Tunnel Geothermal Field Based On GOCAD Platform 3D Visualization Research And Practice

With the increasing development of social economy,various engineering constructions are constantly increasing.However,geological conditions are the most important factor restricting engineering construction.In order to ensure the safety and feasibility of the construction project,it is necessary to have the A comprehensive and accurate understanding.The construction of 3D geological model is an important basis for a series of geological applications such as geological body spatial analysis,geological phenomenon interpretation and underground space utilization.Accurately predict analytics problems.A tunnel is close to the Jiali active fault and the Yajiang suture zone.Due to the influence of the active fault and the suture zone,the geothermal problem is relatively prominent.In order to describe the geothermal situation more intuitively and clearly,a three-dimensional geological model with integrated vector grid was constructed.According to the thermal infrared remote sensing data of the study area,the atmospheric correction method is used to invert the surface temperature of the study area,and the distribution characteristics of the surface temperature in the study area are clarified.Combined with the engineering geological survey data of a tunnel in the Qamdo-Nyingchi section of a railway,the geothermal distribution within a certain depth range underground in the study area was clarified.A 3D geological structure model and a 3D geothermal attribute model of a tunnel are established.According to the constructed three-dimensional geological model of ground temperature,the distribution of ground temperature is analyzed,and the distribution of ground temperature in the study area is clarified.In view of the influence of heat damage on the construction of tunnel engineering,the prevention and control measures of tunnel heat damage are put forward.The main research results obtained are as follows:(1)In order to better build a 3D geological model,the 3D spatial data model,modeling techniques and interpolation techniques were studied and compared.The results show that the surface model can better represent the curved surface,and the volume model is not suitable for the uneven data inside the geological body.It can be better expressed,and the advantages of the two models can be combined to build a three-dimensional geological model.For areas with high accuracy requirements and complex site conditions,multi-source data can be used to construct a 3D geological model,and a high-precision model can be obtained through kriging interpolation technology.(2)In order to clarify the ground temperature distribution in the study area,the thermal infrared remote sensing data was used to invert the surface temperature of the study area,which showed that there was a phenomenon of high surface temperature in the study area.In places with high geothermal gradients,heat damage is mainly controlled by the suture zone.The comprehensive analysis revealed that there is thermal damage in a certain tunnel,and the geothermal anomaly is closely related to the fault zone.(3)Using GOCAD 3D geological modeling software as a platform,using DEM digital elevation data to construct topographic surface,constructing a 3D geological structure model of the study area through borehole information and profile information,and using hexahedral meshing technology to achieve 3D geological structure The grid conversion of the model uses grid interpolation technology to store the ground temperature data on the grid,completes the fusion of the structural model and the attribute model,and builds a three-dimensional geological model of ground temperature integrated with the vector grid.Then,the tunnel model is embedded in the above-mentioned in the 3D geological model of geothermal.(4)The three-dimensional geothermal model is analyzed to show the geothermal conditions of the study area,and the thermal damage of a certain tunnel is obtained.The tunnel temperature below 28°C accounts for about 52% of the total length of the tunnel;7%;37 ℃ ～50 ℃ paragraphs account for about 25%;50 ℃ ～ 60 ℃ paragraphs account for about 14%;more than 60 ℃ paragraphs account for about 2%.The influence of heat damage on tunnel engineering construction is clarified,and preventive measures are put forward for the problem of tunnel heat damage.