CLC number: TU992

On-line Access: 2014-11-04

Received: 2013-04-18

Revision Accepted: 2013-11-04

Crosschecked: 2014-10-30

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Isa Ebtehaj, Hossein Bonakdari, Ali Sharifi. Design criteria for sediment transport in sewers based on self-cleansing concept[J]. Journal of Zhejiang University Science A, 2014, 15(11): 914-924.

@article{title="Design criteria for sediment transport in sewers based on self-cleansing concept",

author="Isa Ebtehaj, Hossein Bonakdari, Ali Sharifi",

journal="Journal of Zhejiang University Science A",

volume="15",

number="11",

pages="914-924",

year="2014",

publisher="Zhejiang University Press & Springer",

doi="10.1631/jzus.A1300135"

}

%0 Journal Article

%T Design criteria for sediment transport in sewers based on self-cleansing concept

%A Isa Ebtehaj

%A Hossein Bonakdari

%A Ali Sharifi

%J Journal of Zhejiang University SCIENCE A

%V 15

%N 11

%P 914-924

%@ 1673-565X

%D 2014

%I Zhejiang University Press & Springer

%DOI 10.1631/jzus.A1300135

TY - JOUR

T1 - Design criteria for sediment transport in sewers based on self-cleansing concept

A1 - Isa Ebtehaj

A1 - Hossein Bonakdari

A1 - Ali Sharifi

J0 - Journal of Zhejiang University Science A

VL - 15

IS - 11

SP - 914

EP - 924

%@ 1673-565X

Y1 - 2014

PB - Zhejiang University Press & Springer

ER -

DOI - 10.1631/jzus.A1300135

**Abstract: **This study of bed-load transport was undertaken on the basis of laboratory data in two states, i.e., limit of deposition and deposited bed, by using new design criteria, whereby, compared to earlier similar studies, fewer parameters were considered, yet with almost the same or in some cases an even greater level of accuracy. The modified criterion in the new design for transport in the limit of deposition was using only three dimensionless parameters, i.e., Froude number, volumetric concentration of sediment, and relative size of the grain. But the new design criterion applied to the deposited bed case used four dimensionless parameters, i.e., three parameters used for the preliminary case besides the relative thickness of sedimentation. Compared with other known relationships in sediment transport, the produced equations introduced here yield better results than previous studies. With the lessened number of parameters, the results are much easier to obtain.

沉积床；推移质；沉积限制；沉积物；下水道

**
**

1. Introduction

The wastewater system must convey the existing flow in the network under different hydraulic conditions of the plan period. The wastewater collection system must be as free as possible of any deposits. The flow in the wastewater collection and conveyance systems is a free surface and these networks are generally designed and calculated for the estimated ultimate contributory population. In the initial years there will be an expected shortage of flow while the subscribers connect to the network. Moreover, the design of a combined wastewater system must allow for the collection of both wastewater and the surface runoffs. During dry seasons, water levels decrease and the flow rate in the sewers slows down. Therefore, these systems always face the problem of sediment deposition.

Based on the minimum velocity or minimum shear stress at a specified depth of flow or period, two simple criteria, which are generally used as source, have been defined in different countries for estimations in preventing sedimentation at different flow sections under the non-deposition conditions (Ashley et al.,

Extensive theoretical analyses and experimental work on sediment transport of non-cohesive sediments were carried out in channels by different researchers. Novak and Nalluri (

The previous studies have introduced different parameters, such as the mean sediment size (

2. Self-cleansing design concept

May et al. (

Vongvisessomjai et al. (

To present the equations proposed in this study, the set of data provided by Ghani (

3. Data collection

To validate the accuracy of the results presented in this study, Ota and Nalluri (

4. Methodology

5. Results and discussion

Since criteria, such as the minimum square of error or the absolute value of error, do not offer simultaneous comparisons of the average and variance of the models, the Akaike information criterion (AIC) was used to compare the proposed equation to the equations obtained by the previous studies (Ghani,

To obtain the coefficients (

The same margin of error of 1% was obtained with a confidence interval of 99% differing in the ranges of (−0.314, 0.385) and (−0.394, 0.545) for Eqs. (

For statistical significance, testing the

Fig.

Fig.

Fig.

Table

Equation | MARE | RMSE | AIC |

Eq. (3) (May et al., 1996) |
3.7 | 0.69 | 26.64 |

Eq. (5) (Vongvisessomjai et al., 2010) |
0.21 | 0.51 | 23.61 |

Eq. (6) (Vongvisessomjai et al., 2010) |
0.31 | 0.26 | 20.72 |

Eq. (17) |
0.09 | 0.21 | −12.85 |

Eq. (18) |
0.15 | 0.24 | −4.43 |

According to Table

Fig.

Moreover, the average error presented by Ota and Nalluri (

To obtain the coefficients of Eq. (

Fig.

Based on Table

Equation | MARE | RMSE | AIC |

Eq. (9) (Ghani, 1993) |
0.28 | 1.93 | 14.8 |

Eq. (20) |
0.07 | 0.76 | 1.83 |

Eq. (21) |
0.07 | 0.76 | 1.87 |

Table

Based on the evaluation conducted by mathematical reasoning, the devised self-cleansing equations show good consistency with the lab data in explicating the design criteria and for validation. The studies conducted for non-deposited bed-load in two states, the limit of deposition and deposited bed, show a good correlation with the self-cleansing equations of May et al. (

6. Conclusions

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