Abstract:The scattering of seismic waves by underground structures can change the dynamic characteristics of a site. However, the current safety evaluation and seismic design of aboveground and underground structures ignore the influence of underground structures on the ground motion of the original site. The scattering of cylindrical SH waves by a circular tunnel in an elastic half-space is analyzed on the basis of the elastic wave theory by using the wave function expansion method and the mirror image principle, and the analytical solution to displacement in the elastic half-space with a circular tunnel is obtained. The influence of the circular tunnel on the ground motion of the original site is analyzed with numerical examples, and the influence laws of parameters, such as tunnel depth, tunnel radius, and modulus ratio between the lining and surrounding rock, are investigated. Results show that the underground structure drastically affects the dynamic characteristics of the site and can provide some reference value for the seismic design of engineering structures.Keywords:cylindrical SH wave; circular tunnel; scatter; earthquake-resistance of underground structure

Abstract:Using the performance-based fragility analysis method, this paper analyzes a base-isolated RC frame-wall structure. This paper selects 20 actual ground motion records with 0.2 g as the step length, adjusts the ground motion parameter PGA, and sets up 140 structure-ground motion sample spaces. The peak inter-story drift ratio of a super structure and the displacement of the isolation layer are then selected as structural performance indices. After dynamic nonlinear time history analysis of each sample, statistics of the structural responses are obtained, and the probability of collapse of the structure beyond each limit damage state is determined. A global reliability method is then used to calculate the collapse reliability indices of the structures and draw them into a base isolation RC frame structural fragility curve. The collapse probability and collapse reliability indices can reflect the performance of base-isolated frame-wall structures and provide a reliable basis for structural earthquake damage assessment.

Abstract:A complicated interaction exists between the infilled wall of high-rise buildings and the surrounding structural components under seismic action, and this interaction exerts a great influence on the seismic performance of the structure. Therefore, accurate evaluation of the influence of infilled walls on the seismic performance of structures is crucial. Based on the results of random vibration tests, three types of finite element models are built using Perform-3D for a high-rise frame-shear wall structure and a high-rise shear wall structure. For models that do not consider the infilled wall, the period reduction coefficient by the established specification is employed. Incremental dynamic analysis is implemented on the three models to discuss the influence of infilled walls on the seismic performance of a structure under the action of an earthquake with potential hazard. The calculated results reveal that the infilled wall can strengthen the initial stiffness of the structure in the elastic stage, but this contribution to decreases with increasing ground motion intensity. The period reduction coefficient suggested by the established specification is more conservative compared with the analysis results obtained from the proposed model considering the infilled wall. Findings also indicate that the influence of infilled walls on high-rise frame-shear wall structures is greater than that on shear wall structures.

Abstract:Vibration isolators and infill walls have great effects on the seismic performance of buildings. In order to explore the influence of the infill wall layout and material on the dynamic characteristics and seismic performance of the reinforced concrete (RC) frame structures, an equivalent model based on the equivalent brace theory was adopted to compare and analyze three anti-seismic system schemes of differing filled-wall arrangements with the cooperative work of a vibration isolator. It was found that the seismic performance of the RC frame structure is best with no infill wall on the top floor. On this basis, the effect of different filling materials on the seismic performance of RC frame structure was analyzed. The results showed that the seismic performance of the RC frame with aerated concrete block filled wall is best.

Abstract:Historical earthquake damage shows that the connection stiffness of infilled walls and frames exerts an important influence on the seismic performance of frame structures. Code for Seismic Design of Buildings (2010) suggests that infilled walls should be separate from or connected flexibly to columns but does not provide the appropriate connection stiffness between these structures. In this work, pseudo-static tests on frame structures considering the effect of connection stiffness between infilled walls and frames were numerically simulated by using ABAQUS. Then, based on a typical frame structure, finite element models that do not consider infilled walls but consider different levels of connection stiffness between infilled walls and frames were established. The failure features and hysteretic curves of frame structures with infilled walls were compared with those without, and the reliability of the finite element models was verified. Modal analysis indicated that connection stiffness exerts a small influence on the frequency of the structure and that the structures showed the same dynamic properties. By analyzing the elastic-plastic time histories of the structures under frequent and rare earthquakes, the appropriate connection stiffness was confirmed to improve the seismic performance of the structures of interest. This paper provides a reference for the seismic design of frame structures.

