracy requirements for measurement. , and then familiar with and check the general plan, construction drawings and structural construction drawings related to the layout. Check whether the overall size is consistent with the sum of the dimensions of each part, and whether the overall plan is consistent with the details.

2. Check the positioning control points and leveling points.

For the plane control points on the construction site, check whether their points are correct before use, and check the elevation of leveling points on site. Through inspection, the correct starting data and measuring points are obtained.

3. Make layout (lofting) plan

According to the design requirements, positioning conditions, site topography and construction scheme, the construction lofting scheme is formulated. As shown in figure 1 1-8, according to the design requirements, the planned No.3 single dormitory is parallel to the existing No.2 building, the distance between two adjacent walls is 18m, and the south wall is in a straight line. Therefore, according to the existing Building No.2, rectangular coordinate method is proposed for layout.

Figure 1 1-8 construction site plan

4. Prepare layout data

In addition to calculating the necessary layout data, it is also necessary to check the plane size and elevation data inside the house from the following drawings.

1) Find out or calculate the plane size and height difference between the designed building and the original building or the survey control point from construction site plan (Figure 1 1-8) as the basis for measuring the overall position of the building.

2) From the building plan (including the ground floor and floors, figure 1 1-9), check the relationship between the overall size of the building and the internal positioning axis. It is the basic data of construction lofting.

3) From the foundation plan (figure11-kloc-0/0), check the plane dimensions of the foundation sideline and positioning axis, and the positional relationship between the foundation layout and the foundation section.

The above three kinds of design drawings are the basis of construction positioning and setting-out.

4) Check the dimension of foundation elevation, design elevation and the dimensional relationship between foundation sideline and positioning axis from the detailed foundation drawing (longitudinal section of foundation, figure111). It is the basis of foundation elevation measurement.

5) Check the design elevation of foundation, floor and floor from the elevation and section of the building. It is the main basis of elevation measurement.

5. Draw a layout sketch

Figure11-91:100 plan

Figure 1 1- 12 is a schematic diagram of survey and layout drawn according to the general design plan and foundation plan. The plane size, the plane size between the positioning axes and the positioning axis control piles between the built house 2 and the proposed house 3 are indicated on the drawing. According to figure 1 1- 10 and figure 1 1- 1, the external wall of the proposed house is 0.25m away from the positioning axis. In order to make the south walls of the two buildings flush after construction, the positioning size is set as 10 in the sketch of plane layout.

Figure 1 1- 10 Foundation Plan

Figure11-1/foundation details

Second, the building positioning and alignment

1. Location of buildings

Building positioning is to measure the intersection point between the axis of building external wall (corner pile for short) and the ground according to the sketch of plane layout, as the basis for setting out and setting out in detail. Due to different positioning conditions, civil buildings can be positioned according to existing buildings in addition to measuring control points, building baselines (building red lines) and building grid. As shown in figure 1 1- 12, measure the intersection number III of the external wall axis to construct the ground building. The steps are as follows:

Figure 1 1- 12 lofting sketch.

1) Use a steel ruler to cling to the MN and PQ sides of the built No.2 building, measure out two points A and B with equal distance (1 ~ 4m) according to the actual terrain, drive the stake, and nail the nail mark on the pile top nail (each point is marked by the pile top nail).

2) Put the theodolite at point A, aim at point B, measure point C 18.250m from point B along the direction ab, and then continue to measure point D 21.300m..

3) Place the theodolite at point C and D respectively, aim at point A, then measure 90 clockwise, measure point F and point G of 4.25m along this direction with a steel ruler, and then continue to measure point I and point H of 1 1.600m .. F, G, H and I are the intersection points of the external wall axes of the proposed house. When measuring the distance between corner piles with a steel ruler, the relative error between the value and the design length should not exceed 1: 2000, or 1: 5000 when the house is large. Place the theodolite on four corners of F, G, H and I, and test each right angle. The difference between theodolite and 90 should not exceed 40 ",otherwise it should be adjusted.

