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Changgen Yan

Bio: Changgen Yan is an academic researcher from Chang'an University. The author has contributed to research in topics: Direct shear test & Cohesion (geology). The author has an hindex of 6, co-authored 18 publications receiving 118 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, nearly 3,600 vertical joints were measured in sand-mud interbedded rock masses from 30 outcrops in the Yan'an area, China, and information such as joint spacing, joint aperture and the thickness of sandstone formations was obtained.

40 citations

Journal ArticleDOI
TL;DR: In this paper, the joint roughness coefficient (JRC) is an important indicator that characterizes the physical and mechanical behaviors of a jointed rock mass, and the effects of sampling interval on JRC were assessed during the JRC calculation process.

39 citations

Journal ArticleDOI
Changgen Yan1, Qi Wan1, Yu Xu, Yongli Xie1, Peijie Yin1 
TL;DR: In this paper, the effect of coarse sand barrier on the water infiltration was investigated, and it was concluded that the existence of capillary barrier could effectively decrease the possibility of moisture movement and improve the mechanical behavior of loess soil in terms of strength and deformation.

28 citations

Journal ArticleDOI
TL;DR: Wang et al. as discussed by the authors proposed a time-dependency model for evaluating the evolution of the excavation heavily damaged zone (EHDZ), which can be used to predict EHDZ depths at different times after rock mass excavation.

24 citations

Journal ArticleDOI
TL;DR: In this article, the authors used on-site monitoring data of the Ansai Dam in Yan'an, Shaanxi Province, China, to identify three types of damage from the onset of monitoring until the dam broke.
Abstract: A loess dam is not fully compacted, so there may be a high permeability area in a loess dam. The seepage channel appears inside the dam body, and osmosis damage occurs; these events cause the dam body to be unstable and destroyed. In this paper, the loess dam in the Ansai Area, Yan’an, Shaanxi Province, China, is used as an example monitoring target, and the whole life cycle of the dam is monitored by measuring cracks, liquid level and pore pressure. The timeline regarding multiple instances of damage during the period is used as the basis for subdividing the whole life cycle, and dam damage types are distinguished according to the internal factors and external conditions. By analysing the on-site monitoring data, the dam experienced three obvious types of damage from the onset of monitoring until the dam broke. The triggering factors of the three damage types differ. One factor type is the difference in liquid levels on the two sides of the dam and the seepage channel that is then formed inside the dam. The fine-grained soil in the dam is removed from the seepage channel under the action of hydrodynamic force, the soil at the foot of the dam slope tends to be saturated under the action of osmotic water and the shear strength of the dam slope is reduced. When the soil weight of the upper soil is greater than the shear strength of the soil at the foot of the dam, the first damage type occurs; therefore, it is called “internal erosion damage”. The second type of damage is attributed to the softening of the dam feet under immersion by rainwater, resulting in the dam collapse; it is called “slumping damage”. The third type of damage is due to the infiltration of rainwater through a crack at the top of the dam. The soil at the top of the dam slides along the rainwater intrusion surface, and the width of the dam top is continuously decreased until it completely disappears; therefore, it is called “slippery damage”. On that basis, the loess dam failure modes are proposed due to the difference in hydrodynamic forces on the two sides of the dam and formation of a seepage channel. The fine-grained soil is removed from the seepage channel under the action of hydrodynamic force. The seepage channel is continuously expanded, the soil at the foot of the dam is saturated under the action of seepage water, the soil shear strength is reduced, the dam body becomes unstable and the width of the dam crest is decreased. Under the joint action of infiltration and rainfall, the dam begins the next round of infiltration and erosion and the width of the dam roof continues to decrease. The cycle continues as the width of the dam roof is continuously reduced until overtopping occurs.

21 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, an index system of factors influencing water inrush from coal floor is established based on the current water in-rush controlling theory and detailed analysis of in situ data obtained from mining regions.
Abstract: For water inrush from coal floor, due to different kinds of controlling factors and their internal correlations, the accuracy of prediction model is mostly below expectation. In this paper, it studies on which controlling factors should be selected for water inrush prediction model because all these factors have different influence on water inrush incidents based on the analysis of in situ data. Some factors are proved having limited impacts on water inrush, it is no necessary to collect in situ data of those factors from coal mining work face. Therefore, the workload and expense will decrease. In this paper, an index system of factors influencing water inrush from coal floor is established based on the current water inrush controlling theory and detailed analysis of in situ data obtained from mining regions. Following the Wrapper method in feature selection, 10 main controlling factors were selected from 14 existing indicators which were thought could affect water inrush. After training on dynamic GRU model which is made for water inrush prediction, a comparison among dynamic GRU model and stable SVM and BPMN models turns out the advantages of the previous with a higher accuracy in train, validation and test set against the latter. It is believed GRU model is able to predict water inrush water inrush from coal floor with high accuracy and hence enhances mining safety.

66 citations

Journal ArticleDOI
TL;DR: In this paper, the authors conducted extensive true-triaxial unloading tests on rectangular Miluo granite specimens to investigate their crack propagation behavior and peak unloading strength properties, and they demonstrated that their failure mode transforms from shear to slabbing with the increase in intermediate principal stresses σ2.

46 citations

Journal ArticleDOI
TL;DR: In this paper, a high-resolution digital outcrop model (DOM) generation method for rock exposures based on unmanned aerial vehicle (UAV) photogrammetry integrated with a structure from motion (SfM) technique was introduced.

41 citations

Journal ArticleDOI
TL;DR: In this paper, the joint roughness coefficient (JRC) is an important indicator that characterizes the physical and mechanical behaviors of a jointed rock mass, and the effects of sampling interval on JRC were assessed during the JRC calculation process.

39 citations