Bohai Steel Structure Co., Ltd.

Bohai Steel Structure Co., Ltd.
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    time:2019-10-11 09:11:19


    2. The establishment and vertical survey of the control network are based on the principal axis points of the plane control point layout plan provided by the general contractor and the owner. Combined with the actual situation of the site, the plane control network needs to be measured and released several times to complete the installation control of the entire steel structure project. According to the construction characteristics of the building, the combination of external control and internal control is adopted to control the axis position and overall verticality of the steel components, and the control network of the site is arranged as a quadrilateral. The GTS332 Total Station in Japan is used to observe the horizontal angle four times and to measure the distance between the two sides. Close adjustment according to triangulation. Major accuracy indicators: angle measurement error (+1.6); average point position error (4mm); relative mean error (RME) of the weakest side (1:105,000). Point B is a single triangle, coordinates are measured by side angle. The axis control point is close to the layout of the building, and there are redundant observation conditions. Horizontal angle observation, two back and forth ranging. In elevation measurement, the geometric leveling method is used to measure the BM leveling point and the control point nearby. Peripheral control points are determined by triangular elevation method.


    The local coordinate system is used to calculate the control points in the field. The construction survey adopts the engineering coordinate system with the building center as the origin point. The details are shown in Figure 2. 2.1 After the construction of the negative 2 floor of the basement has been completed and the strength has reached a certain level, the first measurement and placing of the plane control network is carried out on the negative 2 floor of the basement according to the ground control points outside the foundation pit. The initial coordinate is the intersection coordinate of the axis provided by the Civil Engineering and Surveying and Mapping Institute. The field's visual condition is laid out by total station through coordinates, and the control axis piling around the foundation pit is made for measuring and laying out. The datum of Surveying and laying-out for 1-2 underground floors starts from the ground control axis around the foundation pit. Before each surveying and laying-out, the coordinates of the axis are checked again to ensure that the position of each laying-out is correct and the control network of the above ground part is set up. The method of one-internal control is adopted for (+0.000m) above. When (+0.000m) floor concrete is poured and checked, the method of one-internal control is adopted. After reaching a certain strength, the second control axis can be measured and released.

    According to the four control points of the main axis of the foundation pit, the main axis points are vertically directed to the floor of (+0.000m), four laser measurement control points are established in the tower tube, and the distance and angle are closed. After the accuracy of the first-level control network is achieved, the cross lines on the cartridge are saved and painted, which are used as the knots on the ground. Because the construction of inner cylinder structure in this project should be ahead of outer cylinder, in order to meet the construction progress of the project, four laser measuring control points are set up on the layer (+0.000m) to control the installation of inner cylinder column and outer cylinder column respectively, and four laser measuring control points are set up at the centers of 1000mm and 4350mm from the axis respectively. Internal control points, as shown in Figure 32.3 below, the corresponding positions of the internal control points above the first floor of 2.31 are set up with 200*200 reserved holes. The reserved holes are well marked for measurement. Laser straighteners are set up at the internal control points marked by the first layer of paint, and the internal control points are vertically measured to the upper floor one by one, so that the axis of the upper layer can be measured and placed.

    The construction of high-rise joints has some particularities. For example, with the continuous increase of the construction height of joints, the position of reserved laser holes is easily obstructed by the construction obstacles. In order not to influence, the progress of construction survey points and the elevation of elevation are affected by the length of steel ruler when they are transmitted vertically, so the relay of the surveying layer is about 50 m higher. Relay survey layers are selected at 11, 22, 33 and 43 layers. The axis of each middle floor can be measured vertically upward from the cyclic reference point, and the control points of the floor axis obtained from the input point need to be.

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