Back-Calculation Method of Rock Mass Pressure in a Shallow-Buried Super Large-Span Tunnel Using Upper-Bench CD Method

2021 ◽  
Author(s):  
Yanbin Luo ◽  
Yunfei Wu ◽  
Jianxun Chen ◽  
Fangfang Dong ◽  
Weiwei Liu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Calculation Method ◽  
Large Span ◽  
Back Calculation

Back-Calculation Method of Subgrade Modulus Based on Traffic Speed Deflectometer

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Guoshuai Zang ◽  
Haizhu Lu ◽  
Guanglai Jin ◽  
Zhixiang Zhang
Keyword(s):  
Calculation Method ◽  
Back Calculation ◽  
Subgrade Modulus ◽  
Traffic Speed

scholarly journals Weightage Effect during Back-Calculation of Rock-Mass Quality from the Installed Tunnel Support in Rock-Mass Rating and Tunneling Quality Index System

2019 ◽  
Vol 9 (10) ◽  
pp. 2065 ◽  
Author(s):  
Jonguk Kim ◽  
Hafeezur Rehman ◽  
Wahid Ali ◽  
Abdul Muntaqim Naji ◽  
Hankyu Yoo
Keyword(s):  
Rock Mass ◽  
Quality Index ◽  
Rock Bolt ◽  
Rock Mass Rating ◽  
Rock Mass Quality ◽  
Back Calculation ◽  
The Difference ◽  
Bolt Spacing ◽  
Q System ◽  
Selection Of

In extensively used empirical rock-mass classification systems, the rock-mass rating (RMR) and tunneling quality index (Q) system, rock-mass quality, and tunnel span are used for the selection of rock bolt length and spacing and shotcrete thickness. In both systems, the rock bolt spacing and shotcrete thickness selection are based on the same principle, which is used for the back-calculation of the rock-mass quality. For back-calculation, there is no criterion for the selection of rock-bolt-spacing-based rock-mass quality weightage and shotcrete thickness along with tunnel-span-based rock-mass quality weightage. To determine this weightage effect during the back-calculation, five weightage cases are selected, explained through example, and applied using published data. In the RMR system, the weightage effect is expressed in terms of the difference between the calculated and back-calculated rock-mass quality in the two versions of RMR. In the Q system, the weightage effect is presented in plots of stress reduction factor versus relative block size. The results show that the weightage effect during back-calculation not only depends on the difference in rock-bolt-spacing-based rock-mass quality and shotcrete along with tunnel-span-based rock-mass quality, but also on their corresponding values.

Precise grading of surrounding rock based on the numerical calculation of the jointed rock mass

2022 ◽  
pp. 1-32
Author(s):  
Dan Huang ◽  
Xiao-Qing Li ◽  
Wen-Chao Song
Keyword(s):  
Rock Mass ◽  
Numerical Calculation ◽  
Calculation Method ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Geological Survey ◽  
Survey Method ◽  
Synthetic Rock ◽  
Numerical Calculation Method

In this study, grading of surrounding rock was based on rock mass basic quality (BQ) values according to the specifications in China. Numerical approach was to construct synthetic rock mass (SRM) model to represent the jointed rock mass, and obtain the strength of the rock mass. It represented intact rock by the bonded particle model (BPM), and represent joint behaviour by the smooth joint model (SJM) to construct the discrete fracture network (DFN). In the Hongtuzhang Tunnel, the micro properties of granite cores with different weathered degrees were determined by the validation process, and the calculation representative elementary volume (REV) of surrounding rock was 15 m×15 m. Five slightly weathered, three slightly to moderately weathered, and two moderately weathered granite surrounding rock mass models were established based on the probability distribution of joint sets in each borehole, the conversion BQ value was acquired according by the calculated strength of rock mass model. It was discussed the differences of surrounding rock grades between the geological survey method and the numerical calculation method, and then found that the geological survey report is higher than the numerical calculation method predicted. And the numerical calculation is consistent with the actual excavation of rock mass at borehole A1388.

Numerical Simulation for Construction Process Large-Span Flat Tunnel under the Condition of Shallow Buried

2014 ◽  
Vol 580-583 ◽  
pp. 1100-1104
Author(s):  
Jun Jie Li ◽  
Li Tuo ◽  
Guan Jun Zhang
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Tunnel Construction ◽  
Construction Process ◽  
Large Span ◽  
Tunneling Method ◽  
Stress Changes ◽  
Flac 3D ◽  
3D Software ◽  
Grade Rock

The thesis takes a three-lane tunnel construction in Zhejiang as an example. Simulating the course of dynamic construction of large-span tunnel on geology condition of four-grade rock mass and shallow buried by FLAC 3D software ,it carries out comparative and stress situation in the runnel surrounding rocks .Getting the displacement and stress changes rule of the construction by using benching with a small pilot tunnel tunneling method can guide the construction scientifically.

scholarly journals AIDS Incubation Period: A Statistical Review

2006 ◽  
Vol 5 (2) ◽  
pp. 39-56
Author(s):  
Sahana Prasad ◽  
Nagaraja Rao C. ◽  
T. Srivenkataramana
Keyword(s):  
Statistical Analysis ◽  
Incubation Period ◽  
Calculation Method ◽  
Statistical Review ◽  
World Today ◽  
Rapid Spread ◽  
The World ◽  
The Future ◽  
Back Calculation ◽  
Socioeconomic Consequences

One of the major concerns of healthcare in the world today is HIV/AIDS.The health and socioeconomic consequences of a rapid spread of AIDS are very serious.Thus we need accurate forecasts of the future course of the epidemic.The special feature of AIDS is its long incubation period,whose distribution is difficult to estimate partly due to its length and partly due to its nature of the infected cohorts being followed or identified.This article mainly discusses the features of AIDS incubation period and reviews statistical analysis of a few models developed for the estimation of the incubation period.One of the i9mportant methods of projection namely,Back Calculation method is also discussed.

scholarly journals Calibration Method of Accelerometer Based on Rotation Principle Using Double Turntable Centrifuge

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 62
Author(s):  
Xianshan Dong ◽  
Xinlong Huang ◽  
Guizhen Du ◽  
Qinwen Huang ◽  
Yixiong Huang ◽  
...  
Keyword(s):  
Calculation Method ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Scale Factor ◽  
Centripetal Acceleration ◽  
Mems Accelerometer ◽  
Key Technology ◽  
Acceleration Vector ◽  
Back Calculation ◽  
Input Acceleration

For linear accelerometers, calibration with a precision centrifuge is a key technology, and the input acceleration imposed on the accelerometer should be accurately obtained in the calibration. However, there are often errors in the installation of sample that make the calibration inaccurate. To solve installation errors and obtain the input acceleration in the calibration of the accelerometer, a calibration method based on the rotation principle using a double turntable centrifuge is proposed in this work. The key operation is that the sub-turntable is rotated to make the input axis of the accelerometer perpendicular to the direction of the centripetal acceleration vector. Models of installation errors of angle and radius were built. Based on these models, the static radius and input acceleration can be obtained accurately, and the calibration of the scale factor, nonlinearity and asymmetry can be implemented. Using this method, measurements of the MEMS accelerometer with a range of ±30 g were carried out. The results show that the discrepancy of performance obtained from different installation positions was smaller than 100 ppm after calibrating the input acceleration. Moreover, the results using this method were consistent with those using the back-calculation method. These results demonstrate that the effectiveness of our proposed method was confirmed. This method can measure the static radius directly eliminating the installation errors of angle and radius, and it simplifies the accelerometer calibration procedure.

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