Analysis of different weak interlayers on the stability influence of geological drilling hole
YAN Xiaolong;Shaanxi Railway Engineering Survey Co., Ltd.;
The stability of drilling holes wall with weak interlayers is the key issue to restrict geological drilling, and the stability is restricted by many factors. Based on the analysis of the elastic-plastic theory of circular hole, this paper establishes a three-dimensional borehole model of weak intercalation, and uses the Moore-Coulomb criterion to study the variation law of stability coefficient of surrounding rock under the conditions of different geological borehole diameter, dip angle and thickness of weak intercalation, as well as its elastic modulus, cohesion and Poisson's ratio. The research results show that(1) the stability coefficient of the intact surrounding rock(the thickness of weak interlayer is 0 m) is significantly higher than that of the hole wall with weak interlayer;(2) the stability of the hole wall decreases with the increase of the diameter of the hole, and decreases with the increase of the dip angle and thickness of the weak interlayer;(3) the stability of the hole wall decreases with the increase of Poisson.s ratio, and the change law is opposite with the increase of the elastic modulus and cohesion. The sensitivity of stability coefficient to Poisson.s ratio, cohesive force and elastic modulus decreased successively.