吕梁山区黄土边坡工程地质分区及强度参数选取

在山西省黄土高原综合治理分区图基础上，通过实地调查最典型黄土丘陵沟壑区（I区）的53个典型公路黄土边坡，根据边坡类型、地层组合形式以及边坡破坏模式等要素，将其进一步划分为晋西北（Ia）、晋西（Ib）和晋西南（Ic）3个亚区； 并对53个边坡的黄土进行了强度特征的试验研究，获得了边坡黄土在不同直剪试验方法下的峰值强度、启动强度与残余强度的参数值。根据边坡工程地质特征与工程调查类比，对3个亚区边坡在3种强度参数下的稳定性进行了统计和数值分析，结合应力变形计算实例分析发现：强度参数在不同地域具有明显的差异特征，晋西北区（Ia）降雨少，构造活动不频繁，边坡以坡面破坏为主，采用峰值强度进行边坡设计更为合适； 晋西区（Ib）构造发育，老滑坡较多，且地震活动使得土体强度相对下降，公路边坡设计的强度参数选用残余强度，有较高的安全保证； 晋西南区（Ic）降雨多，优先选用启动强度，能最大程度地避免地质灾害的发生。

ENGINEERING GEOLOGY DIVISION OF LOESS SLOPE AND ITS STRENGTH PARAMETER SELECTION IN LV-LIANG MOUNTAINOUS AREA

Based on Shanxi highway engineering geological zoning map, the most typical loess hilly and gully area(I) is further divided into the Northern Shanxi(Ia),Jin West(Ib), and Jin Southwest(Ic). The three sub-regions are distinguished according to the elements of the slope types, stratigraphic combination and slope failure mode loess. The parameter values of peak intensities, start strengths and residual strengths are obtained from different direct shear test methods after experimental study on the area(I) of 53 highway slopes. An analogy between the geological characteristics of the slope and the real engineering surveys is drawn. Statistic and numerical analysis of slope stability under the three intensity parameters in the three sub-regions are made. It is then found that the strength parameters have significant differences in different geographical characteristics. The Jin Northwest(Ia) has less rainfall and less tectonic activity. For slope to slope failure, the peak intensity slope design is more appropriate. The Jin West End(Ib) has structural development. Its seismic activity makes the relative decline in the strength of the soil. It has more old landslides. The residual strength should be used as the strength of the highway slope design parameters. There is a higher security guarantee. The Shanxi South West(Ic) has more rainfall. The start strength should be used in order to avoid geological disasters.