黄土高原边坡特征与破坏规律的分区研究

为了研究黄土高原自然边坡的特征及破坏规律,按山系与水系或水系的分水岭、地貌单元、地层岩性特征等条件,将黄土高原划分为8个区:临洮—永靖区、天水—通渭区、兰州—会宁区、陇东区、靖边—安塞区、隰县—离石区、甘泉—吉县区和汾渭区.根据极限状态边坡的4个野外判别标准,测量了8个区510个自然极限状态黄土边坡断面,分区采用指数模型回归边坡坡高与坡宽的相关关系,计算各区20、50、100m坡高的边坡稳定系数和失效概率.结果表明:黄土高原的边坡特征与破坏形式具有分区特征,且南北差异性明显.临洮—永靖区边坡坡高与坡宽呈线性关系,表明该区边坡坡度不随坡高变化,边坡稳定性受内摩擦角控制;兰州—会宁区和靖边—安塞区高坡陡,低坡缓,高坡不稳定,易发生错落式滑坡;天水—通渭区、甘泉—吉县区和汾渭区高坡缓,低坡陡,稳定性计算结果显示高坡和低坡都较为稳定,但由于地层结构和地貌的特点,高边坡易发生低速蠕变型滑坡或高速远程滑坡;陇东区边坡整体上较为稳定;隰县—离石区受黏粒含量较高的Q1地层控制,高边坡稳定性较差;50m左右坡高的黄土边坡稳定性对强度指标内聚力、内摩擦角的敏感度都高,易于失稳.

Study on Regionalization for Characteristic and Destruction Rule of Slope in Loess Plateau

In order to study the characteristics and destruction rules of natural slope in Loess Plateau,according to the mountain and water systems or watershed of water system,geomorphic unit and strata lithological condition,Loess Plateau was divided into eigth regions which were Lintao-Yongjing Area,Tianshui-Tongwei Area,Lanzhou-Huining Area,Longdong Area,Jingbian-Ansai Area,Xixian-Lishi Area,Ganquan-Jixian Area and Fenwei Area.According to the four criteria identifying the critical slope in field,510 natural critical loess slope sections in the eigth regions were investigated,the relationship between slope height and width was regressed with exponential model in each area,and stabilizing factor and failure probability of slopes with the height of 20,50,100 m were calculated.The results showed that the characteristics and destruction rules of slopes in Loess Plateau were different for each area,especially the difference of slopes between southern and northern areas was significant.The relationship between slope height and width in Lintao-Yongjing Area was linear,so that the slope gradient was the same when slope height changed,and slope stability was controlled by internal frictional angle;the high slopes were steep and unstable,and low slopes were slow,and dislocation landslide easily happened for the high slopes in Lanzhou-Huining Area and Jingbian-Ansai Area;the high slopes were slow,and low slopes were steep in Tianshui-Tongwei Area,Ganquan-Jixian Area and Fenwei Area,and the calculation result of stability showed that the high and low slopes were stable,but the lowspeed and creep deformation landslide or highspeed and long runout landslide easily happened for the high slope because of the characteristics of strata structure and geomorphy;the slopes were stable in Longdong Area on the whole;because the slopes were controlled by Q1 stratum with high content of cosmid,high slopes were unstable in Xixian-Lishi Area;the stability of loess slope with the height of about 50 m was sensitive to cohesion and internal frictional angle,and was easy to fail.