| In this paper, Guilin - Yangshuo K9 ~ K23 highway subgrade works, for example, is mainly directed against the current domestic TDR monitoring techniques, like by studying the soil-hole (collapse) of the evolutionary process to find a reasonable sub-soil-hole instability It is, and to evaluate its stability; on unstable soil holes adopt TDR for monitoring, taking into account the difficulty of its monitoring to one of the best calculated by simulating the monitoring beam depth and soil Dongding the relationship between plate thickness and the span . Research is mainly manifested in the following areas:(1) investigation of the soil through the three hole instability criterion of:â—‹1 No holes in the stability of underground activities;â—‹2 holes in the stability of the water level drops;â—‹3 hole the stability of the ground water level recovery. By numerical simulation, simulation of the different soil hole span, the nature of soil under different soil thickness of the roof for the relationship. Finally, Guilin - Yangshuo Highway K9 ~ K23 section to make holes in the stability analysis. The conclusion that stability of the hole when soil from the stability coefficient and can withstand the maximum load of two considerations.â—‹1 hole in the soil above the groundwater level, and no additional load on the top, the soil stability factor of the hole depth of the hole has nothing to do with the soil, the stability coefficient depends on the soil hole radius, radius, the smaller the coefficient of stability.â—‹2 is located above the groundwater level, the same span of holes in soil can bear the maximum load with the hole depth increases; are relatively prone to collapse; or shallow holes in the deep hole the more likely than collapse.â—‹3 holes in the soil below the groundwater level, soil hole stability is a function of span and depth. The same span, the greater depth of soil in the absence of the upper hole stability when load factor is smaller; the same depth, span larger holes in the absence of the upper soil stability factor smaller loads, can bear the greater maximum load.â—‹4 holes in the low water level than the high water level stable, and therefore, the stability of the high water level on the stability of buried soil from the hole controlling. Workspace concealed hole in the annual maximum water level of soil can withstand the maximum load is 19 ~ 187 KN/m2, this can never reach the soil bearing capacity requirements, therefore, measures must be taken to deal with.(2) unstable hole the use of TDR monitoring. First calculated by simulating the best fiber optic cable for monitoring the depth of soil thickness and span of the roof for the relationship. Further monitoring of the TDR signal analysis, and applied to sections of the signal collected in Guiyang analysis and evaluation. Obtained by numerical simulation of buried fiber optic cable when the TDR depth of 2m, you can get the best detection results. TDR test last section of the Guiyang-signal analysis In addition to laying fiber optic cables x3 line TDR soil hole deformation may have caused damage beyond the breakpoint, until now (when completed thesis) x1, x2, x4, x8-line monitoring of the waveform basically the same, no holes exist due to soil deformation caused by fiber optic cables for TDR shear failure. The power line damage x3 warning has been issued, to the TDR monitoring and early warning purposes.
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