12-土壤耕作及管理.ppt

第十一章土壤耕作及管理 Settling of foundation due to unstable soil due to high shrink swell potential 土壤物理机械性能关系到建筑材料与建筑体的稳定性 第一节 土壤物理机械性质 Shrink / Swell Potential- soils with more than 30% clay have a high Shrink Swell clay more S.S. Potential (if clay is 2:1) to avoid this problem soil must be compacted and water must be kept out. Without the above - Shrink/swell will crack foundations and pavements or move telephone poles. 第二节 土壤耕性 soil tillage Tillage - old Disk Plowing （圆盘犁地） Similar to Chisel plowing（凿耕法）, some residues （残茬）are turned under by the disk lifting and inverting the soil. Chisel Plowing （凿耕） No till This planting system prepares a seedbed 2 inches wide or less, leaving most of the surface undisturbed and still covered with crop residues. The result is a wetter, colder environment that protects the seed and soil with its insulating （松软）effect of the surface residue. NO - Till Planting Conservation Tillage保护性耕作 energy saving time savings erosion control cold spring soils disease and insect problems lower yields compaction relief OM incorporation weed control harder Chisel Plowing （凿耕） Ridge Tillage（垄耕） Turf (草坪） Tillage Objectives Improve Aeration Increase Infiltration Ease root movement Procedures Coring（刨心） Slicing （切片） Coring and top-dressing golf greens SOIL STRENGTH PENETROMETER This penetrometer is a easy and reliable method for determining in?place soil strength. Great for checking building pads, excavations, or potential building sites. Simply measure the penetration and look up soil strength on the strength chart included with the unit. Chemical Soil Stabilization Lime, cement, and pozzolan (high silica volcanic ash) can be used as chemical additives. Lime is most effective on clay soils, and can be used in combination with cement and pozzolan. 第二节 土壤耕性 soil tillage 第二节 土壤耕性 soil tillage Advantages Disadvantages This system does not turn the soil over, but rather leaves it rough with c