PERILAKU PERKERASAN SISTEM PELAT TERPAKU PADA LEMPUNG LUNAK

ANAS PURI, -

2015 | Disertasi | S3 Ilmu Teknik Sipil

rigid pavement on soft soils. It will bring into being good serviceability pavement; avoiding the excessive differential settlements and pumping, and has higher durability. This research is conducted to learn the behavior of Nailed-slab System on soft clay due to loadings and how the contributions of short micro piles in increasing the stiffness and equivalent modulus of subgrade reaction of this system. The method of analysis will be proposed and validated with full scale test. Small and full scale model tests had been conducted in the Soil Mechanics Laboratory of Gadjah Mada University. Nailed-slab used reinforced-concrete and conducted on soft clay. On model tests (model scale 1 : 5) the slab dimensions were 120 cm in length and 3 cm in thickness, and varied in slab width; 20 cm, 40 cm, and 60 cm. Each variation of slab width was divided by two kinds of models; slabs with installed piles underneath and slabs alone. Slabs with installed piles underneath had 3 variations in number of pile row; 1, 2, and 3 pile rows respectively. Piles used were 4 cm in diameter with variation in length; 20 cm, and 40 cm. Pile spacing (s) were varied with s/d ratio = 2,5, 5, and 7,5. The dimension of 3 pile-rows nailed-slab test was 600 cm × 354 cm of slab dimension, 15 cm in slab thickness, and reinforced by installing piles underneath. Pile dimension was 20 cm in diameter and 150 cm in length and 120 cm in spacing. Nailed-slab was constructed in the soft clay which 215 cm in depth. Some instrumentation was set up to measure the responses of system. Static and monotonic loadings were conducted by hydraulic jacking on different loading points. The full scale and model of Nailed-slabs show behavior of smooth deflected bowl shape due to loadings. It is indicated that all piles gave similar responses on 3D. Piles mobilized the compression bearing capacity and acted as anchorage to resist the slab uplift on the parts of slab which uplift was occurred. Slab deflection was reduced up to 35.04% for centric loading and the negative deflection was reduced up to 100%. Maximum deflection of slab for interior and edge loadings was reduced 58.45% and 35.48% respectively. The tested full scale Nailed-slab had higher stiffness to bear the loads. It is evidenced that up to 160 kN centric load gave linear-elastic deflection response. The higher stiffness of this system was also shown in the small deflection about 4.35 mm for edge load (P = 80 kN ≈ 2x single wheel load). This system has higher resistance concerning vibration that the piles gave good responses which indicated on loading repetitions—deflections of all points tend to zero again in unloading condition. Increasing in number of pile row, pile spacing, and pile length, including vertical wall barrier increase stiffness which is defined as equivalent modulus of subgrade reaction (k’). Proposed equation and curve of displacement factor in defining the additional modulus of subgrade reaction can be used for analyzing Nailed-slab system. Results show that the Nailed-slab performance is promising for application. Keywords: Nailed-slab System, short piles, deflection, soft clay, rigid pavement.

rigid pavement on soft soils. It will bring into being good serviceability pavement; avoiding the excessive differential settlements and pumping, and has higher durability. This research is conducted to learn the behavior of Nailed-slab System on soft clay due to loadings and how the contributions of short micro piles in increasing the stiffness and equivalent modulus of subgrade reaction of this system. The method of analysis will be proposed and validated with full scale test. Small and full scale model tests had been conducted in the Soil Mechanics Laboratory of Gadjah Mada University. Nailed-slab used reinforced-concrete and conducted on soft clay. On model tests (model scale 1 : 5) the slab dimensions were 120 cm in length and 3 cm in thickness, and varied in slab width; 20 cm, 40 cm, and 60 cm. Each variation of slab width was divided by two kinds of models; slabs with installed piles underneath and slabs alone. Slabs with installed piles underneath had 3 variations in number of pile row; 1, 2, and 3 pile rows respectively. Piles used were 4 cm in diameter with variation in length; 20 cm, and 40 cm. Pile spacing (s) were varied with s/d ratio = 2,5, 5, and 7,5. The dimension of 3 pile-rows nailed-slab test was 600 cm × 354 cm of slab dimension, 15 cm in slab thickness, and reinforced by installing piles underneath. Pile dimension was 20 cm in diameter and 150 cm in length and 120 cm in spacing. Nailed-slab was constructed in the soft clay which 215 cm in depth. Some instrumentation was set up to measure the responses of system. Static and monotonic loadings were conducted by hydraulic jacking on different loading points. The full scale and model of Nailed-slabs show behavior of smooth deflected bowl shape due to loadings. It is indicated that all piles gave similar responses on 3D. Piles mobilized the compression bearing capacity and acted as anchorage to resist the slab uplift on the parts of slab which uplift was occurred. Slab deflection was reduced up to 35.04% for centric loading and the negative deflection was reduced up to 100%. Maximum deflection of slab for interior and edge loadings was reduced 58.45% and 35.48% respectively. The tested full scale Nailed-slab had higher stiffness to bear the loads. It is evidenced that up to 160 kN centric load gave linear-elastic deflection response. The higher stiffness of this system was also shown in the small deflection about 4.35 mm for edge load (P = 80 kN ≈ 2x single wheel load). This system has higher resistance concerning vibration that the piles gave good responses which indicated on loading repetitions—deflections of all points tend to zero again in unloading condition. Increasing in number of pile row, pile spacing, and pile length, including vertical wall barrier increase stiffness which is defined as equivalent modulus of subgrade reaction (k’). Proposed equation and curve of displacement factor in defining the additional modulus of subgrade reaction can be used for analyzing Nailed-slab system. Results show that the Nailed-slab performance is promising for application. Keywords: Nailed-slab System, short piles, deflection, soft clay, rigid pavement.

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