Abstract:Dynamic triaxial compression tests are conducted to study the effects of corrosive media and dynamic loads on the mechanical properties of cement soil. The experimental parameters of dynamic stress are obtained, and the effects of the dynamic strength of the cement soil are analyzed in different environments. Results show a gradual increase in the dynamic strength of the cement soil with an increase in the concentration of sodium sulfate corrosion solution when it is less than 0.03 mol/L. However, when the concentration is greater than 0.03 mol/L, there is a gradual decrease in the dynamic strength of the cement soil. In addition, there is a gradual decrease in the dynamic strength of cement soil with an increase in the concentration of sodium chloride solution. Furthermore, there is a gradual increase in the dynamic strength of cement soil in 0.03 mol/L of sodium sulfate solution with an extension of corrosion time. Results show the following: when the concentration of sodium sulfate solution is between 0.1~0.3 mol/L, there is a gradual decrease in the dynamic strength of the cement soil. Moreover, when the cemented content is at a greater ratio, the stronger dynamic strength of cement soil is greater. Furthermore, when the confining pressure is greater, the dynamic strength of cement soil is stronger. In addition, when the solution concentration is less than 0.03 mol/L, the dynamic strength of cement soil is enhanced in a sodium sulfate environment, but when it is greater than 0.03 mol/L, the cement soil is corroded and damaged within the same environment and the corrosion effect is greater than that of the sodium chloride solution.

Abstract:To investigate the effect of freeze thaw action on the seismic behavior of masonry structures,in this study,we investigated the responses of four pieces of brick walls with a constructional column,all having the same properties.We conducted freeze thaw action experiments and low cyclic loading experiments for freeze thaw cycles numbering 0,40,80,and 120.By observation and analysis of the failure modes and mechanical properties of the brick walls with a constructional column,we obtained the performance degradation characteristics associated with an increase in the number of freeze thaw cycles in brick walls.The results show that the failure modes of brick walls under freeze thaw action differ from those that remain intact.With an increase in the number of freeze thaw cycles,cracks appeared earlier and developed more quickly,and the specimens were damaged more seriously.The bearing capacity,stiffness,and ductility of the specimens also decreased significantly and their dissipation capability decreased with an increase in the number of cycles.To gain a more in-depth understanding of the effect of freeze thaw cycles on brick walls,in this paper,we analyze the damage mechanism of the brick wall from both the microcosmic and macroscopic perspectives.The main microcosmic factor influencing the walls is the hydrostatic pressure result from freezing,and the main macroscopic factors are the efflorescence phenomenon and the interface damage caused by freezing.

Abstract:In this study, we used ABAQUS software to calculate the seismic response of a twin-bore tunnel in a saturated soil deposit. To simulate the saturated soil deposit, we employed a pore pressure element based on a fluid-solid coupling dynamic model for fluid-saturated porous media, and we input earthquake motion into the calculation model by a visco-elastic artificial boundary. Our numerical results show that at the end of the seismic response the displacement amplitudes of the soil between the two tunnels and near the tunnels is relatively large, while that far away from the tunnels is small. In addition, at the end of the seismic response, the pore pressure amplitude of the soil deposit at the bottom area of the site is relatively large, while that at the top is small. The stress of the tunnel lining at both tunnel arch waists is relatively large, while that in the tunnel vault is small. With respect to the study of the seismic response of tunnels in saturated soil deposits, we verified the applicability of the pore pressure element based on a fluid-solid coupling dynamic model for fluid-saturated porous media.

