在我国西北某试验场进行了一次全封闭水平坑道方式的地下核试验。这次试验是在下古生界石灰岩地层中进行的,爆心附近为巨厚层石灰岩,单层厚度3米以上。岩石质纯,几乎全部为方解石,碳酸钙含量高达95—98％。距爆心67米以内无断层通过。因此, In a test site in the northwestern part of China, an underground nuclear test was conducted in a fully enclosed horizontal tunnel. The test was carried out in the lower Paleozoic limestone formation, near the heart of the explosion is a thick layer of limestone, a single layer thickness of 3 meters or more. Pure rock, almost all calcite, calcium carbonate content up to 95-98%. No fault within 67 meters from the burst heart through. therefore,