| The earth-rock dam has become the mainstream dam in the world because of its advantages such as using local materials,convenient construction,good deformation ability and saving investment.Although the construction of the high earth-rock dam in China is relatively late,the development speed is the fastest in the world.Several 300m high earth-rock dams are under construction.In recent decades,the construction practice of earth-rock dams has shown that:the technology of constructing 100m class earth-rock dam is relatively mature.200m high earth-rock dam engineering practice experience is lacking,affected by different test conditions and damming materials.Chinese Dam Engineering Community has not yet formed a unified understanding of engineering characteristics of dam materials,deformation analysis and deformation coordination.As a result,some longitudinal and transverse cracks appear after the dam has been constructed,which endangers the long-term operation of the dam.Construction of 300m high earth-rock dam is more complicated,and there are more uncertain factors in the construction process,and more strict requirements on damming materials and deformation of dam body.In this paper,the highest core earth-rock dam in the world with a dam height of 312m is regarded as an example.Through field test,laboratory test and three-dimensional numerical analysis,the paper conducts research on the characteristics and constitutive model,deformation analysis of dam body and intelligent control of dam deformation construction.A new technology of automatic blending of gravel core wall and a new method of consolidation drainage test is proposed.The intelligent control system of dam deformation construction is constructed,which lays a foundation for the smooth construction and efficient management of the project.The research results mainly include:(1)The density of deep cover layer of riverbed was determined by comparing the field pressuremeter test and the indoor pressuremeter model test.The riverbed overburden layer has the characteristics of complicated causes,multiple layers,soft and hard,and empty space.The overburden density of river bed was determined to overcome the objective conditions of dry land construction.According to the preliminary geological exploration data and covering material composition,the deep overburden layer of river bed is divided into 3 layers.The pressuremeter modulus of each layer was calculated by the pressuremeter test of 103 measuring points in 8 holes.Field sampling was carried out,and 24 groups of model tests of indoor pressuremeter model test under different gradation,different density and different overburden pressure were carried out,and corresponding pressuremeter modulus was obtained.The results of indoor model test were analyzed,and the actual field density of deep overburden layer was taken as the field density of deep overburden layer when the average pressuremeter modulus measured on site was equal to that of indoor pressuremeter modulus.The density of deep overburden of riverbed is the foundation for the study of its engineering characteristics.(2)A new method of automatic mixing of gravel and soil materials with accurate measurement,controllable gradation,uniform mixing and continuous production is proposed.Detailed survey data of completed and planned high core wall earth rock dam at home and abroad show that the particle content of natural impermeable soil material less than 5mm generally exceeds the standard value.Gravel should be added to improve its deformation resistance.However,the traditional blending method of horizontal paving vertical mining is not accurate enough to control the gradation.Inhomogeneous mixing can easily lead to uneven settlement deformation,and large construction site demand leads to large investment.To solve the above problems,according to the design theory and engineering practice of screw conveyor,this paper analyzes the admixture aggregate stress state,the motion law,put forward the double estuary hydropower station automatic blending screw machine parameters,realized the core wall material blending evenly and continuous production.According to the measuring accuracy requirement,this paper puts forward the quantitative feeder,feeder,vibrating feeder,belt feeder measurement of frequency method and the related equipment parameters,realized the measuring precision,gradation and controllable.This method is proved reliable by 3D simulation,which ensures the production quality of core wall material,effectively avoids problems such as uncontrollable grading and uneven settlement of dam body caused by inhomogeneous mixing.(3)A new test method,which can guarantee test quality and improve test efficiency,for accelerating consolidation and drainage of gravel soil core wall material is presented.The clay content of gravel core wall material is large,the permeability coefficient is low,and the sample drainage is slow and the test efficiency is low in the large triaxial consolidation and drainage shear test.In order to overcome the defect of long test cycle of conventional triaxial shear test method,this paper draws lessons from the experience of sand well foundation accelerated consolidation and drainage method.Gravel core wall materials mixed with gravel by mass ratio of 50%were carried out at different densities and different test confining pressures of Three groups of sand core gravel and three groups of non-sand core samples were compared in this paper.Comparison test of three axes with sand core and one without sand core is also carried out.The results show that the results of sand core test and no sand core test are basically the same.The consolidation time of samples with sand core is only about 1/10 of that of samples without sand core.Sand core has obvious effect on quickening sample drainage,and it is concluded that the results of sand core test can replace the results of no sand core test.