CN116876580B - A vortex well construction anti-floating structure and construction method thereof - Google Patents
A vortex well construction anti-floating structure and construction method thereofInfo
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- CN116876580B CN116876580B CN202310915847.1A CN202310915847A CN116876580B CN 116876580 B CN116876580 B CN 116876580B CN 202310915847 A CN202310915847 A CN 202310915847A CN 116876580 B CN116876580 B CN 116876580B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D31/00—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
- E02D31/10—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against soil pressure or hydraulic pressure
- E02D31/12—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against soil pressure or hydraulic pressure against upward hydraulic pressure
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D29/00—Independent underground or underwater structures; Retaining walls
- E02D29/12—Manhole shafts; Other inspection or access chambers; Accessories therefor
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
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Abstract
The invention provides a construction anti-floating structure of a cyclone well and a construction method thereof. The anti-floating structure is formed by constructing a support pile during construction of a cyclone well and comprises a plurality of buffer grooves formed by digging one side, adjacent to the wall of the cyclone well, of the support pile and fixed dowel bars reserved during construction of reinforcing steel bars of the wall of the cyclone well, one part of each fixed dowel bar is used as a main reinforcement to be poured into the wall of the cyclone well, and the other part of each fixed dowel bar is inserted into the corresponding buffer groove.
Description
Technical Field
The invention belongs to the field of construction of cyclone wells in metallurgical industry, and particularly relates to an anti-floating structure for construction of a cyclone well and a construction method thereof.
Background
In the construction process of steel mill construction in metallurgical industry, the cyclone well is one of the main water resource circulation systems in the steel mill, and the wastewater is filtered, separated and purified through the cyclone well, so that the water resource is fully utilized.
The construction of the cyclone well mainly adopts a forward construction method, and comprises three parts, namely a deep foundation pit supporting part, a soil and stone part and a cyclone pool structure part. The method is mainly characterized in that the foundation pit is excavated deeply, the underground water is rich, the requirements of the stratum with high anti-floating water level on construction precipitation are high, foundation pit precipitation is started before earth excavation, and earth excavation and cyclone well structure construction can be carried out after the elevation of the underground water level meets the construction requirements.
In general, the dewatering water level in foundation pit construction is required to be reduced to-50 cm to-100 cm below the foundation pit, and the design of the main body structure of the cyclone well can be carried out by increasing the dead weight of the main body structure or directly increasing the gravity of the water stored in the built well in a certain range. Therefore, in the whole construction period, the pouring height of the main body structure of the well wall of the cyclone well is increased, the cyclone well gradually forms a whole, the foundation pit and the periphery of the foundation pit are required to be continuously subjected to water descending and draining work, the water level of the foundation pit is ensured to be always kept at-50 cm to-100 cm at the bottom of the foundation pit, meanwhile, the load and the counterweight are temporarily increased through the bottom of the well when necessary, the cyclone well is ensured not to generate larger buoyancy due to the rising of the underground water level in the construction process, and the main body structure of the cyclone well is caused to float upwards. However, in rainy season or rainstorm weather, the main structure of the cyclone well still floats due to the fact that the groundwater level is high or the water level in the well suddenly rises.
Disclosure of Invention
The invention provides a construction anti-floating structure of a cyclone well and a construction method thereof, aiming at the problems existing in the prior art, the method comprises the steps of inserting a reserved dowel bar into a pile body buffer groove of a support pile in the construction process of the wall of the cyclone well, the reserved dowel bars and the wall of the cyclone well are integrated, downward gravity is generated by utilizing the integrated structure formed by foundation pit support, and the cyclone well body floats upwards due to the increase of the rising buoyancy of the groundwater level in the construction process of the cyclone well.
The invention provides an anti-floating structure for construction of a cyclone well, which is characterized in that the anti-floating structure is constructed by a support pile during construction of the cyclone well and comprises a plurality of buffer grooves formed by digging one side of the support pile adjacent to the wall of the cyclone well and fixed dowel bars reserved during binding of reinforcing steel bars of the wall of the cyclone well, wherein one part of the fixed dowel bars is used as a main dowel bar to be poured into the wall of the cyclone well, the other part of the fixed dowel bars are inserted into the corresponding buffer grooves, and the part inserted into the buffer grooves is vertical to the part inserted into the wall of the cyclone well.
The technical scheme is that the buffer grooves horizontally extend into a pile body of the support pile from one surface of the support pile, which is adjacent to the wall of the cyclone well, the vertical section of each buffer groove is semicircular at the top, the lower part of each buffer groove is gradually-changed into a trapezoid, the diameter of the semicircle at the top of each buffer groove is equal to the diameter d of the fixed dowel bar, the width of the upper section of the gradually-changed trapezoid at the lower part of each buffer groove is d, the width of the lower section of each buffer groove is d+10mm, the heights of the semicircular area of each buffer groove and the whole gradually-changed trapezoid are 2 d-3 d, and the depths of the buffer grooves horizontally extend into the pile body of the support pile are 10 d-15 d.
The technical scheme is that the fixed dowel bar is an inverted L-shaped dowel bar, the vertical part of the fixed dowel bar is fixed in the wall of the cyclone well and is used as a main dowel bar of the wall of the cyclone well, the horizontal part of the fixed dowel bar is horizontally inserted into the buffer groove, and the diameter d of the fixed dowel bar is larger than or equal to the design diameter of the main dowel bar of the wall of the cyclone well.
According to the preferred technical scheme, the buffer grooves are distributed at equal intervals along the vertical direction and the horizontal direction of the support pile, the vertical distance between every two adjacent buffer grooves is 2.5-5.0 m, and the horizontal distance is 1.2-4.8 m.
