PENGARUH MATRIC SUCTION TERHADAP PARAMETER GESER TANAH LEMPUNG TERSTABILISASI KAPUR DAN ABU VULKANIS KELUD

PUPUT RISTANTY, Dr. Eng. Iman Haryanto, ST., MT.

2015 | Tugas Akhir | D3 TEKNIK SIPIL SV

Tanah lempung ekspansif dipengaruhi oleh perubahan kadar air sehingga memiliki karakteristik kembang susut yang besar. Hal ini sangat merugikan apabila tanah ekspansif digunakan sebagai dasar konstruksi sebuah bangunan. Untuk itu perlu dilakukan perbaikan tanah dengan penambahan abu vulkanis Kelud yang dikombinasikan dengan kapur untuk meningkatkan sifat fisis dan mekanis. Penelitian menggunakan benda uji campuran 70% tanah asli + 25% abu vulkanis Kelud + 5% kapur. Dilakukan pengujian dengan uji kuat geser (Direct Shear Test) dan uji matric suction. Pengujian kuat geser menggunakan variasi beban 8kg, 12kg, 16 kg, 24kg, 28kg, dan 32kg. Pengujian matric suction menggunakan metode filter paper. Dimana keduanya menggunakan variasi kadar air 20%, 22%, 24%, 25%, 28%, 30%, 32%, 34%, 36%, 38%, dan 40%, dengan waktu pemeraman 24 jam. Tanah terstabilisasi dengan abu dan kapur diperoleh nilai kadar air campuran (8,88%) lebih kecil dibanding dengan kadar air tanah asli (12,77%). Pengujian kuat geser langsung nilai phi maksimum (32,01) kadar air 32%. Pengujian matric suction, kadar air 20% mengalami penurunan hingga kadar air 40%. Semakin besar kadar airnya, semakin kecil nilai suction (kPa) yang dihasilkan. Hubungan nilai suction dengan shear strength, diperoleh nilai kuat geser maksimal (52,09 kPa) ketika tanah mempunyai daya hisap (0,40 kPa), pada kadar air 34,80%.

Expansive clay is affected by the water content so that it has the characteristic of a large swelling-shrinkage. This is very harmful if use expansive soil as the basis construction of a building. For it is necessary to improve the soil with the addition of Kelud vulcanic ash combined with lime to improve the physical and mechanical properties. Study using specimen a mixture by 70% of original soil + 25% of Kelud vulcanic ash + 5% of lime. Testing samples of soil shear strength test using by direct shear test, and test matric suction. The direct shear test used load variations 8kg, 12kg, 16kg, 24kg, 28kg, and 32kg. The matric suction test used by filter paper method. Both of which use a variation of moisture content of 20%, 22%, 24%, 25%, 28%, 30%, 32%, 34%, 36%, 38%, and 40%, in curing time 24 hours. Soil stabilized with ash and lime, water content values obtained mixture (8,88%) is smaller than the original soil (12,77%). In direct shear test maximum value of phi (32,01) at 32% moisture content. On matric suction test, the water content has decreased to 20% moisture content of 40%. The greater the water content, the smaller value of suction generated. Relationship values suction with shear strength, maximum shear strength values obtained (52,09 kPa) when the soil has the suction (0,40 kPa), in the water content of 34,80%.

Kata Kunci : Tanah Lempung Ekspansif, Stabilisasi, Waktu Pemeraman, Kuat Geser, dan Matric Suction.