Abstract:When bridge cranes lift heavy weights, the load is borne by the lower column of single-storey mill buildings. In view of this fact, the mathematical expression of dynamic response of the lower column's vertical displacement was deduced by analyzing the vibration characteristics of the system composed of the crane beam and lower column under vertical dynamic load. The mathematical expression based on the theory of vibration mechanics showed that the vibration lasts about 5.5 s and that the vertical vibration displacement has two sudden increases. The first sudden increase of displacement is the most severe vibration of the lower column. By specific example, several factors influencing the vibration were researched. The results showed that if we increased the viscosity coefficient and elastic modulus of column material and the attenuation coefficient of dynamic load, then the vibration time is shortened, the displacement amplitude is reduced, and the peak of the second displacement is postponed or eliminated altogether. Increasing the lifting weight had no effect on the vibration duration, but did increase the amplitude significantly. On this basis, taking the work of vertical dynamic load as the potential function, the cusp catastrophe theory was used to establish the discriminant formula of the stability state of the lower column, and the method of predicting any parameter in the stable system is illustrated.

Abstract:Through several earthquake damage investigations, it has been found that the casualties and economic losses during earthquakes are mainly caused by the building damage. Buildings in rural areas should be given more attention as they are mostly substandard, and hence, would have poor seismic performance. As a kind of green building structure system, cave structures have the advantages convenience, simple construction, low cost, and thermal insulation, so they are widely used in rural areas. Through the investigation of cave dwellings in the rural areas of northern Shanxi, it is concluded that most cave dwellings are independent adobe caves, where the predominant system is the adobe masonry structure, and there is no unified standard of cave construction, which leads to differences in shapes. As the internal force distribution of an arch structure is sensitive to change in shapes, to study the influence of shape characteristics of a cave on its seismic performance, a finite element model is established and analyzed. Combined with historical seismic disasters of caves, the damages of caves with different shape characteristics under earthquakes were compared. The results show that caves with thicker overburdened soil are more fragile, and two sides of a multi-span cave dwelling are more vulnerable to damage. The curved shape of an arch has some influence on the seismic performance of its structure, and an arch cave with reasonable shape has better seismic performance.

Abstract:The failure and collapse of reinforced concrete building structures during earthquakes is a key factor in earthquake disasters. The effective evaluation of the seismic collapse-resistant capacity of a building structure is a vital component of building structure design, and also serves as the basis for improving the seismic performance and reinforcement of building structures. In this paper, we propose the extreme value of the deformation index, the failure judgment criterion, and the collapse limit state. Based on these factors, we can obtain evaluation criteria such as the collapse reserve coefficient, collapse vulnerability, structure integral superstrength coefficient, and structure integral ductility coefficient. We use the pushover analysis method to select the corresponding seismic waves. Given the influence of beam-to-column linear stiffness ratio on the anti-collapse capacity of a building structure, we can analyze the vulnerability of the building structure. From our study results, we can draw the following conclusions:equal-span building structures are more resistant to earthquake damage and collapse; the bottom layer of the building structure is weakest; and the higher is the COF value, the more easily a structure will collapse.

Abstract:To ensure the active application of seismic construction technology of long-span space steel structure hangars in urban construction and planning, it is necessary to study the seismic technology of these hangars. This paper proposes a seismic construction method for such hangers based on building information modeling (BIM) technology. This method introduces composition, seismic construction requirements, construction basis, and the construction procedure of long-span space steel structure hangars, and describes the specific application of BIM technology in seismic construction of these structures, including construction process and construction principle. A simulation engineering example analysis proved that after seismic construction using BIM technology, the bearing capacity and lateral stiffness of long-span space steel structure hangars were clearly improved, and the structure bore most of the seismic internal forces of the building structure in the early stage of an earthquake.

Abstract:To reduce the severe structural damage caused by the collision of adjacent buildings during an earthquake, in this study, we applied the Lyapunov method as a control algorithm to conduct a stability analysis to determine the best controller design. Here, we compare and analyze the performances of semi-active and two types of hybrid control schemes. The results reveal that a hybrid control strategy is more effective than semi-active control in mitigating the seismic response. The selection of an appropriate hybrid control scheme can reduce the bearing displacement, and thus effectively prevent impact. In addition, we found that an increase in the damping and strength of the isolation leads to an increase in the base shear force and reduces the bearing displacement. The selection of an appropriate parameter value can ensure that the resulting response is within a limited range.

