scholarly journals Development and Application of Model Test System for Reconstruction and Expansion of Existing Shallow Single-Hole Tunnel into Twin-Arch Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yanling Jia ◽  
Aohui Ouyang ◽  
Siyu Wang ◽  
Xing Liang ◽  
Bin Wang ◽  
...  
Keyword(s):  
Model Test ◽  
Ground Surface ◽  
Test System ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Laboratory Model ◽  
Internal Stresses ◽  
Tunnel Excavation ◽  
Single Hole ◽  
Ground Surface Settlement

In this study, we developed a tunnel excavation model test system to investigate the deformation and mechanical response of the surrounding rocks and tunnel structure during the reconstruction and expansion of an existing shallow single-hole tunnel into a twin-arch tunnel. A model test was conducted to study the variation in the ground surface settlement characteristics, surrounding rock pressure, and internal stresses of the supporting structure and midwall during the construction process. The influence of the excavation distance on displacements and structural stress between the faces of the left and right tunnels was analysed using numerical software. A comparison between the model test results and the monitoring and measurement construction results revealed a fairly consistent ground surface settlement, indicating that the system is stable and reliable and can be widely applied to laboratory model test research on tunnel excavation. Results show that the excavation of the first tunnel had a significant effect on the stability of the surrounding rock within the distance of a single-tunnel span behind the tunnel face. When the excavation distance between the two tunnels exceeded twice the length of the single-tunnel span, its effect on the stresses and deformation of the reconstructed twin-arch tunnel was negligible.

Estimation of the ground surface settlement induced by the tunnel excavation in Changchun, China

2021 ◽  
Author(s):  
Jian Lu ◽  
Jingjing Sun ◽  
Yang Shen ◽  
Wei Zheng ◽  
Aijun Yao ◽  
...  
Keyword(s):  
Ground Surface ◽  
Surface Settlement ◽  
Tunnel Excavation ◽  
Ground Surface Settlement

Analysis of the Ground Surface Settlement of Metro Tunnel by Using Peck Formula

2014 ◽  
Vol 1065-1069 ◽  
pp. 414-420
Author(s):  
Xiong Fei Yang ◽  
Hong Yuan ◽  
Jia Yu Wu ◽  
Hou Mei Zhang
Keyword(s):  
Surface Deformation ◽  
Ground Surface ◽  
Surface Subsidence ◽  
Central Point ◽  
Surface Settlement ◽  
Point Method ◽  
Linear Regression Method ◽  
Tunnel Excavation ◽  
Ground Surface Settlement ◽  
Ground Surface Subsidence

Based on the peck formula, this paper has analyzed measured data of ground surface subsidence, and get the regression curve of ground surface subsidence. Expression for degree of reliability of the maximum ground surface settlement is derived analytically by using central-point method. On the basis of a certain section of tunnel of Guangzhou subway constructed by mining excavation method, linear regression method can be effectively fitting the ground surface deformation data due to tunnel excavation. The central-point method provides a new way for reliability analysis of the ground surface settlement of shield construction.

The Study of Construction Countermeasures about Subway Tunnel Passes through High Fill Geological Area of Crushed Rock Soil

2012 ◽  
Vol 170-173 ◽  
pp. 1801-1809
Author(s):  
Lin Qing Huang ◽  
Tong Qing Wu ◽  
Zhi Gang Qi
Keyword(s):  
Technical Problem ◽  
Ground Surface ◽  
Surface Settlement ◽  
Crushed Rock ◽  
Subway Tunnel ◽  
Tunnel Excavation ◽  
Existing Building ◽  
Ground Surface Settlement ◽  
Calculation Results ◽  
Pass Through

This is an important technical problem that subway tunnel excavation pass through a filled area of crushed rock soil in mountainous city,and to control the ground surface settlement and reduce the influence for existing building have great significance. The paper presents an example that tunnel excavation pass through complex geological area of metro line no.3 project in Chongqing.At first,according to the monitoring results,the big surface subsidence and structures cracking appear in the process of the tunnel excavation are discussed.And then,use the finite element method analysis and calculation. On the basis of the analysis and calculation results, many effective technical measures are proposed to ensure stability of surrounding rock and control the ground surf ace settlement. Such as small catheter grouting consolidation, CD construction method, excavation speed control and so on. The monitoring results show that the vault sinks and convergence value reduce significantly after the improved technology measures are used.At same time,the ground surface settlement is controlled effec- tively. The results show that the improved construction measures achieve the purpose to control the settlement and deformation. The study result of construction scheme can provide reference for the similar project.

Study on Creep Constitutive Model of Stratified Siltstone and its Application to Environmental Hazards Treatment

2021 ◽  
Author(s):  
Yiran Yang ◽  
Xingping Lai ◽  
Tao Luo ◽  
Kekuo Yuan ◽  
Feiyong Wang
Keyword(s):  
Numerical Simulation ◽  
Constitutive Model ◽  
Ground Surface ◽  
Environmental Hazards ◽  
Surrounding Rock ◽  
Living Environment ◽  
Surface Settlement ◽  
Main Body ◽  
Ground Surface Settlement ◽  
Simulation Results

