公路土质边坡注浆加固稳定性研究

Study on Stability of Grouting Reinforced Soil Slope in Highway

为解决目前在设计中普遍采用的抗剪强度加固区域置换法计算结果偏保守的问题,总结了前人的研究成果,分析了抗剪强度加固区域置换法的计算原理,以内蒙古经乌高速K91+768-K91+798左侧风积沙路堑高边坡为研究对象,基于极限平衡法对置换法的计算准确性进行了研究。首先,根据既有边坡稳定系数计算结果确定预加固区域,由潜在滑动面得到注浆深度;其次,对不同区域加固后潜在滑动面位置进行了讨论,边坡局部预加固稳定系数偏低,需对边坡进行整体预加固,整体预加固后边坡稳定系数为1.185,未达到规范稳定安全系数不小于1.2的要求,需增大注浆设计深度;基于此分析了强度置换法出现此计算结果的原因,判断强度置换法具有一定的保守性;最后,提出了更贴合实际的注浆桩体模型法,基于Rhino和Flac3D建立实体加固土桩模型分析加固边坡的稳定性,明确了具体的分析步骤,并结合国内注浆施工技术对注浆顶面设计高程进行了讨论。计算结果显示:基于注浆桩体模型法对高边坡进行整体预加固后,边坡稳定系数较抗剪强度加固区域置换法增加了30.4%,验证了抗剪强度加固区域置换法在边坡稳定性计算上的偏保守问题,注浆桩体模型法可以更准确地模拟边坡预加固的情况,避免工程浪费;结合两种方法的计算结果进行了优缺点对比,并对2种方法的设计适用阶段提出了建议。

In order to solve the problem that the calculation result obtained by the shear strength reinforcement area replacement method which is commonly used in design are conservative,the previous research results are summarized,and the calculation principle of the shear strength reinforcement area replacement method is analyzed.Taking the high slope of the aeolian sand road cut on the left side of K91+768-K91+798 of Jingpeng-Ulanhot Expressway in Inner Mongolia as the research object,the calculation accuracy of the replacement method based on the LEM is studied.First,the pre-reinforced area is determined according to the calculated existing slope stability coefficient,and the grouting depth is obtained from the potential sliding surface.Second,the position of potential sliding surface after reinforcement in different areas is discussed.It is found that the stability factor of local pre-reinforced slope is low,and the slope needs to be pre-reinforced as a whole.After overall pre-reinforcement,the slope stability factor is 1.185,which does not meet the requirements of the normative stability safety factor not less than 1.2.The design depth of grouting needs to be increased.Based on this,the reason for the calculation result using the strength replacement method is analyzed,and the strength replacement method is judged to be conservative.Finally,a more practical method(grouting pile model method)is proposed.The solid strengthened soil pile model is established by Rhino and Flac3D to analyze the stability of the reinforced slope.The specific analysis steps are determined,and the design elevation of the grouting top surface is discussed by using domestic grouting construction technology.The computation result shows that(1)after the high slope is pre-reinforced as a whole based on the grouting pile model method,the slope stability factor is increased by 30.4%compared with the shear strength reinforcement area replacement method,which verified that the shear strength reinforcement area replacement method is conservative in the slope stability calculation;(2)the grouting pile model method can more accurately simulate the situation of slope pre-reinforcement and avoid project waste.The advantages and disadvantages of the calculation results of the 2 methods are compared,and the suitable application stages of the 2 methods for design are proposed.