Longitudinal vibration characteristics of a tapered pipe pile considering the vertical support of surrounding soil and construction disturbance

This research is concentrated on the longitudinal vibration of a tapered pipe pile considering the vertical support of the surrounding soil and construction disturbance.First,the pile-soil system is partitioned into finite segments in the vertical direction and the Voigt model is applied to simulate the vertical support of the surrounding soil acting on the pile segment.The surrounding soil is divided into finite ring-shaped zones in the radial direction to consider the construction disturbance.Then,the shear complex stiffness at the pile-soil interface is derived by solving the dynamic equilibrium equation for the soil from the outermost to innermost zone.The displacement impedance at the top of an arbitrary pile segment is obtained by solving the dynamic equilibrium equation for the pile and is combined with the vertical support of the surrounding soil to derive the displacement impedance at the bottom of the upper adjacent segment.Further,the displacement impedance at the pile head is obtained based on the impedance function transfer technique.Finally,the reliability of the proposed solution is verified,followed by a sensitivity analysis concerning the coupling effect of the pile parameters,construction disturbance and the vertical support of the surrounding soil on the displacement impedance of the pile.

A Visible Light Imaging System for the Estimation of Plasma Vertical Displacement in J-TEXT

A wide-viewing-angle visible light imaging system （VLIS） was mounted on the Joint Texas Experimental Tokamak （J-TEXT） to monitor the discharge process. It is proposed that by using the film data recorded the plasma vertical displacement can be estimated. In this paper installation and operation of the VLIS are presented in detailed. The estimated result is further compared with that measured by using an array of magnetic pickup coils. Their consistency verifies that the estimation of the plasma vertical displacement in J-TEXT by using the imaging data is promising.

The Vertical Deformation and Horizontal Displacement Fields,Movement, and Seismicity of the Island Arc Tectonics

In this work,the vertical deformation,horizontal displacement,and stress fields of arcuate tectonics are theoretically derived from the horizontal tectonic stress; then the characteristics of tectonic movement,seismicity,and focal mechanism of arcuate tectonics of the entire world are explained.It is pointed out that the island arc and other arcuate tectonics are gradually developed under the displacement and stress fields of the arcuate tectonics and that the under-thrusting action of the ocean plate is secondary.The distance formulas between the volcanic arc and the trench are suggested and also that theoretical results are consistent with actual data.

Effect of passive plates on vertical instability in the EAST tokamak

The effect of passive plates on vertical displacement control in the EAST tokamak is investigated by open loop experiments and numerical simulations based on a rigid displacement model. The experiments and simulations indicate that the vertical instability growth rate is reduced by a factor of about 2 in the presence of the passive plates, where the adjacent segments are not connected to each other. The simulations also show that the vertical instability growth rate is reduced by a factor of about 10 if all adjacent segments on each passive plate loop are connected to each other. The operational window is greatly enlarged with the passive plates.

Study on the Phenomenon of Geomagnetic Low-value Displacement before Moderately Strong Earthquakes in Gansu

This paper analyzes the distribution characteristics of geomagnetic low-value displacement in Gansu and its adjacent areas from 1995 to 2003 on the basis of the data of the daily amplitude minimum value time of the geomagnetic vertical component. It is shown that in addition to the changing rules of geomagnetic low-value displacement itself, there is a better correlation between geomagnetic low-value displacement and the occurrence of moderately strong earthquakes. There appeared to be geomagnetic low-value displacement before the moderately strong earthquakes in Gansu in the 9 years from 1995 to 2003. This result indicates that geomagnetic low-value displacement is of instructive significance for earthquake prediction to some extents.

Study on the seismic performance of a double spherical seismic isolation bearing

In this paper, the configuration and working mechanism of the recently developed double spherical seismic isolation （DSSI） bearing are introduced in detail. Then, vertical displacement of the DSSI bearing due to sliding on a spherical surface is analyzed. The results from seismic performance testing of the bearing are given, and a numerical analysis of a four span continuous girder bridge is performed. The numerical analysis compares the influence of three different bearing arrangement schemes on the structural seismic response, and the results show that the DSSI bearing is effective in increasing the vertical load bearing capacity, reducing the vertical displacement, and controlling the energy dissipation capacity within a certain range.

