By using finite element software, the influence of different karst cave span on the bearing characteristics of bridge foundation is analyzed. It is found that when other conditions are certain, with the increase of karst cave span, the ultimate bearing capacity presents a decreasing trend, and the lateral friction of pile drops steeply within the range of karst cave and decreases to a greater extent, showing a certain degree of depth effect, and the end resistance proportion also increases. The results show that when the span of the karst cave is more than 9m, the lateral friction resistance within the range of the karst cave of the pile body drops sharply. The research results can further deepen and perfect the design of pile foundation in karst development area and guide the construction, which has certain theoretical significance and engineering application value.

No abstract

In order to study the influence of anti-slipping layer color on driving safety before the tunnel entrance, based on color theory and psychology, this paper used UC-win/Road, Adobe Photoshop, and 3D Max to simulate the real scene, and 8 different color schemes were designed for anti-slipping layer paving. The analog driving device was used to simulate driving, and the eye tracker was adopted to collect the characteristic data of driver’s eye movement. Through data processing, driver’s pupil area change, gaze point proportion and reaction time for targets in the 8 color scheme conditions were obtained, and then the impact of different anti-slipping layers color on driver’s driving safety was evaluated. The anti-slipping layer pavement schemes with different colors have different degrees of impact on driver vision, which in turn affect driving safety. According to the characteristics of optical illusion, a discontinuous multicolor anti-slipping layer pavement scheme was designed, which can provide strong guidance to improve the security of high-speed driving on Wenshan Guangnan-Nasa Expressway.

In major city, buried pipelines are more and more important in our life. Its types and layouts are very various, and its surroundings are very complicated. Now, it has been a research hot topic in world earthquake engineering field that how to ensure its safety when extreme earthquake occurred in the future. So, in this paper, based on the ABAQUS software, seismic responses of the soil-pipeline system under different cases are studied, then, the effects of some factors on seismic response of buried pipeline are analyzed, including the vibration direction of earthquake, embedded depth of pipe, pipe diameter, wall thickness of pipe, and tube spacing. Finally, some effect laws are proposed.

In order to study the influence of steep slope-karst coupling on the vertical bearing characteristics of pile foundation, the orthogonal simulation tests of pile foundation under 4 different roof thickness and 5 different slope are carried out by using Marc finite element software, and the correction coefficient of vertical partial bearing capacity of pile foundation according to roof thickness and slope is put forward. The test results show that when the thickness of the roof is more than 3 times the pile diameter, the ultimate bearing capacity of the pile foundation tends to be stable, and the value is about 19% when the slope is 45°; the ultimate bearing capacity of the pile foundation decreases gradually with the increase of the slope, and the reduction reaches 29.83% when the slope is greater than 45°. According to the calculation results, the variation law of vertical partial bearing capacity of pile foundation is analyzed, and the calculation formula of standard value of vertical ultimate bearing capacity of pile foundation in steep slope karst area considering both roof thickness and slope is put forward, and the correction coefficients αi and β are put forward.