Catalog 1 General requirements 2 support line measurement 3 steel sheet pile entering and stacking area 4 construction sequence of steel sheet pile 5 inspection, hoisting and stacking of steel sheet pile 6 installation of guide frame 7 construction of steel sheet pile 8 extraction of steel sheet pile 1 General requirements 1
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The setting position of steel sheet pile shall meet the design requirements to facilitate earthwork construction of trench foundation, that is, there is room for formwork support and removal outside the most prominent edge of foundation
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2
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The support plane layout of steel sheet pile in foundation pit trench should be straight and neat as far as possible to avoid irregular corner, so as to facilitate the use of standard steel sheet pile and support setting
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All peripheral dimensions should be combined with plate module as much as possible
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3
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During the whole foundation construction period, it is strictly forbidden to collide with the support, dismantle the support at will, cut and weld the support at will, and lay heavy objects on the support during the construction operations such as excavation, lifting, steel bar binding and concrete pouring
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2
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According to the design section width requirements of foundation pit and trench excavation, the position line of steel sheet pile driving is measured and set out, and the driving position of steel sheet pile is marked with white lime
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3
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Steel sheet pile entering and stacking area shall organize the time of steel sheet pile entering according to the construction schedule or site conditions to ensure that the construction of steel sheet pile meets the schedule requirements
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The stacking position of steel sheet pile shall be scattered along the support line according to the construction requirements and site conditions, so as to avoid secondary handling caused by centralized stacking together
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4
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Steel sheet pile construction sequence: positioning and setting out – trench excavation – guide beam installation – driving steel sheet pile – guide beam removal – purlin and support construction – earthwork excavation – foundation construction (force transfer belt) – support removal – basement main structure construction – earthwork backfilling – steel sheet pile removal – clearance treatment after steel sheet pile pulling out 5
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Inspection, hoisting and stacking of steel sheet pile 1
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Inspection of steel sheet pile on steel sheet pile, Generally, there are material inspection and appearance inspection to correct the unqualified steel sheet pile, so as to reduce the difficulties in the process of piling（ 1) Appearance inspection: including surface defects, length, width, thickness, end rectangle ratio, straightness and lock shape
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Attention should be paid to: a
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the welding parts that affect the driven steel sheet pile should be cut off; b
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If the hole is cut or the section is defective, it should be reinforced; c
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If the steel sheet pile is seriously corroded, the actual section thickness shall be measured
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In principle, the appearance quality of all steel sheet piles shall be inspected（ 2) Material inspection: comprehensive test on chemical composition and mechanical properties of steel sheet pile base material
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It includes chemical composition analysis of steel, tensile and bending tests of components, lock strength test and elongation test
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At least one tensile and bending test shall be conducted for each specification of steel sheet pile: two test pieces shall be conducted for every 20-50t steel sheet pile
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2
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The method of two-point hoisting should be used for lifting and loading steel sheet piles
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When lifting, the number of steel sheet piles lifted each time should not be too many, and attention should be paid to protect the lock mouth to avoid damage
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There are two kinds of lifting methods: bundle lifting and single lifting
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Bundle lifting usually uses steel cable binding, while single lifting usually uses special lifting tools
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3
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Steel sheet piles shall be stacked on a flat and solid site which will not be subject to great subsidence and deformation due to heavy load, and shall be transported to the piling construction site
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When stacking, attention should be paid to: (1) the stacking sequence, location, direction and plane layout should be considered in the future construction（ 2) Steel sheet piles shall be stacked according to model, specification and length, and signs shall be set at the stacking place to explain（ 3) Steel sheet piles shall be stacked in layers, with no more than 5 piles in each layer
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Sleepers shall be placed between each layer
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The spacing between the sleepers is generally 3 ~ 4m, and the upper and lower sleepers shall be on the same vertical line
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The total height of stacking shall not exceed 2m