Application of a Current and Voltage Mixed Control Mode for the New Fast Control Power Supply at EAST

A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magnetic field to control the plasma＇s displacement. With the development of EAST, new demands on the new fast control power supply have led to an enhanced ability of fast response and output current, as well as a new control mode. The structure of cascaded and paralleled H-bridges can meet the demand of extended capacity, and digital control can reMize current and voltage mixed control mode. The validity of the proposed scheme is confirmed by experiments.

Investigation of the different weight models in Kalman filter:A case study of GNSS monitoring results

During geodetic monitoring with GNSS technology one of important steps is the correct processing and analysis of the measured displacements. We used the processing method of Kalman filter smoothing algorithm, which allows to evaluate not only displacements, but also the speed, acceleration, and other characteristics of the deformation model. One of the important issues is the calculation of the obser- vations weight matrix in the Kalman filter. Recurrence algorithm of Kalman filtering can calculate and specify the weights during processing. However, the weights obtained in such way do not always exactly correspond to the actual observation accuracy. We established the observations weights based on the accuracy of baseline measurements. In the presented study, we offered and investigated different models of establishing the accuracy of the baselines. The offered models and the processing of the measured displacements were tested on an experimentally geodetic GNSS network. The research results show that despite of different weight models, changing weights up to 2 times do not change Kalman filtering ac- curacy extremely. The significant improvements for Kalman filtering accuracy for baselines shorter than 10 km were not got. Therefore, for typical GNSS monitoring networks with baseline range 10-15 km, we recommend to use any kind of models. The compulsory condition for getting correct and reliable results is checking results on blunders. For baselines, which are longer than 15 km we propose to use weight model which include baseline standard deviation from network adjustment and corrections for baseline length and its accuracy.

Analysis of terrestrial water storage changes in the Shaan-Gan-Ning Region using GPS and GRACE/GFO

Both the Global Positioning System(GPS)and Gravity Recovery and Climate Experiment(GRACE)/GRACE Follow-On(GFO)provide effective tools to infer surface mass changes.In this paper,we combined GPS,GRACE/GFO spherical harmonic(SH)solutions and GRACE/GFO mascon solutions to analyze the total surface mass changes and terrestrial water storage(TWS)changes in the Shaan-Gan-Ning Region(SGNR)over the period from December 2010 to February 2021.To improve the reliability of GPS inversion results,an improved regularization Laplace matrix and monthly optimal regularization parameter estimation strategy were employed to solve the ill-posed problem.The results show that the improved Laplace matrix can suppress the edge effects better than that of the traditional Laplace matrix,and the corre-lation coefficient and standard deviation(STD)between the original signal and inversion results from the traditional and improved Laplace matrix are 0.84 and 0.88,and 17.49 mm and 15.16 mm,respectively.The spatial distributions of annual amplitudes and time series changes for total surface mass changes derived from GPS agree well with GRACE/GFO SH solutions and mascon solutions,and the correlation coefficients of total surface mass change time series between GPS and GRACE/GFO SH solutions,GPS and GRACE/GFO mascon solutions are 0.80 and 0.77.However,the obvious differences still exist in local regions.In addition,the seasonal characteristics,increasing and decreasing rate of TWS change time series derived from GPS,GRACE/GFO SH and mascon solutions agree well with the Global Land Data Assimilation System(GLDAS)hydrological model in the studied area,and generally consistent with the precipitation data.Meanwhile,TWS changes derived from GPS and GRACE mascon solutions in the SGNR are more reliable than those of GRACE SH solutions over the period from January 2016 to June 2017(the final operation phase of the GRACE mission).