Abstract:An inerter is a novel mechanical element that translates linear motion to high-speed rotational motion. In this work, we propose a novel passive vibration control system based on the inerter and eddy current principle. First, to study the damping mechanism of this new system, a mechanical model of a single-degree-of-freedom system with an inerter is derived. Next, the influences of key parameters of the inerter system on the structural response in the frequency domain are discussed. The results show that the eddy current damper can amplify the quality and that the inerter system can effectively reduce the displacement, velocity, and acceleration response of the structure.

Abstract:This study investigates a double-column pier system with buckling-restrained braces (BRB), while focusing on the transmission mechanism of the superstructure inertial force in the system. Taking a 3×30 m highway viaduct as the engineering background, the positioning of BRB and the influence of different parameters on the seismic response of the bridge were studied by a nonlinear time-history response analysis to understand the working mechanism of BRB in double-column piers. The following can be concluded from the study:(1) For double-column piers with BRB, when BRB do not yield, it changes the force transfer path of a structure through its axial stiffness, thereby decreasing the bending moment and sheer force of the pier bottom; however, the change of axial force at the pier bottom would be enlarged. (2) When the BRB yields, it influences the seismic response of the structure by changing the force transfer path of the substructure and its hysteretic energy dissipation mechanism. The energy consumption of BRB would reduce the change of axial force of the pier and optimize the damping effect. (3) Double-column pier with BRB in transverse bridge direction is an effective damping system, and the damping effect is relevant to the specific arrangement and mechanical parameters of BRB.

Abstract:The traditional method of achieving an anti-seismic effect in walls uses materials with low thermal conductivity and increases the thickness of wall. This method not only wastes energy, but also has poor seismic performance. Therefore, a seismic structure of glazed hollow bead insulation concrete shear wall was designed. A constitutive model of glazed hollow bead insulation concrete was constructed, and the theoretical data related to seismic structure was obtained. According to the obtained data, the seismic structural unit of the shear wall was selected. The shell element SHELL63 was selected as the seismic structural unit. According to the seismic structural material parameters and the seismic structural unit, ANSYS software was used to simulate the seismic structure of the glazed hollow bead insulation concrete shear wall. The experimental results showed that the designed building displayed good energy saving and seismic performance, and, thus, was of high practical value.

Abstract:To study the failure mechanism of single-layer spherical reticulated shell structures under multi-point impact loading, a finite element model of a Kiewitt-6-type single-layer reticulated shell with a 60 m span is established in ANSYS/LS-DYNA. The reticulated shell structure is divided into six sectors along the rib rod and divided into five ring zones along the ring bar; each area has an impact point. The dynamic response and energy transfer rule during the impact process of the reticulated shell structure under the combination of different impact regions are analyzed. Four failure modes of the single-layer spherical reticulated shell structure under multipoint impacts are defined based on the failure and deformation characteristics of the lattice shell structure, and the corresponding failure mechanism of each failure mode is revealed according to the energy transfer characteristics of the entire impact process.

Abstract:When detecting the damage of masonry structures under moderate-strong earthquakes, there are high limitations with the current seismic record method, as it is based on the known ground motion records of masonry structures. A new method for detecting damage of masonry structures under medium-strong earthquakes is proposed. A double-arm spectrometric (DASP) dynamic test analyzer and an 891-type piezoelectric displacement sensor were used to detect the masonry structure model after quasi-static testing, and the parameters inter-revising method was used to obtain the natural frequency and vibration mode of the structure. The displacement of the masonry structure was obtained by finite element analysis. The damage of the masonry structure was detected by the signal matching method according to the frequency and displacement. The experiment proved that the proposed method can accurately detect the damage of masonry structures under medium and strong earthquakes.

Abstract:The traditional modal superposition method cannot be used to model mixed structures because the damping matrix of mixed structures does not meet the classical damping condition. In addition, the complex damping theory cannot be applied in time domain calculations because of the divergence in structural free vibration response. To solve these problems, in this paper, a mathematical optimization model for solving Rayleigh damping coefficients is constructed based on the frequency domain equivalence principle. Modal mass participation factors are used as weighting function and the coefficients are used as variables, which can be calculated by the mathematical model. The Rayleigh damping motion equation, which is equivalent to complex damping theory, is obtained. The calculated results show that the correctness of Rayleigh damping motion equation is proved according to the displacement-time history response and structural equivalent damping ratio. Based on the results of this study, the Rayleigh damping motion equation of mixed structures, which is equivalent to complex damping theory, can directly use the modal superposition method. Combined with structural equivalent damping ratios, it can provide a theoretical basis for mode-superposition response spectrum methods of mixed structures.

