改善灰岩裸露区地震激发环境的方法探讨

提高灰岩裸露区地震激发效果是我国南方复杂山地探区地震勘探重点攻关的难题之一。通过对砂岩、灰岩中雷管爆炸后破裂情况的分析,认为灰岩为刚性岩石,脆性强、弹性差,在炸药爆炸瞬间不易产生弹性波,尤其地震勘探所需要的低频弹性波;分析炸药与灰岩的匹配关系,认为目前的炸药性能均无法与灰岩匹配;依据炸药爆炸半径和柱状炸药应力场分布情况,进行了在药柱下方垫入长度大于爆炸半径的砂岩岩心、含沙水泥柱从而改善灰岩激发环境的试验,收到了较为明显的效果。

Improving the shooting quality in limestone outcropped area is one of the difficulties for the seismic exploration in South China complex piedmont zone.By the analysis on the rupture status of sandstone and limestone after explosion,the limestone is verified as rigid rock with strong brittleness and worse elasticity,which is hardly to generate elastic wave especially the low-frequency elastic wave (which is necessary for seismic exploration) at the explosion moment.By the matching relationship analysis on explosive and limestone,it is revealed that the existing explosive performance cannot match the limestone.In terms of the explosion radius and the distribution of the stress field for columnar explosive,we tried to pad sandstone core longer than the explosion radius under the explosive column.As a result,the shooting quality has been obviously improved.