TOP-DOWN CONSTRUCTION METHOD TOP-DOWN CONSTRUCTION METHOD  Use of diaphragm wall as the side support Use of diaphragm wall as the side support for the earth for the earth  Construction progress upwards and Construction progress upwards and downwards at the same time downwards at the same time  Savings in construction time Savings in construction time  Schematics and pictures give ideas on Schematics and pictures give ideas on ongoing activities during construction ongoing activities during construction Diaphragm Wall Installation Diaphragm Wall Installation Conventional Open-cut Conventional Open-cut & Bottom-up & Bottom-up Construction Method Construction Method (For comparison with (For comparison with Top-Down Method) Top-Down Method) Conventional Open-cut & Bottom-up Conventional Open-cut & Bottom-up Construction Method (For Construction Method (For comparison with Top-Down Method) comparison with Top-Down Method) Top-Down Top-Down Construction Construction Method Method Top-Down Construction Method Top-Down Construction Method Main Advantage of Top-Down Construction Main Advantage of Top-Down Construction Details of Top-Down Details of Top-Down Construction Method Construction Method Excavation to Level -1 Excavation to Level -1 Excavate to Level -2 Excavate to Level -2 [...]... basement reinforcement slab ready for concreting Concreting of basement slab for top- down construction method Top- down construction work in progress Complete construction of project Another example of top- down construction Another example of top- down construction Conclusion Need careful consideration for use in HCMC since method is new here  Ideal for 5 basements or more  May need some soil improvement . Construction Method (For Construction Method (For comparison with Top- Down Method) comparison with Top- Down Method) Top- Down Top- Down Construction Construction Method Method Top- Down Construction. Construction Method Top- Down Construction Method Main Advantage of Top- Down Construction Main Advantage of Top- Down Construction Details of Top- Down Details of Top- Down Construction Method Construction. Concreting of basement slab basement slab for top- down for top- down construction construction method method Top- down construction work in progress Top- down construction work in progress