Seismic Stability Analysis Of Sub Grade Engineering And Optimization Measures Research

The seismic damage data of subgrade engineering of Wenchuan earthquake provided rare conditions for researching the seismic stability of subgrade engineering in a high seismic area, we can draw lessons from Wenchuan earthquake that keeping the stability of the subgrade engineering and providing expesite traffic for the rescue after the disaster under earthquake condition. Embankment engineering should be the first choice as a type of lifeline project to cross through the active seismic belt because of its low cost and easy to be renovated, however,embankment engineering occupies a large amount of land and the slope toe is inconvenience to control, which requires the study of a new type of structure with good seismic stability and easy control of the slope; It is clear that retaining wall inclination and its application is a common phenomenon under the action of earthquake after survey in highways in Wenchuan earthquake disaster zones. It is necessary to research the stability of the retaining wall, and come up with a practical and effective measures to repair the inclination retaining wall. It is expected to provides some references for the stability analysis of the subgrade engineering in mountainous seismic areas and optimization measures through the above research.The main research contents and conclusions are:(1) According to the requirement of normal standard, this article analyzed and calculated the stability of general embankment and embankment with height of4m to20m, and did research on the influence of height classified and berm width to the stability of the embankment, the calculation results show that:the embankment of8m and below is stable under9degrees earthquake intensity,so there’s no need to consider reinforcement;9degrees earthquake intensity,so geotechnical grille is required to improve the seismic stability; From the most dangerous non-circular critical slip surface, the destruction of embankment is shallow slide crack destruction, smaller height of the grading setting, the higher stability of the whole embankment, considering both of the seismic stability and occupied land area, general embankment (20m and the following) is recommended to set the upper height as8m with a berm at the bottom, then the slope directly to the toe of slope; The wider the berm, equalling to decrease the slope, the higher the global stability.(2) Combined with the embankment design of Yalu highways, this paper discusses the optimization of reinforced high embankment, comparing the traditional reinforcement method with arrangement short reinforcement materials.Calculations show that, both of the two methods can guarantee the stability and control the fracture plane of embankment, the methods of layout short reinforcement can greatly reduce the using of material as well as prevent the slip crack of the slope close to the road surface effectively.This method ensure the normal function of the road.So the optimization of layout of short reinforcement methods is superior to the traditional reinforced ways.(3) Based on the NCMA method and combined with the domestic related standard, this article deduced the stability calculation formula of reinforcement gabion retaining wall in the normal working conditions, earthquake conditions and steep slope embankment, and program composition using Matlab. For a shoulder retaining wall in the specific road, research has been done about the influence of change with height and slope of the reinforcement gabion retaining wall on its stability. Also safety factor of the local shear failure was calculated when there is no connection between each unit of the reinforcement gabion retaining wall under the earthquake. Calculations show that:reinforcement gabion retaining wall have superior earthquake stability at different heights and slopes. It is a kind of superior retaining type which can satisfy different height and the slope requirements. External stability coefficient is much larger than specification values in normal condition and the internal stability (resistance to pull out and tensile) can meet the requirements too; In7and8degrees earthquake conditions, the internal satisfy stability can meet the standard requirements; When designing the wall’s height and slope, bearing capacity of base stress should be considered as well.The most suitable slope is about1:0.15;Under the condition of9degrees intensity earthquake, the retaining wall with height of12m and the following is stable.The local stability of the retaining wall is becoming more and more friable from top to bottom,and the local stability close to the bottom of the wall appeares to be less than overall anti-sliding stability. Thus it is suggested that connections at the bottom of the unit should be strengthened in strong earthquake resistance area.(4) Based on the survey and assessment on retaining wall stability along Puhong highway built after the earthquake, this article reserched about the calculation method of declining retaining wall stability. Through calculation about the declining retaining wall worksite along the PuHong highway, it is found that the inclination deformation stability reduced much more obviously than the original design.After tilting a certain degree, it can’t satisfy the standard requirements, According to the condition that abandoned side are abundant in mountainous area highway construction, a new method is put forward to put soil at the front of the retaining wall to strengthen the retaining wall’s stability.The results show that:putting soil at the front of retaining wall is benefit for the wall to strengthen its stability, and it is suggested to do so especially in mountainous highway,which is helpful for the stability of the retaining wall.