| With the rapid development of China's national economy and the country's increased efforts on infrastructure construction,a large number of tunnel projects based on TBM construction are in the process of being planned and under construction,which makes the stability of the surrounding rock of the tunnel and the jamming problems encountered during the construction of the TBM have increasingly become the focus of research in the field of underground geotechnical engineering.In the process of construction,the engineering geological problems caused by the bad geological conditions such as high ground stress,weak surrounding rock and fault fracture zone are often the key factors affecting the personal safety of construction personnel,the construction progress and the property loss of construction equipment.Therefore,it is necessary to systematically study and analyze the problems of tunnel construction under the action of deep and undesirable strata.This paper relies on the Qinghai Province "Yinda Jihuang" water transfer main channel project,through three-dimensional numerical simulation technology and combined with actual engineering data analysis,aiming at the surrounding rock deformation,TBM jamming,cavern reforming,support measures and other issues have been studied in depth.The specific work content is as follows:(1)by consulting a large number of literatures and relevant design specifications,the theories and analysis methods of surrounding rock stability,TBM jamming and tunnel support are systematically summarized.on this basis,the basic research methods of this article are clarified.(2)The basic theoretical equations,constitutive models and basic calculation theory of fluid-solid coupling used in numerical simulation were explained,which lays a foundation for the subsequent calculation and analysis.(3)Based on the analysis of TBM jamming and its escape techniques,the TBM jamming escape techniques under some specific conditions(high geostress,fault fracture zone)were summarized,and it is also found that the side pilot method is widely applicable in the escape technology of TBM jamming.(4)According to the actual engineering geology of the jamming section,a 3D finite difference model under the excavation condition of normal hole diameter was established,the deformation and stress states of surrounding rock under the condition of only stress field and fluid-solid coupling are analyzed respectively according to different geological processes and construction conditions(with or without water and segment reinforcement).The results show that: Compared with the condition of no water and segment reinforcement,when water was taken into account,the deformation of the surrounding rock was larger,the disturbance range of the surrounding rock was wider,and the TBM jamming was more serious.Under the condition of no water but with segment reinforcement and the segment support measures could be applied in time,the deformation of the surrounding rock of the tunnel could be better controlled,and the deformation amount of the segment was also within a reasonable range.When there was water effect,although the segment support structure could play a certain role in controlling the deformation of the tunnel surrounding rock,but the segment deformation was relatively large.Therefore,during the subsequent operation of the project,attention should be paid to the deformation of the segment at the location of the water inrush during the tunnel construction period.(5)According to the commonly used supporting measures in underground engineering,the mechanism of action of different supporting structures was defined.On this basis,according to the actual excavation and support of the reconstruction tunnel section,a 3D finite difference calculation model was established,the influence of the excavation and support structure on the stability of the surrounding rock of the tunnel was analyzed,and the deformation and stress state of the support structure was mainly studied.The study found that: Under the premise that the closed steel arch ring support form can be completed in time,the deformation and stress state of the surrounding rock and other support structures are within a reasonable range,which proves the effectiveness of the support measures. |
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