scholarly journals Analysis of Re-Tensioning Time of Anchor Cable Based on New Prestress Loss Model

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1094
Author(s):  
Keyou Shi ◽  
Xiaoping Wu ◽  
Yurong Tian ◽  
Xiaotian Xie
Keyword(s):  
Rock Mass ◽  
Compensation Effect ◽  
Prestress Loss ◽  
Loss Model ◽  
New Model ◽  
Anchor Cable ◽  
Calculation Results ◽  
Time Point ◽  
Stable Stage ◽  
The Ideal

Considering the interaction among anchor cable, frame beam and rock mass, a new model of prestress loss of anchor cable was established. The accuracy and applicability of the new model were verified by comparing the field monitoring data and the calculation results of existing models. In addition, based on the new model, the effect of the re-tension of the anchor cable at different time nodes was analyzed, and the later compensation time of anchor cable prestress was discussed. The research shows that: the accuracy of the new model is higher after considering the effect of the frame beam, the new model can not only calculate the loss of prestress of anchor cable, but also accurately predict the time when the prestress of anchor cable reaches the stable stage. The ideal effect of prestress compensation can be achieved when the anchor cable is re-tensioned at each time point after 20 days of the construction completed. The original prestress loss of the anchor cable is different, and the re-tension effect is also different, the greater the loss of the original prestress of the anchor cable, the more obvious the prestress compensation effect during the re-tension.

A Calibrated Combination of Probabilistic Precipitation Forecasts to Achieve a Seamless Transition from Nowcasting to Very Short-Range Forecasting

2020 ◽  
Vol 35 (3) ◽  
pp. 773-791
Author(s):  
Peter Schaumann ◽  
Mathieu de Langlard ◽  
Reinhold Hess ◽  
Paul James ◽  
Volker Schmidt
Keyword(s):  
Real Time ◽  
Short Range ◽  
Lead Times ◽  
New Model ◽  
Combination Model ◽  
Logit Transformation ◽  
Interaction Terms ◽  
Probabilistic Forecasts ◽  
Seamless Transition ◽  
The Ideal

Abstract In this paper, a new model for the combination of two or more probabilistic forecasts is presented. The proposed combination model is based on a logit transformation of the underlying initial forecasts involving interaction terms. The combination aims at approximating the ideal calibration of the forecasts, which is shown to be calibrated, and to maximize the sharpness. The proposed combination model is applied to two precipitation forecasts, Ensemble-MOS and RadVOR, which were developed by Deutscher Wetterdienst. The proposed combination model shows significant improvements in various forecast scores for all considered lead times compared to both initial forecasts. In particular, the proposed combination model is calibrated, even if both initial forecasts are not calibrated. It is demonstrated that the method enables a seamless transition between both initial forecasts across several lead times to be created. Moreover, the method has been designed in such a way that it allows for fast updates in nearly real time.

scholarly journals Coupling Effect of Creep Deformation and Prestress Loss of Anchored Jointed Rock

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Bairu Zhu ◽  
Yang Song ◽  
Heping Wang ◽  
Yongqi Li
Keyword(s):  
Rock Mass ◽  
Stress Level ◽  
Coupling Effect ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Calculation Model ◽  
Prestress Loss ◽  
Stress States ◽  
The Stability ◽  
Anchor Design

To explore the variation behaviour of anchor jointed rock subject to high in situ stress states, a coupling effect calculation model based on stress equality was established based on the original rheological model of rock by combining element combination theory and experiment, and the model was verified. The coupling effect between rock mass creep and bolt prestress loss is established by setting the deterioration function of bolt prestress loss. The uniaxial creep test is performed on specimens with different joint angles, and the results show that the prestress loss time in anchor rods decreases linearly with increasing stress level. With increasing stress level, the time of prestress loss decreases linearly with the increase in stress level. With increasing axial load, the deformation caused by the transverse expansion stress of the specimen can offset the compression deformation of the prestressed anchor rod. The relationship between prestress loss in anchors and creep of rock is solved theoretically, and the stability criterion for anchor jointed rock is proposed. The results of this study provide a scientific reference for anchor design of deep jointed rock mass.

Building the Simple Model of Bridge Reinforced Shallow Foundation

2014 ◽  
Vol 1079-1080 ◽  
pp. 127-130
Author(s):  
Hai Zhang ◽  
Yuan Cheng Ni ◽  
Li Jiao
Keyword(s):  
Simple Model ◽  
Reference Value ◽  
Shallow Foundation ◽  
Actual Situation ◽  
Analysis Method ◽  
Substantial Agreement ◽  
Safety Requirement ◽  
Finite Element Software ◽  
Calculation Results ◽  
The Ideal

In order to calculate the shallow foundation for moreappropriate, the paperbuildinga simplemodel in line with the actual situation of reinforced shallow foundation andcalculates, thereby improves the existing analysis method. By analyzing themodel of shallow foundation reinforced by supplementary pile, the paper getsthe method for the new model, and combined with the specificexample. Then we compare theresult between the simple model calculation and theanalysis of finite element software Midas/GTS. The analysis of specific exampleshows that, the calculation results of this new simple model and finite elementsoftware are in substantial agreement, and satisfied the safety requirement,and achieves the ideal target.It has a certain practical and reference value,because itcan be quickly and conveniently to calculate the bridge shallow foundation.

