Mathematical Problems in Engineering / 2020 / Article / Tab 2

Research Article

Study on the Evaluation Method of Subgrade Slope Green Protection Effect in Dry-Hot Valley of Sichuan-Tibet Railway

Table 2

Indexes’ standard level.

IndexesExcellentGoodGeneralPoorVery poor

Volumetric weight of soil (g cm−3)<1.11.1∼1.21.2∼1.31.3∼1.4>1.4
Total soil porosity (%)>6060∼5656∼5252∼50<50
Organic matter content (g kg−1)>23.217.4∼23.211.6∼17.43.5∼11.6<3.5
Duration of soil PWP (month)<22∼55∼77∼9>9
Soil infiltration rate (mm h−1)>3020∼3010∼205∼10<5
Content of mineral nutrients (g kg−1)Total N (g·kg−1)>2.01.5∼2.01..0∼1.50.75∼1.0<0.75
Available P (P2O5) (g kg−1)>0.0150.01∼0.0150.005∼0.010.002∼0.005<0.002
Available K (K2O) (g kg−1)>0.10.08∼0.10.06∼0.080.04∼0.06<0.04
Ability of soil to preserve moisture and fertilityVery strongStrongMediumWeakVery weak
Soil expansion and contractionVery weakWeakMediumStrongVery strong
Coverage of vegetation (%)>9080∼9070∼8050∼70<50
Vegetation survival rate (%)>9080∼9070∼8050∼70<50
Incidence of pests and diseases in vegetation (%)<2020∼4040∼7070∼90>90
Vegetation species richness index>1.00.8∼1.00.6∼0.80.4∼0.6<0.4
Rationality of vegetation spatial collocationExtremely reasonableReasonableMediumUnreasonableExtremely unreasonable
Ability of vegetation to resist drought and heatVery strongStrongMediumWeakVery weak
Vegetation tolerance to barrennessVery strongStrongMediumWeakVery weak
Slope resistance to leaching erosionVery strongStrongMediumWeakVery weak
Antiscouring abilityVery strongStrongMediumWeakVery weak
Ability of slope to protect against wind and sandVery strongStrongMediumWeakVery weak
Slope resistance to natural disastersVery strongStrongMediumWeakVery weak
Ability of slope to prevent water and soil lossVery strongStrongMediumWeakVery weak

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