PENGARUH PERUBAHAN KADAR AIR TERHADAP SIFAT TEKNIS TANAH LANAU KELEMPUNGAN PADA JALAN TOL SEMARANG-SOLO SECTION II

ARY SISMIANI, ST, Dr. Ir. Ahmad Rifa’i, MT.

2013 | Tesis | S2 Teknik Sipil

Pekerjaan pembangunan jalan tol Semarang-Solo Tahap I, yaitu ruas Semarang-Bawen seksi II Gedawang-Penggaron jenis tanah dasar timbunan adalah tanah lanau kelempungan terutama di Km 18+600. Di Km ini terjadi longsor di sisi badan jalan pada koordinat S 7º5’54,5” dan E 110º25’20,4”.Tujuan penelitian ini untuk mengetahui karakteristik tanah lanau kelempungan tersebut apabila dipengaruhi oleh perubahan kadar air. Penelitian ini menggunakan 9 variasi benda uji (dengan kadar air yang berbeda), yaitu 10,59% , 14,27% , 20,01% , 25,19% , 30,06% , 34,48% , 39,91% , 45,93% , dan 50,67%. Selanjutnya dilakukan uji sifat mekanis tanah, yaitu uji CBR (terendam dan tidak terendam air) dan uji geser langsung. Hasil uji yang diperoleh berupa nilai CBR terendam air (soaked) sebesar 5,55% (w=10,59%) , 2,43% (w=30,06%) , dan 1,04% (w=50,67%), sedangkan untuk CBR tak terendam air (unsoaked) adalah 12,25%, 9,71% , 9,02%, 8,67%, 6,24%, 4,86%, 2,43%, 1,73%, dan 1,39%. Dari hasil uji geser langsung didapatkan nilai kohesi dan sudut gesek internal sebagai berikut : nilai kohesi 0,20kg/cm2, 0,23kg/cm2, 0,27kg/cm2, 0,55kg/cm2, 0,57kg/cm2, 0,46kg/cm2, 0,34kg/cm2, 0,28kg/cm2 dan, 0,28kg/cm2, sedangkan sudut gesek internal tanah 26,05º, 25,64º, 24,60º, 23,42º, 18,67º, 16,89º, 16,69º, dan 15,76º.Berdasarkan hasil yang diperoleh nilai CBR yang memenuhi syarat untuk subgrade berada pada kadar air w 30,06% (SR 48,62%ማ yaitu 6,24%, nilai kohesi dan sudut gesek internalnya adalah c 0,57 kg/cm2 dan

Development work Semarang-Solo highway Phase I, the Semarang-Bawen section II Gedawang-Penggaron embankment foundation soils are claysilt mainly in Km 18 +600. The landslide occurred at Km on the side of the road at coordinates S 7 º 5'54, 5 \\"and E 110 º 25'20, 4\\". Purpose of this study was to determine the characteristics of the claysilt if affected by changes in water content. This study uses a variation of 9 specimens (with different water content), ie 10.59%, 14.27%, 20.01%, 25.19%, 30.06%, 34.48%, 39.91% , 45.93%, and 50.67%. Further test the mechanical properties of the soil, the CBR test (submerged and submerged in water) and direct shear tests. The test results were obtained in the form of submerged CBR value (soaked) by 5.55% (w = 10.59%), 2.43% (w = 30.06%), and 1.04% (w = 50.67 %), while the CBR is not submerged in water (unsoaked) was 12.25%, 9.71%, 9.02%, 8.67%, 6.24%, 4.86%, 2.43%, 1, 73%, and 1.39%. From direct shear test results obtained values of cohesion and internal friction angle as follows: cohesion value of 0.20 kg/cm2, 0.23 kg/cm2, 0.27kg/cm2, 0.55 kg/cm2, 0.57 kg/cm2, 0.46 kg / cm2, 0.34kg/cm2, and 0.28 kg/cm2, 0.28kg/cm2, while the soil internal friction angle 26.05 º, 25.64 º, 24.60 º, 23.42 º, 18.67 º,16.89 º , 16.69 º, and 15.76 º. Based on the results obtained CBR value of subgrade eligible to be on the water content w ≤ 30.06% (SR ≤ 48.62%) is 6.24%, the value of cohesion is c ≤ 0.57 kg/cm2 and friction angle is 􀁉≥ 23.42 º . Influence of the higher moisture content will cause silt soil kelempungan became increasingly ugly, ie a decrease in shear strength and carrying capacity of the land is marked by the increasing size of the internal friction angle and the value of CBR nya.Untuk increase soil shear strength parameters and soil bearing capacity, then an effort that needs to be done to maintain or reduce excess soil moisture by reducing excess pore water pressure. Recommended for the open drainage or surface drainage lengthwise on the foot slopes.

Kata Kunci : lanau kelempungan, kadar air, kuat dukung, kuat geser tanah.