黄土洞室稳定条件及深浅埋计算方法研究

Study on stability conditions of loess caverns and dividing line criterion between shallow and deep bury

在分析黄土洞室开挖过程中顶部和侧墙破坏机制的基础上,将洞室顶部土体假定为自重应力场与梁构件附加应力场叠加的模型,以洞顶不出现拉应力为破坏准则,推导出了洞室顶部土体保持稳定的条件。在此基础上提出了黄土洞室深埋和浅埋分界线的计算公式,得到的结论与目前黄土设计规范推荐的经验公式吻合。将洞室侧壁假定为边坡模型,采用普氏围岩压力理论计算出传到侧墙顶部的荷载,利用楔形体极限平衡理论,推导出了洞室侧墙保持稳定的条件,为黄土洞室侧墙稳定的判断提供了理论依据。

Based on the analysis of the failure mechanism of the top and side walls of loess caverns during excavation,the soil at the top of the caverns is assumed to be a model subject to the self-weight stress field and the additional stress field of the beam.Based on the failure criterion that there is no tension stress on the top of the cave,the condition of soil stability on the top of the cave is deduced.On this basis,the calculating formulas of dividing line criterion between deep and shallow loess caverns are put forward,and the conclusions are in good agreement with the empirical formulas recommended by current loess design codes.The side wall of the cavern is assumed as a slope model,and the load transmitted to the top of the side wall is calculated by using the pressure theory of Prussian surrounding rock.Based on the limit equilibrium theory of the wedge,the conditions for the stability of the side wall of the cavern are deduced,providing a theoretical basis for judging the stability of the side wall of the loess cavern.