Contents
I. Preparation basis 1
II. Basic overview 1
III. Positioning of the tower crane foundation 3
IV. Design of the tower crane foundation 4
V. Construction practice of the tower crane foundation 5
VI. Handling measures for the tower crane passing through the basement top plate 6
VII, tower crane foundation checking book: 7
VIII, attached drawings 10
I, the preparation of the basis
1, the project geological survey report
2, the project construction drawings
3, "Technical specification for pile foundation of building" (JGJ94-2008)
4, "acceptance of the quality of the construction of building foundation engineering construction specification" ( GB50202-2002)
5, "Code for the Design of Concrete Structures" (GB50010-2002)
6, "Safety Technical Regulations for the Installation, Use and Demolition of Tower Cranes for Building Construction" (JGJ196-2010)
7, QTZ6015 tower crane instruction manual
8, Reinforced concrete structure design table (China Construction Industry Press)
9, "construction project pit, high supporting molds, tower crane construction special safety training handout"
10, PKPM safety calculation software
2, the basic overview
2.1, the project profile
This project is located in Guangzhou City, Luogang District Yongshun Avenue, north of the site traffic is more convenient. North, the site traffic conditions are more convenient, 6 residential buildings, respectively (1 ~ 6 buildings), of which six buildings for the 16-storey, building height of 51.20m, one to five buildings for the 18-storey, building height of 57.20m. kindergarten for the 3-storey, building height of 9.90m. basement floor height of -5.85m, the first floor height of the buildings are 4.8m, the standard height of the kindergarten is 3m. The height of the first floor is -0.20m, and the height of the standard floor is 3.3m. The reinforced concrete shear wall structure has a total floor area of about 118,435.6m2 (including 108,355.6 m2 above ground and 10,080 m2 underground). Four sets of QTZ6015 tower cranes are installed in this project, which are 1#, 2#, 3# and 4#. This program for the 3 # tower crane foundation construction program, set in the four basements across the basement roof for vertical transportation, 3 # tower crane maximum installation height of 72m, the installation of the center of the position from the 4-N axis 6.00m, D-15 axis 3.20m, (see the attached figure for details of the specific location), the foundation of the tower crane bearing platform basement natural ground foundation form, the tower crane foundation bearing platform excavation and basement pit Simultaneous excavation, excavation slope 1:1.2, tower crane pit bottom elevation is -7.850m. tower crane first installation height of 19 meters.
2.2, site topography and geomorphology
The site is located in guangzhou city luogang district lingtou village yongshun avenue west road of the north side of the site north side of the hills, east side of the residual hill. The surrounding terrain is wide. The original geomorphological unit of the site belongs to the alluvial and slope accumulation zone at the front edge of the hills, and the site is slightly undulating locally.
2.3, geotechnical layering description
According to the Guangdong City Kecheng Architectural Design Co., Ltd, Guangdong Province, Guangdong Provincial Engineering Survey Institute, September 2008 "Geotechnical Engineering Detailed Investigation Report", the geological information obtained from the borehole exposures, after the synthesis and collation of the site can be divided into the rock and soil layers from top to bottom of the artificial fill (Qml), cultivated soil layer (QPb), the fourth alluvial soil layers (Qai), slope deposits (Qdl), weathered residual soil (Qel) and Yanshan period (r) bedrock six categories. The stratigraphic conditions relevant to this project are synthesized as follows:
Stratigraphy
Stratum
Sequence
No.
Soil stratum name
Top elevation
(m)
Top depth
(m)
Characteristics Description Average layer thickness
(m)
QPb, Layer No.2 Cultivated land 37.82~39.82 0~3.60 Loose, undercompacted, poor soil homogeneity.
1.11
Qai,Layer No.3(3-1)
Loose medium-coarse sand
32.47~40.88
0.50~7.00 Water-saturated, loose, poorly sorted, locally interspersed with thin layers of silt and gravelly sand of quartz composition, locally with thin layers of clayey soil.
