山东大汶口盆地采盐溶腔的不稳定性及变化特征

Instability and variation characteristics of dissolved cavity of sale-collecting in Dawenkou Basin

山东大汶口盆地岩盐矿层为多层薄层盐,夹层以硬石膏岩、泥灰岩等为主,厚度较大。在双井对流采盐中,形成横截面近倒梯形的长形体溶腔。由于溶腔顶底板岩石与溶腔存在巨大的压力差,这种形状的溶腔不稳定,顶底板岩石发生向溶腔方向的蠕变,使溶腔大小、形状不断发生变化。一是开采盐层埋藏浅,开采速度慢,虽经多年开采,但溶腔跨度尚未达到极限跨距,顶底板岩石因多年相向蠕变相连接,溶腔得到支撑而不会发生坍塌。另一情况正相反:开采盐层埋藏深,开采速度快,在顶底板岩石蠕变尚未相接时,溶腔跨度已达到极限跨距发生坍塌。大汶口盆地这种采盐溶腔变化特点对类似岩盐开采矿区的溶腔研究具有参考意义。

The rock salt deposit in the Dawenkou basin of Shandong province is a multi-layer thin layer of salt,and the interlayer is mainly composed of anhydrite and muddy limestone,and the thickness is large.In the convection salt collecting of the double wells,a cuboid cavity with a cross section approaching inverted trapezoid is formed.Due to the huge pressure difference between the top rock and bottom rock of the cavity,the cavity in this shape is unstable,and the rock in the top and bottom creeped toward the cavity,which causes the size and shape of the cavity to change continuously.First,the mining salt layer is shallow and the mining speed is slow.Although it has been mined for many years,the cavity span has not reached its ultimate.The top rocks are connected by many years of opposite creep,and the cavity is supported without collapse.In another case,inversely,the mining salt layer is buried deep and the mining speed is fast.When the creep of the top and bottom rock has not been connected,the cavity span has reached its ultimate and the cavity collapses.The variation characteristics of dissolved cavity of salt-collecting in the Dawenkou basin has reference significance for the study of the cavity in similar rock salt mining area.