Abstract Mining causes environmental hazards which have an adverse effect on ecological system and human living environment. Rock is the main body of underground coal mining, and among them stratified siltstone is very common. Creep and instability of underground stratified siltstone is one of the main inducing factors of ground fissures and ground surface settlement. In this study, on the basis of fully considering its stratified structure features, we built and theoretically analyzed the viscoelastic-viscoplastic constitutive model of stratified siltstone. Creep tests and numerical simulation under multi-stress were conducted. Numerical simulation results under high, medium and low stress were consistent with the creep test results, it made up for the deficiency of traditional creep models in predicting plastic deformation at low stress level. Numerical simulation results showed that under different boundary conditions, the proposed model had advantage to more accurately simulate creep behavior of stratified siltstone compared with traditional models. Also, the numerical simulation results reveled creep characteristics of underground roadway surrounding rock, based on which a supporting scheme was put forward. In the stress adjustment stage, the strain rate dropped significantly from 14.6mm/d to 10.3mm/d. Then, it entered the deceleration creep stage. Creep of roadway surrounding rock and ground surface settlement stopped. The environmental hazards were solved to a great extent.

Contrast Analysis on Deformation Characteristic of Urban Subway Tunnel Excavation by Numerical Simulation and Field Measurement

2012 ◽  
Vol 170-173 ◽  
pp. 1704-1707
Author(s):  
Wei Feng Yang ◽  
Xi Liu ◽  
Yi Wang ◽  
Ming Li
Keyword(s):  
Numerical Simulation ◽  
Field Measurement ◽  
Ground Surface ◽  
Horizontal Displacement ◽  
Surface Settlement ◽  
Loss Ratio ◽  
Tunnel Excavation ◽  
Geological Conditions ◽  
Ground Surface Settlement ◽  
Ground Loss

Under the particular geological conditions of clay and sandy soil interbed, through numerical analysis and field monitoring, the surface settlement, horizontal deformation and the stress distribution were analyzed after the tunnel excavation in a metro station in Beijing, China. There are differences of surface deformation whether the backfill grouting behind arch during tunnel excavation. While the backfill grouting behind arch, the ground surface settlement and the horizontal displacement reach 9.36 mm and 2.16 mm respectively. But while no backfill grouting behind arch, the ground surface settlement and the horizontal displacement are 14.51 mm and 8.85 mm respectively. The maximum ground settlement induced by tunnel excavation is directly proportional to ground loss ratio. When the ground loss ratio is 1%, the result is well consistent with the field measurement value and the numerical simulation result.

Analysis of Surface Subsidence Rule of the Shallow Subway Tunnel Construction

2013 ◽  
Vol 671-674 ◽  
pp. 1081-1086 ◽  
Author(s):  
Fei Fei Wang ◽  
Hui Ren Bai ◽  
Jing Jing Li
Keyword(s):  
Ground Surface ◽  
Calculation Model ◽  
Surface Subsidence ◽  
Surface Settlement ◽  
Tunnel Construction ◽  
Maximum Point ◽  
Subway Tunnel ◽  
Monitoring Frequency ◽  
Ground Surface Settlement ◽  
Value Range

In order to study the Dalian Metro section 202(Cujin Road station-Chunguang Street station, which is shallowly buried and covered with plain fill)’s ground surface settlement, the monitoring measuring station was built during the construction. After 3 months’ measuring by precision level,the data shows that the maximum point is in the center line of the tunnel of the upper part. The settlement is about 25.66-31.82mm. This paper put forward the concept of the distance span ratio β, β effective value range was - 4 <β< 4,Surface subsidence is closely related with β, Severe surface subsidence stage is -2 <β< 2, Occupy whole deformation is 67.5-77.6%,settlement rate about 0.84-0.93mm/d, so should strengthen the monitoring frequency, Suggest increases site tour. Field test results and the ground surface settlement calculation model winkle are identical with each other; the monitoring results have important guiding significance and reference for Dalian subway and the similar shallow depth excavation tunnel construction.

scholarly journals Deformation Characteristics of Raising, Widening of Old Roadway on Soft Soil Foundation

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2117
Author(s):  
Keke Li ◽  
Wenyuan Xu ◽  
Liang Yang
Keyword(s):  
Lateral Displacement ◽  
Soft Soil ◽  
Ground Surface ◽  
Surface Settlement ◽  
Deformation Characteristics ◽  
Construction Methods ◽  
Ground Surface Settlement ◽  
Total Settlement ◽  
Soil Foundation ◽  
Soft Soil Foundation

The deformation characteristics of a raised and widened old Chinese roadway on a soft soil foundation are investigated in this study via finite element numerical simulation. The rules of ground surface settlement, slope foot lateral displacement, and ground surface settlement evolution of the roadbed under three modes (one-time construction of an eight-lane expressway, widened four-lane expressway, and raised/widened four-lane expressway) are compared. The ground surface settlement process of the eight-lane road foundation, which is formed by first widening and then raising the road, is highly complex. The ground surface settlement curve under the old road foundation increases and then decreases. The lateral displacement of the slope foot also interacts with the widening and raising of the eight-lane roadbed foundation. The range of lateral displacement is 70.05, 42.58, 124.81, 104.54 mm. Fifteen years after construction, the total settlement of the raised and widened roadbed is much larger than that of the one built directly. The total settlement values at the center of the two roadbeds are 297.05 and 234.85 mm, respectively. This manuscript provides data support for the reconstruction and expansion of roads on soft soil foundations, for choosing appropriate construction methods to build roads, and for avoiding major road damage, which is of great significance to the construction of road infrastructure in the future.

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