Double-arch Tunnel Research Articles

Skewed pressure characteristics induced by step-by-step excavation of a double-arch tunnel based on infrared thermography

Skewed pressure characteristics induced by step-by-step excavation of a double-arch tunnel based on infrared thermography

Mechanical behaviour of a large-span double-arch tunnel

A scaled physical model test and numerical simulations of a shallow-buried double-arch tunnel, the Great Wall Ridge Tunnel (GWRT), are performed as a first step toward a full understanding of the deformation of double-arch tunnels in shallow formations. The instrumentation of the model experiment includes high-accuracy dial gauges, miniature stress sensors, and strain gauges to record the mechanical responses of the tunnel supporting system and the surrounding rocks. The experiment strictly follows the designed excavation procedure planned for the GWRT, and the results show good agreement with those obtained from numerical simulations. We focus on the accurate approximation of the ground movement in order to ensure the safety of a neighbouring ancient relic, the Great Wall of the Qi. We also investigate the stress distributions of the surrounding rock formations and the middle wall. Based on the settlements of the ground and the plastic zone distribution, we conclude that the current design of the GWRT construction could potentially damage the neighbouring historical site.

Evolution characteristics analysis of pressure-arch in a double-arch tunnel

Evolution characteristics analysis of pressure-arch in a double-arch tunnel

Settlement Impact Analysis and Countermeasure Research of the Down Traversing Formed by the Double-Arch Subway Tunnels through the Existing Railways in Loess Area

With the large-scale construction of city subways, the down traversing formed by subway running tunnels through the existing railways or railway yards are increasing day by day. Down traversing in shield method becomes common; however, the engineering cases which can be referable in the down traversing formed by the shallow-buried excavation of double-arch tunnels through the existing railways are very little. The ability to effectively control the excavation of shallow-buried subway tunnels can directly affect the safety of railway operation. According to the engineering characteristics of the down traversing formed by the shallow-buried excavation of double-arch tunnels in loessial layer, this paper proposed the standards for railway bed and track settlement control, and offers underground water treatment measures with assistant steps implemented on the ground surface during construction, so as to ensure the railway operation safety during the construction of the tunnel. Moreover, this paper applied MIDAS-GTS finite element software to make numerical simulation analysis of the down traversing formed by the double-arch tunnel through the railway and obtained the deformation laws during down traversing. The calculations suggest the railway track deformation caused by the down traversing construction of the double-arch tunnel in this project can meet related control standard requirements. There’s certain reference value contained in the deformation laws for the point locations of monitoring measurement. The research conclusions can provide scientific proof and technical guidance for the design and construction of this running tunnel project in order to offer reference for similar projects in the future.

Study on Train Vibration Response and Cumulative Deformation of Double Arch Tunnel in Kast Foundation

Using a dynamic finite difference method, the dynamic response of double arch tunnel in Kast region of Baiyunshan tunnel on the Yichang–Wanzhou railway in China was analyzed. The method of analysis for the cumulative deformation of Kast foundation under long-term train loading was discussed further based on Dingqing Li plastic strain model. The results demonstrated that the vibrations at specific positions of the Baiyunshan double arch tunnel in Kast region are small, and both the tensile and compressive peak value and the displacement are less than the design values. Under the long-term train loading (i.e. 100 a), the cumulative plastic deformation of Kast foundation was shown to be <20 mm, which satisfies the requirement for riding comfort of low to high speed trains.

Force Analysis of the Middle Wall in Multi-Arch Tunnel under Central Hole + CRD Method

arch tunnel construction in the presence of construction mechanics often unclear, the lack of systematic design and construction of the theory can learn. Harbin Clinic Road thesis double-arch tunnel project as the basis, the construction process through its hole + CRD using the finite element simulation analysis and on-site monitoring measurement data processing, engineering arch tunnel song used in the wall study the mechanical properties.

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

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.

Design of Shallow Depth Tunnel with Asymmetric Twin Arches and its Construction Procedure in Poor Rock Mass

An asymmetric twin arched tunnel is designed to meet the line development of triple track railway in accordance with ground geological condition and topography in this paper. A partition wall is adopted to support the double arches of the tunnel, and the pilot drift and bench cut method is utilized to preserve the safe excavation of the double arch tunnel in poor rock mass in the paper. The design technique and construction method may guide the driving of such tunnels under similar condition.

Comparison and Analysis of Different Excavation Methods in Soft Rock-Extremely Soft Rock Tunnel

In order to further study the law of surrounding rock deformation of soft rock-extremely soft rock double arch tunnel, resolve problem of tunnel excavation in complex geology conditions, based on project example, the central heading full section, central heading step and division method (three heading method) as research object, measured and simulated results were compared and analyzed, and used ANDIA software to do dynamic simulation. The results show that the characters of surrounding rock deformation are different with different excavation methods; Simulated and measured results are almost the same ,and the maximum difference has only 6%, reflecting simulated value has a certain reliability; The more the step numbers are excavated in soft rock-extremely soft rock tunnel, the smaller the area excavated is, the smaller the rock is disturbance, the smaller the surface subsidence and two state convergence value is, more be able to meet construction requirements; Compared with the other two methods, division method is more to reduce the deformation in the surrounding rock with class of V.

Research on Construction Methods Affecting on Stress and Strain Distribution of Double Arch Tunnel

This paper presents the stress and strain distribution and change during the tunnel construction, and the stress and strain are compared with different construction methods. Mathematical model was firstly introduced. Then the stress and the strain during the up tunnel construction from two methods were compared. The historical stress and strain curves of key node of tunnel during the tunnel construction were analyzed. The different stress changes from different construction methods were compared. We can get the conclusion that the construction method affects the stress distribution and change.

