大型碎屑堆积体工程特性及稳定性评价

ENGINEERING PROPERTY OF A LARGE-SCALE CLASTIC ACCUMULATION BODY AND ITS STABILITY EVALUATION

在中国西部水电工程建设中,由于地质条件复杂,面临许多工程地质问题,其中在坝址区和库区的大型堆积体对电站建设影响很大。分布在峡谷斜坡的大型碎屑堆积体,由于方量巨大、粒径多为30～200cm,极难进行强度试验和稳定性评价。以澜沧江中上游乌弄龙电站坝前大型堆积体为例,介绍该类碎屑堆积体的强度参数、粒度组成等工程特性的评价方法,并进行稳定性计算。研究结果表明:堆积体在天然条件下安全系数为1.11～1.15之间,处于稳定状态。地震条件下取Φ=36°～37°,K=0.98～1.02,表明该堆积体处于基本稳定状态,与现场调查的变形动态较吻合。这说明采用的分析评价方法是正确的,取得较好的效果。这些研究方法对于大型堆积体的研究具有借鉴意义,对于类似工程问题具有参考价值。

There are many engineering geological problems about hydroelectric development in west of China,which will lead to a large effect on hydropower engineering for accumulation body in reservoir area or dam site.A large-scale clastic accumulation body with grain size of 30–200 cm is distributed on the slope of a gorge.It is difficult to carry out strength test and stability evaluation for such an accumulation body.Taking Wunonglong large-scale accumulation body located in front of the damsite in middle-upstream of Lancang River as an example,the method to estimate the engineering properties of the accumulation body such as strength parameters and grain size distribution is introduced;and the stability analysis of this body is carried out.The results show that it is stable under natural conditions,and the safety factor is 1.11–1.15;under the action of seismic loading,considering that the internal friction angle is 36°–37°,the obtained safety factor is 0.98–1.02,which indicates that the accumulation body is stable.It is shown that the method adopted is proper.The method can provide references for the research of large-scale accumulation body and similar engineering.