EFFECT OF MUTUAL INTERFERENCE PILES ON SEEPAGE PROPERTIES UNDER HYDRAULIC STRUCTURES

Mohammed Rasool

doi:10.30572/2018/kje/090419

Abstract

The seepage phenomenon (uplift pressure - flow rate - exit gradient of hydraulic structures) is one of the main causes of failure or collapse of hydraulic structures, so it has been reduced using sheet piles under floor of hydraulic structures. In this study, effect of mutual interference piles were studied on seepage phenomenon by using finite elements program ANSYS. The results were verified with the practical results L-SAYED which given a good correlation. It was found that the use of the pile in the upstream reduced the uplift pressures by 8.36%, and the pile in the downstream increased it by 11.66%, the flow rate reduced by 66.8% and exit gradient of the hydraulic structures reduced by 28.28%.

Highlights

Because the different head of water between upstream and downstream to weirs, regulator and dams ..etc. lead to the water movement from higher head to lower head passing through the permeable layer of soil, it's under structures
The effect of location pile no.2 on uplift pressures at key points shown in Fig. 6 (ØC1, ØD1, ØE3, ØD3,), quantity of seepage and exit gradient that’s shown in Figs. 9, 10, 11 and 12 respectively with constant other variable . 1.Form Fig. 9 which the percentage pressure at point (ØC1 & ØD1) reducing (5.43 & 1.47) % respectively when the distance between piles expansion perform the mutual interference low effect. 2.From Fig. 10 the percentage pressure at point (ØE3 & ØD3) increase (10.7 & 2.56) % when the distance between piles shrinking perform the mutual interference increase effect. 3.From Figs. 11, 12 and 13 location of pile no.2 no effect on quantity of seepage and exit gradient
Effect of depth pile no. 1 on uplift pressures at key points shown in Fig. 6 (ØC1, ØD1, ØE2, ØD2, ØC2, ØE3, ØD3), quantity of seepage and exit gradient that’s shown in Fig. 14, 15, 16, 17, 18 and 19 respectively with constant other variable

Summary

INTRODUCTION

Because the different head of water between upstream and downstream to weirs, regulator and dams ..etc. lead to the water movement from higher head to lower head passing through the permeable layer of soil, it's under structures. Nassralla and Rabea, (2015) studied the effect use two- layers of soil on seepage properties with sheet pile was studied experimentally and discussed with numerically computer program (Geo – Studio SEEP/ W model) ,the result were uplift pressures degreased path the floor in case the upstream pile was less than half depth of soil layer to comparison with numerical results given good agreement. Saleh and Hayder, (2011) studied the effect of location and angle of sheet pile at downstream on uplift pressure and exit gradient used finite element method analysis by computer program software (ANSYS version 11.0). In this study used one layer isotropic homogenous soil with three sheet pile and discussed the effect mutual interference between pile on uplift pressures under and exit gradient at toe of hydraulic structures by finite element software (ANSYS). The best mesh of modeling to find path uplift pressure under structures without sheet pile shown in Fig. 1 number element between 714 and 6250 no deference result so used diminution of element (1m*1m) is (1000) element at Fig. 2 and physical properties of soil at Table 1 , the result of uplift pressure at Figs. 3 and 4 comparison with Experimental result ELSayed and Ali, (2002) at Fig. 5 given good agreement

CASES OF SHEET PILES AND STRUCTURES USED

RESULTS AND DISCUSSIONS

CONCLUSION