Môc lôc GMS Ben Luc Long Thanh Expressway Project Package A5 Civil Works Km 32+450 to Km 35+900 CONSTRUCTION METHOD STATEMENT FOR BORED PILES TABLE OF CONTENTS I DESCRIPTION II MATERIALS FOR PILING II[.]
GMS Ben Luc - Long Thanh Expressway Project Package A5 Civil Works Km 32+450 to Km 35+900 CONSTRUCTION METHOD STATEMENT FOR BORED PILES PHUONG THANH TRANCONSIN GMS Ben Luc - Long Thanh Expressway Project Package A5 Civil Works Km 32+450 to Km 35+900 TABLE OF CONTENTS I DESCRIPTION II MATERIALS FOR PILING III CONSTRUCTION OF BORED PILES PHUONG THANH TRANCONSIN GMS Ben Luc - Long Thanh Expressway Project Package A5 Civil Works Km 32+450 to Km 35+900 I DESCRIPTION The work under this section consists of the construction of Bored piles using the reverse circulation drilling method, crab type hammers, and steel casing or any other earth drill method approved by the Engineer, in accordance with this specification and in conformity with the drawings or as may be required by the Engineer Reference standards: The following Standards in their latest edition shall be particularly applies to the works covered by this Specification ASTM A36 Carbon Structural Steel OCMA DFCP4 Drilling Fluid Materials Bentonite Oil Companies Materials Association (OCMA) API S13A Specification for Oil Well Drilling Fluid Materials (APIS: American Petroleum Institute Standard) 22TCN272-05 Specification for Bridge Design TCVN 9393:2012 Piles – Standard test method in situ for piles under axial compressive load TCVN 9395:2012 Construction and Measurement of Bored Piles TCVN 9396:2012 Bored Piles – Determination of identity of concrete – Pulsed ultrasonic method TCVN 9397:2012 Bored Piles – method of detection of defects by low strain dynamic test II MATERIALS FOR PILING Concrete Bored piles shall be constructed in accordance with the details shown on the drawings using the class of concrete noted on the drawings and in accordance with Specification - Concrete and Concrete Structures Concrete shall be mixed and placed in accordance with the applicable provisions of Specification - Concrete and Concrete Structures Reinforcing steel Reinforcement shall comply with the provisions of Specification - Reinforcing Steel Temporary casings Bored piles shall be excavated with a temporary steel casing through water and upper soil layers which might otherwise collapse PHUONG THANH TRANCONSIN GMS Ben Luc - Long Thanh Expressway Project Package A5 Civil Works Km 32+450 to Km 35+900 Temporary casings shall be free from significant distortion They shall have a uniform cross-section throughout each continuous length During concreting they shall be free from internal projections and encrusted concrete which might prevent the proper formation of piles Permanent casings Permanent casings required for construction purposes shall be of the thickness and length proposed by the Contractor, and shall be of steel grade ASTM A36 unless otherwise approved Steel casings shall be furnished in appropriate lengths approved by the Engineer The casings shall be handled and stored in a manner that prevents buckling and other deformation and the accumulation of dirt, oil and paint When placed in the work they shall be free from dirt, oil, grease, paint, mill scale and loose or thick rust Bentonite and bentonite slurry ( drilling fluid ) 5.1 Supply Immediately prior to mixing Bentonite shall be in accordance with Specification DFCP4 of the Oil Companies Materials Association (Drilling Fluid Materials Bentonite), or the American Petroleum Institute Standard 13A 5.2 Mixing Bentonite shall be mixed thoroughly with clean fresh water to make a suspension which will maintain the stability of the pile excavation for the period necessary to place concrete and complete construction Where chemically contaminated groundwater occurs, special precautions shall be taken to modify the bentonite in all respects for the construction of piles III CONSTRUCTION OF BORED PILES Preparation works Construction equipment includes : - Drilling equipment: is a self-propelled crane for craning casing, equipment and erecting the drilling machine - Drilling equipment includes of grab buckets as mechanical or hydraulic dredging buckets - Mixing equipment, tanks and bentonite pumps - Vibrating hammer is enough capacity for lowing the casing into the hard ground - Cleaning equipment: betonite pumps, compressors 10m3/minutes - Other construction equipment such as tremie pipes, concrete vehicles, mix truct, welding equipment, etc PHUONG THANH TRANCONSIN GMS Ben Luc - Long Thanh Expressway Project Package A5 Civil Works Km 32+450 to Km 35+900 Construction site preparation For the abutment, pier on land: remove organic soil and leveling to create construction site For the pier next to river side: Driving sheet pile system, leveling to create construction site The main purpose of preparing site plan is creating space for the installation and operation of drilling equipment and construction of bored piles Positioning the pile centre by Total Sation and marker is made by wooden piles to avoid the lost during construction process Drawing a circle with diameter the same with casing on the ground and take this ring to locate the casing when lowering Pile center under water shall be located based on the casing and positioning frame Mobilization of material, equipment for bored pile (installation of drilling equipment, crane, casing, positioning pile, air compressor, manufacture of rebar for pile) Checking the operation of equipment, concrete supply, water and power Mixing of bentonite Bentonite is mixed with cleaned water to create the slurry, maintain the stability of the drilling work in the concrete placing and completion of execution The temperature of the water used for mixing Bentonite is not less than degrees C Bentonite grout is mixed and operation in a specialized equipment in a closed process includes all stages of mixing, filtering, pumping to drilling holes and gather mortar for reusing Bentonite is strictly in accordance with the technical standards by Contractor Benonite mixing ratio dry / water is adjusted according to actual geological drilling Contractor shall conduct the tests in accordance with bentonite specification before commencement of work The contractor will propose test methods, sampling procedures, inspection frequency and bentonite grout and submit to the Engineer Betonite's certificate Contractor’s site lab is sufficiently equipped with equipment to examine the density, viscosity, pH, shear force of the bentonite mixture to deploy test in the construction process PHUONG THANH TRANCONSIN GMS Ben Luc - Long Thanh Expressway Project Package A5 Civil Works Km 32+450 to Km 35+900 The tests and inspections must be taken regularly for bentonite: Properties to be measured Density Viscosity Sand content Proportion of colloidal material Fluid loss Thickness of clay layer Shear strength (gel strength) Stability PH Drilling hole 4.1 Driving casing Requirement Test method 1.05 – 1.15 g/cm3 Mud density balance (ASTMD4380) 18-45 seconds Marsh cone (ASTM D 6910) 95% Measuring beaker