新建汶（川）-马（尔康）高速公路沿线发育多处影响路线安全的千枚岩堆积体边坡。该类堆积体具有孔隙比大、透水性强等特点。大气降雨是诱发该类边坡失稳破坏的重要因素，尤其是连续高强度降雨。目前，针对千枚岩堆积体边坡中千枚岩岩块定向排列特征的研究较少，稳定性分析评价中也鲜见考虑定向性的研究。抗滑桩是最常见的边坡治理措施之一，桩间水平土拱效应被众多学者广泛认可，主要应用在桩间距的确定上，但是其在抗滑桩加桩措施组合结构的受力分配计算中的应用较少，特别是圆桩加固工程中研究更少。本文以汶马高速K54+487～K55+417段左侧千枚岩堆积体边坡为研究对象，分析了该类边坡暴雨失稳机理及考虑桩间土拱效应的桩间组合结构的力学分析方法。主要包括以下内容：
（1）通过薄片鉴定及X射线粉晶衍射实验，研究分析了研究区千枚岩的结构、构造及矿物成分特征。
（2）自工程现场取千枚岩岩块，进行千枚岩堆积体定向排列特征的模拟实验，认为千枚岩由于片理构造发育，导致一定角度下定向排列现象明显，不利于边坡稳定；
（3）通过对研究区千枚岩岩块进行室内大型粗颗粒直剪试验，研究分析了千枚岩的定向排列现象及降雨入渗对千枚岩堆积体抗剪强度的影响。
（4）采用Midas-GTS-NX软件分析了边坡的稳态特征及经历暴雨12h、24h后的瞬态特征，总结了孔隙水压力、体积含水量的分布特征及变化趋势，分析了降雨对边坡稳定性的影响，认为降雨是边坡发生失稳破坏的主要因素。
（5）运用传递系数法对边坡进行稳定性分析，采用FLAC3D软件模拟分析圆形抗滑桩桩间土拱的形状及拱高，提出了考虑桩间土拱效应的桩间组合结构的力学分析方法，并与传统设计方法进行了对比分析。
 

There are multiple developed phyllite accumulations endangering the safety along Wenchuan-MaErkang Highway, which are large porosity ratio and strong water permeability. Atmospheric rainfall is an important factor in such slope failure, especially continuous high intensity rainfall. Presently,studies on the orientation acteristics of the phyllite in the slopes of the phyllite accumulation are few, so are the stability analysis. Anti-slide pile is one of the most common slope control measures. The effect of horizontal soil arching, which is widely recognized by many scholars, is mainly used in the determination of pile spacing; but the application of its force distribution calculation in anti-slide pile is less, especially in the consolidation of the round pile. This paper, based on the phyllite accumulations slope on the left side of the K54+487~ K55+417.of Wen-ma Highway, analyzes the rainstorm instability mechanism of such kind slope and the analytical method of the soil arching effect in composite slope structure. The main work is as follows:
(1)Studying the structure, geological structure and mineral composition of phyllite by thin film identification and X-ray powder diffraction experiment.
(2)Doing simulate experiments on the orientation of the phyllite accumulation carried out from the engineering site. And it is considered that the microstructures are developed due to the structural development of the microstructures, which is not conducive to the stability of the slope ;
(3)Analyzing the effect of rainfall infiltration on the shear strength of the phyllite accumulation is analyzed and studied by using the large - scale coarse - grain direct shear test.
(4)Analyzing the steady-state acteristics and the transient acteristics of the slope after rainstorm for 12h and 24h with Midas-GTS-NX software, and summarizing the distribution acteristics and trend of pore water pressure and volume water content. The impact of the impact of the slope that is the main factors of instability occurred.
The stability analysis of the slope is carried out by using the transfer coefficient method. The FLAC3D software is used to simulate the shape and arch height of the arch of the circular anti - slide pile. Then put forward the mechanical analysis method of the pile and it’s compared with the traditional design method.
 

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