2. Building alignment

Building setting-out refers to setting out the cross piles (or central piles) of each axis of the building in detail according to the located cross piles of the external wall axis, and then determining the excavation boundary line of the foundation trench according to the cross piles sprinkled with white ash. Pay-off method is as follows:

(1) Measure the intersection point of the set axis at the periphery of the external wall axis.

As shown in figure 1 1- 12, put the theodolite at point F, aim at point G, measure the distance between two adjacent axes in the FG direction with a steel ruler, and determine 1, 2, 3, ... (You can also set a point every 1-2 axis). Similarly, we can determine the points of 6, 7, …. The measurement accuracy should reach 1: 2000 ~ 1: 5000. When measuring the distance between shafts, the zero end of the steel ruler is always at the same point.

Because the corner pile and the center pile will be excavated after the foundation trench excavation, in order to facilitate the recovery of the position of each axis in the construction, each axis should be extended to a safe place outside the foundation trench and marked. The method includes setting axis control piles and dragon door plates.

(2) layout axis control pile

As shown in figure 1 1- 12, put the theodolite on the corner pile, aim at the other corner pile, and use a steel ruler to measure it to the outside of the foundation groove for 2 ~ 4m along the line of sight. Lay a stake, nail a small nail on the top of the stake, accurately mark the axis position, and protect the stake with concrete (figure113). When setting out a large building, in order to ensure the accuracy of control piles, axis control piles are usually laid out first, and then corner piles are laid out according to axis control piles, while axis control piles in small and medium-sized buildings are laid out according to corner piles. If conditions permit, the axis can also be measured on the surrounding original features, and signs should be made instead of axis control piles.

Figure 1 1- 13 Axis Control Pile

(3) set the gantry plate

In general civil buildings, the portal frame plate (Figure 1 1- 14) is often nailed at a certain distance outside the foundation trench excavation line. The steps are as follows:

Fig. 1 1- 14 gantry plate

1) Set gantry piles outside the excavation line of the foundation trench at the four corners of the building 1.5 ~ 3m (depending on soil quality and trench depth) and at the middle positioning axis. The pile nail should be vertical and firm, and the outer side of the pile should be parallel to the foundation groove.

2) According to the site leveling points, set the elevation of plus or minus 0 on each gantry pile with a level, and draw a horizontal line with a red pencil.

3) Nail the gantry plate along the zero line released from the gantry pile, so that the elevation of the upper edge of the plate is exactly 0. If site conditions permit, the elevation can also be measured as an integer higher or lower than 0 m, and the elevation tolerance of portal frame plate is 5 mm. ..

4) As shown in figure 1 1- 14, put the theodolite at point F, aim at point G, fix a point on the gantry near point G along the line of sight, and nail a small nail (called an axial nail). Turn the telescope upside down and nail a small nail on the frame near point F along the line of sight. In the same way, all axes can be measured on the corresponding gantry plate. The error of the axis point of putright should be less than 5 mm If the building is small, aim the hammer ball at the pile point, then tighten the rope along the two hammer ball lines to extend the axis, and mark it on the gantry plate.

5) Use a steel tape measure to check the distance between the pins along the top surface of the portal frame plate, and the accuracy should reach 1: 2000 ~ 1: 5000. After passing the inspection, mark the wall sideline, foundation sideline and foundation trench excavation sideline on the gantry according to the axis nail. When calibrating the excavation width of the upper mouth of the foundation trench, the slope should be considered according to the relevant regulations.

6) Spread the foundation trench excavation boundary lime line. At both ends of the axis, excavate boundary markers according to the foundation grooves marked on the gantry plate, straighten the thin rope, spread white lines along this line, and excavate according to this line during construction.

