| As an important strategic resource in my country,coal has been mined in high intensity for many years,so a large number of mined-out areas have been formed.With the acceleration of China's industrialization development process,my country's land resources are becoming increasingly tense,and projects such as buildings,industrial plants,roads and bridges are gradually advancing toward the edge of the goaf.However,most mining areas in my country are located in areas where seismic intensity is required.Building structures on the edge of mined-out areas have been adversely affected by coal mining disasters and earthquake disasters.At present,there are few reports on the RC frame structure seismic shaking table test under the influence of coal mine mining disasters and earthquake disasters.Dissertation relies on the National Natural Science Foundation of China "Research on rock formation dynamic instability and building safety control under mining action" Project No.(51474045)",according to "Building Seismic Test Regulations"(JGJT101-2015)and "Building Seismic Design Specifications"(GB50011-2010).Based on mining subsidence,structural dynamics,and seismic engineering,through a combination of on-site investigation,experimental research,and numerical simulation,the RC frame structure at the edge of the goaf is taken as the research object.The structure produces two-way uneven settlement under the long-term impact of mining disasters Under the influence of mining disasters,the research work on the mechanism of seismic performance degradation and dynamic catastrophe law under the action of earthquake disasters is carried out.This article mainly discusses the following aspects,and the main research results are as follows:(1)Shaking table test design of RC frame structure under the influence of coal mining.In order to simulate the uneven settlement caused by mining disasters,a mining simulation test bed was designed.Based on the theory of uniform similarity ratio,an intensity model with a geometric similarity ratio of 1/10 is designed.Both the horizontal and vertical directions have two spans,and the aspect ratio is 2.25.Particulate concrete and galvanized iron wire were used to simulate the prototype concrete and steel bars.In order to further improve the accuracy of the shaking table test,the influence of the weight of non-structural members and live load was considered.(2)Through the shaking table test,study the dynamic response of the test model under the excitation of 7-degree fortification and 8-degree fortification,the structural destruction form and destruction mechanism.Under the disturbance of coal mining,the structure produces uneven settlement,which causes initial damage to the structure and reduces the natural frequency of the structure.The greater the amount of uneven settlement,the more the natural frequency of the structure decreases.The initial damage of mining will increase the seismic damage of the structure under the action of earthquake.The influence of mining increases,the plastic damage is easy to occur at the bottom of the structure,and the energy transmitted to the upper structure by the earthquake is consumed,which is not conducive to the transmission and dispersion of seismic energy to the upper layer.Under the strong earthquake disturbance,the maximum interlayer displacement angle of coal mining damage buildings exceeds the specification limit,the position of the weak layer extends from the first floor to the second floor,there is a phenomenon that the weak area expands upward,and the plastic hinge of the bottom structure increases sharply.The corner column is the most damaged,the center column is the least damaged,and the seismic robustness is reduced.The dynamic failure test shows that the faster the seismic stability attenuation rate of the structure with the largest mining damage,the first failure of the corner column AI occurs,the collapse range gradually expands to form a vertical collapse area,and there is a P-? second-order effect The contribution to the collapse of the structure eventually led to the collapse of the entire bottom structure.(3)Damage to buildings caused by uneven settlement in one direction and two directions.Under the influence of the two types of uneven settlement,the common point is that the additional stress or additional deformation of the first layer member is the largest,and the stress concentration is mainly located at the beam end,column end,and frame node.As the location of the floor increases,the effect of mining is greatly attenuated.The difference is that under the influence of unidirectional uneven settlement,the column is mainly subjected to unidirectional eccentric stress along the tilting direction of the building,and the beam is mainly subjected to bending deformation.However,under the influence of two-way uneven settlement,the column is eccentric in two directions along the diagonal direction,and the beam has bending and torsion deformation.(4)Under the bidirectional seismic excitation,the effects of soil-structure interaction and rigid foundation assumption on the seismic performance of coal mining damage structure are considered.In order to reduce the cost of numerical simulation calculation and improve the efficiency of structural simulation analysis,a variety of calculations have been made on the influence range of the foundation soil,and a method to determine the effective range of the foundation soil of the finite element model is proposed.Comparing with the assumption of rigid foundation,we can see that after considering the soil-structure interaction,the structural constraints are relatively weakened,showing a flexible system,and the natural vibration period of the structure becomes longer.Compared with the rigid foundation,the acceleration response of the top layer of the structure in the X and Z directions is weakened.The greater the impact of coal mining,the greater the magnitude of acceleration reduction.Considering that the displacement of the structure vertex after the soil-structure interaction is greater than that of the rigid foundation,the acceleration time-history curve changes softer,and the dynamic response in the X direction is stronger than that in the Z direction.The greater the effect of coal mining on the building,the more significant the change in displacement of the structural apex.When considering the soil-structure interaction,the maximum interlayer displacement angle of the structure is generally smaller than that of the rigid foundation,and the change trend of the interlayer displacement angle is slower than that of the rigid foundation,especially for the structure under the influence of uneven settlement.The changes are more significant.Compared with the rigid foundation,after considering the soil-structure interaction,the horizontal interlayer shear force decreases with the increase of the floor position.(5)The law of collapse of the frame structure under the influence of coal mining under different soil layers was studied.Under different soil conditions,the destruction time of the structure is all different.The structural failure time under the assumption of rigid foundation is mostly earlier than that of hard soil and soft soil.The softer the soil,the more significant this delay effect of damage.Under the same conditions of mining and mining,the overall damage of the soft soil foundation structure is smaller than that of the hard foundation and less than the rigid foundation.The softer the foundation soil,the greater the amount of uneven settlement,the greater the depth of the structure into the soil under the action of seismic dynamics,and the more severe the lateral deformation of the structure.The collapse failure process indicates that the structural failures include both "column hinge" and "beam hinge" failures,and there is a "mixed collapse" mechanism.After considering the soil-structure interaction,the upper structure reacts more strongly,and the members form plastic damage to varying degrees,dissipating part of the seismic input energy,and the overall collapse probability of the bottom is reduced. |
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