以廢輪胎碎片壓縮層降低側向土壓力

Abstract

本論文探討以廢輪胎碎片壓縮層降低作用在靜止擋土牆之側向土壓力。本研究以渥太華砂作為擋土牆後之回填材料，實驗所採用的廢輪胎碎片壓縮層厚度包括：無壓縮層，20 mm，40 mm，70 mm，120 mm，180 mm及250 mm。回填土高度分別為0.3 m，0.6 m，0.9 m，1.2 m，1.5 m。本研究利用國立交通大學靜止土壓力擋土牆設備進行模型實驗。根據實驗結果，獲得以下各項結論。 1. 土壤夯實在回填土頂部附近造成高側向壓力；隨著回填土高度增高，夯實影響區的位置隨之往上方移動。 2. 在沒有壓縮層狀況，在夯實影響區下方的側向土壓力會趨近於Jaky值。 3. 有壓縮層作用時，夯實影響區內所量到的側向壓力大於Jaky值，但遠小於純砂回填夯實造成的側向壓力。在夯實影響區下方的側向壓力會趨近於Coulomb主動土壓。 4. 在夯實影響區內，壓縮層厚度愈厚，降低側向壓力的成效愈顯著。為能有效降低側向壓力，建議壓縮層厚度至少需0.05H。 5. 於1.5 m高的回填土狀況，與純砂回填夯實相較，70 mm厚的壓縮層可降低大約41%的側向土壓合力。 6. 為更經濟的設計與快速的施工，只在夯實影響區內設置壓縮層是可行的。由實驗結果顯示，此種配置可降低夯實影響區內大約61%的夯實土壓合力

This paper presents the application of a tire-chip compressibe layer to reduce earth pressure against a non-yielding wall. Ottawa sand was used as a backfill material. Thickness of the compressible layer adopted in the experiments included: no compressible layer, 20 mm, 40 mm, 70 mm, 120 mm, 180 mm, and 250 mm. Height of backfill rose from 0.3 m, 0.6 m, 0.9 m, 1.2 m, up to 1.5 m. The NCTU non-yielding wall facility was used to conduct all earth-pressure experiments in this study. Based on this study, the following conclusions can be drawn. 1. Soil compaction will induce high lateral presure near the top of the backfill. With the rise of the surface of the compacted fill, location of the compaction influenced zone moved upward. 2. Without the compressible layer, lateral pressures below the compaction influenced zone tend to converge with Jaky’s solution. 3. With the compressible layer, the lateral pressures measured in compaction influenced zone were still higher than Jaky’s solution. However, the magnitude of the compaction-induced pressure was much less than that without the compressible layer. Below the compaction influenced zone, the lateral pressures tend to converge with Coulomb active earth pressure. 4. In the compaction influenced zone, the thicker the compressible layer is, more compaction-induced pressure will be released. To effectively reduce the earth pressure acting on the non-yielding wall, it is recommended that the thickness of the compressible layer should be at least 0.05H. 5. For 1.5-high backfill with a 70 mm-thick compressible layer, about 41% of the total soil thrust had been reduced than that measured without the compressible layer. 6. To achieve a more economical design and faster construction, it may be feasible to place tire-chip compressible layer only in the compaction influenced zone. Based on the experimental results in this study, this type of compressible-layer arrangement can reduce approximately 61% of the compaction induced pressure.