急需解决

new
def setup
K=E/(3*(1-2*v))
G=E/(2*(1+v))
v=0.24
E=1.1e9
end
gen zone radcyl p0 12.5 0 0 p1 25 0 0 p2 12.5 1 0 p3 12.5 0 25 &
size 10 1 10 5 dim 7.5 7.5 7.5 7.5 rat 1 1 1 1.1 fill
gen zone reflect normal = (-1,0,0) origin = (12.5,0,0)
gen zone radtun p0 0 0 0 p1 50 0 0 p2 0 1 0 p3 0 0 57.5 p4 50 1 0 &
p5 0 1 57.5 p6 50 0 57.5 p7 50 1 57.5 &
p8 25 0 0 p9 0 0 25 p10 25 1 0 p11 0 1 25 &
size 10 1 10 10 rat 1 1 1 1.1
attach face range z 24.9 25.1 x 24.9 25.1
gen zone reflect normal = (-1,0,0) origin = (0,0,0)
gen zone reflect normal = (0,0,-1) origin = (0,0,0)
plot show
plot block group
;return
; assign material
model mohr
prop bulk K shear G
prop fric 32 coh 1.3e6 tens 1.5e6
; set global conditions
set grav 0 0 -9.81
ini dens 2400
; set boundary conditions
fix x range x -49.9 -50.1
fix x range x 49.9 50.1
fix y
fix z range z -57.6 -57.4
hist unbal
hist gp zdisp 0 0 50
solve



FLAC3D运行之后出现
zero stiffness in grid-point 1
请问各位大侠怎么修改啊 谢谢啊 小弟刚学啊