Abstract:A three-dimensional finite element model was established for a shaking table test of dynamic pile group-soil interaction. Governing equations of u-p formulation were used to describe the dynamic properties of saturated sand. We choose a plastic multi-yield surface constitutive model to describe the dynamic properties of saturated sand, and a nonlinear beam-column element was used to simulate the pile in this model. The results of the test verify the validity and effectiveness of the numerical model. In an experiment using a 2×2 pile group, a three-dimensional nonlinear finite element model of soil-pile-bridge structure interaction was established. Based on this 2×2 pile group model, with a 2 piles in row pile group model (2PR) and a 2 piles in parallel pile group model (2PP), a 3×3 pile group model (with a 3PR pile group model and a 3PP pile group model) have been expended. Based on different configurations of pile group foundations, an analysis of soil-pile group interaction in liquefied ground was made. When using the same number of piles and a pile array direction parallel to the direction of seismic wave, stress is reduced by 5%~10%. However, there are few obvious effects on site liquefaction conditions. Under the same parallel array of piles, in comparison to the two-pile model, the three-pile model ground-liquefaction time results in delays of 5 s, and pile bending moment and shear force decreases 33%~38%. With an increase in the number of piles, the ground-liquefaction time is delayed, and the stress of pile body decreases. The results of this study will be of significant use for bridge engineering design.

Abstract:To research the dynamic characteristics and vibration mechanism of low-story masonry structures in rural buildings, we used ABAQUS to establish seven finite element models based on a survey of rural buildings. In the models, we considered structure layout, strength of the materials, and mesh density. Then, we analyzed the dynamic characteristics of each model and compared their vibration shapes, modal components, and vibration periods. The results show that the vibration characteristics of traditional masonry structures are not conducive to seismic design and that the degradation of materials reduces the bearing capacity of the structures, while at the same time amplifying the seismic action of the wall oscillation component, which increases the probability of outward collapse in earthquake. If the basic vibration type is horizontal along the transverse direction, the seismic capacity of the structure is improved with respect to both the bearing and deformation abilities of load-bearing walls. In addition, we propose ABAQUS mesh requirements for shell elements with respect to thickness.

Abstract:Rock embedded excavated foundations are widely used in power engineering. As undisturbed soil may be characterized by slight disturbance, strong cementation, and good shear strength, undisturbed soil can have an important influence on the uplift bearing capacity of an excavated foundation. Therefore, it is of great significance to study the influence of changes in undisturbed soil parameters on the uplift bearing capacity of excavated foundation. This study carried out an in situ test on a foundation in Anhui Province, China. The numerical model was built using FLAC^3D software, and Q-S curves were obtained. In addition, the foundation underwent direct shear and consolidation tests. Model parameters were based on the results of the in situ test. The simulation results and experimental results were fitted well, so the model can be considered as a reasonable model. Within the model, the single factor method was used to adjust the internal friction angle, cohesion, and the elastic modulus of the soil. This study demonstrates that the uplift bearing capacity increases as both the internal friction angle and the cohesion of soil increase, but shows only a small increase in uplift bearing capacity with increases in elastic modulus. With increasing soil cohesion, internal friction angle, and elastic modulus, there appears to be no difference in the change of foundation soil plastic zone.

Abstract:This paper presents a comparative evaluation of elastic and viscoelastic solutions to identify more suitable and practical engineering solutions. Based on the viscoelastic solutions of a Kelvin's space half-infinite body, as an example, we analyzed the dynamic stress response under moving subway loads to illustrate the characteristics of dynamic stress, the stress path, and the principal stress axis rotations. By applying two solutions, we found the numerical results for the development trends of the dynamic stress state and principal stress axis rotation to be similar. We also found discrepancies in the dynamic stress of the ultimate state and stress path. Additionally, our results indicate that a viscoelastic solution is more applicable to actual working cases of long-term metro tunnel deformation in soft soil areas. Moreover, according to our analysis of viscoelastic solutions of dynamic stress characteristics under single-wheel loads, we found different feature coefficients to have different influences on stress characteristics.

Abstract:This study examines the dynamic response characteristics of surface waves mainly comprising Rayleigh waves in surface soils under impact and seismic loads. Moreover, the study analyzes, through numerical simulation, the settling methods of soil layer damping. The research area for this study is the shallow plain fill and silty clay of the Xiamen area. The model was generated using finite element dynamic analysis, with a hardening small strain model (HSS) for soil constitutive. The hysteresis characteristics of the model allowed the input of different small strain parameters to study the influence of HSS model's small strain parameters on site dynamic response. Results were then compared with the combined Mohr-Coulomb (MC) model and Rayleigh damping model (MC+Rayleigh damping). The study shows that when using HSS model with hysteresis, the wave speed increases with increases in the initial shear modulus; however, amplitude and residual deformation decline. While the HSS model can reach the residual deformation value, "MC+Rayleigh damping" cannot. This reflects the accumulation of plastic strain and the damping effect during the process of unloading and reloading as the constitutive model is an ideal elastic-plastic model that demonstrates pure elastic behavior under the conditions of unloading and reloading. However, as the HSS model cannot fully reflect the accumulation of plastic volume strain under the effect of reloading and taking hysteresis damping into consideration, the use of the Rayleigh damping model is advised to allow full simulation of the real damping characteristics of the soil.