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The installation of guide frame in the construction of steel sheet pile, in order to ensure the correct position of pile sinking axis and the verticality of pile, control the driving accuracy of pile, prevent the buckling deformation of sheet pile and improve the penetration capacity of pile, it is generally necessary to set a rigid and solid guide frame, also known as “construction purlin”
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The guide frame adopts single-layer and double-sided form, which is usually composed of guide beam and purlin pile
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The spacing between purlin piles is generally 2.5 ~ 3.5m, and the spacing between double-sided walls should not be too large, which is generally 8 ~ 15mm thicker than sheet pile wall
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The following points should be paid attention to when installing the guide frame: (1) use theodolite and level to control and adjust the position of guide beam（ 2) The height of the guide beam should be appropriate, which is conducive to controlling the construction height of the steel sheet pile and improving the construction efficiency（ 3) The guide beam cannot sink and deform with the driving depth of steel sheet pile（ 4) The position of the guide beam shall be vertical as far as possible, and shall not collide with the steel sheet pile
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7
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The construction of Larsen steel sheet pile is related to the construction water stop and safety, and it is one of the most critical processes in the construction of the project
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The following construction requirements should be paid attention to in the construction: (1) Larsen steel sheet pile is driven by crawler excavator
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Before driving, we must be familiar with the situation of underground pipelines and structures, and carefully set out the accurate support pile center line（ 2) Before piling, the steel sheet piles shall be inspected one by one, and the steel sheet piles with serious corrosion and deformation at the connection lock shall be removed
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They can only be used after they are repaired and integrated to be qualified, and those that are not qualified after repair shall be prohibited（ 3) Before piling, grease can be applied in the lock of steel sheet pile to facilitate driving and pulling out of steel sheet pile（ 4) In the process of steel sheet pile driving, with the measurement and monitoring of the inclination of each pile, when the inclination is too large to be adjusted by the method of alignment, it must be pulled up and driven again（ 5) The steel sheet pile shall be tightly fastened and the excavation depth shall not be less than 2m to ensure the smooth closure of the steel sheet pile; In particular, the four corners of the inspection well should use angle steel sheet pile
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If there is no such steel sheet pile, it should be sealed with old tires or rotten cloth and other auxiliary measures to avoid the ground collapse caused by water leakage（ 6) In the process of foundation trench excavation, the change of steel sheet pile shall be observed at any time
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If there is obvious overturning or uplift, symmetrical support shall be added at the overturning or uplift position immediately
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8
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Steel sheet pile shall be removed after foundation pit backfilling for reuse
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Before the steel sheet pile is pulled out, the method sequence, time and soil hole treatment should be carefully studied
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Otherwise, due to the vibration effect of pile pulling and too much soil with pile pulling, the ground settlement and displacement will be caused, which will bring harm to the constructed underground structure and affect the safety of adjacent original buildings, buildings or underground pipelines
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It is very important to try to reduce the soil with pile pulling
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At present, the main measures are irrigation and sand filling（ 1) Pile pulling method: the project can use the vibration hammer to pull out the pile: the forced vibration generated by the vibration hammer will disturb the soil, destroy the cohesion of the soil around the steel sheet pile, so as to overcome the pile pulling resistance, and pull it out by the action of additional lifting force（ 2) Matters needing attention when pulling out piles A
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starting point and sequence of pulling out piles: for closed steel sheet pile wall, the starting point of pulling out piles should be more than 5 away from corner piles
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The starting point of pile pulling can be determined according to the situation of pile sinking, and the jumping method can also be used when necessary
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It is better to pull out the pile in the reverse order
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b
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Vibro driving and vibro pulling: when pulling out the pile, first use the vibro hammer to vibrate the lock of sheet pile to reduce the adhesion of soil, and then pull out while vibrating
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For the sheet pile which is difficult to pull out, the diesel hammer can be used to lower the pile by 100 ~ 300 mm, and then the vibration hammer can be used to alternately drive and pull out
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c
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The crane should be loaded gradually with the start of the vibration hammer, and the lifting force is generally slightly less than the compression limit of the shock absorber spring
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d
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The power supply for the vibrator is 1.2 ~ 2.0 times of the rated power of the vibrator itself.
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