KONSISTENSI TANAH
SUMBER: www.water-research.net/course/soilconsistence.ppt KONSISTENSI TANAH Soil consistence provides a means of describing the degree and kind of cohesion and adhesion between the soil particles as related to the resistance of the soil to deform or rupture. Since the consistence varies with moisture content, the consistence can be described as dry consistence, moist consistence, and wet consistence. Consistence that is evaluated includes rupture resistance and stickiness. The rupture resistance is a field measure of the ability of the soil to withstand an applied stress or pressure as applied using the thumb and forefinger. SUMBER: www.water-research.net/course/soilconsistence.ppt
SUMBER: www.water-research.net/course/soilconsistence.ppt KOHESI – ADHESI Cohesion is the attraction of one water molecule to another resulting from hydrogen bonding. Adhesion is similar to cohesion except with adhesion involves the attraction of a water molecule to a non-water molecule. SUMBER: www.water-research.net/course/soilconsistence.ppt
When We Describe Consistency – We Attempt to Describe the Following Environmental Applications (our focus) Rupture Resistance – Moist and Dry Consistency Stickiness – Wet Consistency Plasticity- Wet Consistency Geophysical / Engineering Manner and Type of Failure Penetration Resistance Consistence is the degree and kind of cohesion and adherence that soil exhibits, and/or the resistance of soil to deformation or rupture under applied stress. Moisture content strongly influences soil’s consistence. There are 5 ways to record consistence in the field; Rupture Resistance, Manner of Failure, Stickiness, Plasticity, and Penetration Resistance. Each type is recorded at specific moisture contents or within given moisture content ranges. SUMBER: www.water-research.net/course/soilconsistence.ppt
A measure of the strength of the soil to withstand an applied stress. Rupture Resistance A measure of the strength of the soil to withstand an applied stress Moisture content is also considered Dry Moist (field capacity) A measure of the strength of the soil to withstand an applied stress. Separate classes are made for; Blocks, peds, and clods and Surface crusts and plates. Moisture content is also considered; Dry and Moist. Cementation classes obtained by submergence of overnight air-dried samples for at lease 1 hour before test. Calibrating ones fingers against known standards is need in order to estimate the force being applied. SUMBER: www.water-research.net/course/soilconsistence.ppt
Dry Consistency Class Description 1 Newton (N) = 0.224 lb/ft Loose Noncoherent Symbol L or LO or lo Soft (<8 N) Soil crushes under very low pressure Slightly Hard (8 to < 20 N) Soil material crushes- low pressure - little resistance Mod Hard (20 to < 40 N) Soil material crushes- moderate pressure -resistance Hard (40 to < 80 N) Soil material crushes under strong pressure Very Hard (80 to < 160 N) Can not be crushed between thumb and forefinger. Extremely Hard Pressure applied by foot with full body 1 Newton (N) = 0.224 lb/ft SUMBER: www.water-research.net/course/soilconsistence.ppt
Dry and Moist Consistency Stress Specimen Fails Loose Very Friable Soft < 8 N Friable Slightly Hard 8 to < 20 N Firm Moderately Hard 20 to < 40 N Very Firm Hard 40 to < 80 N Extremely Firm Very Hard 80 to < 160 N 1 Newton (N) = 0.224 lb/ft SUMBER: www.water-research.net/course/soilconsistence.ppt
SUMBER: www.water-research.net/course/soilconsistence.ppt Wet Consistency Describe Stickiness- The capacity of soil to adhere to other objects Estimated at moisture content that displays maximum adherence between thumb and fore finger Describe Plasticity Degree a soil can be molded or reworked causing permanent deformation without rupturing. The capacity of soil to adhere to other objects such as your fingers. Estimated at moisture content that displays maximum adherence between thumb and fore finger. SUMBER: www.water-research.net/course/soilconsistence.ppt
SUMBER: www.water-research.net/course/soilconsistence.ppt Stickiness Classes Non-Sticky – little or no soil adheres to fingers after release of pressure Slightly Sticky – soil adheres to both fingers after release of pressure with little stretching on separation of fingers Moderately Sticky – soil adheres to both fingers after release of pressure with some stretching on separation of fingers Very Sticky - soil adheres firmly to both fingers after release of pressure with stretches greatly on separation of fingers Non-Sticky – little or no soil adheres to fingers after release of pressure. Sands typically fall in this category Slightly Sticky – soil adheres to both fingers after release of pressure with little stretching on separation of fingers. SUMBER: www.water-research.net/course/soilconsistence.ppt
SUMBER: www.water-research.net/course/soilconsistence.ppt Non-Sticky Slightly-Sticky Very Sticky SUMBER: www.water-research.net/course/soilconsistence.ppt
