Application Of 3D Laser Scanning Technology In Deformation Monitoring Of Foundation Pit And Parameters Inversion Of Rock Mass

In recent years,3D laser scanning technology has received more and more attention in the field of civil engineering.The technology can obtain the three-dimensional coordinate information of the target without contact and has the characteristics of high precision,high density and high speed.In the field of deformation monitoring,this technology not only overcomes the shortcomings of traditional monitoring,but also improves the working environment of workers and promotes the implementation of automated monitoring and digital monitoring.However,the current domestic research on this technology still needs to be improved.This paper mainly studied the application of 3D laser scanning technology in the aspect of deformation monitoring of foundation pit and the parameters inversion analysis of rock mass.First,the principle and characteristics of the technology were introduced in detail.Then through the accuracy test,the distribution law of the mean square error in the distance measurement and angle measurement of the scanner was studied.Thirdly,a new monitoring method based on 3D laser scanning technology was proposed and applied in engineering case.Finally,aiming at the characteristics of continuous and big data,the number of input samples was increased,and the parameters inversion analysis of rock mass was carried out.The main research work and contents of this paper are as follows:(1)The development status of 3D laser scanning technology,foundation pit monitoring and parameters inversion of rock mass was expounded,and the research status of 3D laser scanning technology in the field of deformation monitoring was analyzed.Although 3D laser scanning technology has some applications in the field of deformation monitoring,it has not yet formed a mature system,and the application of parameters inversion analysis of rock mass is rarely studied.(2)The composition and characteristics of the 3D laser scanning technology were analyzed in detail,and the method used in this study,such as the Focus S150 3D laser scanning system,was introduced.The concept of point cloud was systematically expounded and the research of data processing algorithms was carried out,which laid a foundation for the follow-up work.(3)The optimal scanning distance test of the target ball and the accuracy test of the scanner were carried out.The accuracy of the scanner is mainly divided into ranging accuracy and angle measurement accuracy.Through the test,mean square errors in ranging and angle measurement were obtained,which verifies the feasibility of applying the 3D laser scanner to the deformation monitoring of foundation pit.(4)Based on the engineering case,the scheme of 3D laser scanner for deep foundation pit monitoring was studied,and a method of 3D laser scanner applied to the deformation monitoring of foundation pit was proposed.The point cloud was acquired and processed in combination with the construction site,and the deformation visualization cloud image was obtained.Further,the deformation law of the supporting and surrounding roads were analyzed.Finally,the accuracy of scanning monitoring was compared and analyzed by means of traditional monitoring methods.(5)The point cloud of 3D laser scanner was studied as the training sample of rock mass parameters for parameter inversion.The data of the scanning monitoring was extracted as an input layer,and the parameters inversion analysis of rock mass was performed.The sample was selected by a uniform design method and substituted into MIDAS software to obtain the response data required for the inversion.The training of BP neural network was carried out using the MATLAB toolbox,and the inversion results were brought into MIDAS software for a forward analysis to evaluate the effect.