Browsing by Author "Chen, Tsang-Jiang"

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Earth pressure due to vibratory compaction
(2008-04-01)
Chen, Tsang-Jiang
;
Fang, Yung-Show
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工學院
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土木工程學系
;
College of Engineering
This paper presents experimental data on the variation of lateral earth pressure against a nonyielding retaining wall due to soil filling and vibratory compaction. Air-dry Ottawa sand was placed in five lifts and each lift was compacted to achieve a relative density of 75%. Each compacted lift was 0.3 m thick. The instrumented nonyielding wall facility at National Chiao Tung University in Taiwan was used to investigate the effects of vibratory compaction on the change of stresses at the soil-wall interface. Based on the experimental data it has been found that, for a compacted backfill, the vertical overburden pressure can also be properly estimated with the traditional equation sigma(upsilon) = gamma z. The effects of vibratory compaction on the vertical pressure in the backfill were insignificant. On the vertical nonyielding wall, extra horizontal earth pressure was induced by vibratory compaction. After compaction, the lateral earth pressure measured near the top of the wall was almost identical to the passive Rankine pressure. It is concluded that as the cyclic compacting stress applied on the surface of the backfill exceeded the ultimate bearing capacity of the foundation soil, a shear failure zone would develop in the uppermost layer of the backfill. For a soil element under lateral compression, the vertical overburden pressure remained unchanged, and the horizontal stress increased to the Rankine passive pressure. It was also found that the compaction-influenced zone rose with the rising compaction surface. The horizontal earth pressure measured below the compaction-influenced zone converged to the Jaky state of stress.
Earth pressure on an unyielding wall due to a strip surcharge
(2007)
Fang, Yung-Show
;
Tzeng, Shi-Han
;
Chen, Tsang-Jiang
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土木工程學系
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Department of Civil Engineering
The horizontal pressure acting on a non-yielding wall due to a strip loading was studied in this paper. Based on the experimental results, the following conclusions were made. If the strip surcharge was located near the face of the wall, the surcharge loading would induce a decrease of lateral pressure in the upper part of the compacted backfill. It may be deduced that the surcharge applied on the top of the soil near the wall would compress the soil element vertically. The induced lateral deformation would make the compacted soil "less passive" and the lateral soil thrust to decrease. This phenomenon would disappear if the surcharge loading was removed. The experimental lateral soil thrust induced by surcharge loading was apparently smaller than the theoretical predictions.