Stability Analysis And Supporting Design Optimization On Typical Phyllite High Slope Of Shiyan To Tianshui Expressway

Slope stability has always been a difficult problem in highway, especially themountainous area highway construction. With the rapid development of highway in ourcountry in recent years, highway slope problems presented increasing slope height, slopegeological conditions of increasingly complex and overhead expenses increased trend,therefore to carry out highway slope (especially metamorphic rock slope) stability analysisand evaluation and support design research has important theoretical and practicalsignificance.This article depends on key scientific research project “ShiTian highway Weathered andbroken metamorphic rock high slope stability evaluation and countermeasures study”ofShaanxi Provincial Communications Department, select Ankang period of ShiTian highwayK57+265~K57+325typical phyllite high side slope as the research object, by means of fieldinvestigation, laboratory test and numerical simulation analysis and other technical means,reveals the causes for deformation and failure of slope initial level4support system, contrastanalyzed the applicability of the variety of supporting design in nine grade and six grade, putforward the optimal design scheme that could satisfy the requirement of safety, economy andenvironment coordinated. The main conclusions are as follows:1、Based on the investigation and analysis of the slope engineering geological conditions,that：the slope is metamorphic rocks (phyllite) kind of fragmentation-layered reverse highslope, is formed by the highway line cut through the beam-like original slope, slope lithologyis strong-medium weathered phyllite; Slope integral sliding failure occurred during theconstruction process; There are many factors lead to the slope deformation and failure oflandform, stratum lithology and heavy structure, rainfall, construction excavation and supportdesign is not reasonable, etc.2、Using Geo-studio (Sigma/w) module to do step-by-step excavation numericalsimulation comparison analysis shows that with the gradual slope excavation, loose circlescope expands unceasingly, and adopts the topdown construction method caused loose rangeis less than no support excavation; Slope support scheme in the original four cases there maybe damage to the overall slip, while heavy rainfall is the direct cause of the slope deformation and failure.3、Using Geo-studio (slope/w) module to calculate the slope stability and compared itfor the level4supporting schemes in front of the slope deformation and instability and thelevel9supporting schemes that has been changed, concluded that the original level4supporting schemes under the rainstorm condition does not meet the security requirements,change of level9supporting schemes under all conditions are met safety requirements.4、According to the actual condition of the slope, discussed and put forward a relativelysimple optimization design idea: screen the slope shape→lattice design optimization→friction pile design optimization→lattice combined friction pile design optimization; Incomprehensive analysis of all kinds of computing support scheme under the premise ofstability, to the principle of safety, economy and environment coordinated,finally selected theoptimization design schemes by anchor cable lattice combined friction pile.