加筋砾石土坡安全系数的实用计算方法  

A Practical Method of Calculating Stability Factor for Reinforced Gravel Soil Slope

作　　者：胡幼常[1] 陈晓鸣 毛爱民 HU You-chang;CHEN Xiao-ming;MAO Ai-min(l.School of Transportation,Wuhan University of Technology,Wuhan 430063,Chin;Xinjiang Transportation Planning Survey and Design Institute,Urumqi 830006,China)

机构地区：[1]武汉理工大学交通学院,武汉市430063 [2]新疆维吾尔自治区交通规划勘察设计研究院,乌鲁木齐市830006

出　　处：《公路》2018年第11期78-88,共11页Highway

基　　金：新疆维吾尔自治区交通运输厅科技项目,项目编号2012-303-5

摘　　要：我国新疆属地震多发区,区内广泛分布着砾石土,特别适合修筑土工格栅加筋路堤。这不仅因为土工格栅对砾石土的加筋效果好,而且还因为加筋土有优越的抗震性能。但实际上,加筋路堤在新疆还几乎没有应用。虽然主要原因是对加筋机理的认识不足,但缺乏相对简单的设计计算方法也是阻碍加筋土技术在新疆推广的原因之一。为此,结合新疆的实际情况,将置于坚硬地基上的土工合成材料加筋砾石土坡按准黏聚力原理转化为等代均质土坡,分别按简化Bishop法计算两者的稳定安全系数Fsg和Fsj。取砾石的黏聚力c=0kPa,内摩擦角φ=35°～40°,分别对坡率m=0.5、0.75和1的单级加筋土坡和多级加筋土坡进行计算,发现Fsg和Fsj具有良好的相关性,且当加筋层距S=0.3～0.8m、Fsg=1～2时,Fsg～Fsj关系曲线仅与边坡的平均坡率ma和砾石土的内摩擦角φ有关。经回归分析,分别得到了坡率m=0.5、0.75和1等3种情况下的单级和多级加筋砾石土坡的Fsg～Fsj回归公式,从而将复杂的加筋土坡安全系数Fsg的计算转化为简单的均质土坡安全系数Fsj的计算,使计算大为简化。而且,按这些回归公式计算出的Fsg,其绝对误差在Fsg∈[1.25～1.45]及其附近区域时不超过±0.03,满足工程设计的要求。Geogrid reinforced embankment is suitable to be constructed in China＇s Xinjiang where is an earthquake-prone area with widely distributed gravel soil,and it has been proved that geogrid reinforced gravel structure has not only good reinforcement benefit,but also excellent performance against earthquake.Whereas as a matter of fact,the reinforced embankment is hardly applied in Xinjiang,on the one hand,there is insufficient knowledge to the mechanism of reinforcement,on the other hand,there is not simple analysis method of design.In order to find out a practical method to evaluate the stability of Geosynthetic-Reinforced Gravel Soil（GRGS）slope,a GRGS slope constructed on firm ground is simulated by an equivalent homogeneous soil slope according to the quasi-cohesion principle.Fsg,the stability factor of the GRGS slope,and Fsj,the stability factor of the said homogeneous slope are calculated respectively using Bishop＇s simplified method.A lot of computations are carried out to determine the Fsg and the corresponding Fsjfor a series of simple and multistage GRGS slopes with the soil＇s cohesion of 0.Each GRGS slope varies in the soil＇s internal friction angle form 35°to 40°,in the slope ratio of 1∶0.5,1∶0.75 or 1∶1,or in the reinforcement spacing from 0.3 mto 0.8 m.A good correlation between Fsgand Fsjis demonstrated by the calculated data.Furthermore,if the reinforcement spacing is specified from 0.3 mto0.8 m,and Fsg=1～2,the Fsg～Fsjcurves are nearly effected only by the average slope ratio ma and the soil＇s internal friction angleφ.Based on the mathematical analysis,the fitting equations are respectively presented for estimating Fsgby Fsjfor the simple and multistage GRGS slopes with a slope ratio of 1∶0.5,1∶0.75 or 1∶1,which leading to replace the complex calculation of Fsgwith an easy computation of Fsj.The absolute errors of Fsg given by these fitting formulas are not larger than ±0.03 when Fsg ≈1.25～1.45,which satisfy the specifications of engineering design.

关 键 词：加筋砾石土坡 土工合成材料 稳定安全系数 实用计算公式 

分 类 号：U416.1[交通运输工程—道路与铁道工程]