3.06
Qai,Layer No.3(3-2)
Silty soil
32.76~40.66
0.50~7.00 Grayish-black or dark grey, saturated, fluid~soft plastic, locally containing sand grains, locally interspersed with thin layers of medium-coarse sand or clay.
1.98
Qai,Layer No.3(3-3)
Medium-coarse sand
31.17~36.32
2.00~10.00 Grayish-yellow, dark gray, gray, grayish-white, etc., saturated, slightly dense, poorly sorted, with thin layers of silt and gravel in local intervals.
4.15
Qai,Layer No.3(3-4)
Powdery clay
31.81~40.24
4.10~13.80 Possessing the color of grey, greyish-yellow, brownish-yellow, brownish-red etc., plastic, with local sand grains and average cohesion, locally interspersed with thin layers of medium-coarse sand or clay.
2.56
Qai,Layer No.3(3-5)
Medium-coarse sand
27.90~35.74
4.10~13.80 Possesses the color of gray-yellow, dark gray, gray, gray and grayish-white etc., full of water, medium-dense, poorly sorted, locally interspersed with thin layers of powdery and gravelly sands, with quartz as the constituent, and locally containing 1~8cm of Siliceous pebbles, locally containing clayey soil or sandwiched with thin layers of clay. 3.61
Qdl, Layer No.4
Powdery clay
31.49~40.60
1.00~9.50 reddish-yellow, maroon, grayish-yellow and other colors, plastic, with quartz sand grains, and average clay.
6.25
Qel, Layer No. 5
Granite Weathering
27.17~37.64
3.80~14.10 Possessing brownish yellow, greyish green, brownish grey, greyish white and other colors, rigidly plastic, easy to soften and disintegrate in water.
4.70
2.4 Hydrological situation
Most of the holes in the site section of the quaternary pore water-bearing sand layer is developed, rich in water content; poor permeability of the clay layer, is a weakly permeable layer, poor in water content; bedrock in the process of drilling did not find the phenomenon of water leakage, indicating that the bedrock fissures are poor in connectivity, poor in containing vein fissures; therefore, the site is mainly for the groundwater of the pore water of the sand layer, rich in water content. Therefore, the groundwater of the site is mainly pore water of sand layer, which is rich in water content. Groundwater recharge mainly comes from atmospheric precipitation and lateral runoff recharge of sand layer. The variation of groundwater level varies with seasonal changes, with the water level rising in the rainy season and falling in the dry season. During the drilling period, the depth of water level in the borehole was measured to be 0.2-5.8m, and the type of groundwater is slightly pressurized water. Groundwater is non-corrosive to concrete and steel reinforcement in reinforced concrete, and weakly corrosive to steel structures.
2.5, tower crane
Tower crane QTZ6015 tower crane (fixed attached), the maximum size of 60m, the maximum design free height of 44m, attached to the lifting height of up to 176m. the project installation height of about 72m.
Three, the tower crane foundation positioning
1, the center of the tower crane is located in the 4-N axis distance of 6.000m, from the 4-51 axis 3.000m. Distance from 4-51 axis 3,600m (see attached drawing)
2, tower crane pre-buried anchor bolts positioning dimensions (see attached drawing:)
Four, tower crane foundation design
3 # tower crane foundation bearing platform below the bottom of the geotechnical data (refer to the geological data of the column diagram of ZK26 holes)
Sequence No. name of the soil layer thickness (m) characteristic value of the foundation capacity ( kPa) Standard value of soil side resistance (kPa) Standard value of soil end resistance (kPa)
1 Sandy clay 3.5 250 45
2 Fully-weathered granite 3.80 400 80
3 Strongly-weathered granite 2.90 700 120 4500
3#Tower crane foundation holding force in sandy clay layer; ±0.000 equals to Absolute elevation 41.40
Depth of excavation -7.400m (34.00) (if see and geological data do not match, then until digging to meet the requirements of the soil,, and then fill tamping to -7.400m)
Description: tower crane bearing bearing in the sandy clay layer (layer No. 5); in the excavation of the soil layer does not match with the geological report, (such as soft soil and silt) must be dig until it meets the requirements.
