垃圾堆体固有渗透率及孔隙度演化特征试验研究

发布时间：2018-01-08 11:37

本文关键词：垃圾堆体固有渗透率及孔隙度演化特征试验研究　出处：《辽宁工程技术大学》2014年硕士论文　论文类型：学位论文

【摘要】：填埋场内气体流动的孔隙空间——“迁移通道”既受上覆载荷的作用,也同时由于垃圾土骨架自身的降解而发生改变。如何有效地对垃圾填埋气体的迁移规律及气井的收集效能进行合理评估已成为填埋场沼气收集和利用工程中的重要研究课题,而定量描述垃圾堆体渗透特性的变化规律及建立固有渗透率和孔隙度的表征模型是解决这一难点的关键性科学问题之一。本文以多孔介质气-固耦合渗流理论、土力学以及生物降解动力学等多学科交叉理论为基础,以室内试验研究为主导,实现了对垃圾堆体固有渗透率和孔隙度的协同演化过程进行定量化预测；同时以数值仿真分析为依托,开展了渗流-应力全耦合条件下填埋气体迁移过程模拟。具体研究成果如下：(1)开展了不同载荷作用下垃圾堆体固有渗透率和孔隙度的协同演化试验,建立了固有渗透和孔隙度的定量表征模型,分析了不同含水率条件下固有渗透率和孔隙度的变化规律。传统K-C模型无法描述这一变化规律,而幂函数形式(κ=AnB)和线性函数形式(Ig(κ)=a+blg(n))两种协同表征模型均与试验结果达到了良好的拟合效果；模型尺寸从50mm增大至500mm,固有渗透率从10-15 m2增加至10-12m2,孔隙度从0.378增加至0.685。(2)分析了降解1个月、2个月和3个月后的垃圾固有渗透率和孔隙度的变化规律,发现降解时间越长,垃圾堆体固有渗透率和孔隙度下降的幅度越明显。当含水率为45%时,随着降解时间的增加,孔隙度最小降低至0.1,同时固有渗透率的变化幅度达到4个数量级。幂函模型对新鲜垃圾的k-n拟合效果较好,而K-C模型对降解后垃圾的k-n拟合效果较好。(3)构建了填埋气体迁移渗流-应力全耦合模型,分析了填埋场气体迁移规律,预测了气井收集效能,结果表明：考虑k-n模型的情况下填埋场内气体压力值高于不考虑k-n模型的情况,封场10年后压力差值最大达到0.346kPa；由于载荷的作用,气井平均流量较无载荷作用时偏低14.8%；加入快速渗透层可有效提高填埋气体的横向迁移速率,减小填埋气体的逸散,显著增加了气井的收集量。以上研究成果为进一步丰富和完善气-固耦合条件下填埋气体迁移演化特征、有效评估垃圾填埋场内气体迁移规律以及合理设计填埋气体的收集控制系统提供了依据。
[Abstract]:The pore space of landfill gas flow - "migration channel" is affected by the overlying load, also due to degradation of garbage soil skeleton itself and change. How to collect performance of gas migration and landfill gas effectively and reasonable assessment has become an important research topic of landfill gas collection and utilization project the quantitative describe the change rule of landfill seepage characteristics and characterization model of intrinsic permeability and porosity is one of the key issues to solve this problem. In this paper, the porous medium gas solid coupling seepage theory, soil mechanics and biodegradation kinetics of interdisciplinary theory based on experimental study the indoor LED, realizes the process of co evolution of the inherent permeability and porosity on the rubbish heap of quantitative prediction; at the same time according to the numerical simulation analysis Support, carry out the hydro simulation migration force full coupling conditions of landfill gas. The main research results are as follows: (1) to carry out co evolution test under different loads of dustheap intrinsic permeability and porosity, established quantitative characterization of mold intrinsic permeability and porosity, analyzed the variation of intrinsic permeability and porosity under the condition of different water content. The traditional K-C model can describe the change law, and the form of power function (K =AnB) and linear function (Ig (k) =a+blg (n)) of two kinds of collaborative representation model and the test results are up to the good fitting effect; model size increases from 50mm to 500mm. The intrinsic permeability increased from 10-15 m2 to 10-12m2, the porosity increased from 0.378 to 0.685. (2) analysis of the degradation of 1 months. The changes of the 2 and 3 months after the garbage intrinsic permeability and porosity, found that the degradation time longer. The garbage heap decreased the inherent permeability and porosity was more obvious. When the water content is 45%, with the increase of the degradation time, minimum porosity decreased to 0.1, while changes in intrinsic permeability up to 4 orders of magnitude better fitting effect. K-N power function model of fresh garbage, while the K-C model fitting effect of K-N garbage the degradation is good. (3) the migration of landfill gas seepage stress coupling model is established, the analysis of landfill gas migration law, predict the gas collection efficiency, the results show that the value is higher than the K-N model without the landfill gas pressure K-N model under the condition of considering, closed after 10 years of pressure difference the maximum 0.346kPa; because of the effect of load, the average load flow in gas wells is low 14.8%; adding rapid infiltration layer can effectively improve the lateral migration rate of landfill gas, reducing landfill gas escape Scattered, significantly increased the amount of collected gas. The above research results to further enrich and perfect the gas-solid coupling conditions of landfill gas migration and evolution characteristics, provide the basis for the collection of control system for effective assessment of landfill gas migration and reasonable design of landfill gas.

【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU993;TU43

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