catalogue
I. Compilation Basis 1
Two. Basic overview 1
Three, tower crane foundation positioning 3
Four, tower crane foundation design 4
Five, tower crane foundation construction practice 5
Six, tower crane through the basement roof treatment measures 6
Seven, tower crane foundation inspection: seven copies.
Eight. Attached drawings 10
I. Basis for compilation
1. Geological investigation report of this project
2, engineering construction drawings
3. Technical Specification for Building Pile Foundation (JGJ94-2008)
4. Code for Acceptance of Construction Quality of Building Foundation Engineering (GB50202-2002)
5. Code for Design of Concrete Structures (GB500 10-2002)
6. Technical Code for Safety of Installation, Use and Demolition of Tower Crane in Building Construction (JJ196-2010)
7. Instructions for use of Qt Z6015 tower crane
8, reinforced concrete structure design table (China Building Industry Press)
9. Handout on Special Safety Training for Foundation Pit, High Formwork and Tower Crane Construction in Building Engineering.
10, PKPM security computing software
Second, the basic situation
2. 1, project overview
This project is located in the north of Yongshun Avenue, Luogang District, Guangzhou, with convenient transportation. There are six residential buildings, respectively (1 ~ 6 buildings), of which six are 16 floors with a building height of 5 1.20m, and the first to fifth buildings are 18 floors with a building height of 57.20m. The kindergarten has three floors with a building height of 9.90mm. Standard height .. The height of the first floor of the kindergarten is-0.20m, and the standard height is 3.3m. It is a reinforced concrete shear wall structure with a total construction area of about 1 18435.6m2 (including 108355.6 m2 above ground and 10080 m2 underground). Four sets of QTZ60 15 tower cranes are installed in this project, namely 1#, 2#, 3# and 4#. This scheme is the construction scheme of 3# tower crane foundation, which is set in four basements and vertically transported through the basement roof. The maximum installation height of 3# tower crane is 72m, and the installation center is 6.00m away from the 4-N axis and 3.20m away from the D- 15 axis (see attached figure for details). The foundation of tower crane bearing platform adopts the form of basement natural foundation, and the excavation of tower crane bearing platform and basement foundation pit is carried out simultaneously. The first installation height of tower crane is19m.
2.2. Site topography
The site is located in the north of Yongshun Avenue West Road, Lingtou Village, Luogang District, Guangzhou, with hills in the north and residual hills in the east. The surrounding terrain is relatively wide. The original landform unit of the site belongs to the piedmont alluvial-diluvial zone, and the site fluctuates slightly.
2.3, rock and soil layered description
According to the detailed geotechnical investigation report of Guangdong Kecheng Architectural Design Co., Ltd. and Guangdong Engineering Investigation Institute in September 2008, the geological data revealed by drilling holes can be divided into artificial fill (Qml), cultivated soil (QPb), Quaternary alluvial soil (Qai), slope soil (Qdl) and weathered residual soil (QDL) from top to bottom. ：
The formation conditions related to this project are summarized as follows:
land
ground
order
figure
Soil layer name
Top surface elevation
(m)
Top buried depth
(m)
Feature description average layer thickness
(m)
QPb, 37.82 ~ 39.820 ~ 3.60 layers of cultivated land are loose, under-compacted, and the soil uniformity is poor.
1. 1 1
Qai, 3rd floor (3- 1)
Loose medium coarse sand
32.47~40.88
0.50 ~ 7.00 saturated, loose, poorly sorted, locally mixed with thin layers of fine powder sand and gravel sand, composed of timely, locally mixed with thin layers of cohesive soil.
3.06
Qai, 3rd floor (3-2)
Silty soil
32.76~40.66
0.50 ~ 7.00 grayish black or dark gray, saturated, flowing plastic ~ soft plastic, locally containing sand, locally containing medium coarse sand or thin clayey soil.
1.98
Qai, 3rd floor (3-3)
Medium coarse sand
3 1. 17~36.32
2.00 ~ 10.00 is grayish yellow, dark gray, gray, grayish white, etc. , saturated, slightly dense, poor sorting, locally mixed with thin layer of silty fine sand and gravel sand.
4. 15
Qai, 3rd floor (3-4)
silty clay
3 1.8 1~40.24
4. 10 ~ 13.80 is gray, grayish yellow, brownish yellow, brownish red, etc. Plastic, sandy locally, with average viscosity, and medium-coarse sand or thin clay locally.
