Short Note on Components of the Well Foundation

Components of the Well Foundation :

(I)Well Curb and Cutting Edge :

a. Bottom portion of the well is tapered and is called well cur

b. It should be strong enough to transfer the design load. Cutting edge, which is integral part of the well curb, is usually made of rails or mild steel plates and angles. Edge of the cutting is sharp to facilitate cutting of soil. Inclined portion of the well curb facilitates easy sinking. After the well curb, outer dimension of the well is very slightly reduced. and this facilitates in reducing skin friction, while sinking the well.

(II) Bottom Plug : As shown in the drawing, bottom portion of the well is filled up with M-15 grade concrete and is known as bottom plug. In most of the cases, there is always water in the well and bottom plug is to be done under water. Bottom plug should preferably be 300 mm above well curb.

(III) Top Plug : A 300 mm thick plug of at least M-10 grade of concrete is provided to work as top plug, as per section.

(IV) Well Steining : The thickness of steining is normally kept as one fourth the outside diameter of railway bridges. As per latest instructions, the thickness of well steining should not be less than 50 mm. Well steining is either constructed of mass concrete or reinforced concrete. Bond rods, disturbed uniformly on both the faces of steining, should be provided at a rate not less than 9kg/m to bond the units of the steining during the process of construction. They are tied up by providing adequate horizontal hoop reinforcement, which should not be less than 9kg/m. The cover for the rod should not be less than 75 mm.

(V) Well Cap : The bottom of the well cap should, as far as possible, be located 300 mm above the low water level. All the longitudinal bars from the well steining should be anchored into the wall cap. Well cap should be designed as a slab resting on the well steining.