Simulation Of Working Performance Of Super-high Arch Dam During Construction Period Based On Entire Dam And Whole Process

The design of arch dam is mainly based on the control index during operation period, the working performance of construction period and operation period of super-high arch dam are different obviously, such as temperature field, stress field, deformation feild, transverse joints state, etc., and the working performance of operation period will be directly affected by construction period, in addition, cracks occured during construction, and open-close performance of transverse joints will also have a direct impact on the working performance of structure. Therefore, in order to evaluate the safety of super-high arch dam, it is of great significance to conduct the study of working performance of super-high arch dam during construction period.The simulation of entire dam and whole process is given, which consider six process, including:pouring of bulky concrete with separate spacing, material hardening, temperature control, arch closure grouting, impounding and the variation of environmental parameters. As an example, Xiluodu super-high arch dam is studied carefully, and there are many problems to be solved, such as selection of rock deformation modulus during construction, real working performance considering whole construction process, stability of crack extension occurred in super-high arch dam during construction and its impact on the working performance of dam, work state of transverse joints and its impact on the working performance of dam, the main works are listed as follows:1. Back analysis method of mechanical parameters of high arch dam during construction period is studied based on simulation theory of entire dam and whole process.①The back analysis method of concrete elastic modulus and rock deformation modulus of super-high arch dam during construction period are summarized, regression analysis methods of the dam deformation of construction are reviewed. A new hybrid model, which is appled to carry on the back analysis of dam elastic modulus and rock deformation modulus, is proposed based on the construction simulation stress;②Based on the observed results achieved by precise leveling instruments, multiple position borehole extensometer and plumb line monitoring, back analysis is applied to obtain the concrete elastic modulus and rock deformation modulus of Xiluodu arch dam, and the results show that:the back analysis results of bedrock deformation modulus based on three instruments are basically identical, they can be checked with each other, and the new hybrid model of back analysis based on the construction simulation stress is verified to be feasible and raliabe;③The influence of back analysis results of rock deformation modulus and dam deformation, is studied considering the water pressure of reservoir basin, the results show that:If surface force is applied to simulate the basin water pressure, there are of certain differences on the back analysis of rock deformation modulus and dam deformation, permeate volume strength should be used to simulate the water pressure of reservoir basin.2. Research of construction working performance of Xiluodu super-high arch dam is carried on based on the simulation theory of entire dam and whole process. The theory and method of the entire dam and whole process, which consider six process, including pouring of bulky concrete with separate spacing, material hardening, temperature control, arch closure grouting, impounding and the variation of environmental parameters are summarized and it is applied to study the working performance of Xiluodu super-high arch dam during construction. In this analysis:①The overall infuence of stress and deformation according to different weight applied methods and arch closure grouting process is studied;②Based on the actual monitoring results and simulation results of temperature, stress and deformation, the temperature, stress and deformation of construction period are compared, the results show that:the calculation overall rules of the temperature and stress are basically identical with the observing results, temperature and stress control during construction overall is good, however, because of not considering the adiabatic temperature rise of concrete after90days, temperature calculation value is lower than observations; Vertical stress distribution based on caculations agree well with observation, except for measured value of individual dam section is lower than simulation; The overhang effect of arch dam lead to the deformation upstream, with the increase of the dam height and pouring water level upstream, dam deformation gradually turned to downstream;③According to monitoring results based on the transverse joint meter and calculation results, the analysis on the working performance of transverse joints is studied, stress and open-close working performance during different grouting elevation and water level, are also investigated, the studies show as follows: transverse joints aperture are of average of1.0-1.5mm after second-stage cooling, the transverse joints aperture in different dam sections and elevations are also varied due to the process of concrete pouring, pouring season, adjacent height difference, side exposure time and other factors, transverse joints state are normal overal, however, the individual parts of the aperture is higher than normal, such as the maximum value of5.70mm appears in the12#transverse joint, which go to far beyond the temperature shrinkage and need further verification studies.3. Study of Cracks stability and its impact on the structure working performance during constrction of super-high arch dam is conducted, content are included as follows:①The research of crack cause, expansion stability and its impact on dam working performance of super-high arch dam during construction period are summarized;②New interlayer crack, and surface crack in watestop region of super-high arch dam during construction are introduced;③The stability of crack expansion due to the water infiltration and sabotage during construction period, and its effect on dam working performance is analyzed, it shows that:crack propagation is of low sensitivity for the fracture toughness of concrete, however, showing high sensitive for intial bond strength after treatment; the crack is likely to extend upstream and it is difficult to extend downstream; the crack has little effort on the state of stresses and displacements in arch dam;④The new surface crack in watestop region are analyzed, the study shows:Abrupt open of transverse joints at the construction stage is easily to cause the concrete damage in surrounding area beside the waterstop, and the water-pressure tests before the transverse joints grouting lead to the further expansion from local damage to surface crack.4. The state of transverse joints of super-high arch dam and its impact on the structural working performance are studied. It is listed as follows:①The research of transverse joints status impacted on dam are summarized;②An equivalent mechanical model to simulate the spherical keyway is proposed to simulate the mechanical behavior of open, close and slide, which is added to the simulation procedure of Saptis;③The impounding process impacted on transverse joints aperture were analyzed based on Xiluodu high arch dam, the study shows:the transverse joints are pressed due to high water level, which will affect the schedule of arch closure grouting, therefore, the summer water level of Xiluodu arch dam in2013should be controlled at540m;④Analysis is conducted to study the issue of non-grouted transverse joints between two waterstops upstream for the impact on dam, the study shows that:Non-grouted transverse joints between two waterstops upstream have slight effect on the overall deformation and stress of the whole dam, however, it has very significant effect on the end stress of non-grouted transverse joints upstream.