Estimation Of Trace Length And Connectivity Rate Of Joint Based On Digital Close-range Photogrammetry

With the non metric camera imaging quality continues to improve,the price tends to be plebification,using non metric camera to close-range photogrammetry is becoming more and more common.This method has been widely used in many fields because of its advantages such as fast measuring speed,high precision,large amount of information and non-contact measurement.In engineering geology,rock mass structure information collection work is very important,the acquired data is an important basis for evaluation of slope stability,because of its measuring position in high steep slope and high mountain canyon,the environment is extremely dangerous,the objective conditions severely restricted the engineering geological survey work,traditional manual measurement methods have been unable to meet the needs of the work.In this context,digital close range photogrammetry has been introduced into the engineering geological survey by its inherent advantages.Through continuous exploration and practice,the technology of obtaining the information of rock mass structure based on digital close range photogrammetry has gradually matured,in practice,it can give full play to its own advantages,and can quickly obtain high precision geometric information of rock mass structure,which can provide reliable basic data for slope stability evaluation.The occurrence and trace length of rock mass structure surface are the basic information for analyzing and evaluating slope stability,the broken degree of slope is mainly affected by the structure dimension,the trace length of rock mass joints is used to measure the structural plane of rock mass size is an important quantitative index representation structure scale,it controls the shear strength of discontinuous structural plane and hydraulic characteristic,how to accurately obtain the distribution of the joint trace length and the mean trace length of rock mass is the key work to the stability analysis of slope rock mass.A lot of researches have been done on the estimation of the mean trace length of rock mass joints,and a variety of algorithms have been put forward.The common application algorithm is the line method,the rectangular window method and the circular window method,the result of the line method is unstable,because of there are few trace of structural plane in the statistics;the circular window method is limited by the diameter of the window,larger window layout is more difficult,when the window area is too small with no statistical significance;the rectangle window method is more flexible,and can obtain a large window size,the estimation results are stable and widely used.In this paper,using digital photogrammetry to obtain a lot of geometry information of slope rock mass structural plane,basis on the H-H algorithm of trace length estimation,the algorithm is further optimized to improve the stability and applicability,establish the EHH estimation model of mean trace length of structural plane,and analyzed the stability and applicability of the algorithm.And research on the connectivity rate on the basis of the estimation model of mean trace length of rock mass joints,based on the basic theory of the existing window method and projection method,through the analysis of the measured data,the results show that the two algorithms have some defects,which leads to the instability of the calculation results.For this reason,this paper proposes the P-L connectivity rate model,In this model,the line is introduced into the projection method,and the intersection relation between the line and the trace is taken as the criterion to determine the projection range,Combined with the existing projection method to calculate connectivity rate.The experimental results show that the EHH mean trace length estimation model and the P-L connectivity rate calculation model are stable,reliable and applicable.In summary,the main achievements of this paper are as follows: 1 Collect high precision geometric information of the slope structural plane based on the digital close range photogrammetry;2 Obtain the rock structural plane characteristic data by compiling data post-processing software;3.Establish the model of the mean value of the rock joints trace length based on the H-H model;4.Establish calculation model of connectivity rate based on the projection method;...