邊坡管湧現象及坡地安全之探討

The Study of Slope Pipings and Safety of Hillside Fields.

林勝鴻(Sheng-Hung Lin)

指導教授 ： 張德鑫

中原大學/工學院/土木工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500518

摘要

中文摘要

本研究主要目的是探討降雨入滲使得坡地之地下水位抬高，造成坡面產生滲流面，當滲流產生後的實際水力梯度大於土體的臨界水力梯度時，土體中的細顆粒（填料顆粒）將沿著土體骨架顆粒間的孔道移動或被帶出土體而產生管湧現象。本研究為探討此現象，首先在公式推導部分利用動量方程式推估坡地內和坡面管湧現象，及顆粒臨界啟動速度公式，並據以推算坡面臨界水力梯度。
為驗證推導式之正確性，本研究並進行實驗室管湧現象模型試驗，即採用渥太華編號c778標準砂並經篩選後之均勻粒徑砂，進行均勻砂之基本物理試驗，同時求其出水力傳導係數。其次，建立管湧模型試驗系統與供水系統，進行數組管湧現象模型試驗，並得知在不同坡面坡度情況下之臨界水力梯度值。
最後本研究以FEMWATER數值模式模擬管湧滲流實驗在不同坡度之臨界狀態，模擬出坡面土壤顆粒當時之啟動速度。根據理論推導，模型試驗及數值模擬過程，本研究分別得到不同坡度下之臨界水力梯度，並比較其間之差異，據以做為後續探討滲流面管湧現象之參考。

關鍵字

管湧 ； 臨界水力梯度 ； 臨界啟動速度

並列摘要

Abstract

The main purpose of this research is to develop that the underground water level of hillside fields rises up and the seepage face of the slope surface occurs due to rainfall infiltration. When seepage has been formed and the value of actual hydraulic gradient is bigger than the value of critical hydraulic gradient of soil-body, they result in the piping phenomenon, which is produced when soil particles (filler particles) move along the pathway among particles of the soil-body framework or when soil particles are taken out from the soil-body. Firstly , as to formulas, the critical launching speed formula of piping particles of inside hillside fields and slope surface is derived from momentum equations and then calculated the hydraulic gradient in this paper.
In order to verify the accuracy of derivative equations, this research also involves the model experiment on lab piping phenomenon. The experiment herein is adopted uniform size of sands that are selected out from Ottawa serial number c778 standard sands and then is performed basic physical experiment with selected sands to figure out the coefficient of hydraulic conduction. Secondly, the hydraulic gradient model system and the water supply system are built to perform several groups of model experiments in piping phenomenon and to gain critical hydraulic gradient values based on different inclination of slopes.
Finally, this research is simulated critical conditions of the piping infiltration experiment based on different inclination of slopes by using FEMWATER number mode and calculated soil particles’launching speed of slope face. The process of model test and number value simulation are in accordance with the theories. After compared with the difference among critical hydraulic gradient values of different inclination of slopes, the result is a useful follow-up reference for the piping phenomenon of seepage face.

並列關鍵字

Piping ； critical hydraulic gradient ； critical launching speed

參考文獻

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