Construction-related notes:
1, bearing platform concrete grade C35 (impermeability grade ≥ 0.8MPa), its construction should be strictly in accordance with the requirements of the specification; tower crane foundation size width 6000 * 6000, height 1500; reinforcing steel using 2 steel 16.
2, tower crane base and crane installation should be carried out in accordance with the requirements of the factory manual of the tower crane, control the Embedded bolt position and anchoring depth;
3, all steel components of the welding are contact side length of the full weld, weld thickness ≥ 6mm.
4, tower crane embedded cross-section dimensions and embedded position, elevation of the crane according to the crane instruction manual requirements of the construction, the installation unit to send technicians to the site to do technical guidance.
5, foundation pouring concrete should be poured in layers, each layer is not more than 500 mm, the use of insertion vibration vibration compact, pouring to be continuous. Crane foundation construction is completed after the crane installation to do 180 thick brick wall for enclosure.
6, concrete should be watered and maintained after pouring, and the maintenance period should be not less than 14 days. Strictly according to the acceptance procedures for the acceptance of engineering piles, do a good job of concrete test block 28 days compression test.
7, the concrete strength reaches 85% before installing the crane.
8, strengthen safety management, do a good job of site safety signs. Work in accordance with the provisions of the delineation of safety warning area.
9, the foundation plane flatness tolerance 1/1000
10, under no-load conditions, the tower crane and the foundation plane permissible deviation of verticality 4/1000, Ming high anchorage point below the verticality of the permissible deviation of 2/1000.
11, foot bolts into the field should be in accordance with the instructions to check to ensure compliance with the requirements of the depth of burial ≥ 1000mm. 1000mm.
12, the foundation of lightning protection and grounding with reference to the building lightning protection design requirements for construction.
13, ground bolts and lightning protection ground pole connected, grounding resistance ≤ 4Ω.
14, tower crane installation, dismantling program to be compiled separately.
15, waterproofing layer are laid along the perimeter of the bearing platform, the practice of reference to the basement waterproofing samples.
Five, tower crane foundation construction practice
Tower crane foundation pit excavation - pouring bedding and brick mold - brick mold surface 1:3 cement mortar plastering - -Do waterproofing - Tying of reinforcing steel cage - pre-buried anchor bolts - pouring foundation concrete -Concrete maintenance.
1, tower crane foundation pit excavation and basement pit excavation at the same time, excavation slope 1:1, 3 # tower crane bearing platform foundation pit bottom elevation is -7.40m, top elevation -5.850m. In the excavation before the site construction workers in accordance with the tower crane positioning map put out the grey line, excavation by the excavator synchronization, mechanical excavation is completed after the manpower leveling.
2, bedding thickness of 100mm, concrete grade C15, the original mortar polished, using 240 thick gray sand brick M5 cement mortar masonry foundation side mold, the inner surface of 15mm thick 1:3 cement mortar plastering and calendaring. The tower crane foundation is connected with the basement floor as a whole.
3, tower crane foundation with the basement floor waterproofing materials used in waterproofing, and the yin and Yang corner position to strengthen the treatment, and the basement floor waterproofing connected to the system to ensure that the tower crane is removed no longer waterproofing of the foundation position. The bottom surface using 20mm thick 1:3 cement mortar plaster to do waterproof protection layer.
