Volume-weight properties volumes Soil sample Air volume of Water/voids Solid Volume of Solids Soil model The volume-Weight properties of a soil define its state Measures of the amount of void space, amount of water and the weight of a unit volume of soil are required in engineering analysis and design Soil comprises three constituent phases Solid: rock fragments, mineral grains or flakes, organic matter Liquid: water, with some dissolved compounds( e.g. salts) Gas: air or water vapour In natural soils the three phases are intermixed. To aid analysis it is convenient to consider a soil model in which the three phases are seen as separate, but still in their correct proportions
Volume-weight properties The volume-weight properties of a soil define its state. Measures of the amount of void space, amount of water and the weight of a unit volume of soil are required in engineering analysis and design. Soil comprises three constituent phases: Solid: rock fragments, mineral grains or flakes, organic matter. Liquid: water, with some dissolved compounds (e.g. salts). Gas: air or water vapour. In natural soils the three phases are intermixed. To aid analysis it is convenient to consider a soil model in which the three phases are seen as separate, but still in their correct proportions
Volumes of solid. water and air. the soil model masses volumes Air V=e Mw=Srey)Water μ-。re w I solid +-" specific M gravity = G The soil model is given dimensional values for the solid, water and air components: Total volume Ⅴ=Vs+Vw+Va
Volumes of solid, water and air: the soil model The soil model is given dimensional values for the solid, water and air components: Total volume, V = Vs + Vw + Va
土壤孔隙数量 (二)容重(假比重) bulk density(pb)(BD 概念:田间自然垒结状态下单位容积土体(包括土粒和孔隙)的质 量或重量(克/厘米3或吨/米3)。曾称土壤假比重( appare specific gravity)。质量以105-110C下烘干土计,也有人叫干容重。 定义式 式中:M土壤固相质量;Ⅴ土壤总容积(包括了粒间孔隙) The bulk density of a soil is the mass of dry soil per unit of bulk"(total volume of soil or soil particles pore space B D.= mass of oven dry soil (grams) total volume of soil(cm3; =grams cc The bulk density takes into account the total soil volume(the space occupied by the solid particles plus the space occupied by the air of the pores or pore space). To determine the mass of the soil--since air does not have any significant weight--we can just weigh the oven dry soil on a balance. The volume of the soil can be determined by pouring the soil into a graduated cylinder and measuring the volume that it occupies
一.土壤孔隙数量 （二）容重（假比重）bulk density(ρb）（BD） 概念：田间自然垒结状态下单位容积土体（包括土粒和孔隙）的质 量或重量(克/厘米3或吨/米3）。曾称土壤假比重（appare specific gravity） 。质量以105－110℃下烘干土计，也有人叫干容重。 式中：Ms土壤固相质量；Vt土壤总容积（包括了粒间孔隙） t s b V M 定义式： = The bulk density of a soil is the mass of dry soil per unit of "bulk" (total volume of soil or soil particles & pore space). B.D. = mass of oven dry soil (grams) ÷ total volume of soil (cm3;)=grams / cc The bulk density takes into account the total soil volume (the space occupied by the solid particles plus the space occupied by the air of the pores or pore space). To determine the mass of the soil--since air does not have any significant weight--we can just weigh the oven dry soil on a balance. The volume of the soil can be determined by pouring the soil into a graduated cylinder and measuring the volume that it occupies
土壤孔隙数量 湿容重 wet bulk density).Pt=Mt∧t=M+MW(V+w+Va)也有 文献叫土壤总容重( total bulk density).二者差别在于分子 一般情况下都是指干容重. 土壤干比容( dry specific volume)υb=1/pb.容重的倒数,直观地反 映土壤松紧度 土壤容重的影响因素: 影响土壤比重的一切因子会影响到土壤容重,但在更大程度上, 影响容重因子在于土壤松紧程度.土壤容重受到外界环境因素的影 响。如降水以及一切人为活动(耕作、施肥、灌溉、等农业技术 措施)。容重是土壤的一个动态性质。耕层以下相对稳定。 质地影响:砂土(1.2~1.8)>壤土>粘土(1.0~1.5) 土壤结构特征:团聚良好的土壤小于结构不良的土壤 般土壤耕层容重为1.0~1.4g(m容重较小。耕层小于底土。一 土壤松紧程度:根孔、虫孔较多 土壤容重一般是比重的一半左右
一.土壤孔隙数量 湿容重(wet bulk density). t=Mt/Vt=Ms+Mw/(Vs+Vw+Va)也有 文献叫土壤总容重(total bulk density).二者差别在于分子. 一般情况下都是指干容重. 土壤干比容(dry specific volume) b=1/b .容重的倒数,直观地反 映土壤松紧度 土壤容重的影响因素： 影响土壤比重的一切因子会影响到土壤容重,但在更大程度上, 影响容重因子在于土壤松紧程度.土壤容重受到外界环境因素的影 响。如降水以及一切人为活动（耕作、施肥、灌溉、等农业技术 措施）。容重是土壤的一个动态性质。耕层以下相对稳定。 质地影响：砂土（1.2~1.8）>壤土>粘土（1.0~1.5） 土壤结构特征：团聚良好的土壤小于结构不良的土壤 土壤松紧程度：根孔、虫孔较多的容重较小。耕层小于底土。一 般土壤耕层容重为1.0~1.4g/cm3 . 土壤容重一般是比重的一半左右
土壤孔隙数量 典型土壤容重 土壤 容重(g/cm3) 土壤 容重(g/cm3) 泥炭 0.20~0.50 黄土 1.35~1.50 莲松盐土0.80-1.00土壤碱化层 1.50~1.70 灰化层 0.80~1.00 土壤龟裂层 170~1.90 黑钙土耕层「1.10~1.30灌溉后土壤结壳1.60-1.90 沼泽土 1.10~1.30 土壤类型之间容重差异很大 The dry bulk density of most mineral soils varies from 1.00-1.80. lt may also vary due do tillage, compaction swelling aggregation, freezing and thawing. ect., and is not considered a static property at or near the soil surface. It is reasonably constant in the lower portion of the soil profile.土壤容重属于动态 性质,它的时空变异性很大.一般变化在1.00-1.80g/cm3之间 BD of common surface soils=1. 1-1. 4 g/cc BD of common subsoils=1.3-1.7 g/cc Acre Furrow Slice Acre)
一.土壤孔隙数量 典型土壤容重 土壤 容重（g/cm3 ) 土壤 容重（g/cm3 ) 泥炭 蓬松盐土 灰化层 黑钙土耕层 沼泽土 0.20~0.50 0.80~1.00 0.80~1.00 1.10~1.30 1.10~1.30 黄土 土壤碱化层 土壤龟裂层 灌溉后土壤结壳 1.35~1.50 1.50~1.70 1.70~1.90 1.60~1.90 土壤类型之间容重差异很大 The dry bulk density of most mineral soils varies from 1.00~1.80. It may also vary due do tillage, compaction swelling, aggregation, freezing and thawing, ect., and is not considered a static property at or near the soil surface. It is reasonably constant in the lower portion of the soil profile. 土壤容重属于动态 性质,它的时空变异性很大.一般变化在1.00~1.80 g/cm3之间. BD of common surface soils=1.1 - 1.4 g/cc • BD of common subsoils=1.3 - 1.7 g/cc Acre Furrow Slice Acre)