2.56
Qai, 3rd floor (3-5)
Medium coarse sand
27.90~35.74
4. 10 ~ 13.80 is grayish yellow, dark gray, gray, grayish white, etc. Saturated, medium-dense, with poor sorting, locally mixed with thin layers of fine sand and gravel sand. The composition is timely, locally mixed with 1~8cm siliceous pebbles at the bottom, and locally mixed with cohesive soil or cohesive thin layers. 3.6 1
Qdl, 4th floor
silty clay
3 1.49~40.60
1.00 ~ 9.50 is red yellow, brownish red, grayish yellow, etc. Plastic, containing quartz sand particles, generally sticky.
6.25
Qel, layer 5
Granite weathering
27. 17~37.64
3.80 ~ 14. 10 brownish yellow, grayish green, brownish gray, grayish white and other colors, hard, plastic, easy to soften and disintegrate in water.
4.70
2.4, hydrological conditions
Quaternary pore water-bearing sand layer is developed in most hole sections of the site, which is rich in water content. Cohesive soil layer has poor water permeability and belongs to weak water permeability layer with low water content; No water leakage was found in the bedrock during drilling, indicating that the connectivity of bedrock fractures is poor and the water content of vein fractures is poor. Therefore, the groundwater in the site is mainly sand pore water with rich water content. Groundwater recharge mainly comes from atmospheric precipitation and lateral runoff recharge of sand layer. The amplitude of groundwater level changes with the seasons, with the water level rising in rainy season and falling in dry season. During drilling, the measured water level in the hole is 0.2~5.8m, and the groundwater belongs to micro-confined water. Groundwater is noncorrosive to steel bars in concrete and reinforced concrete, but weakly corrosive to steel structures.
2.5, tower crane
The tower crane adopts QTZ60 15 tower crane (fixed attachment type), with the maximum amplitude of 60m and the maximum design free height of 44m, and the lifting height after attachment can reach 176m. The installation height of this project is about 72m.
Third, the tower crane foundation positioning
1, the center of the tower crane is located at 4-N with a wheelbase of 6.000m and a distance of 3,600m from 4-5 1 axis (see attached figure for details).
2. Positioning dimensions of embedded anchor bolts of tower crane (see attached figure for details)
Four, tower crane foundation design
Geotechnical mechanical data below the bottom surface of 3# tower crane foundation cap (see geological data ZK26 hole histogram)
No. Name of soil thickness (m) Characteristic value of foundation bearing 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
The bearing capacity of 3# tower crane foundation is in sandy clay layer; 0.000 is equivalent to the absolute elevation of 4 1.40.
The excavation depth is -7.400m (34.00 m) (if it is inconsistent with the geological data, it will be excavated until it meets the soil quality requirements, and then it will be tamped to -7.400m by replacement).
Description: The bearing layer of tower crane bearing platform is sandy clay (5th layer); During excavation, the soil layer is inconsistent with the geological report, and (if there is soft soil and silt) must be dug to meet the requirements.
Construction related instructions:
1, the concrete grade of pile caps is C35 (impermeability grade ≥0.8MPa), and its construction shall be carried out in strict accordance with the requirements of the specification; Tower crane foundation size is 6000*6000 wide and 1500 high; The reinforcement is grade 2 steel 16.
2. The installation of tower crane foundation and tower crane shall be carried out according to the requirements of the factory manual of tower crane, and the position and anchoring depth of embedded bolts shall be well controlled;
3. All steel members are fully welded within the contact edge length, and the weld thickness is ≥6mm.
4. The section size, embedded position and elevation of tower crane embedded parts shall be constructed in accordance with the requirements of tower crane operating instructions, and the installation unit shall send technicians to the scene for technical guidance.
5, foundation concrete should be layered, each layer is not more than 500㎜, using internal vibrator vibrating compaction, casting should be continuous. Tower crane foundation construction is completed. After the tower crane is installed, 180 thick brick wall is used for enclosure.
6. After concrete pouring, it shall be watered and maintained for a period of not less than 14 days. Carry out acceptance in strict accordance with the acceptance procedures of engineering piles, and do a good job in the 28-day compressive test of concrete blocks.
7. The tower crane can only be installed after the concrete strength reaches 85%.
8, strengthen safety management, completes the site safety signs. When working, delimit the safety warning zone according to the regulations.
9. The allowable deviation of foundation plane flatness is11000.
10. Under no-load condition, the allowable deviation of verticality between tower crane and foundation plane is 4/ 1000, and the allowable deviation of verticality below Gao Ming anchor point is 2/ 1000.
1 1. After the anchor bolt enters the site, it shall be inspected according to the instructions to ensure that it meets the requirements, and the embedding depth shall be ≥1000 mm.
