In order to rationally leave the safety coal and rock pllars under the water body for the fully mechanized top coal caving mining in the ultra thick seam, b
ased on the calculation formula of the " two zone" heights suitable for the fully mechanized top coal caving mining face under the middle hard and soft weak overburden
strata regressively obtained with the site measure information, the left method of the " effective water insulated thickness method" and the " min safety thickness metho
d" were provided to the safety coal and rock pillar protective layer for the fully mechanized top coal caving mining under water body.The left value of the sand preventio
n safety coal and rock pillar and water prevention safety coal and rock pillar protective layer under the middle watery water body and rich watery water body was individ
ually provided.Based on the basis, the left method of the coal and rock pillars under the middle hard and soft weak overburden strata water body was completed for the
fully mechanized top coal caving mining.

为了合理留设水体下特厚煤层综放开采的安全煤岩柱,根据实测资料回归得出了适用于综放开采工作面中硬、软弱覆岩条件下的"两带"高度的计算公式,提出了水体下综放开采安全煤岩柱保护层的"有效隔水厚度法"和"最小安全厚度法"的留设方法,分别提出防砂安全煤岩柱、中等富水性水体和强富水性水体防水安全煤岩柱保护层的留设值。在此基础上,完成了水体下综放开采条件下中硬、软弱覆岩的安全煤岩柱的留设方法。

国家重点基础研究发展计划(973计划)资助项目(2007CB209402)；2010年国家安监总局关键安全科技项目(10-019)；