Rapid Acquiring Of Geometrical Information Of Rock Mass Discontinuities Based On Portable Controller-Close Range Photogrammetry

The stability analysis and evaluation of engineering rock mass are very important in the subjects of engineering geology, rock mass dynamics, rock mass structural dynamics, and they are the basement of the design and construction of rock mass engineering. According to the theory of rock mass structure control, besides the inherent intensity of rock mass, rock mass discontinuity and the rock mass structure controlled by the rock mass discontinuity control the deformation of the rock mass, the damage of the rock mass and the laws of rock mass dynamics property. The rock mass discontinuities include big faults and normal discontinuities that are of different sizes, different shapes and complicate distributions. The rock mass of smaller size and bad ductility, but with huge random discontinuities, presents in groups, this will bring the most serious influence in the dynamic feature of the rock mass, and influence the degree of the stability of the rock mass and destroy mode at the same time. When undertaking the analysis and evaluation of the stability of the rock mass, finding out the geometry information of the discontinuities becomes much more basic. Acquire the geometry information of the discontinuities of the rock mass rapidly, completely and accurately is of great significance.Based on the significance of discontinuities of the rock mass in the analysis and evaluation of engineering rock mass stability, scholars at home and abroad have done a lot of research in it. In conclusion, methods of acquiring the information of rock mass discontinuities are artificial compass measurement, drilling collection, three dimensional laser scanning and photogrammetry and so on. The first method is the most common used, but this is a low technological method with amount of work and limited collected information, the work environment of this method is not sure and can not come up to the requirement of immediately measurement. Drilling method is strict with drilling technique and drilling quality, cannot acquire large scale rock mass discontinuities, and the accuracy is not sure. Three dimensional laser scanning is strict with the distance and scale, exist high cost, and the vegetation and permeable character near rock mass discontinuities lead to cavitation in point data acquired by 3D laser scanning. In contrast, close range photogrammetry has the character of efficient and more complete information and the remote measurement ability, so it has been interested by a lot of scholars as the collection method of discontinuity geometry information. Portable control system is a portable control coordinate system, combined with close range photogrammetry to provide a much more rapider, efficient and accurate way in acquiring the geometry information of discontinuities.Basing on the current studying situation, this paper aims to study the rapid acquiring of geometry information of the discontinuities based on the portable controller close range photogrammetry at cutting excavation, low side slope at stone pit. During the studying, the portable control system is designed and made, and the stability of the portable control system is test with total-station instrument without prism. The designed portable system is a portable, rapid and stable system. Firstly, measure the coordinate values under the coordinate system of the portable control frame indoor, when it comes to the application, the coordinate values of every control site under the engineering coordinate system is acquired with three dimensional coordinate transformation, it provides an efficient and rapid control to the close range photogrammetry measurement. Putting the portable control system in the engineering region can acquire three dimensional image pairs by photographing. After the regulation of original images,3D model of rock mass slope is constructed with VirtuoZo digital photogrammery measurement and measure the coordinates of feature points on the discontinuities, and then acquire the geometry information of the discontinuities of the rock mass. By comparing to orientations measured by the artificial compass, the outer accordance precision of the orientation from VirtuoZo interpretation and free prism total station is analyzed. By the twice VirtuoZo interpretation, this paper studied the inner accordance precision of orientation of discontinuities. This paper has got the following conclusions:1. Design, manufacture and application of portable controller system:to acquire the discontinuity information of slope of cut, low side slope from stone pit, this paper produces the portable controller system with 4 aluminium level rods. This system is portable and flexible; Calibrations on the level rod not only provide amount of marks of control point, but also has a clear image and is facilitate to further processing; the stability test of the portable controller shows that the stability of discounting of the portable controller keeps in 3mm. Combined with close range photogrammetry, the portable control system is applied to the research of rapid acquiring geometry information of rock mass discontinuities.2. Research of Rapid Acquiring of Geometrical Information of Rock Mass Discontinuities based on Close Range Photogrammetry:taking a low slope from an abolished stone pit at Jingyuetan in Changchun as the experiment place, taking the portable controller as the main control measurement method, using a normal digital camera to acquire images, after the regulation of the acquired images, use VirtuoZo digital photogrammetry workstation establish the 3D model of the slope, then test the 3D model. The result shows that the mean error measured from this 3D model is only 1.2cm. This paper acquires feature point coordinates of 109 the discontinuities, and then acquire the orientation information of the discontinuities.3. Precision analysis of orientation acquisition of rock mass discontinuities:by comparing with the orientations from artificial compass measurement, the paper get the outer precision of orientation from VirtuoZo interpretation:error in tendency is±5°, error in dip is±4°,this shows the reliability of rapid acquiring of geometrical information of rock mass discontinuities based on portable controller-close range phtotogrammetry; the paper studied the inner precision of orientation from VirtuoZo interpretation:mean error in trend is±4°, mean error in dip is±3°; The orientation of outer precision measured by total station without prism:mean error in trend is±4°, mean error in dip is±5°. These results show that the precision of orientation measured by portable controller-close range phtotogrammetry, total station without prism is equivalent to the precision from artificial compass. The portable controller-close range phtotogrammetry is a rapid, complete and accurate method to acquire the geometrical information of discontinuities dealing with low side slope.4 This paper concludes the methods and processing of acquiring discontinuities geometrical information based on portable controller-close range photogrammery. The study of this paper provides practical meaning to the acquiring of geometrical information of rock mass discontinuities.