To solve the technical cruxes of the conventional system in deep rock mass, an automatic testing system for hydraulic frac- turing that includes a single tube for hydraulic loop, a pressure-relief valve, central-tubel...To solve the technical cruxes of the conventional system in deep rock mass, an automatic testing system for hydraulic frac- turing that includes a single tube for hydraulic loop, a pressure-relief valve, central-tubeless packers, and a multichannel real-time data acquisition system was used for in-situ stresses measurement at great depths (over 1000 m) in a coalfield in Juye of Northern China. The values and orientations of horizontal principal stresses were determined by the new system. The virgin stress field and its dis- tributing law were decided by the linear regression from the logged 37 points in seven boreholes. Besides, the typical boreholes ar- ranged in both the adjacent zone and far away zone of the faults were analyzed, respectively. The results show that a stress concentra- tion phenomenon and a deflection in the orientation of the maximal horizontal stress exist in the adjacent zone of the faults, which further provides theoretical basis for design and optimization of mining.展开更多
The successful application in drilling for HK simple weathered granite foundation has revealed its further use in instru- mented drilling system as a ground investigation tool in the detection of other lithology forma...The successful application in drilling for HK simple weathered granite foundation has revealed its further use in instru- mented drilling system as a ground investigation tool in the detection of other lithology formations, geohazards, underground water, and boundary of orebody. To expand the further use and test the accuracy in identification of formation, an R-20 rotary-hydraulic drill rig was instrumented with a digital drilling process monitoring system (DPM) for drilling in an intricate decomposed granite site. In this test ground, the boreholes revealed that the weathered granite alternately changes between moderate and strong. The qualitative and quantitative analysis of the penetrating parameters, indicates the effective thrust force, rotary speed, flushing pressure, penetrating rate, and displacement of the bit fluctuate at ground interfaces. It shows that the parameters get a good response with the change of rock strength at the interfaces, which can reveal the change of the intricate granite formation. Besides, a variable-slope method has been established, for identification of dominative and subsidiary interfaces in the granite site. The result from a t-test shows that the confi- dence of the instrumented drilling system in identification of the geotechnical interfaces is up to 99%.展开更多
In order to reveal the strength deterioration law of rock mass under an acidified environment, a series of experiments on strength deterioration and the environmental effect on marble and diabase under the conditions ...In order to reveal the strength deterioration law of rock mass under an acidified environment, a series of experiments on strength deterioration and the environmental effect on marble and diabase under the conditions of three kinds of acids (H2SO4, HNO3and HCl) with three contents (1.0%, 5.0% and 10.0%) in a static fluid surrounding were carried out by single factor simulation. After the stones had been saturated in the above solutions for 90 days, an indoor weathering simulation had been observed for 300 days and its strength characteristics were measured under static/dynamic load and that results were compared with those under the natural condition. It is evident that the strength is emaciated greatly after the stones eroded by the liquids, whether under the static or dynamic load.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No. 50490271)
文摘To solve the technical cruxes of the conventional system in deep rock mass, an automatic testing system for hydraulic frac- turing that includes a single tube for hydraulic loop, a pressure-relief valve, central-tubeless packers, and a multichannel real-time data acquisition system was used for in-situ stresses measurement at great depths (over 1000 m) in a coalfield in Juye of Northern China. The values and orientations of horizontal principal stresses were determined by the new system. The virgin stress field and its dis- tributing law were decided by the linear regression from the logged 37 points in seven boreholes. Besides, the typical boreholes ar- ranged in both the adjacent zone and far away zone of the faults were analyzed, respectively. The results show that a stress concentra- tion phenomenon and a deflection in the orientation of the maximal horizontal stress exist in the adjacent zone of the faults, which further provides theoretical basis for design and optimization of mining.
基金the Research Grant Council of HKSAP Government and Hong Kong Jockey Club Charities Trust(No.HKU7005/01E).
文摘The successful application in drilling for HK simple weathered granite foundation has revealed its further use in instru- mented drilling system as a ground investigation tool in the detection of other lithology formations, geohazards, underground water, and boundary of orebody. To expand the further use and test the accuracy in identification of formation, an R-20 rotary-hydraulic drill rig was instrumented with a digital drilling process monitoring system (DPM) for drilling in an intricate decomposed granite site. In this test ground, the boreholes revealed that the weathered granite alternately changes between moderate and strong. The qualitative and quantitative analysis of the penetrating parameters, indicates the effective thrust force, rotary speed, flushing pressure, penetrating rate, and displacement of the bit fluctuate at ground interfaces. It shows that the parameters get a good response with the change of rock strength at the interfaces, which can reveal the change of the intricate granite formation. Besides, a variable-slope method has been established, for identification of dominative and subsidiary interfaces in the granite site. The result from a t-test shows that the confi- dence of the instrumented drilling system in identification of the geotechnical interfaces is up to 99%.
文摘In order to reveal the strength deterioration law of rock mass under an acidified environment, a series of experiments on strength deterioration and the environmental effect on marble and diabase under the conditions of three kinds of acids (H2SO4, HNO3and HCl) with three contents (1.0%, 5.0% and 10.0%) in a static fluid surrounding were carried out by single factor simulation. After the stones had been saturated in the above solutions for 90 days, an indoor weathering simulation had been observed for 300 days and its strength characteristics were measured under static/dynamic load and that results were compared with those under the natural condition. It is evident that the strength is emaciated greatly after the stones eroded by the liquids, whether under the static or dynamic load.