4, tower crane foundation reinforcement cage binding: tower crane foundation upper horizontal reinforcement with the basement floor reinforcement: upper with two-layer bidirectional Ф20@200, lower with bidirectional Ф16@160, vertical reinforcement for Ф14@300, (the program first pouring tower crane foundation concrete, in advance of the installation of the tower crane put into use), in the tying tower crane bearing platform reinforcement and the basement floor laps up and down the steel bar Staggered reserve, to be tied when the basement slab reinforcement and crane foundation connected as a whole. Tower crane bearing platform around the connection with the basement floor set up water-stopping steel plate. (See attached drawing)
5, concrete pouring: tower crane base concrete grade for C35 waterproof concrete, impermeable grade 0.8MPa. tower crane base bearing platform top surface mortar light, flatness deviation ± 10mm. before pouring, pay attention to the bolt screw with a plastic bag, pouring and pounding, pay attention to do not touch the ground bolt. Concrete pouring samples of test blocks to be sent for inspection, concrete strength of 80% for crane installation, while the test report as a safety data archives for inspection.
6, pay attention to the maintenance of concrete after pouring, maintenance time of not less than 14 days.
7, tower crane foundation size tolerance table.
Allowable deviation of tower crane foundation size and inspection method
Item Allowable deviation (mm) Inspection method
Elevation ±20 level, pulling line, steel ruler checking
Plane external dimensions ±20 steel ruler
Surface flatness 10, L/1000 level
Cave dimensions ±20 level
Elevation of pre-embedded parts ±20 level
Elevation of pre-embedded parts ±20 level
Elevation of pre-embedded parts ±20 level
Elevation of embedded parts ±20 level
Center distance of embedded parts ±2 steel feet
VI. Measures to deal with the tower crane through the basement roof
1. The size of the hole in the basement roof is 2.750×2.750m, which is left in the center and disconnected from the L3 (8) 300×800 frame beam. To be sealed with C40 concrete connection after the removal of the tower crane.
2, the top plate reinforcement: from the original two-layer bidirectional 12@200 to two-layer bidirectional 14@200 (has been designed to agree).
3, in order to ensure safety in construction, before the removal of the tower crane, the top plate reinforcement shall not be cut, the tower crane is removed with oxygen cut and then connected with gang welding. Slab reinforcement must be staggered according to 50% joints, the spacing between the joints is not less than 40d.
4, tower crane in use, the hole around the 2.5m range of the top plate template and support is not demolished, and in the process of template construction, the porta-frame support system and its disconnection to facilitate the dismantling of the reserved.
5, reserved holes in the concrete pouring, holes around the strict treatment of construction joints and set up water-stopping steel plate, waterproofing of the roof, the hole location to add a waterproof layer. (tower crane through the basement roof reserved holes see attached drawings)
seven, the tower crane foundation calculations:
Tower crane natural foundation calculations
a. Parameter information
Tower crane model: QTZ60 Self-weight (including compression weight): F1=573.00kN Maximum lifting load: F2=60.00kN
Tower crane tilting distance: M=1726.00kN.m Tower crane lifting height: H=72.00m Tower body width: B=1.80m
Concrete strength grade: C35 Grade of reinforcement: Grade II Foundation bearing capacity: 250.00kPa
Minimum width of foundation: Bc=6.00m Minimum thickness of foundation: h=1.50m Depth of foundation: D=0.00m
Depth of pre-buried parts: h=0.00m
II. Calculation of minimum size of foundation
Minimum thickness of foundation: H=1.45m
Minimum width of foundation: Bc=6.00m
III. Calculation of bearing capacity of tower crane foundation
Calculation sketch:
1, the overall stability of overturning:
e=(MK+FVKh)/(FK+GK)=(1726+71*1.45)/(573+6*6*1.45*25)
=0.974<b/4=1.5, meet the requirements!
In the formula:
MK - corresponding to the standard combination of load effect, acting on the short side of the top surface of the rectangular foundation in the direction of the moment value (kN * m) FVK - corresponding to the standard combination of load effect, acting on the rectangular foundation FVK - the value of horizontal load in the direction of the short side of the top surface of the rectangular foundation (kN)
h - the height of the foundation (m)
FK - the standard value of vertical load of the tower acting on the top surface of the foundation (kN)
GK --Standard value of self-weight of foundation and soil on it (kN)
b - length of short side of rectangular foundation bottom surface (m)
2. Calculation of foundation bearing capacity
PK=( FK+GK)/ bl=( 573+6*6*1.45*25)/(6*6)=52.17 kPa < fa
Formula:
PK--Average pressure value at the base of the foundation corresponding to the standard combination of load effect (kPa);
l --Length of the long side of the rectangular foundation base (m);
fa --Corrected characteristic value of foundation bearing capacity (kPa).
