交通荷载和降雨耦合作用下弱膨胀软土路基边坡溜塌演化机理研究

Study on Slope Collapse Evolution Mechanism of Weakly Expansive Soft Soil Subgrade Under Coupled Action of Traffic Load and Rainfall

摘要

中国铁路路基已进入建养并举的关键阶段,面临交通荷载与极端降雨等耦合的复杂服役环境,既有线弱膨胀软土路基易出现边坡溜塌病害．本文依托某弱膨胀土铁路路基工程,结合粒子图像测速(PIV)技术,自主研发了可视化弱膨胀软土路基边坡溜塌模型试验装置系统,模拟在交通荷载与降雨耦合作用下弱膨胀软土路基边坡溜塌行为．通过分析不同位置的土压力值和沉降量变化规律,捕捉不同时刻坡面PIV图片变化规律,揭示了弱膨胀软土路基边坡溜塌演化机制．研究结果表明：在交通荷载与降雨耦合作用下,坡顶、坡脚和基底处土压力值随着加载时间和交通荷载应力增量值的增大而增大,而对于坡面处土压力值呈现出初期增大后期降低的两阶段演化规律．沉降随着加载时间延长而增大,在暴雨条件下不同位置处的沉降值与交通荷载应力增量值呈现线性增大的规律．通过PIV图片观察发现：边坡溜塌机制为坡面位移随降雨历时增加而扩大,形成冲蚀沟；动荷载增大将加快边坡沉降和溜塌速度．本文研究成果为类似弱膨胀软土铁路路基边坡溜塌机理研究提供了理论支持,对保障列车安全运营具有重要意义．

Abstract

The railway subgrade in China has entered a stage where construction and maintenance are carried out simultaneously, and it will face a complex service environment involving the coupling of traffic load and extreme rainfall. As a result, the existing weakly expansive soft soil subgrade is prone to slope collapse diseases. Based on a weakly expansive soil railway subgrade project and in combination with the particle image velocimetry(PIV) technology, a visualized model test device system for weakly expansive soft soil subgrade slope collapse was independently developed in this paper, so as to simulate the behavior of slope collapse of weakly expansive soft soil subgrade under the coupled action of traffic load and rainfall. Through the analysis of variation laws of soil pressure and settlement at different locations and those of PIV images of the slope surface at different moments, the evolution mechanism of weakly expansive soft soil subgrade slope collapse was revealed. Results show that under the coupled action of traffic load and rainfall, the soil pressure at the top of the slope, the foot of the slope and the base increases with the increasing loading time and traffic load, while it shows a two-stage evolution law of increasing initially and then decreasing on the slope surface. The settlement increases with the loading time, and under the condition of extreme rainfall, the settlement values at different locations increase linearly with the traffic load stress increment. By means of observing the PIV images, the slope collapse mechanism is determined, i.e., the slope displacement will expand with an increase in rainfall duration, and erosion gullies are formed subsequently. In addition, when the dynamic load increases, both the slope settlement and slope collapse will be accelerated. The research results in this paper provide theoretical support for studies on the mechanism of slope collapse of similar weakly expansive soft soil railway subgrade, which is of significance for ensuring the safe operation of trains.

关键词

弱膨胀土 / 交通荷载 / 降雨 / 边坡溜塌 / 演化机理

Key words

weakly expansive soil / traffic load / rainfall / slope collapse / evolution mechanism

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基金资助

国家自然科学基金资助项目(52378363)

中国国家铁路集团有限公司科技研究开发计划课题(N2023G008)