Abstract:Concrete is a nonhomogeneous composite material. Thus, its mechanical properties are affected by its mesostructure, and the isolation of the influences of various factors on the mechanical properties of concrete is difficult. In this study, concrete is considered as a three-phase material that consists of aggregates, mortar, and interface. Numerical experiments are conducted to analyze the influence of microstructural parameters (e.g., aggregate position, element size, material strength, and aggregate size) on the properties of concrete under dynamic compressive load and dynamic tensile load. The mesostructure of concrete affects the dynamic mechanical properties of concrete. However, different factors have different weights, and the same factor may exert different effects under different loads.

Abstract:Large-scale development and utilization of underground space is threatened by earthquake. For practical approaches of seismic analysis in the Code for Seismic Design of Subway Structures (DG/TJ08-2064-2009) and Code for Seismic Design of Urban Rail Transit Structures (GB50909-2014), this paper briefly introduces the principles, calculation processes of the codes, and the comparisons between them. Earthquake response analyses of a 2D subway station structure with two stories, double columns, and three spans are calculated by some methods:inertial force method, two response displacement methods (methods in national code and Shanghai code), and two dynamic time-history analysis methods with different assumptions (considering linear elasticity property and equivalent linearization of soil particles). The nonlinear dynamic characteristics of soil obtained using dynamic time-history analysis method are similar to those obtained using an equivalent linearization method. The maximum internal forces of structures with different methods are mainly compared. The applicabilities are summarized and evaluated as follows. The analyses show that compared with dynamic time-history analysis method, the inertial force method has more accurate column results and a bit larger shear force on the left side of the wall. Considering the response displacement method, there are some slight differences between the national code and Shanghai code, even if calculations are basically consistent. The results of response displacement method are mainly influenced by forced displacement, equivalent hypothetical spring in foundation, and the dynamic shear modulus of soil layers. For the dynamic time-history analysis method, the results of linear elastic assumption are close to and have the same trend as those of the equivalent linear one. Combining analysis processes with calculation errors, inertial force method is simple but inaccurate, because it is too simplified. The point of soil-structure interaction is well represented in the response displacement method. The above two methods are suitable for seismic response of simple underground structures. Although the dynamic time-history analysis method requires much calculations, it considers more comprehensive factors and has a wide range of applications.

Abstract:Control-structure interaction (CSI) often occurs between structures and active control systems. However, current research on controlling the linear-motor-driven active-mass-damper (AMD) wind-induced vibration in tower structures doesn't always fully consider the CSI effect, which leads to differences in the theoretical and actual control effects. To investigate the influence of the CSI effect on the control of a tower structure's wind-induced vibration, we first used the "electricity-power-movement" interaction model of an electromagnetically driven AMD system to establish a model of a linear-motor-driven AMD wind-induced vibration control system for tower structures that considers the CSI effect. Then, based on a tradeoff between computation efficiency and control accuracy, we adopted a model that considers a reduced-order CSI effect and uses the classical LQR control algorithm. We then performed a corresponding control analysis of the tower structure. Based on our results, we can conclude that the CSI effect plays an important role in controlling wind vibration in tower structures, and must be considered in the linear-motor-driven AMD wind-induced vibration control scheme to better align its results with those of actual projects. The results of this study provide a new consideration for future practical engineering applications.

Abstract:To study the cumulative plastic deformation characteristics of saturated silty soil under subway loads, the GDS cyclic triaxial testing system was used to test the saturated silty soil near the Guoquan Road, Shanghai Metro Line 10. The effects of vibration frequency and dynamic stress amplitude on the cumulative plastic strain were considered. The experimental results show that the cumulative plastic strain increases with the dynamic stress amplitude, and with the same dynamic stress amplitude, the cumulative plastic strain increases as the frequency decreases. By an analysis with the 2² factorial design method, it was found that the vibration frequency, the dynamic stress amplitude, and the interaction between the two have a significant effect on the cumulative plastic strain. Based on the theory of regression analysis, the nonlinear equation of cumulative plastic strain was established, which considers the vibration frequency, the dynamic stress amplitude, and the interaction between the two, and the equation was tested. The research results can provide a valuable theoretical basis for controlling the subsidence induced by subway operation.

