Xiao-ying Zhuang Tongji University 2006. Oct. 21 A study on Permeable Design of Parallel Seepage Tunnel Group

Xiao-ying ZhuangXiao-ying Zhuang

Tongji University

2006. Oct. 212006. Oct. 21

A study on Permeable Design A study on Permeable Design of Parallel Seepage Tunnel of Parallel Seepage Tunnel

GroupGroup

Tongji UniversityTongji University Tunnelling & Underground SpaceTunnelling & Underground Space

Hydropower Station Construction Hydropower Station Construction Status quo in ChinaStatus quo in China

Increase in Total

Augmentation Capacity


Jingping Hydro Power Station under CoJingping Hydro Power Station under Constructionnstruction






Traditional Design CriteriaTraditional Design Criteria• Impervious design ideaImpervious design idea Load-structure method


• Impervious design ideaImpervious design ideaCrack width verificationωmax≤0.3mm

Traditional Design CriteriaTraditional Design Criteria


Background InformationBackground Information

The Pubugou hydropower station, about 200 km away from The Pubugou hydropower station, about 200 km away from the the urban area of Chenurban area of Cheng-g-dudu in Sichuan Province in Sichuan Province, has a total , has a total augmentation capacity over 3000kW and a reservoir capacity augmentation capacity over 3000kW and a reservoir capacity over 5,390 million cubic meters. over 5,390 million cubic meters.


Background InformationBackground Information

The initial design stage gave a dual-layer 18Ф32 The initial design stage gave a dual-layer 18Ф32 reinforcement reinforcement rations rations for tunnel lining of lower part in rock for tunnel lining of lower part in rock Grade IV, which is unreasonable for substantial construction Grade IV, which is unreasonable for substantial construction due to the load-structure method and crack limit requirement due to the load-structure method and crack limit requirement of 0.25mm it employs.of 0.25mm it employs.


Problems to be solved by Problems to be solved by impervious modelimpervious model

How to prove steel ratios is over estimated by impervious design?

Impractical dense reinforcement ratio !

An reasonable reinforcement ratio based on permeable design should be given.

We are not sure if hydraulic splitting could be avoided by Norway Method which is gained from empirical acknowledgement.


Calculation ModelCalculation Model

Upper Part

Inclined Part

Lower Part


Porous Media Material Porous Media Material PropertyPropertyRock, as permeable material, its permeability is mainly controlled by joints and structure surfaces.

Concrete has a constant permeability coefficient under steady seepage field.

F2

(m)

850

(

高程m

)

左岸右岸

强

弱

微

微

地下水位

风化

岩体化风

体岩

化风

体岩

鲜新

体岩

200 400 600 800 1000 1200 1400

600

700

800

900

1000

1100

500


Lining ElementLining Element

Beam element or truss element is usually adopted for the concrete lining in FEM analysis of tunnel. As the lining is assumed porous media material, 4 edge 8 node solid element is selected.


Unfavorable Load combinationsUnfavorable Load combinations

Tectonic stress is unfavorable when the tunnel is empty for maintenances. The tunnel inner force is mostly under compressive stress.If tectonic stress field is counted for operation stage the results might be more on the unsafe side


Stress Field – Inner ForceStress Field – Inner Force

M (kN·m) N (kN) Q (kN)

Construction Stage Construction Stage ((imperviousimpervious))


Operation Stage Operation Stage (impervious)(impervious)



Operation Stage Operation Stage (impervious)(impervious)





Operation Stage Operation Stage (Permeable)(Permeable)



Operation Stage Operation Stage (Permeable)(Permeable)



Comparisons of Analysis ResultsComparisons of Analysis Results

(Permeable)(Permeable)(Impervious)(Impervious)








Seepage Field – Operation StageSeepage Field – Operation Stage


Seepage Field – Maintenances Seepage Field – Maintenances StageStage


Seepage Field – Maintenances Seepage Field – Maintenances StageStage


Thanks for your Thanks for your attention!attention!

Documents

Xiao-ying Zhuang Tongji University 2006. Oct. 21 A study on Permeable Design of Parallel Seepage Tunnel Group