Research On The Failure Mechanism And Protection Technology Of Red Clay Slopes

China's red clay is mainly distributed in the south,such as Guangxi,Guizhou,Yunnan,Guangdong and Hunan provinces.The complex climate environment such as rainfall-induced and dry-wet cycle causes diseases on red clay slopes.The failure mode of red clay slopes is different from other soils,and the failure mode is different from the traditional sliding arc sliding.Some red clay slopes are designed according to the specifications,but damage occurred in the early operation stage and even the construction stage.No good explanation can be given.The model and mechanism of red clay slope instability under dry-wet cycles need further study.For engineering protection measures of red clay slopes,designers with different designs on the same slope often have multiple schemes and the technical,economic,and environmental effects vary greatly.However,there are few studies on the application scope,effect analysis,economic environment comparison and other aspects of different protection schemes,and this is the need of engineering and technical personnel.This article first conducts a field investigation on the red clay slopes of expressways,national highways and other road sections in Jiangxi Province,and investigates the damage form,stability and protection of the red clay slopes.Secondly,based on the investigation,the indoor model experiment of red clay slope was conducted,and a3000 * 1500 * 2000(length * width * height,unit: mm)red clay slope model was made using the model framework of the Forestry College.To explore the failure mechanism of the red clay slope under the action of dry and wet cycles,and then use the finite element software to simulate the stability of the red clay slope under different supporting forms,and analyze the factors such as cost,environment,and construction period.Finally,by referring to the relevant data,the common protective measures of red clay slopes in Guizhou Province are summarized,the principles and processes of each protective measure are summarized,and suitable protective methods of red clay slopes in Guizhou Province are proposed.The main research results are as follows:(1)The failure characteristics of red clay slopes in Jiangxi Province are differentfrom ordinary soils,mainly due to spalling and gully-based shallow failures,which are not structural and have no obvious broken lines or arc sliding surfaces,even if a small amount of collapse It is expressed as a broken line and a circular arc.The cracks on the slope slope are crisscross,the surface is peeled off,and the gravel is mixed;the protection forms mainly include skeletons,protective walls,vegetation,anchor frames and comprehensive protection,of which the single vegetation protection and the retaining wall have poor protection effects,the skeleton Class,protective wall and comprehensive protection effect are remarkable,and there is no obvious damage to the slope.(2)The red clay slopes in Jiangxi Province have the most damage between 45 °and 80 °,and most of the unprotected slopes are damaged.It is recommended that red clay slopes must be protected in time after excavation,and no measures have been taken The slope of the slope should be as low as 1: 1.75 or more;improper inspection of protective measures,aging and cracking of the drainage blockage skeleton,and hidden dangers of slope stability.It is recommended to strengthen inspection and regular maintenance to ensure that protective measures are being used.(3)Comprehensive analysis of the results of indoor model tests on slopes.The damage characteristics under dry and wet cycles are similar to actual slopes,with surface erosion,gullies,and small pieces of collapse,which are mainly manifested as splash erosion-face erosion-fine Gully-gully development-gully penetration-partial collapse.The water content,pore water pressure,and earth pressure are all limited by depth.After the slope reaches a certain depth,about 10-20 cm,the deep pore water pressure and water content of the soil are basically stable,and it is not easy to shear damage,so the red clay edge Slopes are prone to damage in shallow layers.(4)Through finite element simulation,the safety factor of Grade 2 red clay slope under the retaining wall,anti-slide pile and other single supports can not reach 3.5 as required by the specification,the effect is not good,and the combined support can meet the requirements of the specification In combination with the construction period,process,construction difficulty and other factors,the anchor cable frame beam+ vegetation and anchor cable frame beam are selected as the best support scheme.(5)Different types of red clay slopes are suitable for different protection methods.For red clay slopes with a height of less than 5 meters and a slope rate of less than 1: 1,vegetation or spray-mixing protection is suitable,and the slope rate is between 1: 1and 1 : 1.5,the combination of skeleton and vegetation should be used for protection.For multi-level red clay slopes with a height greater than 5 meters and a slope of 1:1.5 or more,it is suitable to use a combination of reinforced skeleton and vegetation for protection.The developed red clay slope adopts window-type protective wall,skeleton and vegetation protection.