| Rockfalls are one of the common geological disasters,which pose a serious threat to the safety of people’s property and life.In the red bed area of the Sichuan Basin,collapse disasters erupt frequently,and the current scale of collapse rock disasters is mainly based on the scale of the collapse rock disasters that have occurred or through more obvious dangerous rock measurements,and the first occurrence or the omen is not predicted.The evidence for the apparent scale of the rockfall disaster is relatively rare.Based on this,this article aims to study the characteristics of the near horizontal red-bed rock mass in the Sichuan Basin when subjected to stress compression,propose the relationship between rock joint spacing and layer thickness,and provide theoretical support for the prediction of the scale of collapse in the near horizontal red-bed area.This paper conducts a large number of detailed data collection and joint investigations on the near horizontal red beds in Longquan Mountain and Langzhong City,studies the relationship between joint spacing and layer thickness,provides data support,and analyzes the longitudinal bending fold mechanism and theoretical calculations.The factors related to the joint spacing are finally simulated by numerical simulation to obtain the relationship between the joint spacing and various factors.Through the size of the joint spacing,the maximum block diameter that may be generated during a collapse can be predicted,so that the size of the collapse can be predicted and targeted protection can be carried out.First,through field investigation and data analysis,the relationship between the joint spacing and layer thickness of the near horizontal red bed in the Sichuan Basin is summarized.In the red bed rock,the relationship between the joint spacing and the layer thickness is the most obvious,and the two are similar to each other.1:1 relationship.From the joint investigation,it seems that it has little to do with other factors such as the magnitude of tectonic stress,rock inclination and rock mechanical parameters.Secondly,the mechanism of joint fissure development is analyzed theoretically and the size of joint spacing is theoretically calculated.This paper uses the mechanism of the development of folds to speculate the stress state of the red-bedded rock mass when compressed.The fold mechanism shows that the rock mass will have a dominant wave that is most likely to develop due to constraints and its own impedance when compressed.The wave trough is the place where joint cracks are most likely to occur,so half of the dominant wavelength is the easiest joint distance to develop.Theoretical calculations show that the size of the dominant wavelength is related to the layer thickness,rock properties and compressive stress,and a calculation formula for the dominant wavelength under ideal conditions is proposed.Finally,numerical simulation software is used to simulate the factors that dominate the wavelength in the theoretical calculations,and the stress curves of the rock mass under compression under different conditions are obtained,and the joint spacing is obtained from this.Numerical simulations of rock masses under compression in various situations show that the joint spacing is significantly affected by the thickness of the layer,but is not significantly affected by the change of rock properties and the magnitude of the compressive stress. |
