Taking the actual project as an example,the mechanism of instability of the wet and soft roadbed of slope in a mountainous area is analyzed through the engineering survey and engineering monitoring.The results show that,the first reason for the instability of the roadbed is that the terrain is conducive to water storage and the groundwater is rich.At the same time,the slope has a thick covering layer and a soft layer of carbonaceous mudstone developed at the rock-soil interface;the second is that sustained heavy rainfall causes the softening of the rock and earth mass,while the fluctuation of the water body in the front edge of the river affects the stability of the slope,causing the sliding deformation and backward development of the slope,and ultimately forming a landslide.Based on this conclusion,the treatment measures for temporary drainage + steel pipe piles for temporary reinforcement and comprehensive waterproof and drainage + anti-slip piles for permanent support are put forward.The monitoring results show that,the treatment effect is good,which can provide reference for similar projects.
During the construction process of mountain tunnels,multiple subparallel fault systems are often crossed simultaneously,which can easily cause geological disasters such as instability of the excavation face rock mass,large deformation of the surrounding rock,and collapse and so on.Based on the Wenyao tunnel project,taking the mountain tunnel crossing the subparallel double fault fracture zone as the object,the numerical simulation and analysis on the layered excavation process is made by using FLAC 3D software,and the influence law of the spacing and inclination angle of the subparallel double fault fracture zone on the deformation characteristics of the surrounding rock is studied.The research results show that:the fault fracture zone is the weak part of tunnel construction and excavation,and its displacement value is significantly greater than the displacement value of the surrounding rock in the upper and lower panels;when the distance between two subparallel fault zones is 10m,the displacement of the surrounding rock induced by tunnel excavation in the two fault fracture zones will have a significant mutual interference effect,which is greater than the displacement of the surrounding rock in a single fault fracture zone;as the inclination angle of the parallel fault zone increases,the displacement value of the surrounding rock gradually decreases;the smaller the distance between the parallel fault zones,the greater the displacement value of the surrounding rock in the fractured zone.
The treatment of the pile foundation of the karst geological bridges needs to be determined according to factors such as stratigraphic information at the pile location,karst cave location,size,and filling situation and so on.The length in the limestone area of the phase Ⅱ project of the Yibin-Zhaotong expressway is 21.41km,and there are 14 bridges in the karst area.In combination with the specific case of this project,the treatment schemes for the pile foundation of the karst geological bridges of expressways in mountainous area are analyzed from multiple perspectives of exploration,design,and construction.The value taking methods for the size,length,rock penetration depth of the pile foundation of the bridges and the thickness of the supporting layer of the karst cave roof in the karst area as well as the key technologies and control points for karst treatment are obtained,so as to ensure the overall quality of the project and guarantee the comprehensive benefits of the project to the most extent.
The tertiary clay rock is mostly in a semi diagenetic state,which greatly reduces its strength when encountering water and is prone to forming weak structural planes,thereby forming landslides.Taking the case of a landslide on a highway in Yunnan as the research object,the causes of the landslide are analyzed comprehensively based on the terrain,formation lithology,and characteristics of landslide and so on in the project area.In combination with indoor test data and landslide conditions,the back calculation on the landslide parameters is made,and the sliding zone parameters are ultimately determined.The stability of the landslide is evaluated.The research shows that:(1)the landslide occurs in the tertiary clay rock strata under the combined action of concentrated rainfall and roadbed filling;(2)landslides are in an unstable state under normal working conditions,characterized by continuous deformation,accumulated stress and possible sliding;under abnormal working conditions,it is in an unstable state with the characteristic of releasing stress and sliding.
In order to solve the problems like slow speed,low safety,poor robustness of traditional image processing methods,and susceptibility to environmental influences and so on in the manual detection for the surface defects of cables of the cable-stayed bridge,the panoramic imaging is used to achieve the surface defect detection for cables of the cable-stayed bridge.Three kinds of common surface defects like holes,gaps,and damages are constructed by using PVC pipes to simulate the cable surface;the panoramic image of the cable surface is obtained by four cameras,the data is transmitted to the computer through the wireless image transmission device,and the background is removed through the image mask and the defect dataset is constructed;the dataset is trained by using YOLOX network and the experiment is made on the test set.The results show that:the average accuracy(mAP)of YOLOX network is 92.77%,and the frame rate(FPS)is 18.The detection results are superior to other mainstream object detection methods,which can achieve the real-time and accurate detection of cable surface defects.