3D Finite Elements Technique for Collapse Causes of the Pylons in Egyptian Temples: A Study of the Great Pylon of Ramesseum Temple, Luxor, Egypt

This research presents damage causes of the pylons in the ancient Egyptian temples based on 3D finite elements analysis. The main purpose of the research determines the failure causes of the first pylon of the Ramessium temple, which is situated in Upper Egypt, at Luxor “Thebes” on the west bank of the Nile River. The first pylon of Ramessium temple subjected to seismic activity effects on long term, combined with several structural damage factors such as the defects resulting from the construction technique, where the builder used the poor quality of stones in foundations of the pylon, the building materials residue was used as filler for the core of the pylon walls, and it lacked vertical joints between the courses. In addition to it founded on alluvial soil that is vulnerable to contaminated water, it is still suffering damage factors and urban trespasses at the moment. All of the former factors helped the pylon to be affected by the earthquakes loads that occurred on it. The structural behavior of the pylon under self-weight and earthquakes loads were carried out by Numerical analysis to find out the loads and stresses which caused collapsing of the pylon. Results of the study indicated that the pylon subjected to a horizontal displacement due to old earthquakes force, led to collapse of the pylon. Finally, the study represents use of modern technique to study the structural behavior of the most important architectural units in ancient Egyptian temples to identify the causes of its collapse.

Vertical and horizontal displacements of a reservoir slope due to slope aging effect,rainfall,and reservoir water

Landslides are common hazards in reservoir areas and significantly affect dam operation and human lives.For the prevention and management of landslides,accurate assessment of the factors influencing their generation is essential.This study evaluated the key external factors influencing horizontal and vertical displacements of Luobogang Reservoir Slope in Hanyuan County,China.Displacements had been monitored by a surface-displacement-monitoring system consisting of 118 GPS stations during 2012-2015.To identify the external driving factors,their influence zones,and slope responses,we analyzed 32 months of displacement measurements and other multi-source datasets using the empirical orthogonal function.Overall,the results show that slope aging effect,rainfall,and reservoir water levels are three main driving factors.For horizontal displacement,aging effect is the most critical factor and predominantly affects the edges of landslides,the gob cave,and the public building zones.The secondary factor is the reservoir water level,which mainly acts on the boundary between the slope and reservoir water surface.The closer the slope zone is to the reservoir water,the more significant the impact is.Regarding vertical displacement,the most important factor is rainfall.The vertical displacement caused by rainfall accounts for 56.76% of the total vertical displacements.However,rainfall induces elastic displacements that generally cause less damage to the slope.The secondary factor is aging effect,and the vertical displacement caused by aging effect accounts for 9.42%.However,seven individual zones are highly affected by slope aging effect,which is consistent with the distribution of public buildings.

Accuracy assessment of global vertical displacement loading tide models for the equatorial and Indian Ocean

The three-dimensional displacements caused by ocean loading effects are significant enough to impact spatial geodetic measurements on sub-daily or longer timescales,particularly in the vertical direction.Currently,most tide models incorporate the distribution of vertical displacement loading tides;however,their accuracy has not been assessed for the equatorial and Indian Ocean regions.Global Positioning System(GPS)observations provide high-precision data on sea-level changes,enabling the assessment of the accuracy and reliability of vertical displacement tide models.However,because the tidal period of the K_(2) constituent is almost identical to the orbital period of GPS constellations,the estimation of the K_(2) tidal constituent from GPS observations is not satisfactory.In this study,the principle of smoothness is employed to correct the systematic error in K_(2) estimates in GPS observations through quadratic fitting.Using the adjusted harmonic constants from 31 GPS stations for the equatorial and Indian Ocean,the accuracy of eight major constituents from five global vertical displacement tide models(FES2014,EOT11a,GOT4.10c,GOT4.8,and NAO.99b)is evaluated for the equatorial and Indian Ocean.The results indicate that the EOT11a and FES2014 models exhibit higher accuracy in the vertical displacement tide models for the equatorial and Indian Ocean,with root sum squares errors of 2.29 mm and 2.34 mm,res-pectively.Furthermore,a brief analysis of the vertical displacement tide distribution characteristics of the eight major constituents for the equatorial and Indian Ocean was conducted using the EOT11a model.

