Study On Geometric Characteristic Parameters Of Discontinuity And Research On 3D Model Of Rock Mass

There are plenty of structure planes developed in the rock mass.The distribution and pattern of structure planes' development are the key factors to assess the properties of rock mass,such as mechanical characteristics,Hydraulic conductivity,stability and so on which cause the inhomogeneity of the rock mass,so that the research on structural planes has been a key issue in all major projects involving rock mass.Based on the large number of structural plane data obtained from the pre-selection area of china high-level radioactive waste disposal,the geometrical characteristics of the rock mass in the typical block of the pre-selected area was studied and the 3D network model of stochastic structure plane with deterministic Information was established in this paper.Based on the coupled model,combining with the field test data,the permeability of the rock mass in the region is analyzed,which provides the basis for the comprehensive evaluation of the prefabricated rock mass.the main research contents are as following:(1)The data which contains the detail property information was collected by using the manual measurement and photogrammetry combining high-accuracy RTK-GPS technology.The 3D spatial distribution of the traces of structure plane is reproduced by using the data which has been stored and processed on computer.Based on the reproduced result,digital processing was carried out to obtain the characteristic parameters of the structural plane.(2)The occurrence amending and dominant group partitioning of structure plane are necessary before the characteristic parameters extraction of structure plane.In this paper,The K-mean clustering algorithm improved by the agglomerative hierarchical clustering algorithm were used to partition the dominant groups,in the meantime,the index Xie-Beni and the index Fukuyama-Sugeno were used to verify the validity of partitioning results.Based on that,the dominant group partitioning and its occurrence value of structure plane of research field can be determined(3)In order to acquire the trace length of structure plane and its distribution,a fitting plane is needed to fit the curved outcrop.The trace value of each structure plane group and its distribution is obtained from the statistic of the trace of the fitting plane after trace emendation.The fitting result suggests that the trace length of the research field follows the lognormal distribution largely,and prat of it follows the Gamma distribution and exponential distribution respectively.The conunon method to estimate the size of structure plane is using the trace length to simulate.In this paper,two kinds of methods are used to simulate the probability distribution of the structural plane diameters:one is based on the numerical solutio n of the conditional probability,the other method is based on the average chord length The results show that the average diameter length of structure plane obtained by the conditional probability solution is lightly smaller than the average length of trace due to the intersection between the trace and sampling windows.however,the disk assumption of the structure plane need the diameter is larger than the trace,so the latter method was used to fit the distribution of diameter of the structure plane.The fitting result show that the diameter and the trace have the same distribution type(4)The density of structure plane is a crucial parameter for 3D network modelling.In this research,several virtual sampling lines and sampling windows are laid in research field on computer.The line density of structure plane can be derivated from the spacing of trace.The line density which can represent the whole research field can be obtained by calculating the average spacing of each sampling line;while the area density of structure plane of whole research field can be obtained by calculating the average area density of very sampling window.In order to get enough sample data and make the data more sensible in statistic,the adjacent sampling window should have reasonable overlapping when do the sampling window layout.(5)According to the Monte-Carlo rule,the Mersenne twister algorithm is used to generate the rardom number and verify it.In order to verify the validity of the random numbers,a fitting distribution of random numbers was developed and compared with the distribution of original data.the result shows that the distribution of random numbers is similar with the distribution of original data generally and within the confidence level,even if there are is slight difference between the random number and the original data.then,a stochastic network model of structure plane is built by using the random number.In order to improve the accuracy of the model and make it more realistic with the real condition a 3D network model of stochastic structure plane with deterministic Information was established under the principle that the volume density of the model is constant based on the stochastic network model.(6)The code was programmed based on MATLAB,as well known as the powerful function in matrix disposing and plotting,by the author,which can do the plane fitting of outcrop,probability density distribution(PDF)fitting of the characteristic parameters of structural plane and establish the network model and develop the structure plane-connected model automatically.the results show that the trace length of structure plane of the survey area is most structure planes belongs to low ductility,and some of them belong to medium ductility,even High ductility;The structure of the survey area is characterized by low ductility,Surface spacing are very wide spacing,the whole body of the survey area belongs to the large block.