In order to test the vertical bearing capacity of the bored pile of the super large bridge,two methods like static load test and numerical simulation are used for comparative analysis.The allowable value of the ultimate load of the pile foundation obtained from the on-site static load test is the same as the numerical simulation analysis result,and the measured value is very close to the calculated value.The axial force test result of the pile body is very close to the numerical simulation calculation result,and the variation trend of the axial force curve is the same.The rationality of the ultimate load of the pile foundation is further verified.Through the comparative analysis,it is concluded that the vertical bearing capacity of the bored pile meets the design requirement,and the numerical simulation calculation result is accurate.
The horizontal evacuation method is adopted for the separated highway tunnel.In order to prevent smoke from flowing through the horizontal channel to adjacent non-fire tunnel,it is necessary to control the jet fan in the left and right tunnels through linkage.Firstly,three linkage control schemes are put forward;then the fire dynamic software FDS is used to simulate the wind speed,wind direction and smoke spread inside the horizontal channel for each scheme;finally the optimal scheme is put forward through the comparative analysis,that is,turn on the upstream fan of the fire source in the fire tunnel,and turn on the fans on both sides of the horizontal channel in opposite directions in the non-fire tunnel to form positive pressure.The research results provide reference for the issue of how to control the linkage of the jet fan in the separated tunnel under fire conditions.
Due to various factors,most tunnel linings in China suffer from varying degrees of diseases,such as incomplete lining,voids,insufficient thickness of steel reinforcement protective layer,and exposed steel reinforcement.Among them,lining disease is the most common type of tunnel disease,which has a significant impact on the stability of the tunnel structure.Considering the factors that affect the stability of the tunnel lining structure in practical engineering,the geological radar is used to detect the tunnel lining,analyze and interpret the detection data with high quality,and collect other influencing factors from the data.By improving the thickness of tunnel lining and the detection accuracy on the tunnel lining defects,the tunnel lining defects are accurately located.
How to solve the reflection cracks at the joints is one of the key issues in the"white and black"project of highway pavement.For this purpose,the impact of changes in asphalt overlay thickness and old cement concrete pavement thickness on the bottom load stress of the asphalt layer is studied by establishing the finite element numerical model of pavement structure.At the same time,the effectiveness of three kinds of treatment measures for crack resistance including polyester fiberglass cloth,stress absorption layer,and a combination of the two is compared and analyzed.The results show that:increasing the thickness of the asphalt overlay appropriately can delay the generation of reflection cracks.Considering the economic effects,there is an optimal value of 10cm for the thickness of the asphalt overlay;the thickness of the old concrete pavement has a little impact on the reflection cracks of the asphalt overlay;both polyester fiberglass cloth and stress absorption layer can weaken the stress concentration at the bottom of the asphalt layer.The anti-crack effect from small to large is:directly adding the asphalt layer
Based on the reconstruction and expansion project of Huangshi expressway(Xinji-Gaocheng section),the maintenance schemes for the widening pavement and the existing pavement of expressway reconstruction and expansion are studied,and the technical scheme for the pavement engineering of expressway reconstruction and expansion is formulated.Taking the coordination between the maintenance needs of the old road and the structural scheme of the widening pavement into account,the reasonable overall pavement construction scheme is determined based on the characteristics of the internal widening of the project and the maintenance history of the project section.
In combination with the engineering project of water inrush treatment in a tunnel in Guizhou province,the special hydrological survey is made to deeply analyze the reasons for water inrush and determine the maximum instantaneous water inflow of the tunnel.On this basis,the comprehensive treatment scheme for tunnel diseases is put forward.This scheme has some guidance and reference significance for similar projects.
Taking a deep canyon bridge in Guizhou province as the example,the survey methods used in bridge survey and design when encountering special geological conditions are elaborated.The research shows that,the Orlan terrace strata in eastern Sichuan and northern Guizhou,namely the Jialingjiang formation and Maocaopu formation are sedimentary strata of the same period on the ground of Shangyangzitai.The diagenetic environment is highly similar,with karst breccia at the top and similar lithological characteristics.Through the engineering case analysis,it has been found that the areas with karst breccia are prone to other unfavorable geological conditions due to their numerous unfavorable characteristics.Through the research and analysis of this geological phenomenon,the reference materials are provided for the smooth construction of bridges,so as to provide reference experience for other similar engineering constructions.
In combination with on-site excavation profiles,the engineering geological conditions of the formation lithology,geological structure,unfavorable geology,and special rock soil and so on within the section are identified through the geological mapping and drilling of excavation slopes.The characteristics of fault thickness,trend,inclination and extension degree and so on are emphatically identified,the impact on the highway construction is judged,and the slope stability is evaluated,so as to provide the engineering geological basis for the design of the excavation section.
