Project R1041: Dubai Parks Access from Sheikh Zayed Road General Specifications Volume 2 Part I

March 2015 Tender Documents Page 2/17

5 40 - 70 2 20 - 50 0.85 5 - 25 0.425 0 - 10 0.180 0 - 2

2/21.3 The stabilising crushed material shall have the following characteristics:-

- Los Angeles Abrasion - Not more than 30% loss (ASTM C-131 or ASTM C-535) - Bulk Specific Gravity - Not less than 2.65 (ASTM C-127 and C-128) - Absorption - Not more than 2.0% (ASTM C-127 and C-128)

2/21.4 The stabilising crushed material will be laid in layers of 15 cm and compacted

until the foundation is fully stabilised such that the total thickness of the stabilising layer shall not be less than 30 cm. Only after inspection and approval by the Engineer the Contractor may be allowed to continue the construction of the embankment with other layers of embankment material and/or subgrade material. The Engineer may decide, after having taken the levels of the existing water table in the area, and keeping in consideration the finished road levels, to excavate portions of the foundation saturated by water, disposing of the excavated material, and replacing it with stabilising crushed material.

2/21.5 Before starting any stabilising of the foundation the Engineer will instruct the

Contractor specifying the areas to be stabilised and the final levels to be reached with the stabilising crushed material.

2/22 GEOTEXTILE FABRIC 2/22.1 In areas where the Engineer deems the use of geotextile fabric necessary, the

Contractor shall furnish and place geotextile fabric as specified and as directed by the Engineer.

2/22.2 The geotextile fabric furnished by the Contractor shall be of an approved

grade suitable for placement over fine sand. The geotextile fabric shall be a woven or non-woven fabric consisting only of long chain polymeric filaments or yarns formed into a stable network such that the filaments or yarns retain their relative position to each other. The fabric shall be stabilised against ultra violet light, inert to commonly uncounted chemicals and chemical properties of the in-situ soil and water, and it shall conform to the following minimum requirements:

Project R1041: Dubai Parks Access from Sheikh Zayed Road General Specifications Volume 2 Part I

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Property Test Method Minimum Required

CBR Puncture Resistance

EN ISO 12236, BS 6906/4, DIN 54307

1500 N 1250 N (min average)

Trapezoidal Resistance ASTM D 4533 300 N

Mean Flow Rate EN ISO 11058, BS6909/3

45-100 l/m2/s

Apparent Opening Size EN 12956, ASTM D 4571

50-180m (microns)

Mass per Unit Area BS EN 965 120 g/m2 (minimum)

Ultraviolet Stability or UV Degradation (Percent Retained Strength)

ASTM D 4355 70% strength retention after 150 hours exposure or 50% after 750 hours exposure

Burst Test ASTM D 3786 2000 N

Grab Strength ASTM 4632 800 N

Thickness under load (2KN/sq.m)

DIN 53855 0.7mm

Tensile Strength (200mm width)

ASTM D1682 1.6KN

Permeability DIN 60500 50 L/sq.m/s 2/22.3 The surface to receive the geotextile fabric shall be prepared to a relatively

smooth condition free of obtrusions, depressions, and debris. The geotextile fabric shall not be laid in a stretched condition, but shall be laid loosely with the long dimension parallel to the centreline of the roadway. In the event that the width of the proposed area for fabric requires more than one panel width of fabric, the panels shall be overlapped a minimum 15 percent of the panel width. Longitudinal joints in the fabric shall have an overlap of 50cm. To prevent slippage of the overlapping fabric, the areas of overlap shall be stabilised as approved by the Engineer with pins, anchor blocks, or aggregate piles. In the event construction machinery is used to place the fabric, the working platform for the machinery shall be the soil and not the previously laid fabric.

2/22.4 Prior to placement of the granular material (Stabilising crushed material) the

Contractor shall spread a layer of sand over the geotextile fabric as directed by the Engineer. The aggregate material shall not be dumped directly on the fabric, nor shall haul trucks be run on the fabric. The aggregate shall be spread by a wheeled front-end loader.

The blade or bucket shall be kept sufficiently high so that the aggregate is not

being pulled over the fabric, but being dropped at a minimum height to the satisfaction of the Engineer.

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2/22.5 Fabric damaged or displaced before or during installation or during placement of overlaying aggregate material shall be replaced or repaired to the satisfaction of the Engineer at the Contractor's expense.

2/23 EXCAVATION FOR STRUCTURES 2/23.1 This work shall consist of all excavation for structures, culverts, headwalls,

catch basins, manholes, inlets, and retaining walls and shall include all necessary clearing and grubbing, all necessary bailing, drainage, pumping, sheeting, strutting and the construction of coffer dams or cribs, if found necessary, and their subsequent removal; also the disposal of all material obtained from such excavation and backfilling to the level of the original ground; it shall include the removal of that portion of existing structures below the ground which is necessitated by the construction of the new structure.

2/23.2 Prior to commencing any structural excavation work 1.5 metres or more in

depth, the Contractor shall design and submit to the Engineer for review and approval, within a minimum period of 1 week before the intended commencement date, detailed working drawings of the structural excavation support member materials, sizes, spacing and engineering calculations to validate their design, including the maximum theoretical deflections of the support members. The system shall be designed in such a manner that no raker struts or any other support members extend through surfaces exposed in the finished construction, and no shoring or bracing is placed under permanent structures.

2/23.3 The engineering calculations shall show lateral earth pressure for the full

excavation depths, forces at various stages of support during installation and removal and concrete placement, the anticipated equipment loads, surcharge loads of any description, the maximum design loads to be carried by various members of the support system and strut preload forces.

2/23.4 If the structure support system proposed includes tieback anchors, the

Contractor's submittal drawings shall show the profile of the soil in which each anchor is to be installed, the design load for the full depth of the excavation, the maximum design and proof loads, surcharge loads of any description; equipment loads, forces at various stages, support during installation and removal, and the criteria proposed for deformations under proof loads. Where a proposed system of tieback anchors projects beyond the vertical projection of the Contract limit lines shown on the Drawings on to the adjoining property, the permission of the owner shall be obtained in writing and such permission submitted to the Engineer at the time the shop drawings of the support systems are submitted.

2/23.5 At locations where the excavation extends below the ground water table, a

dewatering system shall be provided which will effectively reduce the hydrostatic pressure and lower the ground water levels below excavation levels, as required for the safe and proper execution of the work and which will result in obtaining a stable, dry subgrade for the execution of subsequent operations. The Contractor shall design dewatering methods and settling basins so that no critical amounts of soil, sand or silt are removed during either the initial operations or the construction operations. Complete working