Abstract:The dynamic behavior of filling fly ash in ash storage dams is critical for evaluating the dynamic stability of ash retention dams under seismic action. In order to investigate the dynamic deformation and strength characteristics of filling fly ash, the dynamic stress-strain relationship, dynamic strength, damping ratio, and dynamic pore pressure of two types of specimens, i.e., saturated sedimentary ash and flushing ash, were tested by a hydraulic control dynamic triaxial apparatus under conditions of anisotropic consolidation. Results showed that the backbone curves of specimens showed a strain-hardening tendency, which can be an approximate hyperbolic relationship. In addition, the increase in vibration cycles will cause a decrease in dynamic sample strength, and is mainly related to the decrease in the dynamic cohesion rather than the internal friction angle. In the double logarithmic axis, the damping ratio after dimensionless treatment showed a linear relationship with the dynamic shear modulus, but was not closely related to the confining pressure. Under differing confining pressures, the dynamic pore water pressure changed only in a narrow range with increasing vibration cycles. For convenience of calculation, the influence of confining pressure and vibration cycle on the dynamic pore pressure can be neglected. Accordingly, the Finn formula can be used to describe the dynamic pore water pressure of fly ash specimens under anisotropic consolidation.

Abstract:This research was conducted in urban Guangzhou within an area of 270 km².About 12 000 high-density boreholes were used to investigate the soft soil in the region.The distribution features of the soft soil were analyzed in detail according to different standards.The results are summarized as follows:(1) Soft soil deposits shallower than 6 m are distributed in about 80% of the study area, and the soft soil underlying in the north and the south of the study area are both deeper than that in the middle.(2) The thickness of soft soil is rather different in urban Guangzhou, which extends from less than 1.5 m to 13.5 m.Furthermore, the soft soil in the south and the west of the study area is thicker than that in the middle and the north.The soft soil near the river is thicker than that far away from the river.(3) It is predicted that seismic subsidence of soft soil during earthquake is possible in about a third of the study area, mainly in the west and the south of the study area.

Abstract:This paper applies the P-wave initial motion to invert the focal mechanisms of 293 earthquakes with M_L ≥ 2.0 in the Changdao area, Shandong Province. According to focal mechanism solutions, the stress tensor of Changdao was retrieved to calculate the spatial-temporal evolution of the focal mechanism consistency parameter of each node. We then analyzed the stress condition in the study area and the spatial-temporal characteristics of the consistency parameters. Our results showed that (1) The type of earthquake source was strike-slip type > normal faulting type > thrust faulting type, and we judged that the seismogenic fault stretches along the SE and exhibits nearly vertical strike-slip movement, which mainly showed horizontal motion. (2) The inversion showed that the azimuth and plunge of the principal compressive stress axis were 101.4° and 29.1°, respectively; 280.8° and 60.8°, respectively, for the middle compressive stress axis; and 11.3° and 0.3°, respectively, for the tensile stress axis. The stress tensor variance was 0.085. (3) There was a certain correlation between the time-space distribution of focal mechanism consistency parameters and the seismicity of moderate-strong earthquakes. Before the occurrence of a moderate-strong earthquake, the focal mechanism consistency parameters were relatively low, and the tectonic stress field near the earthquake source zones increased. In general, the focal mechanism consistency parameters of the study area exhibited low values in central part and high values on both edges, and all M_L ≥ 4.0 earthquakes occurred in areas with extremely low values and in the transitional areas from high values to low values.