Estimation of Ground Vertical Displacement in Landslide Prone Areas Using PS-InSAR. A Case Study of Bududa, Uganda

Estimation of ground displacement in landslide susceptible regions is very critical to understanding how landslides develop. The knowledge of ground displacement rates and magnitudes helps plan for the safety of the people and infrastructure. The early detection of landslides in Bududa is still a challenge due to the limited technology, hard to access, and a need for an affordable technique that can monitor a wide area continuously. In recent studies, the use of Persistent Scatterer Interferometry Synthetic Aperture Radar (PS-InSAR) has provided vital information on landslide monitoring through the measurement of ground displacement. In this study, Synthetic Aperture Radar (SAR) band C series of Sentinel 1-A and 1-B Satellite images were acquired between 2019 and 2020 along ascending and descending orbit paths. The Line of Sight Sight (LOS) displacement was determined for both satellite tracks, and then the LOS displacement was projected to the vertical direction. The PS-InSAR derived vertical displacement was then compared with GPS vertical displacement magnitudes over three GPS stations in the area. It was observed that vertical displacement velocity reached 20 cm/yr in Mountain Elgon. This displacement rate showed that there are points in the region that are highly unstable. The displacement velocity and magnitude in Bududa reached 6 cm/yr and 13 cm in two years. This rate and magnitude showed that Bududa is highly unstable compared with displacement velocities and magnitudes in landslide susceptible areas globally. The displacement was generally subsidence over the observation period. The vertical displacement estimated by PS-InSAR was comparable with GPS based on the estimated RMSE. The vertical displacement was highest at slopes between 32° and 60° and lowest between 0° and 9°. The vertical ground displacement was highly correlated with the rainfall that was received. The soil texture in Bududa has high clay content, with clay layering hence low drainage rates, field capacity, saturation and bulk density. It was observed that ground displacement was highly influenced by slope, rainfall and soil texture. Displacement could be estimated in three dimensions using PS-InSAR in the future if sufficient SAR images in ascending and descending tracks are made available with significantly different geometries. This would add to the knowledge of displacement patterns in the east and north directions at a large spatial scale.

Analysis on the Observation Data of Three Profiles across the Qilian Mountain-Haiyuan Fault Zone

By analyzing GPS, leveling and gravity observation data from the Minle, Huazangsi and Shagouhe profiles across the Qilian Mountain-Haiyuan fault during 2005 - 2009, the changes of these data and activity characteristics of the main faults in different time are obtained. The results show that the Changma-Erbo, Maomaoshan, Zhunglanghe and Haiyuan faults have been active in recent years. The relationship between the vertical displacement and mobile gravity data is analyzed, and the results reveal the gravity changes are mainly due to mass transfer. The results of GPS observation show that the direction of the horizontal movement velocity was almost along the fault strike in 2006 - 2007, while the horizontal velocity deviated from the fault direction in 2007 - 2008, characterized by increased eastward displacement. Further analysis upon removal of the linear trend on the time series of the N and E coordinate values of the continuous observation stations of the Crustal Movement Observation Network of China near the three profiles reveals that the Wenchuan earthquake had an effect on the observations in 2007 - 2008. Comparing the gravitational changes in 2008 - 2009 with the Bouguer gravity anomaly background, we find that the area near Minle profile is in the stage of adjustment and recovery, while the anomaly is not completely recovered around Huazangsi and Shagouhe profiles.

Synergetic Effects of Runaway Electron and Vertical Instability on the Wall Damage on HL-2A Tokamak

1 Generation of vertical instability Tokamak experiments show that the energy confinement time and performance are better, and the larger plasma current can be achieved for non-circular cross-sectional shape of plasma than circular cross-section. However, the external magnetic fields which are used to produce the non-circular cross sectional shape also cause the confined plasma to become unstable to small vertical displacement. In general, the ratio of elongation k is larger, the possibility of instability is more. In practice, this vertical displacement mode stabilized by feedback control system or other provided external radial magnetic field to balance out the plasma motion. Under some of situations the control system may be fail due to rapid growth rate of instability exceeding the ability of controlling. The plasma will then move vertically upwards or downwards depending upon the characteristics of instability and control failure.

Sensor monitoring of a newly designed foundation pit supporting structure

A new type of pit supporting structure, which was tested and verified using the sensor monitoring technology, was presented. The new supporting structure is assembled by prefabricated steel structural units. The adjacent steel structural units are jointed with fasteners, and each steel structural unit has a certain radian and is welded by two steel tubes and one piece of steel disc. In order to test and verify the reliability of the new supporting structure, the field tests are designed. The main monitoring programs include the hoop stress of supporting structure, lateral earth pressure, and soil deformation. The monitoring data of the field tests show that the new supporting structure is convenient, reliable and safe.

