Experimental Study On Permeability Of GCL Under The Action Of Plant Roots

GCL that bentonite waterproof blanket is following the compacted clay liner(CCL), geotechnical membrane(GM, HDPE) after a new type of composite material. Compared with the compacted clay liner, GCL superiorities in small thickness, light weight, simple construction, and has strong self-healing ability; compared with other geotechnical materials, the GCL flexible, anti uneven settlement ability, in use will not occur aging reaction, construction is simple and advantages. GCL has many advantages which are widely used in anti-seepage engineering. GCL is the biggest characteristic of the self-healing, bentonite will have a large amount of expansion in the water after, makes automatic healing in its damage to a certain extent, so as to play a waterproof effect. Currently researchers of GCL in defect of permeability of do a lot of work, analysis of the different degree of damage after GCL permeability. These are also for the research of this paper provides a lot of valuable experience. In the practical application, the root puncture damages is often appear, but at this point is rarely reported in the literature.This paper mainly through field test and theoretical analysis method, carry out the research on permeability of different plant roots under GCL. The specific studies are as follows:(1)Factors affecting GCL hydraulic conductivity of the theoretical analysis, while the expansion property and moisture permeation samples were tested for the measurement and analysis of the establishment and the permeability coefficient of the test blocks provide theoretical support.(2)Test 3 used a total of planting soil thickness(5cm, 10 cm and 20cm), 7 different types and ratios of plant(more Mulan, Bermuda grass, white clover, tall fescue grass and shrub ratio of 1: 1, 1: 3, 1: 5 mixed plants). Test pieces for different heights of plants on a regular basis for the collection, comparative analysis of the effects of GCL and geomembrane on plant growth, plant growth derived GCL is advantageous, but geomembrane on plant growth inhibitory effect; while planting soil the thinner the thickness, on plants sooner.(3)Environmental Geotechnical use GDS automatic permeameter test the permeability under a single root penetration of the GCL, namely the original test sample, GCL hydraulic conductivity under 10 mm diameter and 20 mm diameter root root role, the results show that plant roots diameter large, the permeability coefficient of GCL is greater, but in an order of magnitude(E-10 m / s), and thus may be determined when a single root diameter is less than 20 mm of GCL action, little effect on its permeability.(4)Model test, use STPZS-2 GCL permeameter test under real plant roots role permeability GCL, in actual plant roots action, compared to the original sample permeability coefficient(E-12 m / s), the actual plant roots the role of GCL hydraulic conductivity increased by 3 orders of magnitude(E-9m / s).(5)By comparing actual effect of plant roots permeability GCL can be drawn, planting soil thickness also affect the permeability of the GCL, at the time of planting soil thickness less than 20 cm, the greater the planting soil thickness, permeability decreases.The results of this experiment can provide some references for the application of GCL in practical engineering.Theoretical basis for scientific research work.