Study On The Safety Warning Distance And Treatment Mechanism Of Horizontal Reinforcement In Karst Region

The Karst cave area often happens to collapse accident, the subsidence damages would occur suddenly without evident signs when the soil caves in its upper development, causing serious safety problems. Hence, the horizontal geotextiles reinforcement method with deformation pre-warnings system is widely adopted abroad. However, existing researchers on horizontal reinforcement technology tend to emphasize on the aspects of reinforcement load and mechanical characteristics, the deformation mechanism of reinforcement has been ignored. Therefore, this thesis firstly makes research on the issues of the critical angle of the soil cave and the method of safety warning distance system in the collapse areas. Then it conducts an analysis of the loading characteristics of the horizontal reinforcement. Lastly the study employs the method of the combination of indoor experiments and numerical modeling, and conducts a systematic research analysis of deformation mechanism of reinforcement. The major completed works are listed as follows:Firstly, in view of the absence of reasonable findings of safety distance calculations concerning soil cave collapse, this thesis employs the numerical method FLAC2 D, employs the slope reduction method, analyzes the critical stable angle of the collapse internal soil cave, and obtains the recommended values of safety warning distance in cave subsidence with the consideration of the circular spatial effect.Secondly, the study makes the analysis of the existing three reinforcement load distribution mode, obtains the respective displacement curve of each distribution pattern based on the existing reinforcement displacement equation under the assumption of the current plane problem. Then the obtained displacement distribution map is compared with the experimental results of the field ditch, and gets the findings that the actual load distribution should be more close to the horizontal reinforcement load distribution pattern.Thirdly, this thesis adopts the method of indoor modeling experiment of trapdoor reinforcement to investigate the whole collapse process of the reinforced soil caves, and gets the relationships between the filled soil surface sedimentation and horizontal geotextile center subsidence. Moreover, the relationship between the geotextile internal changes and the filling soil height can be obtained from the study as well.Lastly, the FLAC3 D numerical modeling method was used to establish the spatial numerical model with the prototype of the indoor modeling experiment. This thesis would compare the obtained statistics with the indoor test data to make parameters analysis, and make the influence analysis of the filling soil height, soil cave span, the geotextile elastic modulus and internal soil cave friction angle in the geotextile deformation. Besides, the deformation mechanism is acquired for the soil-void collapse treatment by the horizontal reinforcement treatment technology, which could provide the theoretical reference for the further researches.