Post-construction settlement and creep law of waste dumps
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摘要: 采用Burgers模型對排土場散粒體蠕變的減速蠕變和等速蠕變兩階段進行描述,利用分層總和法的思想,將垂直填筑的排土場進行分層處理,底層在上覆‘自重’變荷載作用下發生沉降變形,分別采用定常和非定常Burgers蠕變模型從理論解析角度推導排土場填筑動態過程中沉降、工后沉降及累計沉降計算公式.以齊大山鐵礦排土場監測數據進行實例驗算,應用結果表明:非定常Burgers模型和定常Burgers模型擬合的相關系數均較高,非定常Burgers模型沉降最終收斂于5.07 m,定常Burgers模型沉降曲線具有發散性,可見非定常Burgers模型能更好地表述排土場沉降真實工況;將排土場分為十個分層,結合FLAC3D軟件的蠕變數值分析計算,得出各單層沉降率的變化規律,即各單層工后沉降量上層沉降值小于下層和中間層,且上層沉降量呈現單調遞減變化,越接近排土場頂部單層沉降量越小;中間層沉降量相對下層沉降量要大,其中第5單層的沉降量最大.Abstract: The grain body creep of waste dumps including deceleration creep and constant creep was described by the Burgers model.Using the layered summation method,the vertical filling waste dump was sliced and the bottom part settled under the variable weight load of the overlaid part.The computational formulas of settlement in the waste dump filling dynamic process,post-construction settlement and cumulative settlement were derived from theoretical analysis though the steady and unsteady Burgers creep models.The monitoring data of Qidashan Iron Mine were used as a case of proofing.The results show that the correlation coefficients of fitting with both the unsteady and steady Burgers models are high,and the final settlement value of the former is 5.07 m,while the settlement curve of the latter is divergent,thus the unsteady Burgers model performs better in simulating the real working condition of mine subsidence.The waste dump was divided into ten layers and the settle rate of each layer was calculated by the creep simulation model in Flac3D.The post-construction settlement of the top layers is smaller than that of the middle layers and bottom layers,the settlement of the top layers decreases when getting closed to the upper surface of the waste dump.The settlement of the middle layers is larger than that of the bottom layers,and the fifth layer performs a largest settlement.
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Key words:
- waste dumps /
- settlement /
- creep /
- Burgers equation /
- layering summation method
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