Research progress and development trends of highway tunnels in China

The highway tunnel system in China has in recent years surpassed Europe, the United States, and other developed countries in terms of mileage, scale, complexity, and technical achievement. Much scientific research has been conducted, and the results have greatly facilitated the rapid development of China＇s highway tunnel building capacity. This article presents the historical development of highway tunneling in China, according to specific charac- teristics based on construction and operation. It provides a systematic analysis of the major achievements and chal- lenges with respect to construction techniques, operation, monitoring, repair, and maintenance. Together with future trends of highway tunneling in China, suggestions have been made for further research, and development prospects have been identified with the for a Chinese-style highway aim of laying the foundation tunnel construction method and technical architecture.

Kinematical analysis of highway tunnel collapse using nonlinear failure criterion

For different kinds of rocks,the collapse range of tunnel was studied in the previously published literature.However,some tunnels were buried in soils,and test data showed that the strength envelopes of the soils followed power-law failure criterion.In this work,deep buried highway tunnel with large section was taken as objective,and the basic expressions of collapse shape and region were deduced for the highway tunnels in soils,based on kinematical approach and power-law failure criterion.In order to see the effectiveness of the proposed expressions,the solutions presented in this work agree well with previous results if the nonlinear failure criterion is reduced to a linear Mohr-Coulomb failure criterion.The present results are compared with practical projects and tunnel design code.The numerical results show that the height and width of tunnel collapse are greatly affected by the nonlinear criterion for the tunnel in soil.

Analysis of Detection and Treatment Schemes of Highway Tunnel Lining Cracks

Highway tunnels play a very important role in people's daily life.Among them,lining is an essential part of tunnel engineering,and the quality of lining greatly affects the overall quality of the tunnel.On this basis,the causes of lining cracks and the detection methods of existing highway tunnel lining cracks are analyzed,and the treatment countermeasures for highway tunnel lining cracks are proposed.

Field Test of Concrete Impermeability of Side Wall of Lakeside Highway Tunnel

The impermeability of concrete of the exterior wall of the underground tunnel in water-rich stratum is a key concern of engineers.Taking the Aixihu highway tunnel in Nanchang city as an example,the impermeability of the concrete in the side wall of the highway tunnel is tested,through multiple tests,such as the embedded steel pipe,water injection,and field observation.The results show that,under the action of 2mpa of water pressure,no water flow permeates from the side wall of the concrete tunnel,indicating that the impermeable performance of concrete tunnel in this section meets the engineering requirements,and hoping that this research can be used as a reference for other similar projects.

Stability analysis of tunnel face reinforced with face bolts

Face bolting has been widely utilized to enhance the stability of tunnel face,particularly in soft soil tunnels.However,the influence of bolt reinforcement and its layout on tunnel face stability has not been systematically studied.Based on the theory of linear elastic mechanics,this study delved into the specific mechanisms of bolt reinforcement on the tunnel face in both horizontal and vertical dimensions.It also identified the primary failure types of bolts.Additionally,a design approach for tunnel face bolts that incorporates spatial layout was established using the limit equilibrium method to enhance the conventional wedge-prism model.The proposed model was subsequently validated through various means,and the specific influence of relevant bolt design parameters on tunnel face stability was analyzed.Furthermore,design principles for tunnel face bolts under different geological conditions were presented.The findings indicate that bolt failure can be categorized into three stages:tensile failure,pullout failure,and comprehensive failure.Increasing cohesion,internal friction angle,bolt density,and overlap length can effectively enhance tunnel face stability.Due to significant variations in stratum conditions,tailored design approaches based on specific failure stages are necessary for bolt design.

Experimental study on performance of spring damping support structure system for large deformation tunnel in soft rock

According to the convergence confinement theory,it is an effective measure to control the large deformation of high ground stress in fractured soft rock tunnels by using yielding support.The yielding support can be classified as either radial or circumferential yielding support.Circumferential yielding support is achieved by transforming radial displacement into circumferential tangential closure without compromising the support capacity of the primary lining support structure.Based on this,and inspired by the design principle of dampers,a yielding support structure system with spring damping elements as its core was developed,based on the connection characteristics of steel arches in highway tunnel,which can provide increasing support resistance in the yielding deformation section.Then the mechanical properties of spring damping elements were obtained through indoor axial pressure and flexural tests.In addition,according to these results with numerical calculations,the yielding support structure system with embedded spring damping elements can reduce the internal force of the support structure by approximately 10%and increase the area of the plastic zone of the surrounding rock by 11.23%,which can fully utilize the self-bearing capacity of surrounding rock and verify the effectiveness of circumferential yielding support.Finally,the spring damping support structure system was designed with reference to the construction process of the tunnel excavated by drilling and blasting method,and the transformation of the spring damping element to spring damping support structure was achieved.Based on field test results,surrounding ground pressure for the yielding support optimization scheme was reduced by 40%and more evenly distributed,resulting in the successful application and a reduction in the construction cost of large deformation tunnels in soft rock.

Influence of traffic on the temperature field of tunnel in cold region:A case study on the world’s longest highway spiral tunnel

The impact of the piston wind caused by vehicle traffic on the temperature field distribution of the tunnel cannot be ignored,especially in spiral tunnels,where the temperature field distribution is more complicated than that in straight tunnels.Based on the world’s longest highway spiral tunnel,this study explores the influence of traffic on the temperature fields of spiral and straight tunnels,and proposes a new design method for laying length of insulation layer.The results show that traffic has a significant effect on the temperature field dis-tribution in the tunnel.The influence degree of different traffic elements decreases in the following order:average vehicle speed>daily traffic>morning rush hour>evening rush hour.The temperature field distribution of spiral tunnels is asymmetry on the left and right compared with straight tunnels,while the influence degree of traffic on the outside of spiral tunnels is similar to that of straight tunnels.Due to the difference of wind direction and traffic direction at different tunnel openings,an asymmetric insulation layer laying method is proposed.It is suggested that the lengths of the insulation layers of the Jinjiazhuang Tunnel should be 1200 m for the right tunnel inlet,700 m for the right tunnel outlet,700 m for the left tunnel inlet,and 1400 m for the left tunnel outlet.