實驗室名稱 基礎模型實驗室
管理者 方永壽
電話 886-3-5718636
空間尺寸 10 m × 10 m

1.移動式模型擋土牆 - 研究主動及被動土壓力
國立交通大學模型擋土牆設備被用來研究土壤密度、牆移動模式、及背填土傾角對主動及被動土壓力的影響。 移動式模型擋土牆及其推進系統如圖1.1所示。模型擋土牆是以厚120 mm的鋼板製成,高1,000 mm、寬550 mm,有效牆高H為500 mm。在垂直方向,擋土 牆是由兩顆單向鋼珠支撐,側向由四根鋼製推桿支撐。如圖1.1所示,M1及M2變速馬達被用來推動上側及下側推桿。

圖1.1 交通大學移動式模型擋土牆

試驗土槽是由鋼梁及鋼柱所組成,土槽內側尺寸為2,000 mm × 1,000 mm × 1,000 mm,如圖1.1所示。土槽兩側是以30 mm厚的壓克力 板製成,透過透明壓克力板,可以觀察背填土的行為。土槽底部鋪設一層防滑摩擦材料SAFETY WALK(3M),為填土與土槽底 部提供適當的摩擦力。
為研究擋土牆後的側向土壓力分佈,在模型擋土牆中央區域設置一排土壓力計(Soil Pressure Transducer. SPT),總共10個應變計 式土壓力計被安排在擋土牆的中央區域。為了降低土拱(soil arching)效應,高勁度的土壓力計表面被 安置與擋土牆面切齊,圖1.2顯示實驗所使用的Kyowa BE-2KRS17,其最大容許壓力為196 kN/m2。

圖1.2 土壓力計

如圖1.3土壓力計校正設備是一個圓柱形淺盤,其內部直徑為400 mm、高度為30 mm。校正盤是以圓柱形鋼板製成,其材 質與模型擋土牆材質相同。土壓力計被插入於校正盤底部,土壓力計表面與校正盤面齊平,土壓力計表面覆蓋約10 mm厚的砂土。砂層上方覆 蓋0.2 mm厚的橡皮薄膜,可以將施加的空氣壓力均勻的分佈在橡皮薄膜上。

圖1.3 土壓力計校正設備

相關論文

  1. Fan, C. C., and Fang, Y. S., (2010) "Numerical solution of active earth pressures on rigid retaining walls built near rock faces." Computer and Geotechnics, Volume 37, Issues 7-8, November, pp. 1023-1029. (SCI, IF = 0.987, Rank = 12/30, Times cited: 0)
  2. Fang, Y. S., Yang, Y. C. and T. J. Chen. (2003) "Retaining walls damaged in the Chi-Chi earthquake" Canadian Geotechnical Journal, NRC Canada, Vol. 40, December, pp. 1142-1153. (EI and SCI, IF = 0.867, Rank = 15/30, Times Cited: 10)
  3. Fang, Y. S., Ho, Y. C. and Chen, T. J., (2003). Closure to "Passive earth pressure with critical state concept." Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 129, No. 10, October, pp. 962. (NSC 88-2611-E-009-007) (SCI, IF = 1.017, Rank = 10/30)
  4. Fang, Y. S., Ho, Y. C. and Chen, T. J., (2002). "Passive earth pressure with critical state concept." Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 128, No. 8, August, pp. 651-659. (NSC 88-2611-E-009-007) (SCI, IF = 1.017, Rank = 10/30, Times Cited: 6)
  5. Fang, Y. S., Chen, J. M. and Chen, C.Y., (1998). "Earth pressures with sloping backfill." Closure, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 124, No. 11, November, pp. 1153. (SCI, IF = 1.017, Rank = 10/30, Times Cited: 0)
  6. Fang, Y. S., Chen, T. J. and Wu, B. F., (1994). "Passive earth pressures with various wall movements." Journal of Geotechnical Engineering, ASCE, Vol. 120, No. 8, August, pp. 1307-1323. (NSC 83-0410-E-009-032) (SCI, IF = 1.017, Rank = 10/30, Times Cited: 42)
  7. Fang, Y. S., Cheng, F. P., Chen, R. T. and Fan, C. C., (1993). "Earth pressures under general wall movements." Geotechnical Engineering, SEAGS, Vol. 24, No. 2, December, pp. 113-131. (NSC 77-0410-E-009-06) (EI)
  8. Fang, Y. S. and Ishibashi, I., (1986). "Static earth pressures with various wall movements." Journal of Geotechnical Engineering, ASCE, Vol. 112, No. 3, March, pp. 317-333. (SCI, IF = 1.017, Rank = 10/30, Times Cited: 93)
  9. Fang, Y. S., Lee, C. C. and Chen, T. J., (2006). "Passive earth pressure with various backfill densities." Proceedings, Sixth International Conference on Physical Modelling in Geotechnics, Hong Kong, August 4 - 6, Volume 2, pp. 1081-1086.
  10. Fang, Y. S., Chen, T. J., Yang, Y. C. and Tang C. C., (2001). "The behavior of retaining walls under 1999 Chi-Chi earthquake." Proceedings, Fourth International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, San Diego, California, March 26 - 31, Paper No. 10.06, pp. 1-6.

