In-situ profiling of soil to rock strengths by digital data from multi-type applications of hydraulic rotary drilling

Abstract

Drilling, especially hydraulic rotary drilling, is the dominant method for prospecting underground conditions and geomaterial properties. Most drilling projects are costly, time-consuming, and technology-intensive system engineering, involving large amounts of data. Nowadays, more and more researches of drilling information appear to meet the needs of various requirements in engineering and science. This thesis aims to develop the in-situ digital technique with multi-type applications of hydraulic rotary drilling information acquisition and analysis. Firstly, in Chapters 2 and 3 of this thesis, a new analysis method of real-time factual drilling data is provided for the analysis of drilling information. The complete factual data are described as five different processes and four individual operations by statistical analysis results. In the calculated curve of bit advancement depth and net drilling time, a series of linear zones with corresponding constant drilling speeds are presented based on the selected data from net drilling operations. Factual field data along two adjacent vertical drillholes are collected to verify the accuracy of calculated digitalization results. The comparisons of factual data along two drillholes and paralleled traditional loggings show that the calculated drilling information can accurately and consistently present the spatial distributions and interface boundaries of drilled geomaterials. Secondly, in Chapters 4 and 5 of this thesis, a new in-situ ground investigation method is developed for digital profiling of soil to rock strengths. On one hand, the drilling process monitoring (DPM) system and associated analysis method are applied for the 200 m deep drillhole in the loess tableland. The criteria for identifying major constant drilling speed zones are presented in detail. The in-situ profiling of loess ground in terms of spatial distribution of the coring resistances has been enriched and refined by the major zones with constant drilling speeds. On the other hand, the development of traditional rock quality classification is presented by digitalization results along the 108 m deep drillhole. The detailed interface boundaries and spatial distributions of superficial deposits to sedimentary rocks are calculated by drilling information. Thickness distributions of six basic quality grades are determined for the in-situ profiling of different siliciclastic sedimentary rocks. Quantitative relations between drilling speed and strength property are well expressed with explicit fitting functions. At last, in Chapters 6 and 7 of this thesis, two innovative applications of drilling information are summarized. A digital assessment method of soil improvement quality is presented by the case study of embankment reinforcement. By comparing the digitalization results of untreated and treated soils, factual field data along three drillholes are analysed for the in-situ quality assessment. Two indexes are proposed to quantitatively assess the soil improvement quality. In addition, the digitalization results of different drilling projects with various site conditions and geo-environments are presented as a new in-situ drilling management method. A series of analysis methods for time distributions of each process and operation are studied by various factual data. It is shown the new method can have significant effects on the in-situ drilling monitoring and management during current drilling practices.