高速公路软弱路基边坡沉降滑移机理分析及微型桩复合加固

Analysis of the Mechanism of Settlement and Slip of Weak Subgrade Slope of Expressway and Micro-pile Composite Reinforcement

依托中国“一带一路”重点贡献项目格鲁吉亚E60高速公路Ubisa-Shorapani(F3)标段项目,针对公路软弱路基边坡沉降与滑移问题,通过现场实测与数值模拟探究并论证其机理,提出带连系梁式微型桩复合加固措施,并对结构自身参数进行方案优化。结果表明:路基边坡的安全稳定系数随加固区首排桩体距坡顶距离(Lx)逐增且呈现先增大后减小的趋势,在L_(x)=2 m且桩体倾角为15°时安全稳定系数最大,为1.542;不同桩径下的安全稳定系数差异较小,最大差值仅为0.1。基于敏感性分析优化方案,优化处治后的坡脚土体最大水平位移为10.8 mm,相比未处治前约减小88.0 mm,减幅为89.1%;路基左侧地表最大沉降量仅为7.9 mm,相比未处治前约减小12.1 mm,减幅为60.5%;随时间的增长,土体沉降逐渐趋于均匀且稳定。

Based on the Ubisa-Shorapani(F3)tender section project of Georgia E60 Expressway,one of the key contribu-tion projects of China′s″Belt and Road″initiative,and in view of the settlement and slip of the weak subgrade slope of the highways,through on-site measurements and numerical simulations,the mechanism is explored and demonstrated,and the composite reinforcement measures with connected beam type micro-pile are proposed,and the parameters of the structure are optimized.The results are as follows.The safety and stability coefficient of the roadbed slope shows a trend of first in-creasing and then decreasing as the distance(Lx)between the first row of piles in the reinforcement area and the top of the slope increases.When L_(x)=2 m and pile inclination angle is 15°,the maximum safety stability coefficient is 1.542.The difference in the safety and stability coefficients for different pile diameters is small,with a maximum difference of only 0.1.Based on the sensitivity analysis optimization scheme,the maximum horizontal displacement of soil at the foot of slope after optimization is 10.8 mm.Compared with the untreated period,it was reduced by approximately 88.0 mm,a reduction of 89.1%.The maximum surface settlement on the left side of the roadbed is only 7.9 mm,which is about 12.1 mm or 60.5%less than that before the treatment.As time goes on,soil settlement gradually becomes uniform and stable.