| Sudden disasters often have the characteristics of strong intensity and short duration,which can easily cause non-negligible impact on hydraulic structures.In recent years,the academia puts forward a new form of damming gelling gravel dam,its performance between concrete gravity dam and earth dam,can make full use of the engineering site excavation materials and scrap materials,greatly reduce the cost of DAMS will have adverse impact on the surrounding ecological environment at the same time to a minimum,is a new economy,the green dam type.Has built many cemented sand and gravel dams at home and abroad,the research on the properties of its material is increasingly mature,but the study of the structure damage,is still in its infancy,so this article combined with the national key research and development plan project-"the cement particle material dam physical and numerical model and the characteristic evolution law",mainly for the following research:(1)In this paper,through laboratory tests,uniaxial compression test data and splitting test data of cemented sand and gravel materials were obtained.Combined with relevant codes and procedures,the load damage evolution equation applicable to cemented sand and gravel materials was obtained,and the numerical simulation was carried out to verify it.The verified results show that the damage evolution equation has a high degree of fit with the experimental results,and the stress-strain curve also conforms to the general law,which can be used to analyze the damage evolution law of cemented sand and gravel materials.(2)Numerical simulation method is adopted to simulate the water level in front of the dam under the influence of sudden disasters(extreme rainstorm/landslide surge).Meanwhile,the water level variation law is analyzed to obtain the water level quantification process.Subsequently,the water level is equivalent to load applied to the dam body,and the existing structural analysis software is used for secondary development.Based on the damage model(1),the damage degree of the unit is introduced to conduct numerical simulation of the damage evolution process of the cement gravel dam under the influence of sudden disasters(extreme rainstorm/landslide surge).The results show that: When the cemented sand and gravel dam and foundation are regarded as a whole,the contact area between the dam and foundation is a weak area,which is prone to damage and failure.As far as the dam body is concerned,the maximum tensile stress appears at the upstream dam heel,and the maximum compressive stress appears at the downstream dam toe,and the stress increases with the rise of the water level,and the tensile crack is easy to occur at the dam heel.For gravity DAMS,the maximum tensile stress is at the heel of the dam and the maximum compressive stress is at the toe.With the rise of the water level,the stress on the dam increases,and the increment of compressive stress on the gravity dam is much greater than that of tensile stress due to its dam-building characteristics.And the main failure forms of gravity dam are tensile failure at the dam heel and crushing failure at the dam toe.Under the action of gravity and shear force,the plastic yield zone of cemented sand and gravel dam mainly develops vertically and horizontally at the elevation of foundation plane,while the plastic yield zone of gravity dam develops diagonally downstream at the elevation of foundation plane along the direction of 45°Angle.Therefore,it is considered that the cemented sand and gravel dam has a larger dam profile,which is beneficial to the stability of the dam.(3)By analyzing and comparing the calculation results of two sudden disasters(extreme rainstorm/landslide surge),it is concluded that the rising rate of water level under the condition of landslide is faster than that under the condition of rainstorm,and the increasing rate of dam stress is correspondingly larger.Under the condition of considering damage,the larger the dam stress is,the existing micro-defects in the dam material will further develop and expand,and the dam material is more likely to produce new micro-defects.The generation and development of these micro-defects are reflected in the increase of the calculated damage value and the expansion of the damage range.The faster the stress on the dam increases,the faster the dam damage accumulates,so the faster and more serious the damage occurs.The damage caused by landslides is greater than that caused by rainstorms in both cemented sand and gravel DAMS and gravity DAMS. |
