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1、 Hydropower scroll packing pouring concrete three-dimensional simulation analysis of Abstract: The Three Gorges Hydropower Plant scroll using the external packing poured concrete structure. To study the steel spiral case and the external interface of the contact of concrete states, respectively, win
2、ter and summer pouring concrete to simulate the construction process of three-dimensional finite element simulation, the interface is given at different water levels in different seasons of the transmission power of run-time and clearance, results show that the effects of temperature on transmission
3、 power significantly. Pouring concrete in winter conditions to study the water temperature by increasing the holding pressure to reduce the high temperature season high-water run-mass force; pouring of the summer to study the head by reducing the holding pressure to reduce the scroll of concrete at
4、low temperatures, low water season, run-time gap. Keywords: spiral packing effect of pouring concrete temperature three-dimensional finite element method simulation Temperature changes in the concrete and steel spiral case mismatch between the temperature of deformation will affect the interaction b
5、etween the two, this interaction is to run with the seasonal changes and with the pouring temperature of the season and holding pressure, and therefore choose a suitable pouring seasonal and packing the water temperature is equally important. Ruozai consider the construction process and concrete ela
6、stic modulus, creep and cement hydration heat with time-varying effects of the interaction between the two is actually very complicated, and only by simulating the construction process in order to analyze the simulation. However, usually without considering the influence of temperature 1 to simulate
7、 the construction process of the simulation analysis is even more rare. The Three Gorges Hydropower Station scroll using packing poured concrete structure, installed height of 57m. Normal water level 175m (to consider the impact of water hammer force, the corresponding internal water pressure 1.395M
8、Pa), initially operating water level 135m, a difference of more. Through the relevant research work, the design used in packing head of 70m. As the number of multi-unit station and schedule requirements, may be in different seasons, there will be construction crew. On the one hand, due to packing he
9、ad small, low-temperature season, pouring concrete units outside the high water level in the hot season when the load borne by a larger concrete structure; the other hand, due to the initial run head small, high-temperature season, pouring concrete outside units at low temperatures, low water season
10、, run-time, the steel and concrete volute will not be able to run completely snapping. Both were taken to improve the security of water temperature and reduce the packing pressure head measures. To this end, this paper, three-dimensional finite element simulation calculation and analysis of winter a
11、nd summer pouring concrete external circumstances, in different seasons and different water run-steel spiral case and the external interface of the mass of concrete or to the gap that may exist and to study the appropriate security pressure head, and holding pressure water temperature. A calculation
12、 condition 1.1 The calculation model of the Three Gorges Project as the concrete gravity dam block, power plant for the dam toe. This article take a Left Bank Slope dam unit as the research object, due to the penstock segment Changba connection pipes to replace the expansion joint with the cushion a
13、nd cushion the downstream end of pipe has not established a thrust ring, the deformation of the dam through the cushion tube affect the displacement of steel spiral case and the steel spiral case and the external concrete interaction between the calculation model therefore includes the dam and the c
14、ushion tube, including the steel dam dam dam blocks and physical blocks, two blocks of rooms for the permanent cross-dam seam. 51m parting between dam and rock slope to the following joint grouting. Main plant simulation to 67m, upstream and downstream entities, deputy factory only to simulate the l
15、ower part of Figure 1, Figure 2. Cushion tube length 10m, which dam length 5.8m, plant length 4.2m. Factory cushion pipe segment can be divided into two paragraphs, that is, a concrete 2.2m above and 2.0m 3 of concrete segment. Imports of steel spiral case at the downstream side of the cushion tube