Abstract:This study analyzes differences in macro-deformation between saturated intact loess and saturated remolded loess under the same stress state from the perspective of micro-pore distribution. Moreover, the study analyzes differences in the micro-pore size distribution between saturated intact loess and saturated remolded loess in a similar void ratio. Mercury intrusion tests are conducted on saturated intact and remolded loess in Cuishi village, Jingyang county, after one-dimensional and isotropic compression under the state of same stress and a similar void ratio. Results show that (1) The pore distribution of Jingyang intact loess has three peaks while that of remolded loess has two peaks. Moreover, there are differences in the highest peak changes in the remolded loess as compared with that of the intact loess. (2) Under the same stress state, the volume of intra-particle pores is similar in both loess samples but that of the interparticle pores is different. With an increase in stress, the volume of interparticle pores of both specimens becomes more similar, and differences in the macro-deformation are reflected in the differences between the interparticle pores. (3) Under a similar void ratio state, the pore distribution of the two loess samples are similar, but their stress paths are considerably different.

Abstract:Under seismic loads, some phenomena will occur in free field, including lateral deformation of soil and ground response amplification. When evaluating the seismic response of free field, it is the highly nonlinear characteristics of soil that significantly influences the results obtained when utilizing differing damping ratio and shear modulus values and is one of the reasons that experimental results and calculated results can largely differ. Currently, the Rayleigh damping method is most commonly used for site seismic dynamic response analysis. Based on a simplified version of this method, this study analyzes the influence of different values of soil damping ratio and control frequency on calculated results. Using the finite element platform OpenSees, we have adopted the PDMY constitutive model fitted for soil dynamic analysis and established a one-dimensional shear beam model to simulate the three-dimensional free field. Compared with centrifuge model test results, this study analyzed the effects of the Rayleigh damping on the site response and lateral deformation of free field. In the case of Nevada dry sand (relative density 60%), there is good agreement between the calculated results and the test results when the damping ratio and control frequency ratio are set as 4% and 5%, respectively. Our comprehensive analysis suggests that special attention should be paid to value selection of Rayleigh damping in the time domain calculations of site nonlinear response.

Abstract:During seismicity, seismic acceleration first increases then decreases. Using a pseudo-static method and considering the acceleration change during earthquakes, sliding and toppling failure modes were calculated for the unstable rock on Tianlong mountain, Taiyuan city, Shanxi province. We found that the failure mode transformed from sliding to toppling under seismic action. Extending this problem to a general situation, we conclude that: the contribution of seismic forces to unstable rock damage differs and the overturning moment is relatively larger than the sliding force; for stability evaluation, the seismic action process must be considered, and the failure mode of unstable rock whose safety factor first reaches 1.0 should be used to calculate the possible mode; to ensure the stability of unstable rock of different risk states under seismic action, the seismic strengthening design should consider different possible failure modes.

Abstract:A series of tests are performed to explore the post-liquefaction deformation characteristics of saturated loess in the Shibeiyuan tableland area. In addition, we compare the stress-strain curves of liquefied loess with those of non-liquefied ones under monotonic static load using the MTS810 dynamic triaxial testing apparatus. We also discuss the influence of drying density and initial effective confining pressure on the post-liquefaction deformation characteristics of loess. The experimental results show that the ventilation period and water period greatly influence the pore pressure coefficient (B value). The saturated loess in the Shibeiyuan tableland has obvious liquefaction characteristics; it is easily liquefied under strong earthquakes, and its strength is greatly decreased after liquefaction. The stress-strain curve of saturated loess after liquefaction under monotonic static loads changes into the weak hardening type in two stages: strength recovery and stable strength. The drying density and initial effective confining pressure have a certain effect on the strength of liquefied loess. There is a linear positive relationship with good fitting between the initial effective confining pressure and undrained strength after liquefaction.