2.靜止土壓模型擋土牆 - 研究靜止土壓力
交通大學靜止土壓模型擋土牆被用來研究土壤振動夯實造成的靜止土壓力。圖2.1顯示,一座厚45 mm、高1.6 m的鋼板擋土 牆被用來減小擋土牆的側向變形。16個土壓力計被安裝在擋土牆的中央區域,來監測靜止土壓力分佈。在所有的模型擋土牆試驗,氣乾渥太 華砂被用來做為回填土。根據實驗結果,疏鬆回填土內的靜止土壓力分佈大約呈線性分佈,並符合Jaky的理論解。

圖2.1. 交通大學靜止土壓模型擋土牆

圖2.2顯示,氣乾渥太華砂分五層被降入試驗土槽,並加以夯實並達成75%的相對密度。實驗結果發現,夯實對於背填土 內的垂直壓力幾乎沒有影響。振動夯實在靜止牆面造成額外的水平土壓力。夯實後,靠近牆頂測得的水平土壓力接近被動Rankine土壓力。當 作用於被填土表面的反覆夯實應力,超過基礎土壤的極限承載力,在背填土的最上層發展出剪力破壞區。

圖2.2. 砂質填土的振動夯實

相關論文

  1. Chen, T. J. and Fang, Y. S., (2008). "Earth pressure due to vibratory compaction." Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 134, No. 4, April, pp. 437-444. (NSC 89-2211-E-009-092) (SCI, IF = 1.017, Rank = 10/30, Times Cited: 1)
  2. Chen, T. J., and Fang, Y .S. (2002). "A new facility for measurement of earth pressure at-rest" Geotechnical Engineering, Southeast Asian Geotechnical Society, Vol. 33, No. 3, December, pp. 153-159. (NSC 89-2211-E-009-092) (EI)
  3. Fang, Y. S., Cheng L. and Wang, F. J., (2012). "Effects of Adjacent Rock Face Inclination on Earth Pressure At-rest." Proceedings, 22nd International Offshore and Polar Engineering Conference, Rhodes, Greece, June 17-22, Vol. 2, pp. 836-841.
  4. Fang, Y. S., and Y. L. Chien, (2009). "Variation of soil density and earth pressure due to strip compaction." Proceedings, 17th International Conference on Soil Mechanics and Geotechnical Engineering, Alexandria, Egypt, October 5-9, Vol. 1, pp. 700-704.
  5. Fang, Y. S., Tzeng, S. H. and Chen, T. J., (2007). "Earth pressure on an unyielding wall due to a strip surcharge." Proceedings, 17th International Offshore and Polar Engineering Conference, Lisbon, Portugal, July 1 - 6, pp. 1233-1238.
  6. Fang, Y. S., Chen, H. R., and Chen, T. J. (2002). "Measurement of earth pressure at-rest with inclined backfill." Proceedings, International Conference on Physical Modeling in Geotechnics, St. John's, Newfoundland, Canada, July 10 - 12, pp. 871-876.

3.傾斜滑動塊試驗設備 - 研究土壤與擋土牆介面的摩擦力
為了在實驗室模擬平面應變狀態,大型擋土牆模型試驗在土壤與土槽側牆之間的摩擦阻力必須盡量降低。通常採用橡皮薄膜 矽油法(silicon grease method)或多層塑膠膜法(plastic sheets method)。通常採用直接剪力試驗量測土壤-側牆介面之摩擦角。
圖3.1顯示一個新的傾斜滑動塊試驗設備,用來量測土壤與不同材料之間,在低應力狀況下的界面摩擦力。實驗結果顯示 ,使用多層塑膠膜法所獲得的摩擦角與施加正應力大小無關。但是在低應力狀況下,以橡皮薄膜矽油法獲得的界面摩擦角相當高。因此,在低 應力狀況下,多層塑膠膜方法顯然是大型擋土牆模型試驗降低介面摩擦力比較好的方法。

圖3.1.傾斜滑動塊試驗設備

相關論文

  1. Fang, Y. S., Chen, T.J., Holtz, R. D. and Lee, W. F., (2004) "Reduction of boundary friction in model tests," Geotechnical Testing Journal, ASTM, Vol. 27, No. 1. January, pp. 1-10. (EI and SCI, IF = 0.505, Rank = 23/30, Times Cited: 6)

4.反復扭轉剪力夯實設備 - 夯實疏鬆砂土
反復扭轉剪力夯實設備(Cyclic Torsional Shear Compactor, CTSC)可以以較安靜、且低振動的方式夯實砂土。夯實過程以 底部的剪力盤來傳遞反覆剪應力到土層表面。剪力盤以厚度15 mm的鋼板製成,直徑300 mm。為了將有效的反復剪應力傳遞至土壤,剪力盤底 部設計12道凸出的鋼齒,如圖4.1所示。為提供圓盤底面與土壤間的摩擦力,圓盤底面加貼一層防滑材料SAFETY WALK (3M)。

圖4.1.剪力盤底部

剪力盤旋轉角度從 +5 到 -5度。圖4.2顯示角鋼上的雷射測距儀射出的光點,在土壤表面成為固定參考點。作業人員 在鬆砂表面施加反復扭轉剪應力以增加土壤密度。

圖4.2.反覆扭轉剪力夯實疏鬆土壤

實驗結果顯示,靜態垂直載重造成之土壤密度增加,在填土頂部150 mm(即剪力盤半徑R)最為明顯。在施加前2次反覆扭矩 後,土壤表面沉陷明顯增加。在施加20次反復扭轉剪力後,土壤顆粒重新排列並達成緊密排列狀態,土壤表面沉陷增加量甚低。土壤的相對密度 隨著反覆扭剪作用次數的增加而增加。若夯實土層厚度保持0.15 m,夯實後,各層土壤的相對密度都可以達成70%以上。