Acceleration and mitigation of sandstone weathering in the Yungang Grottoes for more than one millennia

2021 ◽  
Vol 62 (3) ◽  
pp. 301-314
Author(s):  
Guanghui Jiang ◽  
Fang Guo ◽  
Jizhong Huang
Keyword(s):  
Sandstone Weathering ◽  
Yungang Grottoes

SANDSTONE WEATHERING THRESHOLDS IN PETRA, JORDAN

1995 ◽  
Vol 16 (3) ◽  
pp. 205-222 ◽  
Author(s):  
Thomas R. Paradise
Keyword(s):  
Sandstone Weathering

Sandstone weathering in the High Atlas, Morocco

1992 ◽  
Vol 36 (4) ◽  
pp. 413-429
Author(s):  
D. A. Robinson ◽  
R. B. G. Williams
Keyword(s):  
High Atlas ◽  
Sandstone Weathering

Sandstone weathering and aspect in Petra, Jordan

2002 ◽  
Vol 46 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Thomas R. Paradise
Keyword(s):  
Sandstone Weathering

Relation of Pyritic Sandstone Weathering to Soil and Minesoil Properties

2015 ◽  
pp. 193-208 ◽  
Author(s):  
R. N. Singh ◽  
W. E. Grube ◽  
R. M. Smith ◽  
R. F. Keefer
Keyword(s):  
Sandstone Weathering

scholarly journals Aeolian activity at a giant sandstone weathering pit in arid south-central Utah

2009 ◽  
Vol 34 (1) ◽  
pp. 99-108 ◽  
Author(s):  
Dennis I. Netoff ◽  
Marjorie A. Chan
Keyword(s):  
South Central ◽  
Sandstone Weathering ◽  
Aeolian Activity ◽  
Weathering Pit

scholarly journals Study on the Seismic Performance of Small-diameter Bolts Reinforced in Grottoes

2020 ◽  
Author(s):  
Ningbo Peng ◽  
Bo Sun ◽  
Jizhong Huang ◽  
Yun Dong ◽  
Ye Zhu
Keyword(s):  
Rock Mass ◽  
Seismic Performance ◽  
Axial Force ◽  
Small Diameter ◽  
Vertical Direction ◽  
World Heritage Site ◽  
Dynamic Responses ◽  
Structural Defects ◽  
Seismic Capacity ◽  
Yungang Grottoes

Abstract The Yungang Grottoes, a World Heritage Site in Datong, consist of 252 caves that are noted for their collection of 5th and 6th century Buddhist grotto sculptures and reliefs. Various diseases have appeared in the grottoes under the general influence of natural and artificial factors. Bolt support is a commonly employed method for grotto reinforcement and has been widely applied in many projects. Small-diameter bolts have also been used in the reinforcement projects at the Yungang Grottoes, but the corresponding effect on the seismic performance of grottoes is still unclear. In this paper, a dynamic analysis via the numerical modelling of an ear grotto of the 19th grotto in Yungang was established, and the rock displacement, acceleration and bolt axial force responses under a seismic wave are analyzed. The results show that the seismic dynamic responses of grottoes are greatly affected by the cliff structure. The displacement and acceleration responses of the cliff body vary greatly within the abrupt transition of the cliff structure. Based on this variation, the seismic capacity of small-diameter bolts in the vertical direction is greater than that in the horizontal direction. The axial force of a bolt is small at both ends of the bolt, large in the middle of the bolt, small on the top of a cliff and large at the bottom of the cliff. Although the axial force is small, the upper rock mass of the grotto has a tendency to undergo relative movement compared with the outer rock mass. The results also indicate that based on the structural defects in the vertical direction of the cliff body caused by grotto excavation, the inclined angle of the bolt should be increased as far as possible or vertical support should be adopted to enhance the stability of the rock mass at the top of the grotto.

scholarly journals An adaptive prediction method for mechanical properties deterioration of sandstone under freeze–thaw cycles: a case study of Yungang Grottoes

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Chenchen Liu ◽  
Yibiao Liu ◽  
Weizhong Ren ◽  
Wenhui Xu ◽  
Simin Cai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Prediction Method ◽  
Rock Properties ◽  
Gradient Boosting ◽  
Physical Factors ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Yungang Grottoes

AbstractDue to the location of the Yungang Grottoes, freeze–thaw cycles contribute significantly to the degradation of the mechanical properties of the sandstone. The factors influencing the freeze–thaw cycle are classified into two categories: external environmental conditions and the inherent properties of the rock itself. Since the parameters of rock properties are inherent to each rock, the effect of rock properties on freeze–thaw degradation cannot be investigated by the control variates method. An adaptive multi-output gradient boosting decision trees (AMGBDT) algorithm is proposed to fit nonlinear relationships between mechanical properties and physical factors. The hyperparameters in the GBDT algorithm are set as variables, and the Sequential quadratic programming (SQP) algorithm is applied to solve the hyperparameter optimization, which means finding the maximum Score. The case study illustrates that the AMGBDT algorithm can precisely determine the effect of each independent factor on the output. The patterns of mechanical properties are similar when the number of freeze–thaw cycles and porosity are used as variables separately and when both are used simultaneously. The uniaxial compressive strength decay rate is positively correlated with the number of freeze–thaw cycles and porosity. The modulus of elasticity is negatively correlated with the number of freeze–thaw cycles and porosity. The results show that the number of freeze–thaw cycles is the main factor influencing the freeze–thaw cycling action, and the porosity is minor. In addition, the fitting accuracy of the AMGBDT algorithm is generally higher than neural networks (NN) and random forests (RF). Studying the influence of porosity and other rock properties on the freeze–thaw cycle will help to understand the failure mechanism of rock freeze–thaw cycles.

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