Abstract:In the strategic action of ore prospecting breakthrough， the drilling depth is constantly increasing， and intelligent working condition recognition has become a necessary measure for safe， efficient and low-cost drilling. Its steps include signal acquisition， feature extraction， state recognition and diagnosis decision， among which the establishment of accurate and reliable in-hole accident discrimination criterion is the difficulty and core of state recognition and diagnosis decision. Firstly， based on the theoretical knowledge and engineering practice experience of in-hole accidents， this paper divides the six types of accidents in drilling holes into buried drilling， stuck drilling， burned drilling， broken drilling， hole leakage and hole overflow， and summarizes their occurrence symptoms. The characteristics and change trend expression of real-time drilling signal parameters are analyzed in detail. On this basis， the relative mean， standard deviation， mean slope， standard deviation slope and their thresholds of six characteristic parameters， including pump pressure， drilling speed， torque， rotation speed， overhead weight and outlet flow， are proposed to characterize the change of each parameter. Finally， the accident discrimination criterion is established in the form of matrix. The discrimination criterion has strong theoretical and practical basis， and can divide the detailed drilling accident categories in actual use， which can provide a discrimination basis for subsequent software development.

Abstract:With the economic development in China and the promotion of the conversion of “coal to gas” policy, natural gas, as a clean energy, will be increasingly applied to the future life of residents. Natural gas storage tank is an important part of natural gas supply gas source system, and the tank safety has received much attention. As a common geological disaster, foundation settlement is likely to cause the gas tank to tilt, which may even cause gas storage tanks to deflate and explode. Therefore, it is particularly important to carry out settlement observations at natural gas storage stations. As a common means of settlement monitoring, seo-robot has the advantages of high precision, low cost and easy operation. In the measurement, due to the observation conditions and some other factors, the measurement data is inevitably superimposed on the “noise” interference, in order to eliminate the abnormal data, Grubbs criterion is used for data processing. Taking No. 1 gas storage tank of Nanchong gas storage and distribution station as an example, this paper introduces the observation technology and data analysis of the gas storage tank settlement.

Abstract:In the process of designing and using the geological drilling tools, strength theory or yield criterion is required to analyze drilling equipment and tool failure problems. In order to help people understand Mises yield criterion (stress), this paper introduces theoretically the relationship between the Mises yield criterion and the distortional strain energy density criterion, it is revealed that the essence of Mises yield criterions is the fourth strength theory. In the elasto-plastic range, Mises yield criterion unifies the first strength theory of the single tension or compression state, the third and fourth strength theory of complex stress state. Thus Mises yield criterion is more widely used in the finite element numerical analysis.

Abstract:Linear elastic constitutive model was used to analyze the stress distribution in the vertical wellbore; Mohr-Coulomb criterion, Drucker-Prager criterion and Mogi-Coulomb strength criterion were respectively applied to calculate the minimum fluid column pressure required to maintain stable wellbore for the crustal stress measurement and monitoring borehole in Pinggu. By the contractive analysis, because of the intermediate principal stress， the minimum fluid column pressure required to maintain wellbore stable could be reduced. The minimum fluid column pressure derived from three criteria show the consistent variation trend with the depth in corresponding diagraph, which indicates that three criteria have their own applicability: Mohr-Coulomb criterion is conservative, Drucker-Prager criteria is somewhat dangerous and Mogi-Coulomb criterion is superior to the first two.

Abstract:Through the study of grading analysis and compacting test, this article analyzes the physical and mechanical property and the compacting capability of silt. As a result, it is one of the important reasons for the highway damage that the criterion of compaction in existence is deficient. In order to solve this problem, volume ratio of air is used as an assistant criterion for the compaction of silt. And, it is suggested that the degree of compaction for the road embankment should be improved.