16、1.1m at the downstream side. Figure 1 dam and plant three-dimensional (including part of the base) Figure 2 plant cross-section of 1.2 Material Parameters (1) steel tube, seat ring and vanes and other steel: E = 210GPa, = 0.30, = 1.2 10-5 / , = 78.0kN/m3; scroll thickness of 20 64mm. (2) rock: rock
17、factory E = 26GPa; dam bedrock E = 10 26GPa; = 0.23, = 0.85 10-5 / , conductivity temperature coefficient a = 0.083m2 / d. (3) large dams concrete: E = 26GPa, = 0.167, = 0.85 10-5 / , a = 0.083m2 / d. (4) steel spiral case and the external interface of concrete: the friction coefficient f = 0.5. (5)
18、 plant Concrete: = 0.167, = 0.85 10-5 / , a = 0.083m2 / d, = 24.5kN/m3; elastic modulus, adiabatic temperature rise and creep-degree, respectively, equation (1) type (3 ), excluding the volume deformation of concrete itself. E (t) = 33.0t / (5.12 t) (unit: GPa) (1) Q (t) = 24.2 (1-e-0.837t0.849) (Un
19、it: ) (2) C (t, ) = C1 () (1-e-0.3 (t-) C2 () (1-e-0.005 (t-) (units :10-6 / MPa) (3) Where: t - Concrete age (d); - loading age (d); C1 () = 7.58 183.1 / ; C2 () = 12.4 35.3 / . 1.3 the main boundary temperature curve T (t) and surface heat transfer coefficient (1) in contact with the atmosphere st
20、ructure of the outer surface of T (t) = 17.35 11.55sin (t-108.8) (), = 15.1w/m2 (4) Where: t - Time (d), to January 1 as the origin; = 2/365, the same below. During the concrete pouring plant, plant the borders of right and left sides according to formula (4) to consider the future consideration by
21、adiabatic boundary. (2) The run-time upstream and downstream vice plant and main plant 67m the inner surface of the surface of T (t) = 22.0 8.0sin (t-120.0) (), = 5.13w/m2 (5) (3) The run-time water pressure pipelines, and the inner surface of volute T (t) = 17.53 8.5sin (t-130.0) (), = 2326w/m2 (6)
22、 (4) The run-time the surface of the dam upstream. Run-time water level below the dam upstream reservoir water surface temperature boundary conditions, reservoir water temperature curve with the elevation change. 1.4 Plant construction process of concrete pouring thickness 1.5 3.0m, sub-4 area, two
23、areas at the same time pouring right corner, intermittent period of 7 8d, 15d floor poured. Simulated winter and summer respectively, pouring concrete external situation, the construction process in Table 1. Factory warehousing concrete temperature in Table 2. 1.5 Packing of water temperature and ho
24、lding pressure head on the winter pouring concrete external situation, 70m head in Bulgaria under pressure to study the packing water temperature control measures, a total of forget three kinds of programs: (1) No insulation measures: scroll within the body of water to take At that time the river, w
25、ater, initial temperature of 11.7 , the outer surface of steel spiral case to take the temperature boundary condition (4); (2) to take heat measures: initial temperature of water 16 , steel volute outer surface of the foam insulation used, = 2.0w / m2 . (3) to take heat measures: water temperature i
26、s lower than 22 when heated, the calculation to take the inner surface of steel spiral case of constant temperature 22 , according to the outer surface of insulation to consider. In (1), (2) program, holding pressure of water divided into units to participate in the same terms, the water conductivit
27、y temperature coefficient of 0.01238m2 / d. above boundary conditions of the outer surface of steel spiral case applies only to areas not yet covered by concrete. Table 1 plant construction process Construction Project External situation of pouring concrete in winter (years. Months) Summer pouring c
28、oncrete external situation (years. Months) A concrete 1999.10 2000.4 1999.9 2000.4 2 (external) Concrete 2000.12 2001.2 2000.6 2000.9 Relief 2001.3 2000.9 Pressure pipe close up 2001.4 2000.10 3 Concrete 2001.5 2001.8 2000.11 2001.2 Table 2 Plant Concrete warehousing temperature () Regional November
29、 March April October May September Strong Constraint Area Nature 20 16 Weak Constraint Area Nature 20 18 From the binding area Nature 20 20 Summer pouring concrete on the external situation, then scroll to take water within the water body, water, initial temperature 25.5 , in the absence of insulati
30、on measures in cases, the calculations of two packing head the program: 70m and 62m. Reposted elsewhere in the paper for free download http: / / 2 Calculation Method 2.1 The calculation of temperature field close up before the water pressure pipelines, taking into account the concrete dam has force
