加勁擋土牆之土壓力分析研究

張程翔(cheng-siang jhang)

指導教授 ： 陳慧慈 ； 李崇正

國立中央大學/工學院/土木工程學系/碩士(2007年)

摘要

現今加勁擋土牆的設計規範於進行內部穩定分析時，對於土壓力的假設皆有所不同，為了釐清實際土壓力與規範假設土壓力間的差異，本研究以包覆式柔性加勁擋土結構為對象，利用地工離心模型試驗探討牆內土壓力的分佈。本研究採用的模型牆高（H）20cm，加勁長度14cm，加勁間距2.5cm，背填材料為福隆砂為之加勁擋土牆。彙整16個試驗結果所獲致的結論為：1. 加勁區後端的垂直土壓力會小於理論值；水平土壓力除了牆底部，亦同樣會小於理論值。在水平總力的計算方面兩者的差異並不大，但在彎矩的計算則有較大之差異。至於利用實驗結果計算出的值皆小於理論值，顯示現今規範以理論值作為計算是偏向於保守的。2. 加勁區內部水平土壓力的分佈，在牆高1/2以上之水平土壓力會小於理論主動土壓力，牆高1/2以下處則會比理論主動土壓力來的大。此外，水平土壓力的分佈與離牆面位置較不相關。3. 加勁區內部垂直土壓力，在模型牆面40mm之後離牆面越遠土壓力會逐漸降低，最後趨於平穩，且在不同的g數下都呈現同樣趨勢。至於垂直土壓力的分佈則與牆面高度較無相關性。

關鍵字

土壓力 ； 離心模型試驗 ； 加勁擋土牆

並列摘要

The lateral earth pressure distributions assumed in the current handbooks or guidelines for designing Mechanically Stabilized Earth Wall for evaluating internal stability are not exactly the same. In order to figure out the actual lateral earth pressure distribution acting on a wall, flexible wrapped-face geosynthetic reinforced earth model walls, backfilled with Fulong sand, were constructed and sixteen centrifuge modeling tests were preformed. At the end of reinforcement, the vertical soil pressure is smaller than the theoretical value, while for the lateral soil pressure, except near the toe of wall, is also smaller than the theoretical value. There is no significant difference for the total lateral force; however, larger difference is observed for the moment; the computed values are always smaller than those computed using code specification, indicating that the method adopted in the design guidelines or handbooks is conservative. Within the reinforced zone, the lateral earth pressure, which does not vary significantly with the distance from the wall face, is smaller than the theoretical value from the surface to mid-height of the wall, while the opposite trend is observed for the region below the mid-height of wall. Behind the region of 40mm from the wall face, the vertical soil pressure, which does not vary significantly with the height of wall, decrease with increasing distance from the wall and approach a constant value.

並列關鍵字

soil pressure ； centrifuge modeling tests ； geosynthetic reinforced earth model walls

參考文獻

范嘉程、周南山，「加勁擋土結構設計及施工規範“準則”之探討」，地工技術，第70期，第93~106頁，1998。

文，國立中央大學土木工程學系，中壢，1999。

Bolton. M.D., Pang, P. L. R., ‘‘Collapse limit states of reinforced earth retaining walls, ’’ Geotechnique, Vol. 32, No.4, pp.349~367, 1982.

Fishman, K. L., C. S. Desai, and R. L. Sogge., ‘‘Field behavior of instrumented geogrid soil reinforced wall, ’’ Journal of Geotechnical Engineering, ASCE, Vol. 119, No.8, pp.1293~1307, 1993.

Shahar, Y., S., Frydman, ‘‘Centrifuge modeling of narrow reinforced retaining walls, ’’ Physical Modelling in Geotechnics, pp.1005~1010, 1993.