Abstract:We first establish two kinematic models of the Bayan Har block and inverse the slip rate of the boundary faults using a block model and GPS data. Model I includes the west segment of the East Kunlun fault and its surrounding areas, while Model Ⅱ does not include this region. The inversion results show that model Ⅱ is more consistent with the reported survey results. The differences between the two models are as follows:(1) In model Ⅱ, the extension rate is higher and strike slip rate is smaller on the southwestern section of the Altyn Tagh fault; this observation is more consistent with the regional characteristics of the area. (2) In model Ⅱ, the sinistral slip rate of the middle part of the East Kunlun fault is about 8 mm/a, which is closer to the reported results of about 10 mm/a. The slip rate is about 7 mm/a in model I. (3) Model I has a larger strike slip rate on the western segment of the East Kunlun fault; this result is not in agreement with the low seismicity and focal mechanism observed in the area. However, in model Ⅱ, the Maergaichaka fault has a high sinistral slip rate, which may be caused by the small slip rate on the Fenghuoshan fault. Hence, we omit the Fenghuoshan fault to obtain a simplified model Ⅱ and refer to it as model Ⅲ. The inversion results for model Ⅲ are more consistent with the reported results. It is known that the middle section of the East Kunlun fault and the Maergaichaka fault are not connected, but the two faults are continuous with regard to the transfer of the crustal material with the corresponding slip rates. Owing to the low slip rate of the Fenghuoshan fault on the southern boundary of the Bayan Har block, we believe that the weak material in the lower crust may have entered to part of the Bayan Har block.

Abstract:To solve some problems in the layout of seismic underground fluid monitoring network in China based on the seismogenic mode of hard body, we take the northern margin fault zone of West Qinling as the study area. Through the detection of high-density underground fluid background value as well as the characteristics of vertical crustal deformation and seismicity, we aim to obtain the relationship of fluid, deformation, and seismic activities in the regional active faults to comprehensively analyze the segmental characteristics of the fault zone. The results show that there is a good correspondence and relationship between fault deformation, seismic activity, and underground fluid activity. The seismic source areas always exhibit characteristics of fault blocking, and the seismogenic sites all show a relatively calm state. Based on the above research, we propose a mobile monitoring scheme of fault gas with a physical prediction mechanism and establish a prototype for the observation network in the northern margin fault zone of West Qinling. This study can provide technical ideas for the layout of fluid flow monitoring network in seismic risk areas of China in the future and provide an important basis for earthquake prediction, earthquake tracking, and earthquake prevention and disaster reduction in China.

Abstract:In this era of globalization, the continuous increase in the frequency of major natural disasters seriously threatens production and lives. Although the frequency of earthquakes, which are major natural disasters, is relatively low, earthquakes result in great economic losses and casualties; hence, it is very important to practically and theoretically forecast earthquake tendencies. In this paper, ternary, quaternary, and pentanary commensurability calculations are used to predict the intensity of seismic signals of M_W ≥ 6.0 earthquakes in Venezuela and surrounding areas for approximately 30 years, and then the butterfly structure diagram and commensurability structure are used to strengthen the time symmetry analysis. Based on the laws of longitudinal and latitudinal migration and space migration of seismic sources, the relationship between the earthquake and the acceleration of the earth rotation is creatively analyzed. It is concluded that (1) in the study area, the strongest signal of M_W ≥ 6.0 earthquakes is in 2018, and relatively strong signals are in 2017 and 2019; (2) M_W ≥ 6.0 earthquakes are likely to occur in 10°-11°N and 63°-65°W; (3) the M_W ≥ 6.0 earthquakes in Venezuela and its surrounding areas have a close relationship with changes in the earth rotation speed. This research can serve as a reference for analyses of earthquakes tendency forecast and provide some insights for future research.

Abstract:The quality of observation data recorded by fixed stations and the reflecting earthquake ability of stations have a significant influence in seismic situation analysis and medium-short term earthquake prediction. Considering this, based on the observation data recorded by the deformation stations of Hebei Province since 2008 (after the network reconstruction of the tenth "Five Year Plan"), the tidal factors are calculated and the reflecting earthquake ability of the stations are analyzed in the study. Through the analysis and summary, deformation stations and observation items with good quality are obtained, which are highly useful in studying the earthquake situation in Hebei Province.

Abstract:Predicting strong aftershocks with Coriolis force is a method of seismic source physics and it was put forward by GUO Zengjian in 1992.This paper reviews the process of predicting the largest aftershock of 2008 Wenchuan M_S8.0 earthquake by using this method.We concluded that the largest aftershock might be M_S 6.5 by qualitative and synthetical judgment.The actual situation is that the largest aftershock is M_S 6.4,and the magnitude difference between the main shock and the largest aftershock is bigger than 1.The verification results further illustrate the scientificity of the method and add an effective example for the Coriolis force effect.