31、d the temperature cooled to a stable line longitudinal joint grouting kitchen, so calculate the temperature at the border of the dam under the action of quasi-steady temperature field, in this based on the simulation scroll packing plant construction process of concrete pouring temperature field sim
32、ulation, plant concrete consideration by natural cooling. The calculation of transient temperature field in space using finite element discretization, in time with the backward difference implicit difference scheme 2. Calculated using self-developed temperature field simulation program 3DUSTPCG. 2.2
33、 Simulation of Stress and Deformation of the dam and the plant in obtaining the temperature field after the stress and deformation analysis, the dam and plant as a whole to conduct simulation, from the beginning to the pouring of concrete plant operation period, analog factory packing concrete pouri
34、ng process and the pressure relief, run-pressing process and the resulting concrete of steel spiral case and peripheral contact between the problems and the process of reservoir water storage and so on, taking into account weight, temperature and creep effects. Among them, using initial strain metho
35、d 2,3 consider the effects of creep, contact element physics equation, see reference 4. Can be calculated using self-developed taking into account the temperature of concrete creep effects and sewing surface contact problem of structure simulation analysis program 3DCRCPCG. 2.3 The finite element me
36、thod calculation of the fast equations include dam, plant underwater structures, steel and some rock foundation. In order to meet the needs of simulation, plant is basically a grid according to hierarchical districts, each pouring two-layer sub-units, the calculation model of division of nodes 50927
37、, unit 45632. Stress analysis, the final total of nearly 145,000 degrees of freedom, not only large-scale computing, computing time more, but also to engage the problem of nonlinear iteration, the amount of calculation is very large. To this end, 3DUSTPCG and 3DCRCPCG procedures used in the author p
38、roposed super-symmetry phase relaxation preconditioned conjugate gradient iterative method (SSOR-PCG) iterative improvement 5 as a solver, with the usual large-scale finite element equation group of one-dimensional variable bandwidth storage compared to direct solution of the triangular decompositio
39、n, in the storage capacity and computational workload is reduced more than an order of magnitude, making the computer for solving large problems quickly possible. Equations larger, its efficiency is more significant. As the calculations less, calculation rounding error is also small. 3 Calculation r
40、esults In July 2003 the reservoir was filled to 135m, the same year in October generating unit went into operation. 2009 Xunhou water to 175m, the design flood level downstream of 76.4m. Simulation of concrete pouring from the plant until 2020, only a few moments the main features of the calculation
41、 of the results shown in Table 3 to Table 4.3 feature points A, B, C, location shown in Figure 2. the initial results of the calculation of water run-time calculations for 2004, and did not take into account the impact of water hammer force; the normal water level period of the calculation results a
42、re calculated in 2020, considering the force of water hammer impact. Calculation, we consider the impact of heavy water pipe. In the table node transmission pressure (ie, steel spiral case and the external interfaces between the laws of concrete to the contact stress), or clearance from the contact
43、element centroid of the value of the unit area around the node, according to the weighted average to obtain, while the average transmission pressure or gap from the scroll all the contact element segment centroid of the values in a weighted average of unit area. These results can be seen from the ta
44、ble, clearance or the transmission pressure distribution is uneven. 3.1 external pouring concrete in winter conditions 3.1.1 No insulation measures can be seen from Table 3, stress-relief Eve (February), the average transmission pressure 0.12MPa. To the initial period of water level in winter (in January, the same below), the average pressure transmission is only 0.10MPa, note at this time internal water pressure borne by the steel spiral case. Run with the same season, the normal water level run-time than the initial operation period, the average mass-load 0.45 0.49MPa,