12, the foundation lightning protection grounding shall be constructed according to the lightning protection design requirements of buildings.
13, the anchor bolt is connected to the lightning protection grounding electrode, and the grounding resistance is ≤4ω.
14, tower crane installation and disassembly plan shall be prepared separately.
15, the waterproof layer is laid along the periphery of the pile cap. For details, see the basement waterproof detail.
Five, tower crane foundation construction practice
Excavation of foundation pit of tower crane foundation-pouring cushion and bricklaying tire mold-plastering the surface of brick tire mold with 1: 3 cement mortar-waterproofing-binding reinforcing cage-burying anchor bolts-pouring foundation concrete-concrete maintenance.
1, tower crane foundation pit and basement foundation pit are excavated at the same time, and the excavation slope is 1: 1. The elevation of foundation pit of 3# tower crane bearing platform is-7.40m, and the elevation of top surface is-5.850m. Before excavation, the site builder will release the grey line according to the tower crane positioning map, the excavator will excavate synchronously, and the mechanical excavation will be completed and leveled.
2. Cushion thickness 100mm, concrete grade C 15, collecting original pulp, laying 240-thick lime-sand brick M5 cement mortar on the foundation side formwork, and plastering 15mm cement mortar on the inner surface for calendering. The tower crane foundation is connected with the basement floor as a whole.
3. The tower crane foundation is waterproof with basement floor waterproof material, and the position of yin and yang angle is strengthened, which is connected with the basement floor waterproof system to ensure that the tower crane will no longer be waterproof after being dismantled. The bottom surface is made of 20mm thick 1: 3 cement mortar plaster as waterproof protective layer.
4. Binding of reinforcing cage for tower crane foundation: reinforcement of horizontal reinforcing bar at the upper part of tower crane foundation and basement floor: double-layer bidirectional Ф 20 @ 200 at the upper part, bidirectional Ф16 @160 at the lower part, and vertical lacing Ф14 @ 300. (In this scheme, the tower crane foundation concrete is poured first, and the tower crane is installed and put into use in advance), and it is bound with the basement around the tower crane bearing platform, and the water-stop steel plate is set at the joint of the basement floor. (See attached figure for details)
5. Concrete pouring: The foundation concrete of tower crane bearing platform is C35 waterproof concrete, and the impermeability grade is 0.8MPa. The protoplasm on the top surface of tower crane bearing platform is exposed to light, and the flatness deviation is10 mm. Before pouring, be careful not to touch the anchor bolts with plastic bags. When pouring concrete, take samples and keep test blocks for inspection. When the concrete strength reaches 80%, install the tower crane and keep the test report as safety data for future reference.
6, pay attention to the maintenance after concrete pouring, maintenance time is not less than 14 days.
7, tower crane foundation size allowable deviation table.
Allowable deviation and inspection method of tower crane foundation size
Inspection method of allowable deviation of the project (mm)
Elevation of plus or minus 20 level, stay, steel rule check.
Plane outline size plus or minus 20 steel rule
Surface flatness 10, L/ 1000.
Cave size is 20.
The elevation of embedded parts is 20 level.
Center distance of embedded parts plus or minus 2 steel rule
Six, tower crane through the basement roof treatment measures
1. The reserved hole in the basement roof is 2.750×2.750m, which is centered. Disconnect L3(8)300×800 frame beam. After the tower crane is dismantled, it is connected and blocked with C40 concrete.
2. Roof reinforcement: The original double-deck bidirectional 12@200 was changed to double-deck bidirectional 14@200 (which has been approved by the design).
3, in order to ensure the safety in the construction, before the tower crane is dismantled, the main reinforcement of the roof shall not be cut. When the tower crane is dismantled, it shall be cut with oxygen and then welded. Plate reinforcement must be staggered by 50% of the joints, and the joint spacing shall not be less than 40d.
4. During the use of tower crane, the roof formwork and support within 2.5m around the hole are not removed. During the formwork construction, the portal rigid frame support system is disconnected from it, which is convenient for reservation when dismantling.
5, the reserved hole concrete pouring, around the hole in strict accordance with the construction joints set water stop steel plate, waterproof roof, hole position to add waterproof layer. (The tower crane passes through the reserved hole in the basement roof. See the attached drawings for details. )
Seven, tower crane foundation calculation:
Calculation of natural foundation of tower crane
I. Parameter information
Tower crane model: QTZ60 deadweight (including ballast): F 1=573.00kN Maximum lifting capacity: F2=60.00kN
Overturning moment of tower crane: M= 1726.00kN.m lifting height of tower crane: H=72.00m width of tower body: b =1.80m.
