Page 4 - การศึกษาลักษณะและสมบัติของดินเพื่อวินิฉัยคุณภาพดินด้านปฐพีกลศาสตร์ในดินตัวแทนหลัก 41 ชุดดินของภาคตะวันออกเฉียงเหนือ

ห้องสมุดกรมพัฒนาที่ดิน
ii

Abstract

The suitable classification on diagnostic of soil mechanics is to be used for land use

management. At present, the soil properties used for diagnostic on soil mechanics are
limited. Therefore, the study on characteristics and properties of 41 representative soil series
in the Northeast Thailand at that time such as soil reaction, soil texture, soil permeability,
grain size distribution, liquid limit, and plastic index. The results showed that soil pH at

0 - 200 cm depth had ranged from 4.3 to 8.7 which reflected the corrosion of non-coated
steel pipes at a low level, but is not limited for light industry.

The result of study on soil texture consisted sandy, loamy sand or sandy loam which
had high sand content (55.4% - 97.3%) but low clay content (0% - 19.8%), resulting in soil

permeability at a relatively fast to very fast level which suitable for roadfill or subgrade,
highways, septic tanks, light industry, and low building foundations. While, clayey soil with
high clay content (40.6% - 66.1%) and low sand content, affected on soil permeability at
slow to very slow level which suitable for excavated ponds and reservoir area. In addition,

the result of relationship of soil texture between USDA system and soil classification in the
Unified and AASHO systems, found that sandy soil was classified by the Unified and AASHO
systems is SM and A-2-4, respectively. Loamy soil was classified in the Unified system as ML,
CL, MH, CH while AASHO systems as A-4, A-5, A-6, A-7. Clayey soil was classified in the

Unified system as ML, CL, MH, CH and AASHO systems as A-7.

Consideration on soil as liquid limit and plastic index, we found that the most of soil
series had liquid limit ranged from 0.51 - 76.70, which had lowest liquid limit (0.51 - 21.63) in
sandy soil but highest (31.76 - 76.60) in clayey soil. The soil with high clay content led to

increase in liquid limit. In addition, the plastic index in most of soil had ranged from
0.50 - 40.04, which high in soil with high clay content. The soils with high plastic index led to
relatively high subsidence which affected on damage to buildings, such as Kantara Wichai
series (Ka), Nakhon Phanom series (Nn), Si Song Khram series (Ss), and Wang Hai series (Wi).
This result stated that the soil with high clay content led to increase in the liquid limit and

the plastic index.

Our results mentioned that suitability of representative soil series for used as a topsoil,
sand and gravel, roadfill or subgrade, highways and streets, excavated ponds, reservoir area,
pond embankment, septic tanks, light industry, low building foundations, and trafficability in

wet season can be used as database for high efficiently land use planning and suitability
mapping of soil mechanics in Northeast Thailand. In order to be in a format that is easy to
understand and convenient for users. In addition, understanding of the limited factors led to

sustainable land management.