The formation of arch effects will bring the sand filling over the region of deep concavity hindered and the degree of compaction of molding sand at the deep concavity reduced.
它的形成会阻碍型砂向深凹区的填充，使得深凹处砂型紧实度降低。
2
The new arch spring of composite truss arch bridge is used to support the middle truss arch of the bridge and the structural formation and force conditions of the joint of the spring are complicated.