Third, the building foundation engineering construction survey

1. Control the excavation depth of foundation trench.

In order to control the excavation depth of the foundation trench, some small horizontal stakes (Figure11-kloc-0/5) will be laid on the trench wall with a leveling instrument when the trench is about to reach the design elevation of the trench bottom, so that the upper surface of the stakes is at a fixed value (such as 0.500m) to control the excavation depth. For the convenience of construction, a horizontal pile is generally arranged at every corner of the pond wall every 3 ~ 4m. If necessary, white rope can be pulled along the upper surface of horizontal pile as the basis for grasping the elevation when cleaning the tank bottom and laying foundation cushion. The allowable error of horizontal pile elevation measurement is 65438 00 mm.

Figure 1 1- 15 Foundation trench elevation measurement

Figure 1 1- 16 wall centerline measurement

2. Measure the center line of the wall on the mat.

After the foundation cushion is laid, according to the axis nail or axis control pile on the portal frame plate, use theodolite or hang a hammer ball with a pull rope to measure the axis on the cushion (Figure 1 1- 16), and use ink lines to pop up the center line of the wall and the foundation sideline for laying the foundation. Because the whole wall is based on this line, this line is the key link to determine the location of the building, and masonry construction can only be carried out after strict inspection.

3. Foundation elevation control

The height of the building foundation (brick wall below 0 m) is controlled by the foundation measuring rod. The foundation pole is a wooden pole (figure 1 1- 17). According to the design size, draw the thickness of brick and mortar joint on the pole in advance, and mark the elevation position of plus or minus 0 and moistureproof layer. When setting the number of poles, you can first make a stake at the vertical pole, draw a horizontal line higher than the elevation of the cushion layer by a certain value (such as 10cm) on the side of the stake with a level meter, then align a line with the same elevation on the pole ruler with the horizontal line on the stake, and nail the pole ruler and the stake together with a tack as the elevation basis of the foundation wall.

Figure 1 1- 17 basic Pi rod

4. Check the elevation of foundation surface.

After the foundation construction, check whether the elevation of the foundation surface meets the design requirements (or check the moistureproof layer). Compared with the design elevation, the elevation of several points on the foundation surface measured by level gauge has an allowable error of +/- 10mm.

Fourth, the general situation of wall engineering construction

1. Wall elastic line positioning

Mark the axis and wall sideline with axis control pile or gantry, cast the axis on the foundation surface or moistureproof layer with theodolite or wire rope hanging hammer ball, and then pop up the wall centerline and wall sideline with chalk line. Check whether the intersection angle of the external wall axis is equal to 90. After meeting the requirements, set out the axis of the wall and draw it on the foundation of the external wall (Figure11-KLOC-0/8) as the basis for measuring the axis upwards. At the same time, the connection lines of doors, windows and other openings are also drawn on the facade of the external wall foundation.

Figure 1 1- 18 wall positioning

Figure 1 1- 19 wall measuring rod

2. The elevation control of each part of the wall.

In wall construction, tape measure is usually used to control the elevation of each part of the wall. According to the design size, draw lines on the wall tape measure according to the thickness of brick ash, and mark the elevation positions of doors, windows and floors (Figure 1 1- 19). The setting of the wall skin bar is the same as that of the foundation skin bar. The allowable error of 0 m lofting elevation line is 3 mm. Generally, after laying 1m on the wall, an elevation line of 0.50 will be set on the indoor wall for the ground construction and indoor use of this floor. In the construction of the wall above the second floor, in order to make the skin pole stand on the same horizontal plane, the elevation of the four corners between floors should be measured with a level, and the average value should be taken as the floor elevation as the sign of the vertical pole.

When the degree requirement is high, the steel ruler can be used to measure directly to the outside of the floor from plus or minus 0 along the wall to determine the sign of the vertical pole.

In civil buildings with frame structure, wall masonry is carried out after the frame construction, so you can draw lines on the cylinder instead of on the skin pole.

Five, the axis of the multi-storey building construction survey

In the masonry process of multi-storey buildings, in order to ensure the correct transmission of axis position, the bottom axis can be measured by hanging hammer ball or theodolite on each floor as the basis of masonry construction on each floor.

