求翻译：第二步是通过开挖孔洞形成溶洞，并在上部建筑物和土体自重力作用下，产生沉降，在这一步中，位移较大，产生不收敛，迭代中断是什么意思？

The second step is the formation of cave excavation holes in the upper part of buildings and soil under gravity, resulting in deposition, in this step, the displacement is greater, resulting in non-convergence, iteration interrupt

Step 2 is formed by digging holes and caves, buildings and land in the upper body from gravity, the resulting settlement, and in this step, the shift is large, the resulting does not converge, the iterative interrupt

Second step is through excavates the hole to form the limestone cave, and in the upside building and under the soil body dead weight action of force, has the subsidence, in this step, the displacement is big, produces does not restrain, iterative interrupt

The second step is cave formed by digging holes and at the top of the building and soil under the action of gravity, settlement, in this step, the larger displacement, not convergent iteration interrupts

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