Analysis on Anchorage Length of Compression Anchor

2011 ◽  
Vol 255-260 ◽  
pp. 345-349 ◽  
Author(s):  
Bing Xiong Tu ◽  
Jin Qing Jia ◽  
Hong Sheng Yuan ◽  
Hai Tao Wang
Keyword(s):  
Rock Mass ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Critical Length ◽  
Friction Angle ◽  
Analytic Solutions ◽  
Internal Friction Angle ◽  
Effective Length ◽  
Anchorage Length ◽  
New Model

This paper proposes a new model to calculate anchorage length for the compression anchor. Then the analytic solutions for the effective length and the critical length are derived according to the model. The analysis to the solutions show that the larger the rock mass’s elastic modulus, cohesion and internal friction angle, the smaller the anchorage length. Besides, the larger the load, the greater the anchorage length. However, the poisson’s ratio of rock mass nearly has no influence on the anchorage length. It is most important that the two calculation length show great agreement with present codes or specification.

scholarly journals Three-Dimensional Numerical Modeling and Roof Deformation Analysis of Yuanjue Cave Based on Point Cloud Data

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhigang Meng ◽  
Manchao He ◽  
Zhigang Tao ◽  
Bin Li ◽  
Gang Zhao ◽  
...  
Keyword(s):  
Rock Mass ◽  
Numerical Calculation ◽  
Point Cloud ◽  
Three Dimensional ◽  
Calculation Model ◽  
Deformation Analysis ◽  
Cloud Data ◽  
Heritage Site ◽  
Calculation Results ◽  
Multifactor Coupling

Yuanjue Cave is the core exquisite cultural relic of the Dazu Stone Carvings World Cultural Heritage Site. For hundreds of years, with the continuous effect of natural forces and the erosion of various deterioration factors, the sidewall and roof rock mass of Yuanjue Cave were eroded, some parts of supporting rock mass were fragmented, and the boundary conditions of the rock mass have deteriorated, which have seriously endangered the Yuanjue Cave; once the roof collapses, the national treasure in the cave will be destroyed. In order to preevaluate the stability characteristics of the Yuanjue Cave rock mass and provide key parameters for the preventive protection of the Yuanjue Cave, this paper firstly established a refined database of key parameters of Yuanjue Cave and adjacent areas (geometry, geology, physical properties) based on three-dimensional laser point cloud scanning, a fine survey of adjacent areas, engineering geophysical prospecting, and indoor multifactor coupling tests. Then, based on FLAC3D finite difference numerical simulation technology, an accurate three-dimensional numerical calculation model of Yuanjue Cave was constructed. Finally, the model was used to analyze the roof stability of Yuanjue Cavern, revealing the deformation laws of the Yuanjue Cave roof under static load conditions, and the numerical calculation results were compared with the on-site measured results, verifying the feasibility of the high-precision modeling method, and the reliability of the numerical calculation results provided a reference for the preventive protection of the cultural relics of the cave temple.

scholarly journals The Effect of Surgical Intervention for Delayed Cervical Central Cord Syndrome

2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
Yanan Liu ◽  
Zongyi Wang ◽  
Shaofeng Yang ◽  
Huilin Yang ◽  
Jun Zou
Keyword(s):  
Surgical Intervention ◽  
Spinal Injury ◽  
American Spinal Injury Association ◽  
Japanese Orthopedic Association ◽  
Sf 36 ◽  
Cord Injury ◽  
Central Cord Syndrome ◽  
Time Point ◽  
The Ideal

The authors retrospectively studied 11 patients with delayed cervical central cord syndrome (CCS) to investigate the efficacy of the surgical intervention on treatment for delayed CCS. The American Spinal Injury Association (ASIA) motor scores, Japanese Orthopedic Association (JOA) scores, SF-36 scores, and neurologic status were analyzed preoperatively and at each time point of postoperative follow-up. The results show that patients with reversible spinal cord injury caused by delayed central cord syndrome can recover significantly after surgical intervention. Therefore, we suggest that surgical intervention is still the ideal choice for delayed cervical central cord syndrome.

The Finite Element Analysis of Crack Propagating in Bolt-Supported Jointed Rock-Mass

2010 ◽  
Vol 163-167 ◽  
pp. 3453-3456
Author(s):  
Zhong Chang Wang ◽  
Qing Yang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Rock Mass ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Element Analysis ◽  
Anchor Cable ◽  
The Finite Element Analysis ◽  
Crack Faces

A new method of inflicting equivalent pre stress is suggested to simulate mechanism on reinforcement of pre stress anchor cable on crack prevention of different angle by mini-plastic zone displacement by finite element method. The change rule of displacement of middle points of crack faces, the change of stress strength gene and strain is compared under different pre-stress consolidated condition. When the angle of crack is 450, the consolidated role of rock mass is the best evident. The effect of compression of jointed rock mass is larger than the effect of shear under pre-stress consolidated condition.

Study on the Characteristics of High Speed near Field Communication Antenna Based on FDTD

2014 ◽  
Vol 1044-1045 ◽  
pp. 1362-1365
Author(s):  
Yan Feng Liu ◽  
Bing Wei
Keyword(s):  
Numerical Simulation ◽  
Field Distribution ◽  
Electric Dipole ◽  
High Speed ◽  
Near Field ◽  
Fdtd Method ◽  
Near Field Communication ◽  
Calculation Results ◽  
The Ideal

The near-field characteristics of the ideal electric dipole are analyzed in this paper. A practical ultrafast band antenna near field FDTD is made and the near field distribution of the antenna is studied by numerical simulation. The calculation results show that the FDTD method is used for the analysis of feasibility and reliability of the near-field communication antenna.

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