Abstract:The Ludian M_S6.5 earthquake on August third,2014,caused heavy casualties and property losses and induced a large number of landslides,collapses,and secondary geological disasters.Based on a geological disaster survey of Longtoushan map (G48E006006) in Ludian County and analysis of typical geological disasters,development laws and distribution characteristics of geological hazards after the earthquake are revealed in this paper:(1) Most of the geological disasters before the earthquake are mainly medium and small shallow landslides and collapses.After the earthquake,large and extra-large landslides and collapses were induced,such as Ganjiazhai and Hongshiyan,and a large number of valley deposits were formed; (2) The distribution of geological disasters is concentrated in high-intensity areas of epicentral region,especially in Longtoushan town and intensively developed along the NNE-NE trending seismogenic fault zone, the geological disasters develop most intensively in epicentral area; (3) The geological disasters show a zonal distribution feature,obviously controlled by linear geomorphic units and linear engineering,such as river systems (Niulan River,Shaba River,and Longquan River) and highways (Zhaoqiao road and Shale road), and the impact of human activity is striking.

Abstract:Wenchuan earthquakes have triggered a large number of geological disasters in Gansu Province, such as structural collapse and landslides. Based on studies of the distribution characteristics of earthquake-induced landslides during Wenchuan earthquake, we used a GIS-based weighted information model to evaluate the seismic landslides' risk in Wudu District and Wenxian County, Gansu Province. Results showed that:lithology types have a certain control effect on the distribution of seismic landslides, and most of the seismic landslides in the study area distribute and develop in both the extremely and relatively slide-prone strata, with a slope of 20°~50° and elevation of 1 000~2 000 m. With increasing seismic intensity, the density of seismic landslide disasters increases; about 70% of the landslides develop in the range of 10 km from the fault-fractured zone. Statistical analysis of the relationship between the risk classification results in the study area and the number and density of landslides showed that the evaluation results are highly accurate. In the elevated area, extremely dangerous areas are mainly distributed across catchment zones with strong surface runoff and frequent human engineering activity. In addition, the route of national highway G215 being along the extreme danger zone is obvious, so attention should be paid to the possibility of collapse and landslides in these areas. The high-risk area spreads along the extremely high-prone area, located on both sides of major rivers such as the Baishui and Bailong. Light risk and extremely light risk areas are relatively small, mainly distributed across high altitude areas with low intensity, poorly developed active faults, and weak human activity. Statistical analysis showed a total of about 780 thousand people in the study area potentially affected by the landslide hazard.

Abstract:Traditional methods for evaluating reconstruction costs in post-earthquake disaster areas have proven insufficient. Therefore, a technique for the rapid evaluation of such costs, based on gray dynamic prediction, is proposed, which is suitable for application in earthquake disaster areas. The cost of building construction was judged by the weighted average index method, and the autoregressive moving model was constructed to prevent the influence of abnormal factors in the construction cost assessment. Labor costs and the use fee for mechanical equipment and material were analyzed, and the project cost index was calculated. Project cost indices were calculated. Based on the calculated results, the gray dynamic prediction map was drawn to realize the rapid evaluation of construction costs in post-earthquake disaster areas. The experimental results showed that the improved evaluation technique can be used to evaluate the cost of post-earthquake reconstruction in a short period of time. The technique is shown to provide the advantages of low evaluation error.

Abstract:The traditional water resources information management model based on GIS adopts GIS network technology to optimize the allocation of water resources. However, the problem exists of poor information management of polluted water resources caused by earthquake damage, since the model can't produce a comprehensive plan for water resource networks in earthquake-prone areas. An information management model considering pollution of regional water resources from earthquake damage has been designed. The model includes modules for information planning and design of polluted water resources, information monitoring and acquisition of polluted water resources, and management of polluted water resource information. The information planning and design module of polluted water resources was used to optimize the water quality monitoring points of polluted water resource networks after earthquake damage. The monitoring and acquisition module based on the Geodatabase data model was used to monitor and collect polluted water resources after earthquake damage. The information management module included the main and supporting modules, which could realize the comprehensive management of pollution information of regional water resources through different management functions. The experimental results showed that by using the proposed model, the average time of management of regional water resource information after earthquake damage was 1.38 s, and the score of each function of the model in the process of information management was higher than 93.5 points, with high management performance.