Study on the Methods of Advanced Geological Prediction of Double-Arch Highway Tunnel in Karst Area

The paper pointed out a comprehensive advanced geological prediction method combining geological radar with advanced horizontal borehole according to the highway double-arch tunnel construction method in karst area, and had a successful application in the highway double-arch tunnel construction in karst area in Guangxi Province. It was proved in the tunnel construction that the prediction effect of the comprehensive geological prediction method was ideal.

Research on Advanced Geological Prediction in Highway Double-Arch Tunnel Construction

In this paper, a comprehensive advanced geological prediction method in highway double-arch tunnel construction was put forward, which could take the advantages of geological radar technology and the horizontal of advanced drilling in karst area. The method would give relatively accurate judgments in the construction of the highway double-arch tunnel by using different geological radar survey line layout, combining with advanced horizontal hole, which ensure the construction safety of the tunnel. The practical application of comprehensive advanced geological prediction in double-arch highway tunnel in karst area had received a good effect, and it showed the method had a certain guiding function.

Study on Predictin of Surface Subsidence of an Exremely Shallow Large-Span Double-Arch Tunnel

The Qi-Great Wall tunnel which crossed the Qi -Great Wall ruins was a large span double-arch tunnel with two-way and six-lane and the maximum depth was less than 5 meters, in order to protect the safety of thr surface ruins in the tunnel construction progress, surface subsidence control was particularly important. Through comprehensive geomechanical model test and numerical simulation , the surface subsidence wich generated in the process of construction according to construction methods of excavation and support was studied, the distribution of surface subsidence got through two methods was fitted well,and research results could provide guidance for the construction.

Analysis on Optimization Construction Procedures of Small Spacing Tunnel in Xiamen Airport Highway

The small spacing tunnel is a kind of tunnel structural style which situates between ordinary tunnel and double-arch tunnel. It has attracted great attention due to its unique merit. This paper takes Xiamen Airport highway tunnel as an example, considering four different construction steps during small spacing tunnel construction. Author applied MIDAS-GTS software to carry on numerical simulation, the influences of excavating orders of four different construction steps about stratum distortion and stable situation of middle rock pillar are analyzed. The analytical results indicate that construction Step 2 and construction Step 4 can suit actual situation of this project.

Design and Application of Formwork Loop Wheel Machine in Complex Structure Double-Arch Tunnel with Large Cross-Section and Longitudinal

For the cut and cover section of "framework + arch” modular structure of Xiamen Airport Road Project. Based on tunnel design section and other construction, technical requirements, we designed a 24.7 meters long and 13.5 meters wide framework loop wheel, with three rows of columns and complex structure and large cross section. In order to prevent to happen bias, two formwork loop wheel machines are symmetrical constructed.For the difference between outer ramp and main line, methods of filling soil and lengthening pillar are used. In order to reduce the load of the roof frame , scaffolding are installed. Obtained through the project monitoring, framework loop wheel machine meets the security requirements, and can improve construction speed and quality.

Deformation mechanism of a shallow double-arch tunnel in a sloping rock mass

The Fuxi double arch tunnel was constructed through a faulted rock mass of metasandstones overlain by slope debris. The paper describes the geological setting, highlighting the poor quality of the ground in the portal area. Following the construction of the exploratory tunnels, the concentrated overburden stress beneath the pillars caused severe deformation and cracking in the tunnel and in the slope above. An integrated analysis was carried out, taking into account the change in stress related to the excavation of the tunnels, the asymmetric pressures and the nature of the fractured overburden. This indicated that control of the tunnel vault deformation was a key step to controlling the deformation of the whole portal area. As a consequence, some additional support was provided to the central pillar prior to the construction of the main tunnels and the secondary lining was installed at an early stage.

Application and Research of Stress-strain Monitoring of Central Division Wall in Double-arch Tunnel

AbstractAccording to the structure characteristics of double-arch tunnel and monitoring-measurement principles of NATM, steel-chord pressure box and DKY-51-2 vibrating-wire sensor recording devices were used to measure the pressure between top rock mass and supporting layer of central division walls of three double-arch tunnels. Photoelastic strain gauges were also used for the measurement of stress and strain of concrete surface. It is indicated from the results that (1) the pressure value of top central division walls increases with the time and reaches 7 MPa at maximum, and it could get a larger mutation after blasting; (2) the stress value of concrete sections of central division walls is smaller than 3 MPa, and it is somewhat different with the directions and depths. The structural stress state was also numerical simulated by 2D∼σ software, and the result is close to the monitoring result.

Case studies of groundwater flow into tunnels and an innovative water-gathering system for water drainage

Groundwater inflow into tunnels can constitute a potential hazard and also is an important factor influencing the speed of tunnel excavation. In this paper the results of numerical modelling are presented to investigate the groundwater flow and the distribution of the pore pressure around tunnels. Two types of tunnels, double-arch tunnel and twin-tube tunnel, were studied. Potential leakage places are identified for the two types of tunnels. The most permeable place in the double-arch tunnel is at the contact interface between the middle wall and the overlying rock. The results of numerical modelling are compared with field observations in the case studies. Based on the results of numerical modelling and the field investigations, an innovative water-gathering system for reducing water leakage was proposed and applied in some tunnels on ChangJi Expressway in China. The water-gathering system can be quickly glued to the rock surface and easily installed for tunnelling. It can be applied in tunnels where water-bearing fractures are well-developed in the rock mass.