[Retracted] Influence of Underground Mining Direction Based on Particle Flow on Deformation and Failure of Loess Gully Area

Table 1

The microscopic characteristics of the rock strata.

Sign	Explanation	Loess layerS10	SandymudstoneS6, S8	Medium-coarsesandstone S5, S7	MudstoneS4, S9	Coal S2	SiltstoneS1, S3
(KN/m^3)	Volume-weight	18	24	25	24	16	24
R (cm)	Minimum radius of particles	40	40	40	40	40	40
Rmax/Rmin	Particle radius ratio	1.6	1.6	1.6	1.6	1.6	1.6
(GPa)	Effective modulus of flat joint	0.4	14.2	22	13.5	4	28.2
	Rigidity ratio of flat joint	2	2	2	2	2	2
(MPa)	Average tensile strength of flat joint/standard deviation	0.1/0.025	0.8/0.2	1/0.25	0.8/0.2	0.25/0.0625	1.2/0.3
C (MPa)	Average cohesion of flat joint/standard deviation	4/1	20/5	20/5	20/5	10/2.5	20/5