Abstract:When the traditional GIS spatial analysis model is used to plan an urban earthquake evacuation scheme, the equivalent length of the evacuation path is not taken into account, and the evacuation efficiency of the obtained model is relatively low. Therefore, a new optimal evacuation model for urban earthquake disaster mitigation and relief has been designed. The equivalent length of the evacuation path was obtained by using the difficulty coefficient of passage, interfe-rence coefficient of secondary disaster, coefficient of bridge obstruction, and minimum equivalent length of evacuation path, all of which were obtained by objective function. Simultaneously, the new model accounted for the capacity requirement of the shelter, the emptying of personnel from the shelter, and the evacuation distance being less than the radius of service of the shelter. The experimental results showed that the new optimal model can give an accurate evacuation path and scheme, and efficiently accomplish the evacuation task of urban earthquake disaster mitigation and relief.

Abstract:The current large-scale monitoring systems of earthquake-prone regions use wired networks to transmit data to manual maneuvers, which leads to problems such as low accuracy of seismic real-time monitoring information and poor system stability. Therefore, we designed a large-scale seismic area monitoring system based on the "Internet of Things", which uses ZigBee technology to communicate. Based on Visual Basic.NET, we designed the system architecture to achieve integrated dispatching and centralized command. In the system, the intelligent earthquake disaster relief control center adopts the server to realize data storage and intelligent operation, so as to realize precise and efficient detection and work guidance in the seismic detection area. Through data acquisition and exchange and an emergency dispatching platform, the real-time monitoring of earthquakes and the use of equipment were monitored. The earthquake disaster data collection and analysis software was applied to conduct comprehensive and accurate analysis of seismic area monitoring data in the "Internet of Things". The system adopted multi-source information fusion technology to comprehensively process the earthquake relief information from multiple perspectives. The experimental results showed that the calculated results of the designed system have low power consumption and high accuracy and stability.

Abstract:Due to the uncertainty of earthquake disasters, the operating rate and efficiency of emergency rescue equipment are affected. Therefore, it is necessary to carry out parallel optimization processing. In this paper, a design optimization method for earthquake disaster emergency rescue equipment, based on two-way parallel computing, is proposed. Based on an evaluation of disaster levels in earthquake disaster areas, the relationship between earthquake magnitude and emergency rescue equipment were standardized and transformed into the problem of solving the optimal solution. Accounting for uncertainty in earthquake disaster scenes, the emergency rescue equipment for earthquake disaster was optimized by two-way parallel processing between communication time and rescue equipment requirements. The experimental results showed that the improved method can be used to accurately predict the demand of emergency rescue equipment for earthquake disasters, improve the running rate of emergency rescue equipment, shorten the communication time, and improve the efficiency of use of emergency rescue equipment.

Abstract:As important indexes for investigating soil dynamic characteristics, the dynamic parameters of soil play a significant role in seismic calculations. Using the GCTS resonant column device, resonant column experiments were carried out on silt, clay, silty clay, and silty sand. A comparative study was conducted on the modulus ratio expression of the hyperbolic model using a linear fitting method and improved nonlinear fitting method. The results show that the curves fitted by the nonlinear fitting method are closer to the original data points than the curves fitted by linear fitting method. In the low strain soil, the nonlinear fitting residual is less than the linear fitting residual, and with an increase of strain, the nonlinear fitting residual gets closer to linear fitting residual. In the large strain soil, the linear fitting residual is less than the nonlinear fitting residual. The standard error and confidence interval width of the maximum dynamic shear modulus Gdmax and reference shear strain γ_r, which was calculated by the nonlinear fitting method, are both smaller than the results calculated by the linear fitting method. The improved nonlinear fitting method has a higher accuracy, stability, and application value than the linear fitting method.

Abstract:In the short-term earthquake prediction method, the geomagnetic low-point displacement method and the rhythm of multiplied nine days after a magnetic storm are proposed by Chinese earthquake scientists. The two methods have been verified for decades, but it is still difficult to use them to accurately predict the earthquake. In view of this, our suggestion is to use the low-point displacement method as the main prediction scheme, and the rhythm of multiplied nine days after a magnetic storm as the second and supplementary prediction scheme. We combine the two methods together to predict the occurrence time of a strong earthquake. It is hoped that more data can be collected to improve the accuracy of the method in the field of short-term earthquake prediction.