A test apparatus used to simulate the dual effects of freeze-thaw and dynamic load on subgrade in cold regions

https://doi.org/10.1016/j.coldregions.2022.103586Get rights and content

Highlights

  • A test apparatus used to simulate the subgrade in cold regions.

  • The freeze-thaw and dynamic load were applied to the subgrade.

  • The failure law of subgrade under freeze-thaw and dynamic load was studied.

  • Study the impact of different vehicle (train, automobile) loads on the subgrade.

Abstract

The highway and railway subgrade built in permafrost and seasonally frozen regions will not only be damaged by freezing and thawing, but also affected by dynamic load. However, there are little apparatus that have both freeze-thaw and dynamic loading functions. In order to study the stability of subgrade under dual effects, the apparatus that can apply freeze-thaw and dynamic load on subgrade has been developed. The verification test was carried out to verify the functional reliability of the apparatus. The test proved that the apparatus can simulate the dual effects of freeze-thaw and dynamic load, and on this basis, it can realize the monitoring functions of temperature, water, pore water pressure and deformation. Further, the apparatus runs stably and reliably, with accurate results and simple operation. It is considered to be a promising tool for studying the stability of subgrade in permafrost and seasonally frozen regions under the dual effects of freeze-thaw and dynamic load.

Introduction

Subgrade diseases and building foundation diseases caused by freezing and thawing are common engineering problems in geotechnical engineering in cold regions. (Zhang et al., 2019a; Wu et al., 2018; Zhu et al., 2010; Niu et al., 2020). In cold regions, the subgrade is not only affected by freezing and thawing process, but also subjected to the dynamic load of vehicles. Therefore, the dual effect of freezing and thawing and load will increase the incidence of subgrade disease. (Xiao et al., 2015).

In order to study the stability of subgrade under freeze-thaw and dynamic load, scholars have carried out a large number of model tests. Some scholars studied the subgrade by establishing mathematical models (Zhang et al., 2021, Zhang et al., 2022; Zhang, 2012), and others studied it by establishing large-scale physical indoor model tests (Mao et al., 2004). After researching the literature, we found that many physical model experimental studies have different concerns. Some physical model tests only focus on the hydrothermal change of the subgrade under the action of freezing and thawing, while ignoring the problem of traffic dynamic load (Zhu, 1987; Bing, 2008; Yu et al., 2002; Liu et al., 2019; Zhang et al., 2019b; Yang et al., 2020). Others consider freeze-thaw and static load issues, but the apparatus has no dynamic load capability (Chang et al., 2011; Li et al., 2019; Mao et al., 2012; Wang et al., 2022). With the increasing systematic requirements for physical model tests, a multifunctional freeze-thaw test system (open system) was developed (Zhao et al., 2020). The test system is used to simulate the freezing and thawing cycle process of subgrade soil in natural environment, and can apply dynamic load, but its single-point dynamic load application process cannot completely simulate the real traffic dynamic load process. The cold regions engineering dynamic load model test system designed by Zhao et al., 2011 also cannot fully simulate the real traffic dynamic load process. Ma et al. (2017) independently designed and developed the soil frost heave test system. The frost heave test system can simulate the working state of subgrade in natural environment, which controls the test condition from loading mode of temperature and overburden, and water supply and lateral constraints, but the function of traffic dynamic load is still not fully realized.

To sum up, the physical model test of subgrade stability has undergone a long period of development, design and research. From simple hydrothermal and dynamic loads, to the combined action of hydrothermal, static loads and single-point dynamic loads, its functions are constantly being improved and developed. In order to promote the research on the stability of subgrade under the dual effects of freeze-thaw and dynamic load, a test apparatus used to simulate the dual effects of freeze-thaw and dynamic load on subgrade in cold regions has been developed, which can simulate subgrade damage in permafrost and seasonally frozen regions. The apparatus can simulate the dual effects of freeze-thaw and traffic dynamic load, and on this basis, it can realize the monitoring functions of temperature, water, pore pressure and deformation.

Section snippets

Apparatus description

As shown in Fig. 1, the apparatus is mainly composed of three parts: loading system, environmental simulation system and data acquisition system. The loading system is mainly used to apply dynamic load to the subgrade. The environment simulation system can simulate the site environment. The data acquisition system collects the data (Temperature, Water, Pore Water pressure, Displacement) changes of subgrade under the dual effects of freeze-thaw and load.

Apparatus can simulate the situation

The freeze-thaw and dynamic load mode can simulate the changes of highway and railway subgrade when subjected to freeze-thaw and dynamic load. According to the different dynamic load forms of the subgrade (trains, trucks, cars), the width of the thin steel plate of the apparatus and the load stress can be adjusted to simulate different load situations.

Some test results with this apparatus

In order to verify the performance of the apparatus, the highway subgrade under the dual effects of freeze-thaw and dynamic load was studied. Among the road vehicles, heavy trucks are the most likely to cause subgrade damage, so heavy trucks are selected as the research object. Next, the highway subgrade of Lanzhou is selected as the test object for research. The water, temperature, pore water pressure and deformation of soil at the cut-fill transition zone of subgrade are studied. The soil

Summary

A freeze-thaw and dynamic load apparatus for subgrade in permafrost and seasonal permafrost regions was developed. The apparatus consists of loading system, environment simulation system and data acquisition system. The apparatus has the following characteristics: 1) Freeze-thaw and dynamic load were applied to the subgrade; 2) The failure law of subgrade under freeze-thaw and dynamic load can be studied;3) The influence of different vehicle (train, car) loads on subgrade can be studied.

In

CRediT authorship contribution statement

Linzhen Yang: Writing – review & editing, Investigation, Visualization. Jinbang Zhai: Data curation, Writing – original draft. Ze Zhang: Conceptualization, Methodology, Project administration, Funding acquisition. Andrey Melnikov: Supervision, Validation, Funding acquisition. Doudou Jin: Supervision, Formal analysis, Software.

Declaration of Competing Interest

We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, “A test apparatus used to simulate the dual effects of freeze-thaw and dynamic load on subgrade in cold regions”.

Acknowledgement

The authors greatly appreciate the support by the following research grants: (a) Heilongjiang Transportation Investment Group Co., Ltd (JT-100000-ZC-FW-2021-0129), (b) the National Natural Science Foundation of China (NSFC) (41771078, 42011530083), (c) the Fundamental Research Funds for the Central Universities (2572021AW36), (d) Russian Foundation for Basic Research: RFBR-NSFC project (20-55-53006).

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  • Cited by (3)

    1

    These authors contributed equally to this work and should be considered co-first authors.

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