| In recent years,with the high grade roads such as highways and high-speed railways extending into mountainous areas,deep excavation and high filling are commonly applied.Due to the complex geological conditions in mountainous area,the engineering problems of the embankment slope have attracted great attention.In particular,as the longitudinal cracking and deformation of the roadbed have frequently occurred,its deformation failure mechanism model,stability evaluation method and engineering prevention and control measures against diseases and so on have attracted more and more concern.Adopting the method of engineering investigation analysis,numerical simulation calculation and field case test,this paper studies on longitudinal cracking formation mechanism of embankment,puts forward the typical failure modes and judgment characteristics as well as the corresponding countermeasures of engineering prevention and control measures.The main contents and research findings of this paper are as follows:(1)After collecting vast information of embankment slope engineering disease case,carrying out field test of various diseases at the scene,combining comprehensive analysis of properties,causes and stability and development trend of embankment slope that suffering deformation failure,the author summarizes the three main types of typical geological models,namely high embankment,soft soil embankment and steep slope embankment.Based on the numerical simulation analysis of the three types of models,this paper puts forward the embankment settlement cracking deformation mechanism and embankment lateral cracking mechanism,and establishes the control factors and the corresponding characteristics of settlement gradient,lateral stretching rate and deep displacement morphology.(2)The mechanism on longitudinal cracking and deformation of high embankment is as follows:with the attenuation of the filling strength parameters,tensile stress occurs at the top of the slope,resulting in the longitudinal cracking of the slope peak.The longitudinal cracking belongs to the subsidence creepage cracking.In this case,the slope peak has the following characteristics:the value of lateral stretching rate is 0.1%,the middle of the slope is lower than its surroundings.(3)The mechanism on longitudinal cracking and deformation of steep slope embankment is as follows:under the comprehensive influence of gravity,steep slope surface and the excavation unloading rebound in back side,uneven settlement and tensile stress will take place near the excavation border of high embankment,resulting in longitudinal cracking in the peak.The cracking is named shear cracking that is caused by differential settlement.In this case,the peak has the following characteristics:lateral stretching rate in the excavation boarder is 0.06%,the gradient settlement is 0.48%,and in the peak,the settlement near embankment slope is larger than that near the mountain.(4)The mechanism on longitudinal cracking and deformation of soft soil embankment is as follows:under the gravity effect of upper filling soil,the weak base will be damaged,in turn resulting in the deformation of upper filling soil.Meanwhile,the deformation causes tensile stress,resulting in longitudinal cracking in the peak.In this case,the longitudinal cracking is,in fact,the slope peak ripping caused by damaged base.However,different geological models lead to different slope state characteristics.(5)According to the mechanism of longitudinal cracking deformation of dif’ferent embankments,this paper adopts foundation treatment measures,support engineering measures and drainage measures and other measures.Based on a project example,combining with the monitoring measures of the displacement of the embankment slope,this paper controls the disease of embankment,predicts the scale and development trend of the disease,and gives feedback on the control measures of embankment. |
