Research On Identification Method Of Rock Mass Structural Plane Based On Digital Drilling Technology

With the continuous development of underground engineering construction,it is particularly important to study the structural plane characteristics of rock masses for identification.In order to analyze the changes of drilling parameters of rock masses containing structural plane during drilling,and to investigate the characterization and identification methods of structural plane of rock masses,in this thesis,gneiss,granite and sandstone were selected as rock materials,and gypsum mortar was used as structural plane interlayer material to produce three rock-like specimens containing structural plane interlayer.Using self-developed indoor digital drilling equipment,indoor digital drilling tests were carried out to analyze the changes in drilling parameters and their energy evolution trends of rock masses containing structural plane under different inclination and thicknesses.(1)Analysis of the entire drilling phase shows that the torque and thrust force of the rock containing the structural plane change with the drilling depth in three general stages:firstly,the curve increases gradually when the bit is drilling into the upper part of the rock and remains stable,secondly,the curve decreases instantaneously when the bit enters the middle part of the structural plane and remains stable,and finally,the curve increases when the bit enters the lower part of the rock and remains stable.Analysis of structural plane,with increasing inclination of the structure plane,the torque and thrust force at the structural plane of the rock decreases obviously,and the radian of the downward trend gradually increases.With the increasing thickness of the structural plane,the distance of the stabilization phase after the decrease of torque and thrust force and at the structural plane of the rock gradually increases.(2)When the drill bit acts on the structural plane,the peak torque and peak thrust force at the structural plane of the rock mass show a non-linear increasing trend with the increase of the structural plane inclination,and a non-linear decreasing trend with the increase of the structural plane thickness.The peak torque and peak thrust force were averaged for different structural plane thicknesses,The results show that,when the structural plane inclination increases,the impact on the peak thrust force at the structural plane of gneiss and sandstone is greater than the peak torque,and the impact on the peak torque at the structural plane of granite is greater than the impact on the peak thrust force.When the structural plane thickness increases,the impact on the peak thrust force at the structural plane of gneiss and granite is greater than the peak torque,and the impact on the peak torque at the structural plane of sandstone is greater than the peak thrust force.(3)Through theoretical analysis,the relationship between the ratio of the change in rotational speed and drilling speed and the peak torque and peak thrust force at the stable stage of the structural plane rock mass,and the relationship between the structural plane inclination and the ratio of the change in rotational speed and drilling speed were obtained,and the influence of the structural plane inclination and thickness on the peak torque and peak thrust force respectively were explained by using the theoretical relationship between them.(4)For the whole drilling stage and the drilling ratio energy evolution trend at the structural plane of the rock mass is similar to the relationship between thrust force and torque.The anisotropy characteristics of the structural plane rock masses were evaluated by using the normalized drilling energy f,that is,anisotropy index.The anisotropy degree of gneiss,granite and sandstone gradually decreases.For the same structural plane rock mass,when the structural plane inclination increases,the anisotropic characteristics of the structural plane rock body become more obvious.When the structural plane thickness increases,the anisotropic characteristics of the structural plane rock mass gradually weaken.(5)Based on the correlation principle of Cook distance,a data anomaly identification method for drilling parameters is proposed,and the abnormal law of drilling parameter data during drilling is obtained,and the properties of rock mass structural surfaces are identified.,and the correctness of this method is proved.The function relationship between the structural plane inclination,the structural plane thickness and the peak Cook distance of the structural plane rock mass is obtained by fitting the peak point data,and the correlation between the three is predicted.The results show that the influence of structural plane inclination and structural plane thickness of the three rock masses on the peak Cook distance of the drilling parameters is greater than that under single factors,and the correlation degree under bivariate is more than 90%,that is,the fitting effect of bivariate fitting model is more obvious and the correlation is higher than that of single-variable fitting model.