Abstract:In the seismic design and analysis of underground structures, in order to select the appropriate boundary conditions and earthquake input types, we conduct simulation experiments on an underground semi-infinite body model, which is vertically incident by a shear wave. The main results are as follows: (1) Considering three viscoelastic artificial boundaries (two lateral boundaries and the bottom boundary) and using stress as the seismic motion input, the model can not only simulate the absorption of the scattered waves but also the elastic recovery of the semi-infinite foundation. However, these model conditions are unrealistic with regard to the equivalent nodal loads on both the two lateral boundaries and the bottom boundary. (2) If the two lateral boundaries are viscoelastic artificial boundaries, the bottom boundary is fixed, and the acceleration time history is used as the seismic motion input, the displacements and stresses are overestimated by the model. In addition, the model cannot simulate the propagation effect of the wave in the medium. If we use the displacement time history as the seismic motion input, although the propagation effect of the wave can be simulated in the medium, the displacements and stresses are underestimated and the reflection wave can only be completely absorbed after several shocks. (3) If the bottom boundary is a viscoelastic artificial boundary and the two lateral boundaries are vertical displacement constraint boundaries, exerting nodal loads on the bottom boundary can be obtained with great accuracy. Moreover, the model is simple to use in ANSYS by APDL programming because only the equivalent nodal loads on the bottom boundary must be input. Therefore, it is a simple method for determining viscoelastic artificial boundaries in the anti-seismic analysis of underground engineering.

Abstract:Ground motion characteristics are seriously influenced by local site conditions, and in recent years, one of the hot spots in the field of earthquake engineering has been the impact of a hard site interlayer on ground motion characteristics. This paper selects the thickness, shear-wave velocity, density, and other actual exploration data from borehole A3 in a certain project site by changing the buried depth of the hard interlayer to analyze the influence of depth and different seismic time history data on ground motion parameters. In this paper, a one-dimensional seismic response analysis of a typical site with a hard interlayer was conducted by using the time domain nonlinear method. Research has shown that when the thickness of the hard interlayer and the total thickness of the model remain invariable, the surface horizontal peak-ground acceleration increased with the buried depth of the hard interlayer, but its amplification reduced gradually, until it was no longer affected when the hard interlayer's buried depth reached a certain value. Furthermore, as the buried depth increased, the values of the response spectrum generally increased. From the surface Fourier spectrum diagram, we found the spectrum values were small and flat in the range of 0~0.2 Hz, and then increased gradually to a range of 0.2~1 Hz. Spectrum values peaked and then reduced again in the range of 1~1.5 Hz. Spectrum values hit the second peak in the range of 1.5~5 Hz, and then dropped down after 5 Hz. For the Fourier spectrum at different buried depths, spectrum values didn't change much in the range of 0~1 Hz. These results will provide an important reference for the seismic design of deep foundation pit engineering such as nuclear power station and underground engineering.

Abstract:Nowadays in China, with increases in the lengths of new highways and the resultant increasing construction times, many personal injuries have occurred as a result of the structural defects such as track-plate fracture, through-cracks, layer alienation gap, and pulping. Investigating the damages of highway structures is an important and difficult subject, especially for defect diagnosis in a structure's support plate and subgrade surface layer. As various current subgrade defect detection methods are limited and ineffective, how to detect faults quickly and accurately is an important issue in civil engineering. In light of the permanent stability of the subgrade of an operational highway, a full-wave field imaging method was developed to detect defects in a highway subgrade. This detection method was a non-destructive testing method based on the characteristics of high-speed highway structures and the existing level of detects. The detection system was composed of a data acquisition system and an imaging system. The data acquisition system utilized a single-point source and a single receiver, in which three-dimensional full-waveforms were created, received, and recorded. First, to evaluate the feasibility of the method to reveal defects, a 3D numerical simulation by a finite-element dynamic method was adopted based on the theory of elastic wave propagation. Using a 3D numerical model, the characteristics of a full-wave field within some defects were studied, then the amplitude and frequency spectrum of the multi-directional response waveforms were analyzed. Based on the synthetic image, the defects were revealed and their locations and sizes agreed well with those of the numerical model. Second, a real full-scale highway subgrade model with pre-setting defects was casted, and relative tests were carried out on it. The size and location of defects revealed by the field experiments were similar to that of the actual model. The accuracy of the full-wave field imaging method proved to meet the detection requirements, such as easy maneuverability and rapid speed of detection. It is concluded that the full-wave field imaging method has high potential in providing quick and effective detection of defects in highway subgrades.

