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 Shaking table test on the seismic response of the portal section in soft and hard rock junction

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110313
Author(s):  
Guangyao Cui ◽  
Jianfei Ma
Keyword(s):  
Seismic Response ◽  
Contact Stress ◽  
Hard Rock ◽  
Shaking Table Test ◽  
Soft Rock ◽  
Active Regions ◽  
Shaking Table ◽  
Inertia Force ◽  
Ground Acceleration ◽  
Seismic Safety

Tunnel portal sections located in the soft-hard rock junction are vulnerable to the strong earthquake motions in seismically active regions. The main objective of this paper is to investigate the seismic response of tunnel portals located in the soft-hard rock junction. Taking the Baiyunding tunnel in northeast China as a background, a shaking table test with a geometric scaling ratio of 1:30 was built. Details of test setup and procedures are introduced first and then the test results are presented. The discussion of the results is based on the peak ground acceleration (PGA), the longitudinal, the contact stress, and the safety factor. The results show that the soft section of the soft-hard rock junction suffers remarkable damages under strong seismic motions, while the hard rock section is less affected by earthquakes. The increasing soft rock range causes a rise of the forced displacement of tunnel linings, which, together with the seismic inertia force, leads to the increase of the contact stress of the linings, and ultimately resulting in the deterioration of the tunnel seismic safety. To mitigate the seismic damage of tunnel portals in the soft-hard rock junction, rock grouting, bolt support, and other effective reinforced methods should be considered in the seismic design of the soft section.

scholarly journals Study on Seismic Performance of UHV Transformer Based on Soil-structure Interaction

2022 ◽  
Vol 2148 (1) ◽  
pp. 012020
Author(s):  
Yaodong Xue ◽  
Yongfeng Cheng ◽  
Zhicheng Lu ◽  
Zhubing Zhu ◽  
Haibo Wang ◽  
...  
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
High Voltage ◽  
Shaking Table Test ◽  
Low Voltage ◽  
Great Influence ◽  
Test Method ◽  
Shaking Table ◽  
Peak Acceleration ◽  
Measuring Point

Abstract At present, the seismic performance of UHV transformers is mostly studied without considering the interaction between soil and superstructure. In practical engineering, the transformer is installed on the foundation slab buried in the soil. Under the action of earthquake, the interaction between the soil and the structure changes the earthquake response of the upper electrical structure. In order to study the influence of the interaction between soil and structure on the seismic performance of the transformer, the shaking table test method of simulated earthquake is used, and the shaking table test of UHV transformer with scale ratio of 1:4 is carried out in class I field conditions. The dynamic characteristics of the equipment and the seismic response of the bushing under different test conditions are obtained respectively. The test results show that when the peak acceleration is 1.2g, the acceleration response at each measuring point on the box is 1.63-1.92 times that when the peak acceleration is 0.4g. With the increase of seismic peak acceleration, the acceleration and strain increase of high voltage bushing are greater than that of medium and low voltage bushing, which has a great influence on the seismic response of high voltage bushing. The research conclusion can provide reference for substation engineering design.

Shaking Table Test on Seismic Performance of Ceiling without Braces and Artificial Spacing to Surrounding Object

2015 ◽  
Vol 104 (1) ◽  
pp. 1-8
Author(s):  
Kenichi Tahara ◽  
Yasuhito Sasaki ◽  
Yukihiro Sato ◽  
Satoshi Sasaki ◽  
Shojiro Motoyui
Keyword(s):  
Seismic Performance ◽  
Shaking Table Test ◽  
Shaking Table

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.

Shaking Table Test Study on Mid-Story Isolation Structures

2012 ◽  
Vol 446-449 ◽  
pp. 378-381
Author(s):  
Jian Min Jin ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Yu Hong Ma ◽  
Chao Yong Shen
Keyword(s):  
Seismic Response ◽  
Seismic Isolation ◽  
Shaking Table Test ◽  
Base Isolation ◽  
Shaking Table ◽  
Natural Period ◽  
Isolation System ◽  
Isolation Layer ◽  
Lead Rubber Bearing ◽  
Complex Structural

Mid-story isolation structure is developing from base isolation structures. As a complex structural system, the work mechanism of base isolation structure is not entirely appropriate for mid-story isolation structure, and the prolonging of structural natural period may not be able to decrease the seismic response of substructure and superstructure simultaneously. In this paper, for a four-story steel frame model, whose prototype first natural period is about 1s without seismic isolation design, the seismic responses and isolation effectiveness of mid-story isolation system with lead rubber bearing are studied experimentally by changing the location of isolation layer. Respectively, the locations of isolation layer are set at bottom of the first story, top of the first story, top of the second story and top of the third story. The results show that mid-story isolation can reduce seismic response in general, and substructure acceleration may be amplified.

scholarly journals Analysis on Loose Circle of Surrounding Rock of Large Deformation Soft-Rock Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Rui Wang ◽  
Yiyuan Liu ◽  
Xianghui Deng ◽  
Yu Zhang ◽  
Xiaodong Huang ◽  
...  
Keyword(s):  
Large Deformation ◽  
Theoretical Calculations ◽  
Rapid Development ◽  
Field Tests ◽  
Soft Rock ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Distribution Law ◽  
Geological Conditions ◽  
Rock Tunnel

With the rapid development of tunnel construction in China, deep buried and long tunnel projects are emerging in areas with complex engineering geological conditions and harsh environment, and thus large deformation of tunnels under conditions of high in situ stress and soft rock becomes increasingly prominent and endangers engineering safety. Therefore, it is of great significance to control the deformation and improve the stability of surrounding rock by analyzing the thickness and distribution law of loose circle according to the unique mechanical properties and failure mechanism of surrounding rock of large deformation soft-rock tunnel. Based on unified strength theory, this paper deduces the radius calculation formula of the loose circle by considering the influence of intermediate principal stress. Furthermore, the theoretical calculations and field tests of the loose circle in the typical sections of grade II and III deformation of Yuntunbao tunnel are carried out, and the thickness and distribution law of loose circle of surrounding rock of large deformation soft-rock tunnel is revealed. The results show that the formula based on the unified strength criterion is applicable for a large deformation tunnel in soft rock.

scholarly journals Seismic Response of Prestressed Anchors with Frame Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Shuaihua Ye ◽  
Zhuangfu Zhao
Keyword(s):  
Seismic Response ◽  
Shaking Table Test ◽  
Coupling Effect ◽  
Soil Mass ◽  
Calculation Model ◽  
Shaking Table ◽  
Frame Structure ◽  
Dynamic Calculation ◽  
Concentrated Mass ◽  
Linear Spring

Based on the equivalent mass-spring model and considering the coupling effect between creep soil and prestressed anchors, the dynamic calculation model of prestressed anchors with frame structure is established. The soil mass is expressed in the form of concentrated mass. The action of the frame structure on the soil is treated as a parallel coupling of a linear spring and a linear damper, and the free section of the anchor is treated as a linear spring. Considering the creep characteristics, the soil is regarded as a Generalized Kelvin body and the anchoring section of the anchor is regarded as an equivalent spring body, which are coupled in parallel. Considering the effect of slope height, the dynamic calculation model is solved and the seismic response is analyzed. Finally, an engineering example is used to verify the calculation method in this paper, and the results are compared with the shaking table test and numerical simulation. It shows that the calculation model proposed in this paper is safe and reasonable for the seismic design and analysis of the slope supported by prestressed anchors with frame structure.

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