Pengaruh Overconsolidation Ratio (OCR) dan Kadar Organik (Oc) Terhadap Koefisien Tekanan Tanah Kesamping “at Rest” (Ko), Tanah Gambut Berserat Halus

Rusdiansyah Rusdiansyah; Noor Endah Mochtar

doi:10.5614/jts.2003.10.2.1

Authors

Rusdiansyah Rusdiansyah Departemen Teknik Sipil, Universitas Lambung Mangkurat
Noor Endah Mochtar Departemen Teknik Sipil, Institut Teknologi Sepuluh Nopember (ITS) Surabaya

DOI:

https://doi.org/10.5614/jts.2003.10.2.1

Keywords:

Koefisien tekanan tanah kesamping ?at rest? (Ko), Overconsolidation ratio (OCR), Kadar organik (Oc), Dan Tanah gambut berserat

Abstract

Abstrak. Koefisien tekanan tanah kesamping ?at rest? (Ko) untuk setiap jenis tanah tidak sama; tanah inorganic mempunyai harga Ko lebih besar dari pada tanah organik. Harga Ko tersebut juga masih dipengaruhi oleh overconsolidation ratio (OCR). Untuk tanah anorganik, harga Ko dapat ditentukan dengan formula yang telah tersedia; tetapi untuk tanah gambut harga Ko masih harus ditentukan dengan melakukan test di laboratorium.Dalam tulisan ini disajikan hasil penelitian yang menunjukkan hubungan antara Ko, OCR, dan Oc (kadar organik) tanah gambut berserat halus. Sampel yang diteliti dibuat dengan kandungan organik bervariasi (55%, 65%, 71%, 85%, dan 99%); tipe seratnya hanya serta halus saja. Ukuran sampel yang di test adalah : tinggi 15cm dan diameter 7 cm. Besar beban yang diberikan adalah 50, 100, 200, dan 400 kPa; harga OCR yang dipilih adalah 1, 2, 4, dan 8. Harga Ko ternyata makin membesar dengan meningkatnya harga OCR dan kandungan organik. Hubungan antara Ko dan OCR merupakan dua garis lurus patah yang mempunyai kemiringan berbeda. Pada OCR ? 2 peningkatan harga Ko terhadap harga OCR adalah sedikit lebih besar jika dibandingkan pada OCR > 2.

Abstract. Coefficient of lateral earth pressure at rest (Ko) is different for each soil type; anorganic soil has higher value of Ko than organic soil. The ko value is also affected by the overconsolidation ratio (OCR) of the soil. For anorganic soil, the Ko value can be determined using the available formula; for peat soil, however, a laboratory testing has to be carried out in order to get the Ko value of the peat. In this paper is presented the research result that show correlation between Ko, OCR, and Oc (organic content) of fine fibrous peat. The soil sample was prepared with different organic content (55%, 65%, 71%, 85%, and 99%); the fibers chosen were only the fine ones. The sample size was 15 cm height and 7 cm in diameter. The loads applied were 50, 100, 200, and 400 kPa; the OCR values chosen were 1, 2, 4, and 8. The study results show that the Ko value is getting higher with the increase of the OCR value and the organic content. The correlation between Ko and OCR shows as two broken straight lines with different slope. At OCR ? 2 the increase of Ko is slightly higher compared to the one at OCR > 2.

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