基于聚合反应机理的膨胀型高聚物浆液平面裂隙注浆仿真方法研究

Study on simulation method for planar fracture grouting of expansive polymer grout based on polymerization reaction mechanism

现行高聚物浆液裂隙注浆扩散模拟方法多采用浆液密度变化经验表达式进行计算,这种简化处理方法没有考虑浆液内在的化学反应驱动机制,其求解结果与实际情况存在较大偏差。为解决这一问题,基于计算流体动力学理论,考虑浆液聚合反应机理,建立了描述高聚物浆液在平面裂隙中流动扩散过程的“化学反应-流体动力学”模型,用龙格库塔方法求解化学反应动力学方程,用平面裂隙注浆准三维模型离散流动控制方程,用SIMPLE算法实施迭代控制,实现了对浆液化学反应、温度场、流场的耦合求解。在此基础上,对绝热条件下高聚物浆液在平面裂隙中的扩散过程进行了数值模拟,分析了浆液组分反应转化率、温度、扩散范围、密度、压力等随时间变化规律,结果表明:伴随浆液化学反应进程,其组分转化率、温度逐渐增大,浆液扩散范围、密度变化表现出明显的阶段性特征;浆液密度随时间经历缓慢减小、急剧下降、逐渐趋缓三个阶段,与此相对应,其扩散范围最初平稳增加,随后快速扩大,最终趋于稳定,其压力则呈现缓慢增大、急剧上升、逐渐下降的三阶段变化特征。所开展工作为深入研究温度、压力等因素对浆液扩散行为的影响奠定了基础。

The empirical density change formula was used to simulate the diffusion of polymer grouting in fracture.However,this simplified method does not consider the intrinsic chemical reaction driving mechanism of polymer,which is quiet different from the actual situation.In order to solve this problem,a chemical reaction-hydrodynamic model for describing the flow and diffusion process of polymer grout in planer fracture was established based on the computational fluid dynamics theory and the polymerization mechanism of polymer grout.The Runge-Kutta method was applied to solve the chemical reaction kinetic equation.The quasi-three-dimensional simulation method for planar fracture and the simple algorithm was respectively used to discretize the flow governing equation and implement the iterative control.The coupling solution of the chemical reaction,temperature field,and flow field of polymer grout were realized.Therefore,the planar fracture grouting process of self-expanding polymer grout considering polymerization reaction mechanism was completed.On this basis,the diffusion process of polymer grout in fracture under adiabatic condition was simulated.The time-domain characteristics of reaction conversion,grout temperature,diffusion range,density and pressure were analyzed.The results showed that with the process of grout chemical reaction,the component conversion rate and temperature increased gradually.The grout diffusion range and density of grout show obvious characteristicof stage change.The grout density experienced three stages,i.e.,slow decrease,sharp decrease and gradual decrease.Correspondingly,the diffusion range increased steadily at first,then expanded rapidly and finally became stable.The pressure showed three stages of slow increase,sharp rise and gradual decline.The research can provide reference for further study on the effects of temperature,pressure and other factors on the grout diffusion behavior.