Back analysis of surrounding rock parameters of tunnel considering displacement loss and space effect

2021 ◽  
Author(s):  
Yong Zhao ◽  
Shi-Jin Feng
Keyword(s):  
Back Analysis ◽  
Surrounding Rock ◽  
Space Effect ◽  
Rock Parameters

Research on Deformation Mechanism of Surrounding Rock during Excavation of Large-Span Shallow-Buried Double-Arch Tunnel

2013 ◽  
Vol 392 ◽  
pp. 890-894
Author(s):  
Shao Rui Sun ◽  
Ye Xu Lu ◽  
Shao Hua Zhang ◽  
Ji Min Wu
Keyword(s):  
Deformation Mechanism ◽  
Back Analysis ◽  
Ground Surface ◽  
Surrounding Rock ◽  
Tunnel Excavation ◽  
Large Span ◽  
Main Work ◽  
Time Space ◽  
Space Effect ◽  
Force Mechanism

The deformation mechanism of surrounding rock during excavation is difficult to stability evaluation for large-span shallow-buried double-arch tunnel. Take Fenghuang mountain tunnel in Suzhou city as an example, the main work and funding are as follow: The measured data in the middle of the tunnel, including settlement on the top of the tunnel and deformation between two lateral walls, were used to calculate mechanical parameters by back analysis method. The obtained parameters were used to calculate the deformation and stress of the main tunnel excavation in the different steps. The rules includes time-space effect during main tunnel excavation, force mechanism of the middle wall and settlement on the ground surface for the surrounding rock in the main tunnel. Finally, the calculated settlement and deformation were compared to the monitoring results. The safety coefficient of surrounding rock for double-arch tunnel was obtained by strength reduction theory.

Study on the Prediction Method of Tunnel Surrounding Rock Pressure Based on the Theory of Progressive Destruction

2012 ◽  
Vol 446-449 ◽  
pp. 1432-1436
Author(s):  
Suo Wang
Keyword(s):  
Rock Pressure ◽  
Characteristic Curve ◽  
Prediction Method ◽  
Surrounding Rock ◽  
Progressive Damage ◽  
Tunnel Excavation ◽  
Practical Engineering ◽  
Surrounding Rock Pressure ◽  
The Relationship ◽  
Rock Parameters

In order to predict tunnel surrounding rock pressure, this paper puts forward a series of dynamic numerical simulative model on the tunnel excavation. According to the change of rock damage in the construction program, it adjusts dynamically the mechanical material parameters of surrounding rock. So the model achieves the purpose which is controlling and simulating the process of tunnel progressive damage. In accordance with the numerical simulative results, it analyzes the relationship between the rock parameters with the plastic strain, radial displacement. Then this paper proposes a prediction method of tunnel surrounding rock pressure based on the theory of the progressive damage and method of characteristic curve. Finally, it compares the pressure on the numerical simulative models with on the site date, and it proves that the prediction method has practical engineering value.

Study on Deformation and Damage of Rock Mass Subject to High In Situ Stress by Using a Elastoplastic Damage Model and Considering the Impact of Weak Planes

2013 ◽  
Vol 838-841 ◽  
pp. 705-709
Author(s):  
Yun Hao Yang ◽  
Ren Kun Wang
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Damage Model ◽  
Back Analysis ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
High In Situ Stress ◽  
Underground Caverns ◽  
The Impact

Large scale underground caverns are under construction in high in-situ stress field at Houziyan hydropower station. To investigate deformation and damage of surrounding rock mass, a elastoplastic orthotropic damage model capable of describing induced orthotropic damage and post-peak behavior of hard rock is used, together with a effective approach accounting for the presence of weak planes. Then a displacement based back analysis was conducted by using the measured deformation data from extensometers. The computed displacements are in good agreement with the measured ones at most of measurement points, which confirm the validities of constitutive model and numerical simulation model. The result of simulation shows that damage of surrounding rock mass is mainly dominated by the high in-situ stress rather than the weak planes and heavy damage occur at the cavern shoulders and side walls.

Back Analysis for Mass Parameters of Tunnel Surrounding Rock

2012 ◽  
Vol 170-173 ◽  
pp. 20-24 ◽  
Author(s):  
Kai Cui ◽  
Xue Kai Pan
Keyword(s):  
Deformation Mechanism ◽  
Strain Softening ◽  
Back Analysis ◽  
Surrounding Rock ◽  
Tunnel Engineering ◽  
Railway Tunnel ◽  
Displacement Back Analysis ◽  
Information Construction ◽  
Engineering Information ◽  
The Common

Tunnel engineering information construction has been widely used, and the back analysis is its core. As the common useful method, displacement back analysis is of special advantages. This paper introduces the calculative method based on the application in a railway tunnel. The result shows that strain softening model can be used to simulate the large deformation mechanism of surrounding rock.

