scholarly journals Cement-Modified Loess Base for Intercity Railways: Mechanical Strength and Influencing Factors Based on the Vertical Vibration Compaction Method

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3643
Author(s):  
Yingjun Jiang ◽  
Qilong Li ◽  
Yong Yi ◽  
Kejia Yuan ◽  
Changqing Deng ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
High Speed ◽  
Cement Content ◽  
Vertical Vibration ◽  
Initial Growth ◽  
High Speed Railway ◽  
Growth Properties ◽  
Vibration Compaction ◽  
Growth Equations ◽  
Compaction Method

Cement-modified loess has been used in the recent construction of an intercity high-speed railway in Xi’an, China. This paper studies the mechanical strength of cement-modified loess (CML) compacted by the vertical vibration compaction method (VVCM). First, the reliability of VVCM in compacting CML is evaluated, and then the effects of cement content, compaction coefficient, and curing time on the mechanical strength of CML are analyzed, establishing a strength prediction model. The results show that the correlation of mechanical strength between the CML specimens prepared by VVCM in the laboratory and the core specimens collected on site is as high as 83.8%. The mechanical strength of CML initially show linear growth with increasing cement content and compaction coefficient. The initial growth in CML mechanical strength is followed by a later period, with mechanical strength growth slowing after 28 days. The mechanical strength growth properties of the CML can be accurately predicted via established strength growth equations. The results of this study can guide the design and construction of CML subgrade.

scholarly journals Investigation on cement-improved phyllite based on the vertical vibration compaction method

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247599
Author(s):  
Yingjun Jiang ◽  
Jiangtao Fan ◽  
Yong Yi ◽  
Tian Tian ◽  
Kejia Yuan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Static Pressure ◽  
Cement Content ◽  
Vertical Vibration ◽  
Pressure Method ◽  
Vibration Compaction ◽  
Modulus Of Resilience ◽  
Compaction Method

The vertical vibration compaction method (VVCM), heavy compaction method and static pressure method were used to form phyllite specimens with different degrees of weathering. The influence of cement content, compactness, and compaction method on the mechanical properties of phyllite was studied. The mechanical properties of phyllite was evaluated in terms of unconfined compressive strength (Rc) and modulus of resilience (Ec). Further, test roads were paved along an expressway in China to demonstrate the feasibility of the highly weathered phyllite improvement technology. Results show that unweathered phyllite can be used as subgrade filler. In spite of increasing compactness, phyllite with a higher degree of weathering cannot meet the requirements for subgrade filler. With increasing cement content, Rc and Ec of the improved phyllite increases linearly. Rc and Ec increase by at least 15% and 17%, respectively, for every 1% increase in cement content and by at least 10% and 6%, respectively, for every 1% increase in compactness. The higher the degree of weathering of phyllite, the greater the degree of improvement of its mechanical properties.

scholarly journals Influencing Factors and Prediction Model for the Antierosion Performance of Cement-Improved Loess Compacted Using Different Compaction Methods

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Kejia Yuan ◽  
Yingjun Jiang ◽  
Luyao Cai ◽  
Jiangtao Fan ◽  
Changqing Deng ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Prediction Model ◽  
Mass Loss ◽  
Influencing Factors ◽  
Cement Content ◽  
Vertical Vibration ◽  
Design Criteria ◽  
Strength Deterioration ◽  
Vibration Compaction ◽  
Compaction Method

To analyze the antierosion performance of cement-improved loess (CIL), several influencing factors have been investigated based on two different compaction methods, which include the quasi-static compaction method (QSCM) and the vertical vibration compaction method (VVCM). Then, a prediction model for the cumulative erosion mass loss (CEML) has been established. The effects of erosion on the strength deterioration of CIL were also studied. The results show that, compared with QSCM, specimens compacted using the VVCM have better antierosion performance. As the cement content and the compaction coefficient are increased by 1%, the antierosion performance is increased by 16% and 6.2%, respectively. The eroding time has a significant effect on the antierosion performance of CIL, and the CEML increases linearly with an increase in the eroding time. The compressive strength of CIL decreases significantly due to erosion, and based on the average deterioration degree of the specimens, the design criteria for strength of CIL are proposed, which can provide reference for the design of CIL.

scholarly journals Comparison of Mechanical Properties of Cement-Stabilized Loess Produced Using Different Compaction Methods

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Yingjun Jiang ◽  
Kejia Yuan ◽  
Qilong Li ◽  
Changqing Deng ◽  
Yong Yi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Cement Content ◽  
Resilient Modulus ◽  
Great Influence ◽  
Field Measurements ◽  
Vertical Vibration ◽  
Dry Density ◽  
Curing Time ◽  
Compaction Method

Mechanical properties are important indexes to evaluate the improvement effect and engineering performance of cement-stabilized loess (CSL). This paper presents a comparison of the mechanical properties of CSL compacted using hammer quasi-static compaction method (QSCM) and vertical vibration compaction method (VVCM). The compaction properties, unconfined compressive strength (UCS), splitting strength (SPS), and resilient modulus (RM) of the laboratory-compacted CSL using VVCM and QSCM are tested and compared. Furthermore, the effects of compaction method, cement content, compaction coefficient, and curing time of the CSL specimens are investigated. In addition, field measurements are carried out to validate the laboratory investigations. The results show that the laboratory-compacted CSL using VVCM has a larger dry density and smaller optimum water content than that using QSCM. And the compaction method has a great influence on the mechanical strength of CSL. The UCS, SPS, and RM of the specimen produced using VVCM are averagely 1.17 times, 1.49 times, and 1.17 times that of CSL produced using QSCM, respectively, and the UCS, SPS, and RM of the specimens produced using these two methods increase linearly as the cement content and compaction coefficient increase, while the mechanical strength growth curve experiences three periods of increasing sharply, increasing slowly, and stabilizing with the curing time increased. Moreover, the results also show that the mechanical properties of laboratory-compacted CSL using VVCM have a better correlation of 83.8% with the field core samples.

