Chapter 9 Sheet-Pile Walls: Cantilevered and Anchored
Chapter 9 Sheet-Pile Walls: Cantilevered and Anchored
9.1 Introduction Sheet-pile walls are widely used for: Both large and small waterfront structures Beach erosion protection Stabilizing ground slopes,particularly for roads Shoring walls of trenches and other excavations Cofferdams The types of sheet-pile walls: Cantilevered:when the wall is under about 3m in height Anchored sheet-pile wall (or bulkhead):for larger wall height
9.1 Introduction ❖ Sheet-pile walls are widely used for: ❖ Both large and small waterfront structures ❖ Beach erosion protection ❖ Stabilizing ground slopes, particularly for roads ❖ Shoring walls of trenches and other excavations ❖ Cofferdams ❖ The types of sheet-pile walls: ❖ Cantilevered: when the wall is under about 3m in height ❖ Anchored sheet-pile wall (or bulkhead): for larger wall height
9.1 Introduction Methods of analyzing sheet-pile walls: 冬 Classical (original)methods:The free-earth support and Fixed-earth support Assumption:active (from filled side)and passive pressure on the free side below the dredge line. The design was based primarily on taking moments about the anchor rod,increasing the depth of embedment D until >F was satisfied, and then computing the resulting bending moments in the piling
9.1 Introduction ❖ Methods of analyzing sheet-pile walls: ❖ Classical (original) methods: The free-earth support and Fixed-earth support ❖ Assumption: active (from filled side) and passive pressure on the free side below the dredge line. ❖ The design was based primarily on taking moments about the anchor rod, increasing the depth of embedment D until ∑Fh was satisfied, and then computing the resulting bending moments in the piling
9.1 Introduction A safety factor was incorporated by using a reduced K for passive pressure or by increasing the embedment depth D some arbitrary amount such as 20 or 30 percent. A finite-difference method by Haliburton (1968) The finite-element method by Bowles(1974) There is no "exact"method to analyze/design a sheet-pile type of wall. There is a complex interaction of construction method, excavation depth,stiffness of wall material,type and state of retained soil,and passive pressure resistance
9.1 Introduction ❖ A safety factor was incorporated by using a reduced Kp for passive pressure or by increasing the embedment depth D some arbitrary amount such as 20 or 30 percent. ❖ A finite-difference method by Haliburton (1968) ❖ The finite-element method by Bowles(1974) ❖ There is no “exact” method to analyze/design a sheet-pile type of wall. ❖ There is a complex interaction of construction method, excavation depth, stiffness of wall material, type and state of retained soil, and passive pressure resistance
9.2 Types and Materials Used for Sheetpiling Timber sheetpiling:used for free-standing walls of H<3m,for temporarily braced sheeting to prevent trench cave-ins,is little used except in temporary retaining structure Reinforced concrete sheetpiling:are precast concrete members,usually with a tongue-and- groove joint.If the joints are cleaned and grouted after they have been driven,a reasonably watertight wall may be obtained
9.2 Types and Materials Used for Sheetpiling ❖ Timber sheetpiling: used for free-standing walls of H<3m, for temporarily braced sheeting to prevent trench cave-ins, is little used except in temporary retaining structure ❖ Reinforced concrete sheetpiling: are precast concrete members, usually with a tongue-andgroove joint. If the joints are cleaned and grouted after they have been driven, a reasonably watertight wall may be obtained
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863.C0M 图2钢支撑安装实景图
9.2 Types and Materials Used for Sheetpiling Steel sheetpiling:is the most common type used for walls because of several advantages:①~⑦ Composite sheet-pile walls
9.2 Types and Materials Used for Sheetpiling ❖ Steel sheetpiling: is the most common type used for walls because of several advantages:①～⑦ ❖ Composite sheet-pile walls
Design of sheet-pile walls Soil properties: Lateral earth pressure are involved,either the Rankine or Coulomb lateral earth- pressure coefficients may be used. Drained conditions Angle of wall friction 8 Modulus of subgrade reaction,Ks
Design of sheet-pile walls ❖ Soil properties: ❖ Lateral earth pressure are involved, either the Rankine or Coulomb lateral earthpressure coefficients may be used. ❖ Drained conditions ❖ Angle of wall friction δ ❖ Modulus of subgrade reaction, ks