Analysis of seepage and dam slope stability for anti-seepage transformation of silt dam
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摘要: 为提高小流域地表水的利用率,解决山区灌溉用水问题,结合山西省偏关县咀儿上淤地坝开展淤地坝防渗改造的技术研究。针对该淤地坝上游坝坡,提出原土培厚、黏土斜墙、复合土工膜共3种改造措施5种改造方案,并考虑渗流场和应力场的耦合影响,对原坝体和各种改造方案的渗流和坝坡稳定性进行数值模拟计算。结果表明:原坝体受渗透水的影响较大,无法安全蓄水;仅对上游坝坡进行原土培厚并不能使坝体满足防渗要求;在上游坝坡铺设黏土斜墙或土工膜可有效降低浸润线、减少渗流量、提高下游坝坡的稳定性;土工膜方案相对于其他方案具有更好的安全性和可行性,可以在条件允许的前提下优先考虑。研究结果对类似淤地坝防渗改造工程具有一定的指导意义。Abstract: In order to improve the utilization rate of surface water in small watersheds and solve the problem of irrigation water in mountainous areas, We have carried out the technical research of anti-seepage modification of Juershang silt dam in Pianguan County, Shanxi Province. Aiming at the upstream slope of the silt dam, five reconstruction schemes were put forward including original soil thickening, clay inclined wall and composite geomembrane. The seepage and slope stability of the original dam and various modification schemes were numerically simulated considering the coupling effects of seepage field and stress field. The results show that the original dam is greatly affected by the seepage water and cannot store water safely; only the original soil thickening of the upstream slope of the dam cannot make the dam meet the requirements for seepage prevention; laying a clay inclined wall or geomembrane anti-seepage body on the upstream slope can effectively reduce the infiltration line and the seepage flow, and improve the stability of the downstream slope of dam; the geomembrane scheme has better safety and feasibility than other schemes, and can be given priority if conditions permit. The research results have certain guiding significance for the anti-seepage transformation projects of similar silt dams.
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Key words:
- silt dam /
- fluid-solid coupling theory /
- seepage /
- slope stability
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表 1 主要材料物理参数
Table 1. Physical parameters of main materials
材料 弹性模量/MPa 泊松比 黏聚力/kPa 摩擦角/˚ 渗透系数/(m·s−1) 坝体 7.53 0.30 23.00 25.00 1.00×10−7 坝基 15.00 0.29 50.00 21.00 2.19×10−9 黏土斜墙 10.00 0.35 12.30 23.60 1.00×10−9 土工膜 1.25×104 0.25 - 20.00 1.00×10−14 表 2 验证结果对比
Table 2. Comparison of verification results
计算方法 出逸点高度/m 单宽渗流量/(m2·s−1) 安全系数 流固耦合 10.67 4.380×10−7 1.084 传统法 10.41 4.240×10−7 1.152 表 3 各改造方案详情
Table 3. Details of each transformation scheme
改造方案及编号 上游边坡系数 下游边坡系数 坝顶宽/m 坝底宽/m 原坝体(A0) 2.25/2.00 2.00/1.75 3.50 95.00 原土培厚(A1) 2.50 2.00/1.75 7.50 105.50 原土培厚(A2) 3.00 2.00/1.75 7.50 116.50 原土培厚(A3) 3.50 2.00/1.75 7.50 127.50 黏土斜墙(B) 3.00 2.00/1.75 7.50 116.50 复合土工膜(C) 2.25 2.00/1.75 7.50 100.00 表 4 各方案渗流稳定分析结果
Table 4. Seepage stability analysis results of each scheme
方案 渗流计算结果 稳定性计算结果 单宽渗流量/(m2·s−1) 出逸点高度/m 蓄水后最大水平位移/m 安全系数 原坝体(A0) 4.380×10−7 10.67 0.141 1.084 原土培厚(A1) 4.073×10−7 10.27 0.138 1.108 原土培厚(A2) 3.756×10−7 10.02 0.132 1.159 原土培厚(A3) 3.579×10−7 9.86 0.126 1.190 黏土斜墙(B) 1.175×10−7 3.00 0.094 1.598 复合土工膜(C) 8.414×10−9 0.86 0.093 1.851 -
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