Technical Studies

Jhong-jheng Bridge, also named as Chu-Chung Bridge, crossing over Tou-cian River, is an important passage connecting Chiung-Ling and Chu-Dong. The elevation of riverbed downstream Jhong-jheng Bridge is severely lowered because the joint of Hsin-Chu fault and Hsin-Cheng fault is nearby and sand exploitation and flood flushing have been undergoing for a long period. The riverbed is exposed extensively. Etched groove is formed because the riverbed, consisted of mudstone, shale and sandstone, cannot resist long-term flushing. The bridge safety will be damaged if the riverbed is continuously lowered. The foundation of the bridge has been reconstructed several times since 1986. However, the riverbed fixation engineering was damaged by typhoons during recent few years. A significant elevation gap has been formed along the main channel of Tou-cian River. To protect the bridge safety, a concrete seal, the riverbed fixation engineering, is constructed along the main channel. Although the pier will be safe for a short term, the water flow rate is accelerated because of the concrete seal. The riverbed upstream will be flushed even deeper because of high potential of water flushing. Retrogressive erosion is likely to happen due to the weathering and erosion of soft riverbed and the joint of channel flows. Eventually, the riverbed fixation engineering, despite of different ways of protection, will be damaged anyhow. Consequently, it is required urgently that the mitigation measures should be proposed by considering the impact of all the existing engineering structures to the overall characteristics of Tou-cian River.

This project is to review the riverbed’s continuous deep flushing problem of Tou-cian River around the Jhong-jheng Bridge. Also, mitigation measures are recommended to recover the long-term stability of this river channel and secure the safety of existing flood control structures nearby.

The work items of this project include:

<!--[if !supportLists]-->1. <!--[endif]-->Collecting and analyzing the baseline data of Tou-cian River.

<!--[if !supportLists]-->2. <!--[endif]-->Site survey and investigation.

<!--[if !supportLists]-->3. <!--[endif]-->Hydrology analysis.

<!--[if !supportLists]-->4. <!--[endif]-->Estimation of sand generated in this watershed.

<!--[if !supportLists]-->5. <!--[endif]-->Parameters verification for the hydraulic and sand estimation models.

<!--[if !supportLists]-->6. <!--[endif]-->Flushing-precipitation potential analysis for the whole river section.

<!--[if !supportLists]-->7. <!--[endif]-->Hydraulic analysis and flushing-precipitation potential analysis around the river section of Jhong-jheng Bridge.

<!--[if !supportLists]-->8. <!--[endif]-->Mitigation measures proposed and evaluated for the river section of Jhong-jheng Bridge

<!--[if !supportLists]-->9. <!--[endif]-->Technology transferring and training.

<!--[if !supportLists]-->10. <!--[endif]-->Report drafting.