Parabolic-Apex Numerical Back-Analysis of Mechanics Parameters of Surrounding Rock

2012 ◽  
Vol 204-208 ◽  
pp. 196-201 ◽  
Author(s):  
Jian Cong Xu ◽  
Yi Wei Xu
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Pressure Coefficient ◽  
Back Analysis ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Monitoring Data ◽  
3D Fem ◽  
Physical Mechanics

The parabolic-apex numerical back-analysis method (PNBM) was proposed to obtain such physical-mechanics parameters as Young's modulus and lateral pressure coefficient of surrounding rock by 3D FEM numerical analysis based on in-situ monitoring data. Taking Xiang-an Subsea Tunnel (located in Xiamen, Fujian Province, China) for example, adopting the PNBM using ABAQUS software, three dimensional elastic-plastic FEM-PNBM of tunnel surrounding rock was validated using in-situ monitoring data. The results show as follows: Using the PNBM, not only may high calculation precision be obtained, better meeting the demand of actual projects, but also more reasonable and reliable physical mechanics indices of surrounding rock such as Young's modulus and lateral confinement pressure coefficient, may be obtained. The applicability and the simplicity of this proposed method also support its usefulness.

Identification of Surrounding Rock Parameters Based on MSVR

2014 ◽  
Vol 580-583 ◽  
pp. 1227-1231
Author(s):  
Xiao Long Li ◽  
Jun Jing Zhang ◽  
Fu Ming Wang ◽  
Bei Zhang
Keyword(s):  
Support Vector Regression ◽  
Surrounding Rock ◽  
Orthogonal Test ◽  
Support Vector ◽  
Inversion Method ◽  
Single Output ◽  
Output System ◽  
Rock Parameters ◽  
Rock Deformations ◽  
Second Use

An inversion method based on multi-output support vector regression (MSVR) is proposed for identifying the mechanical parameters of surrounding rock. This method considers the surrounding rock as a multi-output system during excavation, and the surveyed rock deformations of each monitoring section as its output. First, perform numerical experiments based on the principle of orthogonal test to obtain the calculated deformation values corresponding to different rock parameter combinations, and use them as the samples for training the model of MSVR as reflecting the nonlinear mapping relationship between rock and its deformations. Second, use the PSO to seek the optimal rock parameters based on measured deformations of rock mass. An example is employed to test the presented inversion method. The results showed that compared with the inversion method based on single-output support vector regression (SSVR), the proposed one is more inclined to reach the global optimization goals and achieve more reliable inversion results due to its consideration of the inherent correlativity among the measured deformations of each monitoring section.

3-D FLAC Numerical Analysis of Rheological Character and Stability of Underground Caverns Surrounding Rock Mass of Xiao Langdi Key Water Control Project

2006 ◽  
Vol 306-308 ◽  
pp. 1473-1478
Author(s):  
Wei Shen Zhu ◽  
Jian Hua Liu ◽  
Shu Cai Li
Keyword(s):  
Numerical Analysis ◽  
Back Analysis ◽  
Surrounding Rock ◽  
Construction Process ◽  
Water Control ◽  
Long Period ◽  
Underground Caverns ◽  
Rheological Character ◽  
Measured Displacement

A brief description is given to the visco-plastic constitutive model of 3-D FLAC software and some treating methods for the numerical analysis. The excavation steps and the exerting time of excavation loads are determined in the light of the real construction process. The rockmass mechanical parameters are determined according to back analysis of in-situ measured displacement data. The analysis results of displacement and stability of the opening complex surrounding rocks in the construction process and in a long period of time after excavation completion are given.

scholarly journals An Innovative Elastoplastic Analysis for Soft Surrounding Rock considering Supporting Opportunity Based on Drucker-Prager Strength Criterion

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Rui Wang ◽  
Xu-dong Liu ◽  
Jian-biao Bai ◽  
Shuai Yan ◽  
Jun Xu
Keyword(s):  
Strength Criterion ◽  
Homogenization Method ◽  
Surrounding Rock ◽  
Theoretical Research ◽  
Underground Engineering ◽  
Support Design ◽  
Interval Distance ◽  
Space Effect ◽  
The Stability ◽  
Supporting Condition

In order to study the mechanism of excavation and supporting process of equivalent circular roadway, the model of soft roadway was established firstly. The elastoplastic solutions in excavation process were deduced based on Drucker-Prager strength criterion. Then, the elastoplastic solution under supporting condition was obtained based on homogenization method under the condition of rockbolts and liner supporting. Lastly, an example was analyzed to study the effect of different factors such as “space effect,” supporting opportunity, stresses, surrounding displacement, and the radius of plastic zone. Based on theoretical research case, the change rules of considering the “space effect” and the supporting opportunity when calculating the subarea of the roadway were discussed, the control of interval distance of rockbolts on the displacement of surrounding rock mainly reflecting in the plastic residual zone and the “space effect” in excavation, and the supporting time to control the displacement of surrounding rock not being ignored are revealed. The results can provide an important theoretical basis for the stability evaluation and quantitative support design of roadway surrounding rock. Therefore, the “space effect” and the supporting time to control the displacement and stresses of surrounding rock can not being ignored in underground engineering.

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