Concrete strength grade: C35 reinforcement grade: characteristic value of secondary foundation bearing capacity: 250.00kPa
Minimum width of foundation: Bc=6.00m Minimum thickness of foundation: h= 1.50m Foundation buried depth: D = 0.00m
Embedded depth of embedded parts: h = 0.00 m.
Two. Calculation of minimum size of foundation
Minimum thickness of foundation: h =1.45m.
Minimum width of foundation: Bc = 6.00m
3. Calculation of bearing capacity of tower crane foundation
Calculation chart:
1, overall overturning stability calculation:
e =(MK+FVKh)/(FK+GK)=( 1726+7 1 * 1.45)/(573+6 * 6 * 1.45 * 25)
= 0.974 & ltB/4= 1.5, which meets the requirements!
Among them:
MK—— the bending moment value (kN * m) Fvk corresponding to the standard combination of load effect —— the horizontal load value (kn) corresponding to the standard combination of load effect.
H—— Foundation height (m)
FK—— the standard value of vertical load of tower crane acting on the top surface of foundation (kN)
GK—— standard value of self-weight of foundation and its soil (kN)
B —— Short side length of rectangular foundation bottom (m)
2. Calculation of foundation bearing capacity
PK =(FK+GK)/bl =(573+6 * 6 * 1.45 * 25)/(6 * 6)= 52. 17 kPa & lt； The fourth note of the major scale
Among them:
PK—— the average pressure at the bottom of foundation corresponding to the standard combination of load effects (kPa);
L—— the length of the long side of the bottom surface of rectangular foundation (m);
Fa—— Modified eigenvalue of foundation bearing capacity (kPa).
Eccentricity of this project e = 0.974 < b/6.
pkmax =(FK+GK)/bl+(MK+FVKh)/W = 52. 17+ 1828.95/36 = 102.97 & lt； 1.2fa，
Meet the requirements!
Among them:
Pkmax—— the maximum pressure at the bottom of foundation corresponding to the standard combination of load effects (kPa);
W—— resistance moment of foundation bottom (m3);
3. Checking calculation of foundation bearing capacity
Modified characteristic value of foundation bearing capacity fa=250.00kPa
Because fa≥Pk=64.6kPa, it meets the requirements!
Eccentric load: because1.2× fa ≥ pkmax =102.97kpa, it meets the requirements!
4. Checking calculation of punching bearing capacity
The check formula is as follows:
Among them, HP -- the coefficient affected by the section height of punching bearing capacity, hp = 0.95；;
FT- the design value of axial tensile strength of concrete, taking ft =1.57kpa;
Am—— calculated length of the most unfavorable edge of punching failure cone;
am =[ 1.80+( 1.80+2× 1.45)]/2 = 3.25m；
H0-the effective height of the pile cap, taking h0 =1.45m;
Pj—— the maximum pressure design value, taking pj = pj =147.39kpa; ;
FL- actual punching bearing capacity:
fl = 147.39×(6.00×0.70+7.42)= 17 12.70 kn .
Allowable punching force:
0.7×0.95× 1.57×3250× 1450 = 4750427.00n = 4750.43 kn
The actual impulse is not greater than the allowable impulse design value, which meets the requirements!
5. Calculation of reinforcement of pile caps
1. Bending calculation, the calculation formula is as follows:
Where a 1── the distance from section I-I to the edge of the basement is a1= 2.10m;
Alkali reaction at section I-I of P-:
p = 147.39×(3× 1.75-2. 10)/(3× 1.75)= 88.54 kpa；
A '- the projection length of section I-I on the base, taking a' =1.80m. ..
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
= 958.62 kNm.
2. The calculation formula of reinforcement area is as follows:
According to Code for Design of Concrete Structures (GB 500 10-2002)
Where 1── coefficient, 1 is taken as 1.0 when concrete strength does not exceed C50, and when concrete strength grade is C80,
1 is 0.94, and the period is determined by linear interpolation;
FC- design value of concrete compressive strength;
H0- calculated height of pile cap.
After calculation, 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 ratio is 0. 15%, the minimum reinforcement area is 13500mm2.
So take As= 13500mm2. Use HRB335, fy=300.00N/mm2, and take 6020.
as 1 = 60×3 14 = 18840 mm2 & gt； As= 13500mm2 (meets the requirements), that is, double-layer bidirectional 20@200 meets the requirements!
Eight. attached drawing
1 Schematic diagram of foundation pit supporting plane and tower crane positioning
2. Overview of tower crane foundation
3. Geological Reference Profile of Tower Crane Foundation
4, tower crane foundation positioning and wear plate reserved hole plan