Discussion on Slope Stability Analysis Method of Abandoned Dreg Site Based on Spatial Effect
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摘要: 弃渣场常见于基础设施的建设过程中，影响其边坡稳定的因素众多，其中坡面凹凸形态、滑体端部效应以及坡体走向等空间效应因素对边坡稳定性的影响尤为显著. 为了研究坡体走向对边坡稳定性的影响，针对走向为折线形（弃渣场上下区域走向存在夹角）的某核电厂弃渣场，探讨了其边坡稳定性分析方法. 通过现场地质调查和区域划分，借助ANSYS建立三维模型，利用FLAC3D强度折减法分析稳定性和潜在破坏机制，以此研究弃渣场走向夹角对其潜在破坏机制的影响，最后提出考虑走向夹角因素的不平衡推力法，并展开走向夹角和边坡倾角对弃渣场边坡稳定性影响的分析. 研究结果表明：走向夹角影响弃渣场边坡应力场的分布形式和力的传递能力，走向夹角越大其稳定性越好，走向夹角超过60° 时边坡安全系数明显提高；坡顶区域倾角越大，坡脚区域倾角越小时，其安全系数提升幅度随走向夹角的增大而显著提高. 研究成果可为类似折线形走向边坡的稳定性分析和治理设计提供参考.Abstract: An abandoned dreg site is a common occurrence in construction projects. There are numerous factors that influence the slope stability including the spatial effect of the concave and convex form, and side-body-end and slope strike, which play vital roles in slope stability analysis. In order to investigate the effect of slope strike on slope stability, an abandoned dreg site in a Nuclear Power Plant was considered, of which the strike is a broken line （i.e., an angle of strike exists between the upper region and the lower region） to discuss the method of slope stability analysis. The effect of the angle of strike was then studied for potential failure mechanism of the abandoned dreg site via geotechnical field investigation and region division using a 3D-model that was constructed using ANSYS, and an analysis of the slope stability by the strength reduction method in FLAC3D was conducted. Finally, the imbalance thrust force method was proposed, taking into consideration the angle of strike. An analysis of the effect of the angle of strike and the dip of slope for stability was then performed. The results indicate that the angle of strike has an effect on the distribution of the stress field and the capability for force transmission. Hence, slope stability will be improved with an increase of the strike angle, and safety factors will increase significantly when the strike angle is more than 60°. In addition, there is a significant increase in safety factors with an increase in the angle of strike, while the dip of the slope crest increases and the dip of slope toe decreases. The results provide a scientific reference to evaluate the stability and design treatment for slopes, where the strike is a broken line.
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图 8 不同走向夹角的边坡数值模型
Figure 8. Slope numerical models for different angle of slope strike
图 9 不同走向夹角的边坡数值模型
Figure 9. Slope numerical models for different angle of slope strike
表 1 计算所采用的材料参数
Table 1. Material parameters used in analysis
岩（土）层 密度/（kg•m–3） 弹性模量/MPa 泊松比 抗拉强度/MPa 粘聚力/kPa 内摩擦角/（°） 弃渣土 2 000 9.82 0.30 0.01 5 26.0 粉质黏土 1 950 8.58 0.35 0.02 48 12.5 中风化花岗岩 2 500 11 000.00 0.25 1.50 700 39.0 
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表 2 滑体分区及其受力状态
Table 2. Region division and stress states of sliding mass
弃渣场
区域面积
/m2长度
/m重力
/kN下滑力
/kN抗滑力
/kN①号条块 250.5 36 5 010.6 1 381.1 1 202.9 ②号条块 197.1 43 3 941.6 1 086.5 2 035.0
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表 3 不同走向夹角的剩余下滑力和安全系数
Table 3. Residual sliding force and safety factor of different angle of strike
走向夹
角/（°）${E_{12}}$/kN ${E_{12}}$降低
幅度/%${F_{\rm s}}$ ${F_{\rm s}}$提升
幅度/%0 443.18 0 1.33 0 28 409.53 7.6 1.36 2.2 60 273.59 38.3 1.50 12.5 90 0 100.0 1.87 40.8
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表 4 数值分析所采用的材料参数
Table 4. Material parameters used in numerical analysis
材料 密度
/（kg•m–3）弹性模
量/MPa泊松比 抗拉强
度/MPa粘聚力
/kPa内摩擦
角/（° ）上部
弃渣2 000 9.82 0.30 0.01 5 20 下部
弃渣2 000 9.82 0.30 0.02 8 25 中风化
花岗岩2 500 11 000.00 0.25 1.50 700 39
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表 5 数值模拟和理论计算的比较
Table 5. Comparison of numerical simulation and theoretical calculation
走向夹角
/（° ）数值模拟
安全系数理论计算
安全系数误差
/%0 1.30 1.38 5.80 30 1.31 1.39 5.76 60 1.32 1.43 7.69
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