Study On The Fracture Process And Deformation Of Arch Dam Based On Geomechanical Model Test

The overall stability of the high arch dam and foundation is related to operation and safety of the project normally,as well as involved in the safety of people's lives and property in downstream.Studying the evolution process of the damage of the high arch dam-dam foundation system was significant for determining the overall safety,evaluating the safety of the project and feasibility.It is necessary that to analyse the cracking and failure process of arch dam-foundation under the overload condition based on the geomechanical model test,and the evolution law of the damage of the high arch dam was summarized.There were the main work of thesis:(1)It was proposed that a similar material made from barite powder,bentonite and glue at different mixing ratios based on the similarity principle of geomechanical model tests,and the mixing ratio was determined as barite powder: Bentonite: glue was 12:0.3:1.5(industrial glue: water was 1:2).Under this ratio,the mass proportions of barite powder,bentonite and industrial glue are 89.96%,2.17%,and 3.63%,respectively.When the density of similar materials is 2.0g/cm3,the corresponding deformation modulus and compressive strength respectively are 87.45,0.686 MPa,the similar material can simulate rock masses with a large range of mechanical parameters,and meet the requirements of similar material tests.(2)The geomechanical model test method of small block masonry was adopted to simulate the type of arch dam,the rock mass mechanical characteristics of dam abutment on two sides,discontinuous structural planes,faults,and the treatment measures of foundation according to the geometric similarity ratio of 1: 250,and carried out overload damage test.To study the whole process and overall stability of the dam body and foundation from loading to crack,to analyze and evaluate the deformation characteristics,instability and destructive process,crack form and overload capacity of the arch dam and foundation.By analyzing the displacement of arch dams under normal and overload conditions,the deformation and distribution characteristics of the dam body,and the relative displacement of measurement points in internal fault,to research the whole process of crack and the destructive mechanism of arch dam and foundation.When the overload test was performed,the left side of the dam ridge first appeared micro-fracture on loading was 2.0 to 2.5 times.When the load was 5.0 to 6.0 times,the dam body began to enter non-linearity.As the overload continued,the foundation cracks gradually extended to the banks.When the load is 11.0 to 12.0 times,the structure underwent large deformation,and it is difficult to increase the load upward,and the dam lost its carrying capacity.At the time of the final damage,the damage area was mainly concentrated on the foundation,the dam body was damaged to a lesser extent,and the right bank foundation was more severely damaged than the left bank.The displacement and strain test and acoustic emission processing results was analysed comprehensively.It was showed that under overload conditions,K1 was 2.0?2.5 times as the dam cracking upstream;K2 was 5.0?6.0 times as the dam body is in nonlinear deformation;K3 was 11.0?12.0 times as the dam body loss Carrying capacity.(3)Based on geomechanical model tests destructive process of multiple high arch dams and engineering analogy analysis.It was studied that the rules of destructive evolution of arch dam-foundation under different topographical geological conditions(roughness and narrowness of river valleys and asymmetry of foundations on both sides of the bank)and the impact on overall security.The in-depth analysis of the relationship between the stress intensity criterion and the nonlinear start safety of the arch dam is analyzed.