Stability Analysis and Support Design Methods for Rock Foundation Pit with Combination of Structural Plane and Karst Cave

Table 1

Calculations of the earth pressure.

Calculation method	Depth (m)	Total active earth force (kN)	Note
Rankine’s active earth pressure	0	0	Cohesion is ignored; Fracture angle is 45° + φ/2
	10	197.3
	20	789.2
	30	1775.8
Coulomb’s active earth pressure	0	0	Friction angle between the rock mass and the back of the wall is 0.33 φ; Fracture angle is 45° + φ/2
	10	966.4
	20	1573.7
	30	1814.9
Wedge analysis	0	0	Friction angle between the earth fill and the rock interface is 18°; Fracture angle is 60°
	10	499.3
	20	1997.1
	30	4493.6
Outward sloping rigid structural plane	0	0	Fracture angle is 60°
	10	542.9
	20	2171.7
	30	4886.4
Upper bound analysis	0	0	No cave. Fracture angle is 60°
	10	314
	20	1834.7
	30	4351.2