The Study on the Characteristics of Pressure Arch above the Twin-Parallel Openings in the Jointed Rock Masses

Table 1

Design of the numerical experiment.

Series	Case	(°)			Excavation sequence
a	a1	20	0.7	One opening	—
	a2	20	0.7	5	One time
b	b1	5	0.7	10	One time
	b2	10	0.7	10	One time
	b3	15	0.7	10	One time
	b4	20	0.7	10	One time
	b5	25	0.7	10	One time
	b6	30	0.7	10	One time
c	c1	20	0.3	10	One time
	c2	20	0.5	10	One time
	c3 (b4)	20	0.7	10	One time
	c4	20	1	10	One time
	c5	20	1.2	10	One time
d	d1 (a2)	20	0.7	5	One time
	d2 (b4)	20	0.7	10	One time
	d3	20	0.7	15	One time
	d4	20	0.7	20	One time
	d5	20	0.7	30	One time
	d6	20	0.7	40	One time
	d7	20	0.7	50	One time
e	e1 (b4)	20	0.7	10	One time
	e2	20	0.7	10	Two times
	e3	5	0.5	10	One time
	e4	5	0.5	10	Two times