紅樹林河口段之土壤性質及改良

The Soil Properties of the Estuary with Mangrove Habitat and Its Improvement

楊朝平(Chau-Ping Yang) ； 洪國森(Kuo-Sheng Hong)

《農業工程學報》 51卷1期 (2005/03) Pp. 1-11

https://doi.org/10.29974/JTAE.200503.0001

摘要

「就地取材」為生態工法之大原則，而紅樹林河口段之土層為含砂、粉、粘之土壤，其飽和度高、孔隙比大、承載力低、壓密沉陷量大等，土壤性質不佳。為兼顧防洪及保護紅樹林，以生態工法施做河防構造物最適宜，而河道土壤調查乃工法設計之大根本。為此，本研究以苗栗縣竹南鎭射流溝之河口段為對象，調查該區河道之土壤性質，並建議改良方法。
該河道土壤分類屬CL類土（砂質粉粘土）、含水量約為30.8%、孔隙比0.81、完全飽和、壓縮指數0.229。其有機物含量2.35%、pH=8.3，可藉由夯實及土壤水泥技術改良其工程性質，宜將其含水量控制在8%~23%範圍內。無圍壓縮強度於夯實試體為157kN/平方公尺、於土壤水泥試體（水泥含量12%）為1,066kN/平主公尺，內摩擦角於不擾動試體為10.3°、於夯實試體為33.3°、於土壤水泥試體為57.0°，知曉夯實及土壤水泥技術之改良成效佳。土壤水泥試體內雖含12%之水泥，但其組成仍接近土，植物尚可生長。

關鍵字

紅樹林河口段 ； 土壤性質 ； 夯實 ； 土壤水泥

並列摘要

One of the principal of the ecological construction method is ”full utilization of field materials” However, the stratum of the estuary with mangrove habitat is soft and in saturation state, with high consolidation settlement and lox bearing capacity. The ecological construction methods are suitable for the targets of flood control and preserving mangrove. It is necessary to survey the various properties of soils of mangrove habitat in order to assemble superior construction methods. Therefore, this study surveyed the properties of stratum in the estuary of the Sirlyu River, Miao-Li County. Then, the surveyed soil will be improved tentatively by the methods of compaction and soil-cement.
The surveyed soil is classified as CL and its group name is sandy silt with clay. The moisture content, void ratio and compression index of the undisturbed soil are 30.8%, 0.81 and 0.229 respectively. The content of organic materials and pH-value in the surveyed soil are 2.35% and 8.3 respectively. Accordingly, it is able to judge that the surveyed soil could be improved by the methods of compaction and soil-cement under the condition of controlling its moisture content in the range of 8%~23%. The unconfined compression strengths for compaction's specimen and soil-cement's specimen with 12 percent of cement content are 157 kN/m^2 and 1,066 kN/m^2 respectively. The internal angle of friction Φ of the undisturbed soil is 10.3°. Whereas, the values of Φ of the compacted specimen and soil-cement's specimen are 33.3° and 57.0° respectively, these values are rather higher than the one of the undisturbed soil. Though, the soil-cement's specimen contains 12 percent of cement but its nature is still like a soil and the vegetation could grow up in it.

並列關鍵字

Estuary with Mangrove Habitat ； Soil's properties ； Compaction ； Soil-cement