Co- and post-seismic vertical displacements of Wenchuan Ms8.0 earthquake near Beichuan

Co- and post-seismic vertical displacements of the Wenchuan earthquake derived from two measurements in 2008 and 2010 along two partly-damaged leveling lines near the epicenter show the following features： Co-seismic displacement at Beichuan-Yingxiu fault was as large as 4. 711 m near Beichuan, where the maximum observed fault offset was 5.1 m. In contrast, the observed co-seismic offset of the Qingchuan fault in Pingwu County was only 0. 064 m. During 2008 - 2010, the post-seismic displacement rate was 5 - 27 mm/a near Beichuan-Yingxiu fault in Beichuan area, 20.6 mrn/a at Jiangyou-Guangyuan fault near Dakang, and only 0.2 - 1.3 mm/a at Qingehuan fault near Gucheng.

基于Cat.1技术与阵列式位移计的深基坑监测方法与应用

深基坑开挖的危险系数高,容易引发安全事故,需要采用有效的地质灾害监测系统。为实现深基坑施工阶段变形的有效监测与预警,提出了采用基于Cat.1技术与阵列式位移计的无线自动化监测方法。首先通过与传统的LoRa通信技术对比,分析了Cat.1技术的特点和优势。然后把Cat.1技术与阵列式位移计共同应用于基坑监测,建立了监测系统。最后,以某深基坑监测项目为例,分析了代表性测点的水平位移监测结果。结果表明,所建立的监测系统能够稳定地采集监测数据并上传至监测平台,实时反映基坑测点水平位移变化规律,且监测结果的可解释性高,有助于及时发出预警信号,做好风险防范措施。

Numerical Simulation and Field Monitoring Analysis for Deep Foundation Pit Construction of Subway Station

To investigate the effect of deep foundation pit excavation on the stability of retaining structure, a subway stationin the city of Jinan was selected as a project, and a FLAC3D-based three dimensional model was developed fornumerical simulation. The horizontal displacement of the retaining structure, the axial force of the support, andthe vertical displacement of the column were studied and compared to the collected data from the field. The findingsindicate that when the foundation pit is excavated, the maximum deformation of the retaining structure progressivelydecreases from the top, the distortion of the retaining structure gradually rises, and the final maximumdeformation is around 17 meters deep. In each layer of support, the largest axial force support is located in thefirst reinforced concrete support;the uplift of the pit bottom caused by soil unloading plays a primary role in thevertical displacement of the column, and the column exhibits an upward trend under all construction conditions.When compared to the measured data, the generated findings are comparable and the fluctuation trend is extremelyconsistent. The findings of this article may give technical direction for the development of subway stationswith a comparable engineering basis.

Comparison benchmark between tokamak simulation code and TokSys for Chinese Fusion Engineering Test Reactor vertical displacement control design

Vertical displacement event（VDE） is a big challenge to the existing tokamak equipment and that being designed. As a Chinese next-step tokamak, the Chinese Fusion Engineering Test Reactor（CFETR） has to pay attention to the VDE study with full-fledged numerical codes during its conceptual design. The tokamak simulation code（TSC） is a free boundary time-dependent axisymmetric tokamak simulation code developed in PPPL, which advances the MHD equations describing the evolution of the plasma in a rectangular domain. The electromagnetic interactions between the surrounding conductor circuits and the plasma are solved self-consistently. The TokSys code is a generic modeling and simulation environment developed in GA. Its RZIP model treats the plasma as a fixed spatial distribution of currents which couple with the surrounding conductors through circuit equations. Both codes have been individually used for the VDE study on many tokamak devices, such as JT-60U, EAST, NSTX, DIII-D, and ITER. Considering the model differences, benchmark work is needed to answer whether they reproduce each other＇s results correctly. In this paper, the TSC and TokSys codes are used for analyzing the CFETR vertical instability passive and active controls design simultaneously. It is shown that with the same inputs, the results from these two codes conform with each other.