In order to deeply explore the potential information of bridge data and identify the data exception,the abnormal data of the bridge structure monitoring system is classified,and the causes of different types of data exception are analyzed in combination with the data analysis and application experience of the system in the maintenance work of Liaohe bridge on"abnormal data".For the phenomenon of"abnormal data"and"false alarm"in the monitoring system,the hardware equipment and software function of the system are analyzed and studied,the functions like active identification,intelligent analysis,automatic filtration and so on of the system for abnormal data are strengthened,so as to mitigate the workload of on-site inspection and troubleshooting,and greatly improve the work efficiency of maintenance.
With the development of logistics transportation,the congestion caused by the growth of highway transportation has had a certain impact on the traffic safety and environmental pollution.In order to reduce the negative impact of the logistics industry and maintain its driving force for regional economic development,the thorough exploration is conducted on the coordinated development path of the logistics industry and regional economy from the aspects of optimizing the layout and construction of transportation infrastructure,promoting the multimodal transportation and intelligent logistics system,improving logistics supporting facilities and services,strengthening the transportation safety and environmental protection management,and promoting the regional coordinated development and economic integration and so on.
In order to prevent tunnel accidents caused by the ground surface settlement,taking Fuzhou road station of Qingdao metro line 4 as the research object,the systematic research is conducted on the settlement law and control optimization measures of the shallow-buried tunnel construction of Qingdao metro by using the on-site monitoring data and Midas GTS NX simulation software.Based on the analysis of geological exploration data,settlement data,and advanced geological prediction,the factors affecting the tunnel stability and the settlement law of the section are obtained;by establishing the seepage-stress coupling models under different water level environments,the settlement law on the ground surface is analyzed,and the maximum settlement position,i.e.the most unfavorable position is determined and reasonably optimized,so as to provide reference for similar underground engineering design and construction.
Emulsified asphalt has advantages such as high efficiency,energy conservation,environmental protection,and low pollution and so on,while resin materials have high adhesion and high strength performance.Therefore,the organic combination of emulsified asphalt system and waterborne resin system is made to develop a new type of asphalt pavement pit repair material that not only has good construction and workability of emulsion-type repair materials,but also has excellent resin bonding performance,high-temperature stability and durability.The technical performance of the waterborne resin-emulsified asphalt system is evaluated and analyzed,and the physical engineering is constructed by using the pit repair material based on the waterborne resin-emulsified asphalt system,with good application effect.The results show that:the pit repair material of water-based resin-emulsified asphalt system is beneficial for improving the quality and prolonging the service life of pit disease repair.
There is relatively little experience in the construction of tunnels in high-altitude cold area.The constructed tunnels have problems such as lining icing,tunnel cracking and water leakage,and peeling and crumbling of tunnel walls and so on.The construction quality of tunnels is relatively low,with the greatly weakened function.There are serious safety hazards,making the maintenance work very difficult.In response to the tunnel engineering in seasonal cold area,it is necessary to clarify the shortcomings in the current research on tunnels in cold area,comprehensively consider the influence of temperature and other factors of tunnels in cold area on the frost heave rate of surrounding rock and the constraint strength of lining,and put forward the targeted measures for frost damage prevention and control of tunnels in cold area.
In response to the lack of evaluation indexes for interlayer bonding performance during the pavement construction at present,the necessity of increasing the quantitative evaluation indexes for interlayer bonding performance of pavement is analyzed,and its evaluation indexes and test methods as well as factors that should be considered when formulating the acceptance evaluation standard are discussed.The results show that:it is necessary to increase the quantitative evaluation indexes and evaluation standard for the interlayer bonding performance of the pavement during the acceptance of pavement construction quality;the interlayer bonding performance can be evaluated by using the shear strength and tensile strength,but the test method for determining the shear strength needs to be further unified;when formulating the evaluation standard,influencing factors such as the type of structural layer material,bonding material type and distribution amount,vertical load and external environment(temperature,humidity,etc.)should be considered.
In response to the problem of maintenance road uplift and side wall convergence disease in a high-speed operating tunnel in the western region of Liaoning province,the numerical analysis model is established based on special inspection and geological survey and in combination with the actual disease characteristics on site,so as to analyze the safety of the tunnel lining structure in the presence or absence of inverted arches and the external load increase caused by the expansive surrounding rock.The results show that:the inverted arch structure plays a crucial role in the safety of the lining.In the absence of an inverted arch,the structural bending moment is large,leading to insufficient safety factors.The inverted arch structure greatly weakens the structural bending effect and improves the safety factor of the structure;the inverted arch structure effectively suppresses the structural deformation of the arch foot under external load,reducing the structural convergence.The increase in external load caused by expansion pressure is mainly concentrated in the range of the right arch waist and right side wall.In practical engineering,its influence range should be considered,so as to provide reference for disease treatment through the calculation and analysis.