Analysis and Prediction of Ground Vibration Induced by High-Speed Train

2013 ◽  
Vol 779-780 ◽  
pp. 731-738 ◽  
Author(s):  
Ke Xin Zhang ◽  
Jian Wei Yao ◽  
Ze Ping Zhao
Keyword(s):  
Neural Network ◽  
Test Data ◽  
High Speed ◽  
Ground Vibration ◽  
Vertical Vibration ◽  
Orthogonal Test ◽  
Vibration Level ◽  
High Speed Train ◽  
High Speed Railway ◽  
Vibration Attenuation

The principal aim of this paper is to determine the reasonable design parameters of high-speed railway vibration attenuation. The orthogonal test method is used to design the test of ground vibration induced by high-speed train. Four main factors that impact the maximum ground vertical vibration level are selected, and different values are given to each factor, so 8 groups of combinations can be obtained by using orthogonal test technique. Each group test data of the maximum ground vertical vibration level can be obtained by conducting vehicle testing on-track. In this paper, the primary and secondary factors that impact the maximum ground vertical vibration level are determined by range analysis. Moreover, the neural network theory is used to establish a model of the ground vertical vibration level, and this model can be trained and verified by the test data. The impact factors can be predicted by the method of combining orthogonal test and neural network concerning the specified vibration limit, and the value of maximum ground vertical vibration level with the predicted factors meets the requirement of accuracy. The conclusions provide a valuable reference to the vibration attenuation design of the high-speed railway.

scholarly journals Laboratory Evaluation of a Vertical Vibration Testing Method for an SMA-13 Mixture

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4409
Author(s):  
Yingjun Jiang ◽  
Jiangtao Fan ◽  
Jinshun Xue ◽  
Changqing Deng ◽  
Yong Yi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Heavy Traffic ◽  
Asphalt Mixture ◽  
Vertical Vibration ◽  
Laboratory Evaluation ◽  
Vibration Testing ◽  
Testing Method ◽  
Vibration Compaction ◽  
Compaction Time

In order to simulate the on-site compaction conditions of a Stone Matrix Asphalt (SMA) mixture, The Vertical Vibration Testing Method (VVTM), Superpave Gyratory Compactor (SGC), and Marshall method are used to test the SMA-13 mixture, and the physical and mechanical properties of the asphalt mixture designed by these three methods are tested. Subsequently, the influences of the molding method on the mechanical properties are compared. The influence of vibration compaction time on the volume parameters of the SMA mixture is studied. Following the heavy traffic compaction standards, the vibration compaction time of the SMA mixture is determined. The results show that the densities of the heavy Marshall specimen, VVTM specimen, and SGC specimen are 1.018 times, 1.019 times, and 1.015 times greater than that of the standard Marshall specimen, respectively. The passing rate of the 4.75 mm aggregate of the standard Marshall specimen is 29.9%, and that of the VVTM specimen and SGC specimen is 31.1% and 30.5%, respectively, while that of the heavy Marshall specimen is 34.5%. The mechanical strength of the specimen can be greatly improved as the density increases. On the other hand, by the same compaction work, the mechanical strength of the VVTM specimens can be increased by at least 7% compared with the heavy Marshall specimen. The mechanical strength of the VVTM specimen is increased by at least 22% compared with the standard Marshall specimen. The results also show that under the optimal asphalt-aggregate ratio and the same compaction work, the compressive strength and shear strength of the VVTM specimens are increased by at least 6% and 9%, respectively, compared with the Marshall specimens. In summary, the performance of the asphalt mixture designed by the VVTM is superior, providing a wider choice for future asphalt mixture design.

scholarly journals Predict the Influence of Environmental Vibration from High-Speed Railway on Over-Track Buildings

2021 ◽  
Vol 13 (6) ◽  
pp. 3218
Author(s):  
Guoqing Di ◽  
Ziyin Xie ◽  
Jingyi Guo
Keyword(s):  
High Speed ◽  
Element Model ◽  
Vertical Vibration ◽  
High Speed Railway ◽  
Line Load ◽  
Railway Industry ◽  
Measurement Results ◽  
Environmental Vibration ◽  
Set Up ◽  
Improved Model

The vibration caused by railways is an environmental constraint in the development of over-track buildings. To study the influence of environmental vibration from the high-speed railway on over-track buildings, a finite element model including track, soil, and buildings was set up. Based on the vertical vibration acceleration sampled on the rail, the equivalent line load acting on rails vertically was obtained by a simplified model. On the basis of verifying the simulation model by measurement results, the vertical vibration induced by high-speed railways in over-track buildings was studied quantitatively. Through introducing correction terms relating to the thickness and height of the over-track platform, the story number, and the structure of the over-track building, an existing model released by the railway industry of China was improved. Compared with the existing model only being suitable for predicting vertical vibration of the first floor, the improved model can predict vertical vibration of different floors.

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