Abstract:As the boundary of the Qilian Mountain and Jiuxi Basin, the Yumen-Beidahe fault is located along the western part of the southern margin of the Hexi Corridor, and is an important part of the north Qilian Mountain fault system. The Yumen-Beidahe fault extends from Qingcaowan in the west in an ESE trending for 80 km to near Gutouquan. Considering its geometric structure and active behavior, the fault can be divided into three segments. The eastern segment, whose length is about 20 km, is located on the two sides of Beidahe and about 2 km from the Qilian Mountain. This fault segment is preserved in the form of continuous fault scarp, whose height ranges from less than 1 m to 7 m. At the most recent alluvial fan, some fault scarps still retain a fresh free surface, which suggests that the segment is an earthquake rupture zone. The structure of the middle segment is complex and mainly exhibits thrust characteristics. Its length is about 20 km and it comprises six discrete faults. The topography is expressed as a fault triangle and a fault scarp of different heights. The fault section suggests that the latest earthquake event occurred about 5 000 years ago. The western segment, whose length is about 40 km, does not appear on the ground and becomes a blind thrust-fold belt. Some rivers, such as the Shiyou and Baiyang Rivers, cross over this blind thrust-fold belt. The terraces of these rivers have been described as fold deformation in previous work. This fault segment is also the seismogenic structure of the 2002 Yumen M_S5.9 earthquake. Based on previous data and field surveys, we believe the Yumen-Beidahe fault to be an active thrust fault in the Holocene, and there is no geological or geomorphic evidence of any left-lateral slip along the fault. According to a differential GPS survey of the fault scarps and geomorphic surface dating, we infer the average thrust rate of the Yumen-Beidahe fault since the late Pleistocene to be about (0.73±0.09) mm/a.

Abstract:In this study, we took the northern margin fault zone of West Qinling as the study area, which has many hot-spring dew points and severe deformations. We established the fault soil gas profile overlap and conducted field measurement in the cross-fault deformation area to determine the coupling relationship between fault gas segmental characteristics, fault deformation, and seismic activity. We used a variety of methods to evaluate their usefulness in fault earthquake hazard analysis. The results show that there is a good correlation between the geochemical features of soil gas and the distribution of fault deformation characteristics. The comparison results indicate that fault activity is relatively more active in the Wushan segment than in the Weiyuan-Zhangxian segment, and that the Tianshui segment is relatively locked. In addition, due to the active influence of fluid activity, most of the shocks in the Wushan and Gangu strike-slip pull-apart partitions generate medium to small earthquakes. In contrast, strong earthquakes are likely in the west of the Tianshui and Zhangxian segment, and in the Panguchuan region, as the fluid activity and strain rate are weak in these areas. These results can contribute to a theoretical basis for developing a fault gas flow observation network layout with the potential for physical prediction.

Abstract:The Dagu River fault is a large buried fault in Qingdao area, which extends from the north to the south along the Dagu River. There have been no previous studies that cautiously focused on this fault. As there is no adequate analysis data, researchers are unable to ensure the fault distribution and attitude. In addition, they cannot ensure the fault activity. In this study, we first arranged several geophysical exploration lines based on the geological map. Then, according to the geophysical exploration, we selected three abnormal sites to drill several holes and subsequently developed three combined geological profiles with respect to stratum. On the basis of the geological map, three abnormal sites, and combined geological profiles, we found where the fault passes through. We selected four soil samples from the stratum to test their chronology. Research shows that the Dagu River fault passes through the three abnormal sites because the stratum changed in different holes. We virtually make sure the fault's trend and distribution. Chronology test report shows that the age of the Dagu River fault is early Pleistocene or early mid-Pleistocene, but it is not an active fault. According to statistical regularity, the Dagu River fault will not initiate any destructive earthquakes or rupture the earth's surface. Therefore, large-scale projects should not be away from the fault. As numerous large-scale projects will be initiated in Qingdao area, conducting this study is essential in actual projects.

