压气条件下泥膜进气值测量试验研究

Measuring Test for Air-entry Value of Filter Cake under Air Pressure

在压气条件下,进气是泥膜透气失效的起始点。为测量并研究泥膜在气压下的进气压力值(进气值),通过自制的试验装置,在不同压气条件下对3种泥膜进行进气值测量试验。试验结果表明:1)由闭气排水与固结排水的差值可以辨别泥膜是否进气,得到泥膜进气值; 2)采用泥膜特征孔径D_(90)/2代入推导公式可近似计算泥膜进气值; 3)泥膜在不同压气条件下进气值不同,增压速率越低,泥膜进气值越大; 4)在较快和较慢的增压速率下存在进气值变化趋于稳定的现象,最大进气值为最小值的2倍以上。

Under air pressure, air inflow is the starting point for the failure of filter cake. In order to measure and study air-entry value(AEV) of filter cake under air pressure, through self-made test device, the measurement of the AEV of three kinds of filter cakes under different pressure conditions is carried out. The results show that:(1) The difference value between air-closed draining and consolidation drainage can be used to distinguish whether air inflow happens or not, and AEV of filter cake can be obtained.(2) AEV can be approximately calculated by substituting the characteristic pore diameter D90 / 2 into the derivation formula.( 3) AEV of filter cake is different under different air pressure conditions, the lower the rate of pressurization, the larger the AEV is.(4) The change of AEV at a faster and slower rate of pressurization rate tends to be stable, the maximum AEV is more than two times the minimum.