东部沿海有咸区黏性原状土膜性能的试验研究

为验证黏性土的膜性能,进行了原状土的固结渗透试验。原状土样采自唐山市滨海有咸区地下65m处。对原状土样的粒度组成、孔隙特征及黏土矿物含量进行了测试,并将原状土样压入环刀,饱和固结后,用10g/L的盐水进行稳压渗透,定期监测出水流量及出水溶液的Cl-和Na+浓度。渗透试验结束,测试入流液及原状土表面溶液的浓度。试验结果显示,渗出液中N+和Cl-浓度同步缓慢增长,达到初始入渗溶液的浓度后仍呈增长趋势,试验结束时入渗液的浓度达初始值的1.1倍,原状土表面溶液浓度达初始值的1.5倍。这种浓差极化现象说明原状土具有一定的膜性能,但试验条件下原状土不能起到对盐分的截留作用。

Experimental Study on Membrane Performance of Cohesive Undisturbed Soil Salty Area of Eastern China

An experiment of consolidation and permeability in undisturbed soil was carried out to test and verify the membrane performance of cohesive soil. Undisturbed soil samples were collected from 65 m underground in Tangshan coastal salty area and then size composition, pore characteristics and clay mineral content were tested. The undisturbed soil sample was pressured into ring knife for saturation and consolidation, permeation under stable osmotic pressure was tested with 10 g/L saline, and water flow and Cl^- and Na⁺ concentration of the aqueous solution were regularly monitored. When the permeability experiment came to end, inflow fluid concentration and ion concentration on the surface of the undisturbed soil were tested separately. Results show that Na⁺ and Cl^- concentration almost synchronously increased, and were still rising after reaching the initial infiltration solution concentration. At the end of the experiment, inflow liquid concentration was 1.1 times the initial value of the inflow liquid, and the solution concentration on the surface of the undisturbed soil was 1.5 times the initial value of the infiltration solution. The phenomenon of concentration polarization testifies that the undisturbed soil has certain membrane performance, but cannot play a role in intercepting salt under the experimental conditions.