Abstract:The northern margin fault of Qiamantag is located between the Qaidam basin and the Kunlun orogen. Its active features are responses to the Tibetan Plateau uplift, which we examine in this paper to better understand the Tibetan Plateau's tectonic evolution. To date, the northern margin fault of Qimantag has been little understood, including its active style and slip rate, which are important parameters in an active fault. To address this knowledge gap and to accurately determine the Qimantag fault's slip rate, we used methods related to active tectonics and tectonics geomorphology. We traced fault lines based on satellite imagery interpretation and field surveys, and found the fault scarp to be discontinuous along the strike. In this paper, we examine in detail three sites from the west to the east of this segment. Our results show that the fault widely ruptured young alluvial fans in the field to form 1.5~2.5 m high scarps in the west segment. The slopes of these scarps have angles of ~30°. Due to the lack of dateable depositions in the study area, we took no geochronological samples to date the age of the alluvial fans. However, we used a diffusion equation to constrain the age of the faulted scarps. Based on our calculations, the scarp is about 1 000~15 000 years old at the Q1 site, with a height of about 2.5 m. Based on the age and height of the scarps, we calculated their uplift rate to be about (2.0±0.5) mm/a. This value is similar to the results obtained from river incision and geodetic leveling. Based on our results, we consider the uplift rate to be 1~2 mm/a. In addition, we also established elevation longitudinal profiles and the hypsometric integrals along the Qimantag Mountain. These profiles and HI values indicate that the mountain is experiencing tectonic uplift.

Abstract:In this study, we investigated the medium-wave infrared anomaly characteristics prior to the occurrence of strong earthquakes. We use wavelet transformation and relative power spectrum estimation methods to analyze medium-wave infrared data from an FY stationary meteorological satellite prior to the occurrence of six strong earthquakes with magnitudes of 6.5~7.0. The results show that obvious medium-wave infrared anomalies occurred within three months of the six strong earthquakes. In addition, the relative power spectrum value greatly deviated from the annual average and standard deviation in a 50~105 day period. The anomalies of the Xinyuan-Hejing and Lushan earthquakes appeared in a brief period prior to the two earthquakes and continued until they had stopped. In the brief period before the earthquakes, the power spectrum anomaly values increased by a factor of more than eight. The main evolution and peak of the anomalies of the remaining four earthquakes all appeared prior to the earthquakes and their power spectrum anomaly values also increased by a factor of more than eight. The corresponding areas where the anomaly values reached their peaks ranged from several thousands to tens of thousands of square kilometers, and the corresponding periods ranged from 11 to 32 days. The relative power spectrum value deviates from the annual average and standard deviation and the period of deviation is more than 50 days. All these characteristics can be easily recognized and used to expediently predict earthquakes. Moreover, the use of high-resolution medium-wave infrared data from key earthquake hazardous areas can provide a reference for seismic prediction.

Abstract:In this study, the research status and practical application of frequently used green building materials were surveyed, in addition to a brief analysis of existing problems in the current study. The potential negative effects of existing green building materials were discussed and developing trends in green building materials were forecast. We conclude, in the future development of green building materials, attention should be given across the complete suite of materials used in order to give full play to the advantages of various materials and to make up for any defects in a single material; attention should also be paid to the use of recycled materials to avoid secondary pollution caused by the material substitution; research and development of new materials and new technologies should be encouraged to improve the defects and deficiencies of existing materials used in green buildings.

Abstract:The "frequency hopping" phenomenon often occurs when using the wavelet packet transform to process non-stationary seismic signals. To solve this problem, we examine the relationship between the order number of the wavelet packet tree bands and the order number of the nodes, based on the wavelet packet transform and exclusive or (XOR) operation algorithm. We clarify the arrangement rule between the frequency bands of the signal subspace and the tree nodes of the wavelet packet. Moreover, we propose a conversion algorithm for seismic signals from the order number of the nodes to that of the frequency bands. Based on the MATLAB platform, we use the Tangshan wave (NS direction) as an example and verify the correctness of the algorithm.

