This study experimentally examined the effect of a cracked tunnel underneath a canal bed on both the water and sand inflow through the tunnel hole and the distortion of the canal bed. To simulate the cracked tunnel, a circular hole at the centre of the base plate of the flume was employed. One hundred and eight tests were conducted to investigate the four factors that affected the canal bed morphology, namely, four water depths, three bed material sizes, four hole diameters and three bed material heights above the tunnel hole. The water and sand discharges into the tunnel hole were measured. The scour bed geometry due to the cracked tunnel, including the erosion volume and scour hole dimensions, was also measured and analysed. The results indicated that the sand height, tunnel hole diameter and bed material particle size were the important factors that affected the sand flux, while the Froude number and canal water depth were the dominant parameters that governed the water flow rate. The tunnel hole was jammed when the particle size was larger than 0.2 of the tunnel hole diameter; therefore, this finding can be implied to temporarily block the cracked tunnel hole. Relationships were developed to correlate the investigated parameters and to estimate the flow rate and the volume of water and sand through the tunnel hole. |
