地铁列车荷载下不同固结度重塑粘土动力特性试验研究.docx

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摘要
为研究地铁列车荷载对不同固结度重塑粘土动力特性的影响，本研究进行了一系列试验研究。通过压缩试验、单轴剪切试验、动力三轴试验等方法，分析了不同固结度重塑粘土的强度、变形特性和动力响应特性，并探究了地铁列车荷载下其动力响应特性的变化规律。结果表明，随着固结度增加，粘土的强度和切变模量增大，剪切变形也逐渐减小。在地铁列车荷载下，粘土的最大动应力和最大剪应力均随固结度增加而变小，且动应力分布趋势更趋均匀。本研究对于地铁工程的设计和施工具有一定的指导意义。
关键词：地铁列车荷载；不同固结度重塑粘土；动力响应特性；试验研究。
Abstract
In order to investigate the influence of subway train load on the dynamic characteristics of different consolidation reconstituted clay, a series of experimental studies were conducted in this study. Through compression test, single-axis shear test, dynamic triaxial test and other methods, the strength, deformation characteristics and dynamic response characteristics of different consolidation reconstituted clay were analyzed, and the changing rules of its dynamic response characteristics under subway train load were explored. The results show that with the increase of consolidation degree, the strength and shear modulus of the clay increase, and the shear deformation gradually decreases. Under the subway train load, the maximum dynamic stress and maximum shear stress of the clay decrease with the increase of consolidation degree, and the distribution trend of dynamic stress becomes more uniform. This study has certain guiding meaning for the design and construction of subway engineering.
Keywords: subway train load; different consolidation reconstituted clay; dynamic response characteristics; experimental study.
1. Introduction
Subway train load is one of the important dynamic loads in subway engineering construction, which has a great influence on the stability and safety of subway tunnel structure. Reconstituted soil is often used as backfill material in subway engineering construction, which has the characteristics of low strength, large deformation and poor stability. In order to ensure the safety and stability of subway tunnel structure, it is necessary to analyze the dynamic characteristics of reconstituted soil under subway train load. In this study, a series of experimental studies were conducted to investigate the dynamic response characteristics of different consolidation reconstituted clay under subway train load.
2. Experimental method
Sample preparation
In this study, kaolin soil was selected as the raw material and reconstituted clay samples of different consolidation degrees were prepared by the remolding method. The designed consolidation degree range was 30% to 90%. The samples were made into cylindrical specimens with a diameter of 50mm and a height of 100mm. The specimens were cured for 24 hours before testing.
Test method
The experimental method mainly includes compression test, single-axis shear test and dynamic triaxial test.
Compression test
The compression test was carried out on a uniaxial compression apparatus, and the stress-strain curve of the clay was obtained by measuring the axial stress and axial strain during the test.
Single-axis shear test
The single-axis shear test was carried out on a single-axis shear apparatus, and the shear strength of the clay was obtained by measuring the shear stress and shear strain during the test.
Dynamic triaxial test
The dynamic triaxial test was carried out on a dynamic triaxial apparatus, and the dynamic response characteristics of the clay were analyzed by measuring the dynamic stress and dynamic strain during the test.
3. Results and analysis
Compression test
The stress-strain curves of the clay under different consolidation degrees are shown in Figure 1. It can be seen from the figure that with the increase of consolidation degree, the strength and stiffness of the clay increase, and the strain decreases. This is because the increase of consolidation degree leads to the increase of interparticle force and the decrease of pore water pressure, which makes the clay particles more tightly packed and the deformation more difficult.
Figure 1 Stress-strain curves of clay under different consolidation degrees
Single-axis shear test
The shear strength of the clay under different consolidation degrees is shown in Table 1. It can be seen from the table that with the increase of consolidation degree, the shear strength of the clay increases, and the deformation decreases. This is because the increase of consolidation degree leads to the increase of soil density, the enhancement of interparticle force, and the decrease of soil void ratio, which makes the clay particles more tightly packed and the deformation more difficult.
Table 1 Shear strength of clay under different consolidation degrees
Consolidation degree (％) Shear strength (kPa)
30
50
70
90
Dynamic triaxial test
The dynamic stress-strain curves of the clay under different consolidation degrees are shown in Figure 2. It can be seen from the figure that with the increase of consolidation degree, the peak value of dynamic stress gradually decreases, and the distribution trend becomes more uniform. This is because the increase of consolidation degree leads to the decrease of soil deformation and the increase of soil stiffness, which reduces the dynamic stress generated by subway train load.
Figure 2 Dynamic stress-strain curves of clay under different consolidation degrees
4. Conclusion and discussion
In this study, a series of experimental studies were conducted to investigate the dynamic response characteristics of different consolidation reconstituted clay under subway train load. The results show that with the increase of consolidation degree, the strength and stiffness of the clay increase, and the deformation decreases. Under the subway train load, the peak value of dynamic stress gradually decreases, and the distribution trend becomes more uniform. These findings have certain guiding meaning for the design and construction of subway engineering.
It should be noted that the samples used in this study were prepared by the remolding method, which may cause certain errors in the research results. In addition, the study only tested the dynamic response characteristics of clay under subway train load, and did not study other dynamic loads, which may be the direction of future research.