1. Axis measurement of multi-storey building with brick-concrete structure

(1) hanging hammer method

Use a heavy hammer ball to hang on the top edge of the floor or column. When the tip of the hammer ball is aligned with the axis mark on the foundation wall, the position of the line on the edge of the floor or column is the endpoint position of the floor axis, and the mark line is drawn. Use the same method to measure the endpoint of each axis. After the axis spacing meets the requirements, the construction can continue. This method is simple and easy to operate, and can generally ensure the construction quality. However, when the wind is strong or the building is high, the measurement error is large, so the theodolite measurement method should be adopted.

(2) Theodolite projection method

Figure 1 1-20 theodolite axis measurement

As shown in figure 1 1-20, the theodolite is placed on the axis control pile perpendicular to each other in the middle of the building, and after strict leveling, it is aimed at the bottom axis punctuation (that is, the axis mark marked on the external wall foundation facade). The axis of the upper floor edge or column top is measured by the method of average left and right of the disc. Each floor should be arranged with 1 ~ 2 long axes and 2 ~ 3 short axes. Then check the allowance with a steel ruler, and the relative error shall not be greater than 1: 2000 ~ 1: 5000. Only after passing the qualification can the elastic line be divided on the floor and the construction be continued.

2. Axis measurement of multi-storey building with frame structure

Figure 1 1-2 1 Multilayer building axis survey

As shown in figure 1 1-2 1, the frame composed of beams and columns is the main load-bearing component of the building, and the floor is placed on the beams, which is a frame structure building. If the beam and column are cast-in-situ, the verticality of the formwork should be strictly checked. Inspection method is to use hanging hammer method or theodolite to measure the axis on the corresponding column top, set marks, and then pop up the axis on the cylinder (at least two sides) as the basis for transmitting the axis upwards. For the template for correction, put the template on the top of the column seam, and strictly check the position and verticality of the template according to the axis that has popped up on the lower cylinder. According to this method, the shaft is transmitted upward layer by layer.

3. Axis measurement in high-rise building construction

The positioning and alignment of high-rise buildings are basically the same as those of multi-storey buildings. When the axis is measured upward from the bottom, the vertical error of this floor is less than 5mm, and the cumulative error of the whole building is less than 20 mm The high-rise building axis survey includes theodolite measurement and laser plumb measurement. This section introduces the theodolite measurement method.

According to the different positions of theodolite, it can be divided into extension axis method and lateral line borrowing method.

(1) Extended Axis Method

When the building elevation increases and the axis control pile is close to the building, the elevation angle will increase and the accuracy will decrease. Therefore, the original central axis control pile should be led to a safe place far away from the building or the roof of a nearby building to reduce the elevation angle. As shown in figure 1 1-22, the theodolite is placed on the ground centerline piles B', b 1' and C' and c 1' respectively, and on the floor elevation in the middle and upper part of C 1 (as shown in figure 65438). Aim at point C ′ and point c 1 ′ to guide the superstructure construction, put the theodolite on the new control piles c″ and c 1″, aim at point C and C1point, and measure the axis according to the above method in this section.

Figure 1 1-22 Extended Axis Method

(2) lateral borrowing method

Figure 1 1-23 Side Line Borrowing Method

As shown in figure 1 1-23, when the periphery of the building is narrow and the axis of the high-rise building cannot be extended, the axis can be moved out of the building 1.5m (not more than 2m as far as possible) to obtain the intersection points of the translation axis: A', B', C' and D'. Four operation platforms are set up at the four corners of the construction floor with steel scaffolding, and then the theodolite is placed at two points B' and D' on the ground, aiming at point A' respectively. A 1 will appear on the operating platform through the observation on the left and right sides of the panel. C 1, B 1 and D 1 point intersect in the same way. After measuring the four points A', B', C' and D' on the ground on the platform, A 1B 1, b1,C 1D 1 shall prevail. The axial position of the floor can be obtained by measuring 1.5m inward.