Dynamic Study On The Interaction Between Drilling Bits And Rock Strata For Rotary Drilling Rig In Deep Hole Drilling

As the main construction equipment of pile foundation construction,rotary drilling rig is widely used in foundation construction with high efficiency,good hole forming quality and excellent environmental performance.With the strict requirements of the current national infrastructure construction,the pile foundation construction needs deeper and more stable foundation.However,due to the complexity of deep stratum conditions,It is easy to cause serious vibration,even failure of drill pipe,serious wear of drilling tools and drilling bits,resulting in low construction efficiency.In order to improve the safe and efficient construction of drilling rig in deep and complex formation conditions,This thesis supported by the National Natural Science Foundation of China(51805041),studies the rock breaking process and loading mode of drilling bits based on rock breaking theory analysis,numerical simulation,machine learning and experimental verification.1)The influence of different mechanical properties of rock on rock breaking effect is studied.Based on the comprehensive analysis of the present situation of single drilling bits rock breaking at home and abroad,the four stages of single drilling bits rock breaking are studied according to the rock breaking theory: pick invading rock phase,rock crack forming phase,dense core forming phase,and the stage of rock collapse as a whole.Based on the changes of load and rock cracking during rock breaking process,it is pointed out that the rock breaking efficiency is closely related to the loading mode and loading configuration parameters.2)Based on SPH(smoothed particle hydrodynamics)method,combined with the finite element analysis software ANSYS and post-processing software LS-PREPOST,a nonlinear dynamic model of rock breaking by single drilling bits is established.The influence of different loading methods and loading parameters on the load variation of drilling bits and the range of rock stress damage is studied and analyzed,and the best loading method and loading parameters for hard rock drilling are optimized.3)A single drilling bits rock breaking micro drilling test rig is designed and established,and confirmatory test is carried out.The numerical simulation model corresponding with the experimental loading mode and loading parameters is accomplished.The results show the validity of the numerical model.4)A machine learning model is established to predict the interaction between drilling bits and rock.SVM and BP neural network are used to learn and predict the data of interaction force between drilling bits and rock in the process of rock breaking.The optimal machine learning algorithm model suitable for drilling bits rock breaking process prediction is determined,which provides the corresponding prediction model for subsequent intelligent prediction of rotary drilling rig.