Application Strategies of Shotcrete Anchor Support Technology in Highway Bridge and Tunnel Engineering

This article analyzes the application strategies of shotcrete anchor support technology using a highway bridge-tunnel construction project as an example.The article covers various strategies,including support plan formulation,mortar shotcrete anchor construction,grid steel frame construction,steel mesh construction,and concrete support construction.This analysis aims to provide a guideline for those interested in applying this technology and improving the quality and safety of highway bridges and tunnels construction.

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.

Exploration on Defect Prevention and Maintenance Methods of Highway Tunnel Structure

Highway tunnel traffic safety is an important part of traffic safety.With the aging of tunnels,increase in traffic flow,changes in the operating environment and traffic accidents,the many problems started to occur in tunnels,affecting the operational and structural safety.In this paper,we summarize and analyze the types and causes of defects found in the process of tunnel maintenance at home and abroad,and propose corresponding suggestions for the current maintenance of the main structure of highway tunnels.

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.

Visual fatigue relief zone in an extra-long tunnel using virtual reality with wearable EEG-based devices

Long-time driving and monotonous visual environment increase the safety risk of driving in an extra-long tunnel. Driving fatigue can be effectively relieved by setting the visual fatigue relief zone in the tunnel. However, the setting form of visual fatigue relief zone, such as its length and location, is difficult to be designed and quantified. By integrating virtual reality(VR) apparatus with wearable electroencephalogram(EEG)-based devices, a hybrid method was proposed in this study to assist analyzers to formulate the layout of visual fatigue relief zone in the extra-long tunnel.The virtual environment of this study was based on an 11.5 km extra-long tunnel located in Yunnan Province in China.The results indicated that the use of natural landscape decoration inside the tunnel could improve driving fatigue with the growth rate of attention of the driver increased by more than 20%. The accumulation of driving fatigue had a negative effect on the fatigue relief. The results demonstrated that the optimal location of the fatigue relief zone was at the place where driving fatigue had just occurred rather than at the place where a certain amount of driving fatigue had accumulated.

Wind tunnel tests on aerodynamic characteristics of vehicles on same-storey highway and rail bridge under crosswind

In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck and CRH2 high-speed train as research targets.Wind tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of trucks.The results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of trains.To summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same time.The best shielding effect on lateral forces of trucks occurs when the train is located downstream of tracks.Finally,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.

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.

Effects of different types of guardrails on sand transportation of desert highway pavement

Guardrail,an important highway traffic safety facility,is mainly used to prevent vehicles from accidentally driving off the road and to ensure driving safety.Desert highway guardrails hinder the movement of wind-blown sand,resulting in the decline of sand transportation by the pavement and the deposition of sand gains on the pavement,and endangering traffic safety.To reveal the influence of guardrails on sand transportation of desert highway pavement,we tested the flow field and sand transport volume distribution around the concrete,W-beam,and cable guardrails under different wind velocities through wind tunnel simulation.Wind velocity attenuation coefficients,sand transportation quantity,and sand transportation efficiency are used to measure sand transportation of highway pavement.The results show that the sand transportation of highway pavement was closely related to the zoning characteristics of flow field and variation of wind velocity around the guardrails.The flow field of the concrete guardrail was divided into deceleration,acceleration,and vortex zones.The interaction between the W-beam guardrail and wind-blown sand was similar to that of lower wind deflector.Behind and under the plates,there were the vortex zone and acceleration zone,respectively.The acceleration zone was conducive to transporting sand on the pavement.The cable guardrail only caused wind velocity variability within the height range of guardrail,and there was no sand deposition on the highway pavement.When the cable,W-beam,and concrete guardrails were used,the total transportation quantities on the highway pavement were 423.53,415.74,and 136.53 g/min,respectively,and sand transportation efficiencies were 99.31%,91.25%,and 12.84%,respectively.From the perspective of effective sand transportation on the pavement,the cable guardrail should be preferred as a desert highway guardrail,followed by the W-beam guardrail,and the concrete guardrail is unsuitable.The study results provide theoretical basis for the optimal design of desert highway guardrails and the prevention of wind-blown sand disasters on the highway pavement.

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.

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.

Investigating the Effectiveness of Road-related Mitigation Measures under Semi-controlled Conditions:A Case Study on Asian Amphibians

Road traffic is the main factor causing the decline in amphibian populations worldwide. The proper design of an amphibian tunnel is one of the most efficient measures to mitigate the negative impacts of road traffic on amphibians. However, no study has investigated the effectiveness of amphibian tunnels under semi-controlled conditions in Asian amphibians. Here, we selected two representative amphibian species, the Chinese brown frog, Rana chensinensis, and the Asiatic toad, Bufo gargarizans, which suffer the most severe road mortality along the roads in Northeast China. We placed experimental arrays of culverts of various sizes(diameters of 1.5, 1, and 0.5 m for circular culverts; side lengths of 1.5, 1, and 0.5 m for box culverts), and substrate type(soil, concrete, and metal) to examine the preferences of both species during the migratory season between May and September in 2016 and 2017. The results revealed that the Chinese brown frog preferred mid-and large-sized culverts as well as soil culverts. We concluded that culverts with a side length ≥ 1 m, lined with soil, and accompanied by a ≥ 0.4 m high guide drift fence and ≤ 45° gradient on the roadside ditch wall would best facilitate road crossings for both species and likely for other amphibian species in Northeast China.

Study on the influence of skid resistance on traffic safety of highway with a high ratio of bridges and tunnels

The safety of highways with a high ratio of bridges and tunnels is related to multiple factors,for example,the skid resistance of the pavement surface.In this study,the distribution of accidents under different conditions was calculated to investigate the relationship between the road skid resistance and the incidence of traffic accidents based on the traffic accident data of the Yuxiang highway.Statistical results show that weather conditions and road alignment may affect traffic accidents.The correlation analysis method was used to study the relationship between three factors and traffic accidents.The results show that road alignment,weather conditions and road skid resistance are related to the incidence of traffic accidents.The traffic accident prediction models were established based on back propagation neural network to verify the correlation analysis results.It is confirmed that road alignment,weather conditions and road skid resistance are the factors that affect traffic accidents.

英语中的“路”

在英语中,关于“路”的说法除road,street,way,highway,和railway外,还有多种说法。 1.航路:route 例:He flew from Europe to Tokyo by the route acrossthe pole. 2.索道:cableway。