In the above formulas, ΔH ₁ and ΔL ₂ are respectively the elevation difference of the excavation red line and the difference in the radial direction, and ΔH _{3 and} ΔL ₄ are the elevation difference and the radial direction of the surface of the top arch concrete structure, respectively. Difference.

In the ΔN formula: T=1, representing N≥-1.55, that is, the downstream side of the plant; T=-1, representing N<-1.55, which is the upstream side of the plant (as shown in the figure, the center line of the plant and the center line of the unit The parallel distance is 1.55m.

ΔH is positive, the measuring point should be shifted by ΔH distance is red line, otherwise ΔH is negative, measuring point should be moved downward by ΔH distance is red line;

ΔN is positive, the measuring point should be moved to the direction near the centerline of the plant ΔN distance is the red line, otherwise ΔN is negative, the measuring point should be moved away from the center line of the plant by ΔN distance is the red line. Similarly, in the process of concrete lining of the top arch of the factory, we need to carry out the stakeout and formwork inspection of the vertical arch line of the top arch. The radius of the lower edge of the concrete structure is R=15.36 meters, which has important features of large span and difficulty. In the process of stakeout of the template, there are some differences between the situation and the red line of the excavation. We did not make the difference between the upstream and the downstream of the axis of the plant. According to the actual situation of the construction site, it only has the adjustment of the vertical direction. . In the case of template inspection, relatively speaking, our working environment will be more unfavorable (sometimes may not be able to look at). For the actual situation, we generally use the height of the reflective prism to maintain a certain value or use the microprism to bring it along the top. The arch template arc is placed in the radial direction and then adjusted only for the vertical movement of the template in the radial direction. In the stakeout and inspection of the template, we also use the programming calculator to calculate the field. The calculation principle is similar to the calculation of the red line stakeout of the excavation. However, when calculating the template check, the elevation reference in the calculation program should be The center of the circle corresponding to the circular arc of the concrete structure is the base point, and the difference is determined by combining the radius thereof. On the AutoCAD software platform, it is very convenient to validate the stakeout point coordinates and template point coordinates. That is, by establishing a three-dimensional model of the underground powerhouse on the AutoCAD application platform, in this three-dimensional coordinate system, we directly input a three-dimensional point coordinate within the plane of the factory building, and it can be visually seen from the application platform whether the point is a red line. Or with the red line or whether it is the relationship between the template dotted line, and we use the programming calculator to calculate the input 3D point coordinates, and draw a conclusion, which can be used as the basis for mutual verification.

In view of the situation of Yele Power Station and its design requirements for underground caverns, there is generally a certain slope to facilitate drainage, etc. Traditional cavern excavation and lofting is to lay out basic wires outside the cave or excavation section, and then apply With the cooperation of the theodolite, the level gauge and the steel ruler, the center of the excavation section, the center line and the waist line are found on the face of the face. This traditional method of operation is very difficult to operate in the actual operation process, and the error is large and error-prone. Under normal circumstances, the face of the face will not be a standard vertical plane, but usually the tunnel has a certain slope, and sometimes even the slope is very large. At this time, the design of the non-plumed surface should be considered. Perform related conversions, either on the AutoCAD software platform or directly on the programming calculator. If the ventilation is connected to the hole, the slope is 0.3039. The design of the excavation top arch is an arc, and the vertical plane is an elliptical arc. Then we can use the AutoCAD software platform to establish the spatial model of the longitudinal and transverse sections, and find the long and short semi-axes of the elliptical arc. The corresponding elliptic equations are then programmed using the programming calculator and then verified on the AutoCAD software platform. The results are in good agreement. In this way, it is possible to fully avoid the undercut (e.g., the unevenness of the face) caused by some special circumstances.

2. Calculations with plane turns:

For a slightly more complicated situation, such as the turning section of the ventilation tunnel and the three-fork section of the tail water tunnel, during the excavation process, the face of the face cannot be guaranteed to be the same station number, and the warehouse number is guaranteed during the lining process. If the end faces are all the same, you must use the programming calculator to calculate the coordinate transformation between the coordinate systems on site. For the turning section of the underground cavern, the plane transformation of the construction coordinates should be considered mainly. If some traditional methods of putting the curve are to be used, it is well known that due to poor underground visibility, it is likely that there is no way to stake out. The total station instrument combined with the programming calculator makes it easier to measure some of the optimized construction coordinates. Judging from the construction situation of the Yele Hydropower Plant site pivot project, the above combination method can better control the over-excavation and ensure the excavation effect.

See Figure 4, taking the turning section of the tailwater hole as an example: through the aforementioned coordinates, set the coordinate point to be measured, apply the programming calculator to convert it into the coordinates on the hole axis (curve), and then use the relevant corresponding section. The calculation of elevation and plane coordinates. The specific programming ideas are as follows (take P ₁ C as an example):

Using the relationship of the analytical geometry, the plane distance S _{O1P of} the O ₁ P point is _obtained , and E'=28.00-S _O1P . Calculating the angle between O ₁ P ₁ and O ₁ P, we can get N', and then enter E', N' into the hole digging space model calculation program, and calculate the elevation displacement ΔH and the plane displacement ΔE. The key program of the program is as follows:

Q=tan ^-1 ((L-37.35)÷(28-D))

N=37.35+Q×π÷180×28

E=28-√((28-D) ² +(L-37.35) ² )

I=2002.86+(343.947-N) ×.003-(3.2-√(3.2 ² -E ² ))-H

J=1999.66+(343.947-N) ×.003+√(2.8 ² -E ² )-H

In the above formulas, the direct data is the graphic size provided by the design, L and D are the observation values ​​of the vertical and horizontal coordinates, and N and E are the vertical and horizontal coordinate values ​​calculated by the curve relationship, I, J. For us, the measured elevation of the point corresponds to the difference between the elevation of the concrete surface of the top arch excavation and the top arch structure calculated according to the design section image, ie ΔH. ΔE should be compared with the calculated E and the design value, and will not be described here.

V. Conclusion

For the construction environment of underground caverns, if you can use more advanced, total station with no mark ranging and infrared guiding function, such as TCRA1100 series total station with TMS section measuring system post-processing software. At present, the more advanced multi-functional total station cross-section measuring system is a combination of hardware and software for the measurement of section measurement and blasthole measurement in underground engineering construction. It makes full use of the Leica TCRA type total station. The functions of laser non-prism ranging and motor drive realize the control and automatic acquisition of cross-section field data acquisition software, so as to achieve automation, data and computerization of underground cavern section measurement. The advantages of this system combination are: the latest non-reflective prism technology and servo motor technology, fully automatic cross-section measurement, surrounding rock deformation measurement, blasthole positioning, volume measurement, etc., truly multi-purpose, powerful Excellent quality, economical and practical. They will be able to better reduce the field labor intensity of the surveyors, and improve the efficiency of measurement work and the accuracy of the work. However, with the investment of more advanced instruments, there must be an increase in cost, and the ability requirements of our surveyors must also be Will be higher. There is reason to believe that with the improvement of total station development technology and the improvement of the quality of engineering and technical personnel, as a construction measurement, there will be a broader development space.

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