In-situ monitored seismic response of a rock tunnel

2016 ◽  
pp. 463-468
Author(s):  
C Kung ◽  
Y Chiu ◽  
T Wang ◽  
T Huang
Keyword(s):  
Seismic Response ◽  
Rock Tunnel

Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

2011 ◽  
Vol 90-93 ◽  
pp. 2307-2312 ◽  
Author(s):  
Wen Jiang Li ◽  
Su Min Zhang ◽  
Xian Min Han
Keyword(s):  
Plastic Strain ◽  
Catastrophe Theory ◽  
Soft Rock ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Engineering Practice ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

Modeling in situ 4D seismic response for Otway basin sequestration project

2008 ◽  
Author(s):  
A. Gendrin ◽  
L. Dahlhaus ◽  
S. Nakanishi ◽  
S. Tcherkashnev ◽  
P. Wisman ◽  
...  
Keyword(s):  
Seismic Response ◽  
4D Seismic

scholarly journals Structure Strengthening Method for Enhancing Seismic Behavior of Soft Tunnel Portal Section

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Guangyao Cui ◽  
Jianfei Ma
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
Shaking Table Test ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Shaking Table ◽  
Key Factor ◽  
Rock Tunnel ◽  
Tunnel Portal ◽  
Strengthening Method

Tunnel portal sections always suffer serious damage under strong earthquakes. This paper aims to study the seismic performance of lining strengthening method in soft rock portal section by employing the model test. Firstly, the shaking table test considering the test cases, the modified input motions, the boundary condition, and monitoring equipment are conducted to simulate the seismic response of the soft tunnel portal section. Then, the lining strengthening method of increasing concrete grade is applied to the tunnel structure to study the aseismic performance of the soft rock tunnel portal section, and the seismic effects of the tunnel linings with different concrete grades are compared and analyzed. The result shows that the proportion of soft rock to total surrounding rock is the key factor affecting the seismic response of soft rock tunnel portal section; the larger the proportion of soft rock in surrounding rock, the more vulnerable the structure to earthquake damage; the seismic performance of the lining strengthening in hard rock portal is remarkable while limited in soft rock portal section. The stiffness and strength of the lining are larger than those of surrounding rock; the seismic performance of the soft portal section could hardly be improved only by the lining strengthening method. It is suggested to adopt both the structure strengthening and isolation method in the seismic design of soft portal section.

scholarly journals Analysis of Surrounding Rock Creep Effect on the Long-Term Stability of Tunnel Secondary Lining

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Xiaoqian Zhang ◽  
Chengmin Wei ◽  
Heng Zhang
Keyword(s):  
Stress Measurement ◽  
Soft Rock ◽  
In Situ Stress ◽  
Calculation Model ◽  
Surrounding Rock ◽  
In Situ Stress Measurement ◽  
Rock Creep ◽  
Secondary Lining ◽  
Rock Tunnel

The secondary lining failure of deep buried soft rock tunnel often occurs, which is obviously related to the time factor. The formation mechanism of this phenomenon is studied in this paper. Therefore, the combination of in situ stress measurement and neural network inversion is used to analyze the distribution characteristics of in situ stress. At the same time, the creep characteristics of surrounding rock are tested in laboratory, and the key parameters are obtained. Combined with the characteristics of surrounding rock, the calculation model is established by using discrete element simulation technology and considering the joints of surrounding rock. According to the above multiple information, the stress characteristics of the secondary lining in different time periods are analyzed creatively. Finally, the method of setting arch and adding anchor bolt in key parts is proposed, and significant effect results are obtained.

scholarly journals Seismic Response for Wave Propagation across Joints with Equally and Unequally Close-Open Behaviours

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Qi Zhang ◽  
Zhengliang Li ◽  
Tao Yu
Keyword(s):  
Wave Propagation ◽  
Seismic Response ◽  
Seismic Waves ◽  
Incident Angle ◽  
In Situ Stress ◽  
Rock Joints ◽  
Stress Wave Propagation ◽  
S Wave ◽  
Maximum Deformation

The interaction between rock joints and seismic waves is critical in rock engineering when rock mass is suffered from human-induced or natural earthquakes. Stress wave propagation across rock joints is usually dependent on the seismic response of the joints. Wave propagation may cause joints close or open under the in situ stress. In this paper, the seismic response for wave propagation with an arbitrary incident angle impinging on joints is studied. Both reflection and transmission usually occurring at the two interfaces of the joint are considered, respectively. Wave propagation equations with equally and unequally close-open behaviours are deduced firstly, which can be applied for the general cases of arbitrary incident P- or S-wave. Then, wave propagation across joints with normal and oblique incident P- and S-waves is analyzed by considering the equally and unequally close-open behaviours and verified by comparing with the existing methods. Finally, several parametric studies are conducted to evaluate the effect of in situ stress on transmitted waves, the effect of the incident frequency on the maximum deformation of joints, and the effect of the incident angle on the maximum deformation of joints. The wave propagation equations derived in the study are more feasible and can well analyze the seismic response of wave propagation for the most general cases of different incident waveforms.

scholarly journals In-Situ and Laboratory Investigation on Leaching and Effects of Early Curing of Shotcrete

2019 ◽  
Vol 61 (2) ◽  
pp. 23-37
Author(s):  
Andreas Sjölander ◽  
Anders Ansell
Keyword(s):  
Water Pressure ◽  
Test Method ◽  
Test Results ◽  
Water Penetration ◽  
Sprayed Concrete ◽  
Future Studies ◽  
One Year ◽  
Rock Tunnel ◽  
Short Time