SUMBER: www.water-research.net/course/soilconsistence.ppt Plasticity The degree to which puddled or reworked soil can be permanently deformed without rupturing Evaluation done by forming a 4 cm long wire of soil at a water content where maximum plasticity is expressed Plasticity is: The degree to which puddled or reworked soil can be permanently deformed without rupturing. Evaluation done by forming a 4 cm long wire of soil at a water content where maximum plasticity is expressed. The sample may have to constantly be adjusted for water content. SUMBER: www.water-research.net/course/soilconsistence.ppt
SUMBER: www.water-research.net/course/soilconsistence.ppt Plasticity Class Plasticity classes; Non-Plastic – will not form a 6 mm wire, or if formed , can not support itself if held on end Slightly Plastic – 6 mm wire supports itself, 4 mm wire does not Moderately Plastic – 4 mm wire supports itself, 2 mm wire does not Very Plastic – 2 mm wire supports itself Non-Plastic – will not form a 6 mm dia, 4 cm long wire, or if formed , can not support itself if held on end Slightly Plastic – 6 mm dia, 4 cm long wire wire supports itself, 4 mm dia, 4 cm long wire wire does not Moderately Plastic – 4 mm dia, 4 cm long wire wire supports itself, 2 mm dia, 4 cm long wire wire does not Very Plastic – 2 mm dia, 4 cm long wire wire supports itself SUMBER: www.water-research.net/course/soilconsistence.ppt
Estimating Clay Mineralogy Using Consistence and Color SUMBER: www.water-research.net/course/soilconsistence.ppt
2:1 Clay- Montmorillonite High Shrink and Swell Potential SUMBER: www.water-research.net/course/soilconsistence.ppt
SUMBER: www.water-research.net/course/soilconsistence.ppt 1:1 Clay- Kaolinite SUMBER: www.water-research.net/course/soilconsistence.ppt
KONSISTENSI TANAH Konsistensi bervariasi dengan kadar air tanah. Konsistensi tanah dapat berkisar dari (kering) : solid hingga semi-solid ; Basah: plastik hingga untuk cairan . Kadar air dimana konsistensi berubah dari satu keadaan menjadi keadaan yang berikutnya disebut batas konsistensi (atau Batas Atterberg). Kedua hal tersebut digunakan dalam klasifikasi tanah bertekstur halus: Batas cair (wL) - perubahan konsistensi dari plastik menjadi cair Batas plastis (WP) - perubahan konsistensi dari rapuh / gembur menjadi plastik Ukuran nilai batas cair dan batas plastik dapat diperoleh dari ujilaboratorium. SUMBER: http://environment.uwe.ac.uk/geocal/SoilMech/classification/soilclas.htm
Consistency limits and plasticity KONSISTENSI TANAH Consistency limits and plasticity SUMBER: http://environment.uwe.ac.uk/geocal/SoilMech/classification/soilclas.htm
INDEKS PLASTISITAS Konsistensi sebagian besar tanah di tanah akan plastik atau semi-padat. Kekuatan tanah dan perilaku kekakuan terkait dengan berbagai konsistensi plastik. Kisaran kadar air dimana tanah memiliki konsistensi plastik disebut Indeks Plastisitas (IP atau PI). IP = batas cair - batas plastis = WL - WP SUMBER: http://environment.uwe.ac.uk/geocal/SoilMech/classification/soilclas.htm
KONSISTENSI TANAH Konsistensi adalah istilah yang digunakan untuk menggambarkan kemampuan tanah untuk menahan HANCURAN dan deformasi. Hal ini biasanya diklasifikasikan sebagai “lembut, kaku atau tegas, dan keras”. Kadar air sangat mempengaruhi perilaku rekayasa tanah halus. Dalam urutan kadar air meningkat , tanah kering akan ada menjadi empat keadaan yang berbeda: dari solid state, negara semipadat, negara plastik, dan untuk keadaan cair. Kadar air pada batas negara ini dikenal sebagai batas Atterberg. Antara negara-negara padat dan semipadat adalah batas susut, antara semipadat dan negara plastik adalah batas plastis, dan antara plastik dan negara cair adalah batas cair. SUMBER: http://www.mathalino.com/reviewer/geotechnical-engineering/consistency-soil-atterberg-limits
KONSISTENSI TANAH Batas Atterberg, adalah kadar air pada tahap kritis perilaku tanah. Batas Atterberg ini, bersama dengan kadar air alami, adalah sifat penting dari tanah bertekstur halus. SUMBER: http://www.mathalino.com/reviewer/geotechnical-engineering/consistency-soil-atterberg-limits
KONSISTENSI TANAH Batas cair , LL Batas cair adalah kadar air tanah di mana butiran tanah dipisahkan oleh air hanya cukup untuk massa tanah dengan kekuatan geser kerugian . Sedikit lebih tinggi dari kadar air ini akan cenderung tanah mengalir seperti cairan kental sementara sedikit lebih rendah akan menyebabkan tanah untuk berperilaku seperti plastik . Batas plastik , PL Batas plastis adalah kadar air dimana tanah akan lulus dari negara plastik untuk keadaan semi - padat . Tanah tidak bisa lagi berperilaku seperti plastik , setiap perubahan bentuk akan menyebabkan tanah untuk menunjukkan terlihat retak . Penyusutan Limit , SL Batas susut adalah kadar air di mana tanah tidak lagi perubahan volume tanpa pengeringan lebih lanjut. Ini adalah kadar air terendah untuk tanah harus benar-benar jenuh . Yang lebih rendah dari batas susut akan menyebabkan air yang akan sebagian jenuh . Ini adalah titik di mana tanah akan ditiadakan dari semi- solid untuk solid state . SUMBER: http://www.mathalino.com/reviewer/geotechnical-engineering/consistency-soil-atterberg-limits
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