Calculation and Analysis of Vibration Stress of Guangxi Nanning Subway during Operation

Zhenchao Chang,Haifeng Huang,Shihai Wang,Yuhang Wu,Yuanpeng Chen,Peng Mo,Chunwei Wu,Junhui Luo,Mian Huang,Laixing Liao,Song-He Wang

doi:10.1155/2022/6484969

Abstract

In this study, based on the Mindlin solution in elastic half-space, the stress calculation formula was determined with consideration of any point in the foundation under the dynamic amplification effect. The train load was simplified as a concentrated force moving in the direction of the train, and the stress of the soil under a single wheel load was analyzed. In the state, σz reached a maximum value of 0.56 kPa when the axle was directly above the soil, and the stress decreased until it approached zero as the distance from the soil unit increased. Then, taking the Nanning Metro Line 1 as an example, the load was regarded as the superposition of several single-wheel loads, and the law of the soil stress change at a point directly below the moving line of the train load at different axle loads, speeds, and burial depths was studied. From the analysis of the results, it could be seen that the soil stress under different working conditions was always proportional to the train axle load, speed, and burial depths. The peak stress ratio corresponding to the depths of 9 m, 12 m, and 15 m was 1:2:11, indicating that the closer the load to the soil, the more significantly the stress of the soil element increased. Under multiple wheel loads, the soil stress always exhibited continuous cycle characteristics. The cycle period was related to the time it took for the metro to pass through the point in the soil, and the cycle period was the ratio of the distance between each axle and the vehicle speed.

Highlights

With the development of urban underground space, subway rail transit has gradually become the backbone of major cities
The Boussinesq solution is suitable for road engineering with a load on a surface [1]. e Mindlin formula can solve for the soil stress at any point in the elastic half-space, so it is suitable for subway engineering at any depth [2]
Ishihara [3] used the Boussinesq solution to simulate ground rail transportation to obtain the stress of a soil unit and the stress path of an inspection point. is method reflected the nature of the rotation of the main stress axis of the soil unit caused by the axle load, but soil element stress of underground traffic could not be considered

Summary

Introduction

With the development of urban underground space, subway rail transit has gradually become the backbone of major cities. Ding et al [8, 9] analyzed and studied the foundation stress state change caused by subway train operation and the rotation of the main stress axis and the viscoelastic solution of the foundation based on the Mindlin solution in the elastic half-space without considering the effect of dynamic effects on stress. Alabi [18] gave the parametric research results of the three-dimensional model of a rail traffic vibration load and studied the dynamic response of the moving load speed, train distance, and ground depth to elastic space. E stress calculation formula of the dynamic effect analyzed the stress state of the soil at a certain point directly below the moving line of the train under the load of a single axle and multiple sets of axles, and the effects of the vehicle speed, axle load, and buried depth on the stress were studied Based on the above problems, in this study the metro load was simplified as a concentrated force moving in the direction of the metro based on the Mindlin solution of elastic half-space. e stress calculation formula of the dynamic effect analyzed the stress state of the soil at a certain point directly below the moving line of the train under the load of a single axle and multiple sets of axles, and the effects of the vehicle speed, axle load, and buried depth on the stress were studied

Mindlin’s analytical solution considering speed

Conclusions