(4)The empirical models and parameters of 6 parameters of hydrated deformation and 9 parameters of rheological deformation in Shuangjiangkou hydropower station are presented.Rockfill body is a typical geotechnical structure with complexity,uncertainty and multiphase coupling,and the long-term deformation characteristics of rockfill body vary with different materials.In order to grasp the long-term deformation characteristics of the upper and lower reaches of Shuangjiangkou hydropower station,such as the humidification and rheology of the rock materials.The wetting tests of Feishuiyan granite and Hekou metamorphic rocks at 3 confining pressures and 4 stress levels were carried out by single line method.The rheological tests of Feishuiyan granite under 3 confining pressures and 4 stress levels were carried out with graded loading.The rheological tests of Hekou metamorphic rocks at 4 confining pressures and 4 stress levels were carried out.The rheological tests of Feishuiyan granite under 3 confining pressures and 3 stress levels were carried out with single stage loading.The experimental results show that the confining pressure of two kinds of stone has little effect on the wetting axial strain,the relationship between wetting axial strain and stress level can be expressed by exponential function.The wet volume strain is positively correlated with confining pressure and stress level,the relation curve can be fitted by linear function.The curve of flow variable and time of two kinds of stone materials has a good relationship under logarithmic coordinate,and its rheological properties can be characterized by a nine-parameter rheological model.(5)The paper puts forward the deformation rule of dam body and the key points of deformation control of Shuangjiangkou hydropower station.The deformation of earth-rock dam dam body is directly related to the long and safe operation of the dam body.In order to grasp the deformation rule and weak link of dam body of Shuangjiangkou hydropower station under different working conditions,based on the research results of engineering characteristics of damming materials,the 3D numerical simulation analysis of the dam body under 7 conditions of the benchmark parameters(not considering the rheological humidification,considering the humidification,considering the rheological,filling time)and the variation of parameters(high strength parameter,low strength parameter,core wall arch effect parameter)was carried out.The analysis results show that the maximum vertical displacement of the dam during the completion period under various conditions accounts for between 0.95%and 1.05%of the dam height,and the vertical maximum displacement during the storage period is between 0.93%and 1.13%of the dam height.The ratio of vertical maximum displacement to dam height is basically consistent with the monitoring data of similar projects.The maximum vertical displacement of the dam body occurs within the core wall area of gravel soil,and the key point of dam deformation control is the construction of gravel soil core wall area.(6)A qualitative and quantitative method is adopted,a set of quantitative index system for controlling the deformation of gravel core wall dam is established.In order to quantify the technical and process requirements in the design and construction specifications of earth-rock dams,to achieve strict compliance with design requirements to achieve quantitative construction,the construction quality and dam deformation under control can be ensured.This paper combines the construction practice of Shuangjiangkou hydropower station.Based on the results of 3D numerical calculation and analysis of dam body,according to the construction and design specifications of earth-rock dams,by referring to similar engineering construction experience and multiple regression analysis of gravel core wall materials,a deformation control index system of earth-rock dam body is established,which consists of 8 kinds of dam-building materials and 64 quantitative indexes,from three links of material source control,process control and result control.It provides a quantitative control object for construction intelligent control.(7)An intelligent early-warning decision feedback control system for dam deformation construction with "five-dimension integration" is constructed.There are many kinds of materials for earth-rock dams,the filling requirements are high and the control content is complex.In order to avoid the influence of artificial factors such as isolated islands of control information caused by the traditional management mode of hydropower project,to realize intelligent control of traceable construction process,automatic risk classification and early warning,and independent decision-making feedback of early warning content,this paper makes use of advanced information technology such as big data storage and mining,Internet,reasoning machine and 4S technology.Combined with the construction technology of Shuangjiangkou hydropower station,the construction process of dam is decomposed in coordination.The mathematical model and frame structure of intelligent control of dam deformation are constructed.Based on the intelligent monitoring theory of dam deformation,an intelligent control method for the whole construction process of material source production,dam material transportation,water addition outside the dam,filling and compaction and quality inspection is proposed.Through the established dam deformation control index system,a three-level intelligent warning model is proposed.Based on the blackboard theory,an intelligent feedback method for predicting the deformation index of multi-agent dam is proposed.The intelligent decision and feedback of dam deformation are realized,and the control efficiency and level of dam deformation are improved. |
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