This project eccentricity e=0.974＜b/6
Pkmax=( FK+GK)/ bl + (MK+FVKh)/W =52.17+1828.95/36=102.97<1.2fa,
Satisfy the requirements!
In the formula:
Pkmax--Maximum pressure value at the edge of the foundation base corresponding to the standard combination of load effect (kPa);
W--Resistance moment of the foundation base (m3);
3. Foundation bearing capacity check
The characteristic value of foundation bearing capacity after correction is:fa=250.00kPa
Since fa≥Pk=64.6kPa so it meets the requirement!
Eccentric load: Since 1.2×fa≥Pkmax=102.97 kPa so it meets the requirement!
4. Calculation of punching bearing capacity
The formula is as follows:
where hp---height influence coefficient of punching bearing capacity section, take hp=0.95;
ft---concrete design value of axial tensile strength, take ft=1.57kPa;
am---the most unfavorable side of the cone of punching damage calculation length:
This is the most unfavorable side of the cone of punching damage, take ft=1.57kPa.
am=[1.80+(1.80+2×1.45)]/2=3.25m;
h0-the effective height of the bearing platform, take h0=1.45m;
Pj-the maximum pressure design value, take Pj=147.39kPa;
Fl-the actual punching bearing capacity:
Fl =147.39×(6.00×0.70+7.42)=1712.70kN.
Allowable punching force:
0.7×0.95×1.57×3250×1450=4750427.00N=4750.43kN
The actual punching force is not greater than the design value of allowable punching force, so it can meet the requirement!
5. Calculation of bearing platform reinforcement
1. Bending calculation, the formula is as follows:
where a1 - section I - I to the edge of the base of the distance, take a1 = 2.10m;
P - section I - I at the base of the base of the reaction force:
P = 147.39 × (3 × 1.75 - 2.10)/(3 × 1.75)= 88.39 × (3 × 1.75)/(3 × 1.75)
The actual shear force is not greater than the allowable shear design value, so it can meet the requirements! 1.75)=88.54kPa;
a'──Projection length of section I-I at the base, take a'=1.80m.
After calculation:
M=2.102×[(2×6.00+1.80)×(147.39+88.54-2×1305.00/6.002)+() 147.39-88.54)×6.00]/12
=958.62kN.m.
2. Reinforcement area calculation, the formula is as follows:
According to the "Code for the Design of Concrete Structures" GB 50010-2002
In the form of 1 - coefficient, when the concrete strength is not more than C50, 1 is taken to 1.0, when the concrete strength grade is C80, 1 is taken to 1.0. When the concrete strength level of C80,
1 is taken as 0.94, the period determined by linear interpolation;
fc - design value of the compressive strength of concrete;
h0 - calculation of the height of the bearing platform.
After calculating s=958.62×106/(1.00×16.70×6.00×103×14002)=0.0046
=1-(1-2×0.0046)0.5=0.005
s=1-0.005/2=0.998
As=958.62 ×106/(0.998×1450×300.00)=2208 mm2.
Since the minimum reinforcement rate is 0.15%, the minimum area of reinforcement is 13500mm2.
So As=13500mm2. HRB335 is used, and fy=300.00N/mm2 is taken to be 6020
As1=60×314=18840mm2>As=13500mm2(meet the requirements), that is, two-layer bi-directional 20@200 to meet the requirements!
Eight, attached drawings
1, pit support plane and crane positioning plan
2, crane foundation section
3, crane foundation geological reference section
4, crane foundation positioning and through the plate reserved hole plan