Abstract:This paper introduces the basic principles and system structure of a TJ-II borehole strain meter, the common causes of instrument failure, and maintenance methods and procedures. At present, in China, more than 100 sets of TJ-II borehole strain meters are in use. Failure cannot be avoided during operation, resulting in a reduction in the continuous gathering and accuracy of observation data, which eventually affects its quality. Carefully maintenance and timely repair of the instruments can effectively improve the quality of deformation observation data. For daily maintenance and timely repairs, station staff are required not only to have basic maintenance skills, but also to understand the measurement principles of the system, composition and structure of the equipment, measurement process, and output data, enabling them to make rational analysis and timely detection of any interference source. A underground probe, ground host computer, switch, broadband communication, computer, etc., constitute the observation system. The main components of the system are integrated, so any link failures affect the entire system resulting in the loss of seismic precursor data. This paper takes five typical categories of failure as examples: data, power, communication, open valve, and lightning, analyzes the details, then discusses the cause of these failures and specific solutions. According to the failure phenomena, station staff can analyze the failure and handle the problems effectively; most of the problems can then be solved with the manufacturer's technical support and the repair times can be effectively shortened, thus a continuous data rate can be maintained.

Abstract:The seismic observation system is a multi-disciplined integrated observation technology integration system. The influence of temperature on the material properties and component parameters of seismic observation instruments is a serious problem. When the external temperature changes rapidly, the mechanical structure of seismometers is affected and generates problems such as mechanical friction or zero drift. In this study, we use a temperature test to measure the effect of changing temperature on a very broadband seismometer, then design and develop an intelligent temperature control system for it. This system can monitor real-time temperature in the seismometer shield and compare it with the upper and lower limits of a set temperature. A semiconductor refrigeration device initiates when the monitoring temperature is higher than the upper limit, and heating equipment initiates when the monitoring temperature is lower than the lower limit. Because violent changes in temperature can damage the device, we prevent the system temperature in the seismometer's shield from changing rapidly. Through the system, we can remotely modify the parameters throughout the network, and control the heating and cooling devices or other seismic instruments. This equipment avoids the mechanical failure of seismometers caused by drastic changes in the outside temperature. It can help maintain a stable temperature environment for the seismometer over a long time, extend its lifetime, and reduce performance faults.

Abstract:Based on the application of the Leica TM50 robotic total station to short-distance measurement of cross-fault displacements, the aim of this study is to show the feasibility of an intelligent measuring robot with nominal precision in short-distance measurement. This paper compares the advantages and disadvantages of the traditional invar-wire baseline method, GPS, and measuring robots in relation to aspects such as measurement precision, operational mode, and personnel demand. It finds that the use of a high-precision electro-optical distance meter (EDM) is the best choice at present for relatively short (<3 km) cross-fault displacement measurements. The study then clarifies the operational basis and technical requirements of an EDM and the operational hazards in data collection. In order to ensure repeatable and comparable measurement data, the observational field data need to be corrected with data processing. Meteorological modifications, periodic error correction, and instrumental correction are all discussed. Results are presented from an application example, compared graphically, and briefly analyzed in relation to fault displacements that are contained therein.

Abstract:This paper discusses the development technology of Android platforms for earthquake early-warning software. First, we introduce the entire framework of our project design and Android application, then detail the development methods of JPush push, the Baidu positioning service, Baidu Maps API (Application Programming Interface), and other open-source Android services, and their application to earthquake early-warning software. The tests reveal that the designed Android terminal can effectively acquire earthquake early-warning information using the JPush push technique, which also displays the user’s current position, epicentral distance, and S-wave arrival time. Simultaneous Android system testing showed that this platform can achieve the above functions and is generally compatible with the mainstream mobile phones on the market. Compared with other similar software in this industry, this earthquake early-warning algorithm and communication technology are relatively open, and can provide a secondary service for the identification of targeted settings in different regions.