Abstract During the construction of a rock tunnel in Stockholm, several sections with leaching shotcrete (sprayed concrete) were found one year after the spraying was completed. An investigation was therefore conducted, and its results are presented in this paper. The amount of leaching after such a short time indicated that a one-sided water pressure existed in combination with a permeable shotcrete. The reason for the water pressure was likely a partly unsuccessful grouting that created sections with leaking water. The permeable shotcrete could be a combined result of insufficient curing and the use of accelerators, and the effect of in-situ curing was therefore investigated. A total of six slabs were sprayed and cured under different conditions in the tunnel. Test results according to standards indicated that curing has no significant effect on the development of mechanical strength or water penetration through the shotcrete. However, this is believed to be a result of the test method rather than the non-existing effect of curing. Lastly, some modifications to the test standard were proposed for future studies of in-situ curing.

scholarly journals Simulation of the In Situ Spatially Varying Ground Motions and Nonlinear Seismic Response Analysis of the Cable-Stayed Bridge

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Jin Zhang ◽  
Ke-jian Chen ◽  
Neng-pan Ju ◽  
Shi-xiong Zheng ◽  
Hong-yu Jia ◽  
...  
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
Element Model ◽  
Response Analysis ◽  
Seismic Response Analysis ◽  
Nonlinear Seismic Response ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Wave Effects

To study the nonlinear seismic behavior and seismic resistance of the long-span cable-stayed bridges subjected to earthquakes, the multidimensional and multisupported artificial ground motions are synthesized first based on the in situ site conditions of the bridge considering the coherent and traveling wave effects. Then, considering the material nonlinearity of the cable-stayed bridge, a 3D finite element model is established based on the OpenSees platform, and the nonlinear seismic response analysis of the bridge is carried out under the synthetic artificial ground motions. The nonlinear seismic response of main bridge components such as piers, towers, bearings, and cables is analyzed, and key conclusions and observations are drawn.

scholarly journals Nonlinear Seismic Response Analysis of the Surrounding Rock-Tunnel System in the Mountain Areas Under SV Wave

2021 ◽  
Author(s):  
Dongrui Xia ◽  
Lijiang Han ◽  
Yang Li ◽  
Lichuang Ma ◽  
Junjie Yan
Keyword(s):  
Seismic Response ◽  
Control Variable ◽  
Surrounding Rock ◽  
Response Analysis ◽  
Seismic Responses ◽  
Mountain Areas ◽  
Critical Issues ◽  
Value Range ◽  
Rock Tunnel ◽  
Tunnel System

The seismic responses and failure mechanisms of the tunnels embedded in the rock are quite different from those of the aboveground structures due to the dynamic interactions between tunnel and surrounding rock. In the previous studies, the tunnel models were under some extent of simplification without considering much of critical issues such as the three-dimensional (3D) characteristics, nonlinear mechanical properties or initial in-situ stress in the model, which are bound to bring the unpredictable errors in the evaluation of seismic response of tunnel-rock system. In this paper, some 3D nonlinear finite element models are established to evaluate the seismic response of surrounding rock-tunnel system in the mountain areas, considering the initial stress state of surrounding rock-tunnel system induced by gravity and excavation, General Mohr Coulomb nonlinear constitutive. Based on the proposed model, the optimal value of the longitudinal length of the model is firstly discussed to determine the value range of the model size. After that, a series of numerical parametric analyses are carried out to investigate the deformation of the surrounding rock. One important finding is that there exists a most unfavorable stress condition which makes the tunnel induce maximum seismic responses. Finally, the typical control variable method is employed to compare the results of the models established in this paper with those of the model considering or not some of significance factors, the comparison results further prove the necessity of establishing the 3D nonlinear model.

scholarly journals In Situ Needle Penetration Test and Its Application in a Sericite Schist Railway Tunnel, Southwest of China

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Jiaxing Dong ◽  
Runxue Yang ◽  
Chenggang Guo ◽  
Meiqian Wang ◽  
Yonghong Wu ◽  
...  
Keyword(s):  
Large Deformation ◽  
Soft Rock ◽  
Reference Value ◽  
Surrounding Rock ◽  
Mechanical Parameters ◽  
Penetration Index ◽  
Needle Penetration ◽  
Joint Direction ◽  
Rock Tunnel

Abstract The sericite schist is a typical metamorphic soft rock. Large deformation of surrounding rock often occurs in the construction of a tunnel in this stratum. Due to the broken rock mass structure and poor mechanical strength in Baishitou tunnel project of Dalin line of Southwest railway, it is impossible to prepare standard samples for a traditional rock mechanical test. Therefore, we chose penetrometer (SH-70) for an in situ test. Firstly, we monitored the deformation of typical sections and analyzed the characteristics of large deformation of soft rock in the tunnel. Secondly, we tested the needle penetration index of fresh excavation face and side wall. Then, we estimated some mechanical parameters of sericite schist by a needle penetrometer and Hoek-brown criterion and discussed the acquisition of mechanical parameters of soft rock. The results show the following: (1) the characteristics of extrusion rock tunnel are summarized as large deformation, fast deformation rate, and obvious construction disturbance. (2) The reference value of penetration index of sericite schist (the vertical joint direction) is 3.90~7.77 N/mm, and the parallel joint direction is 1.27~2.99 N/mm. (3) The uniaxial compressive strength estimated by a penetrometer is 0.78~8.53 MPa, and the strength of the surrounding rock is negatively correlated with the amount of deformation. Therefore, it can be considered that the insufficient strength of surrounding rock is the fundamental reason for large deformation. (4) The reference value of cohesion of sericite schist estimated by a penetrometer is 0.203 MPa, and the reference value of internal friction angle is 18.224°. Compared with the common estimation methods, the penetrometer is more convenient and economical, which can provide a new idea for obtaining the mechanical parameters of sericite schist soft rock tunnel.

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