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.