The invention further adopts the technical scheme that the total number N of the reserved fixed dowel bars is N, the reserved number of the horizontal fixed dowel bars to a single circle is N, the horizontal spacing of the fixed dowel bars to the single circle is l, which is determined according to the checking calculation of the anti-floating design of the underground water, so that the sum of the dead weight of the constructed cyclone well and the total anti-floating force provided by the constructed dowel bars at any time in construction is ensured to be greater than or equal to the floating force generated by the constructed cyclone well structure, and the concrete checking calculation process is as follows:
ni＝πDi/li
N=n1+n2+....+ni
fs×F Floating device i≤(n1×F Anti-floating 1+...+ni×F Anti-floating i)+Gi
fs×F Floating device ≤N×F Anti-floating +G
F Floating device ＝γw×V
wherein n i is the number of the fixed dowel bars horizontally to a certain layer at a certain time of construction;
d i is the outer diameter of the cyclone well at a certain time of construction, and the unit is m;
l i is the horizontal spacing of fixed dowel bars at a certain time of construction;
n is the total number of fixed dowel bars of the cyclone well;
f s is an anti-floating safety calculation coefficient, and 1.2 is preferable;
F Floating device is buoyancy generated by the cyclone well structure, and the unit is kN;
F Floating device i is buoyancy (kN) generated by constructing a cyclone well structure at a certain moment;
F Anti-floating provides anti-buoyancy for the single fixed dowel bar, wherein the unit is kN;
f Anti-floating i is the total anti-buoyancy (kN) provided by the construction of a certain moment and horizontally to a certain layer of fixed dowel bars;
G is the dead weight of the cyclone well, and the unit is kN;
G i is the dead weight (kN) of the cyclone well at a certain moment in construction;
Gamma w is the water gravity, 10KN/m 3;
V is the inner volume of the outer edge contour of the cyclone well which is constructed and positioned below the underground water surface, and the unit is m 3.
The diameter d of the fixed dowel bar and the horizontal depth of the buffer groove, namely the horizontal depth h Groove(s) of the fixed dowel bar inserted into the buffer groove, are determined through groundwater anti-floating design calculation and dowel bar stress checking calculation, so that the dowel bar is ensured not to be sheared or sheared and bent to fail and be damaged due to insufficient shear strength, and relative displacement is not generated due to too small relative friction force caused by insufficient insertion depth of the dowel bar into the buffer groove, and the checking calculation process is as follows:
F Anti-floating ＝F Shearing resistance +F Friction of
F Shearing resistance ＝0.25πd2×fv
F Friction of ＝frb×s
s=π×d×h Groove(s) ×50%
h Groove(s) =10d~15d
Wherein F Shearing resistance is the shear strength (kN) which can be provided by a single fixed dowel bar, F Friction of is the limit friction force (kN) which can be provided by a part of the single fixed dowel bar which is inserted into the buffer groove, d is the diameter (m) of the fixed dowel bar, F v is the design value (kN/m 2) of the shear strength of the single fixed dowel bar, s is the surface area (m 2) of the contact part of the fixed dowel bar positioned in the buffer groove and the buffer groove, 50% of the whole surface area can be obtained, F rb is the friction coefficient between the fixed dowel bar and the inner wall of the buffer groove (kN/m 2);h Groove(s) is the horizontal depth (m) of the fixed dowel bar which is inserted into the buffer groove), and the rest is the same.
The invention has the preferable technical scheme that the support pile adopts the reinforced concrete filling pile, the length of the support pile meets the normal stable embedding requirement, the pulling-resistant requirement transmitted to the pile body due to the buoyancy of groundwater in the construction process of a cyclone well is met, and the invention is specifically calculated by the following formula:
fs×F Floating device -G≤(0.5×∑α1j×q1jsi×L1j×πZ1j+G Pile 1)+...+(0.5×∑αij×qijsi×Lij×πZij+G Pile i)
wherein alpha ij is the coefficient of resistance to plucking of the side rock and soil of the j th layer of the ith support pile, q ijsi is the standard value of limiting frictional resistance of the side rock and soil layer of the j th layer of the ith support pile (kPa), L ij is the length (m) of the side rock and soil of the j th layer of the ith support pile, Z ij is the diameter of the side rock and soil pile of the j th layer of the ith support pile, and G Pile i is the dead weight (kN) of the ith support pile.
In order to achieve the technical aim, the invention also provides a construction method of the anti-floating structure for the construction of the cyclone well, which is characterized by comprising the following specific steps:
S1, obtaining various construction parameters of the support pile and the cyclone well through corresponding project geotechnical engineering investigation reports, construction design drawings and engineering specifications of the support pile and the cyclone well, calculating buoyancy force F Floating device generated in the construction process of the cyclone well, selecting steel bars with the diameter d being greater than or equal to the diameter of a main bar of a wall of the cyclone well as fixed dowel bars, and determining the total number N of the fixed dowel bars according to the following formula:
fs×F Floating device ≤N×F Anti-floating +G
wherein f s is an anti-floating safety calculation coefficient, and 1.2 is taken as an ideal value;
F Floating device is buoyancy generated by the cyclone well structure, and the unit is kN;
F Anti-floating provides anti-buoyancy for the single fixed dowel bar, wherein the unit is kN;
G is the dead weight of the cyclone well, and the unit is kN;
S2, determining the horizontal depth of the buffer groove, namely the depth h Groove(s) of the fixed dowel inserted into the buffer groove according to the groundwater anti-floating design calculation and dowel stress checking calculation selected in the S1, wherein the fixed dowel is ensured not to be sheared or sheared bending failure and damage due to insufficient shearing strength, and is not caused by too small relative friction force due to insufficient dowel insertion depth into the buffer groove to generate relative displacement, so that dowel failure and damage or a cyclone well generates floating, and the construction of the cyclone well is influenced, and the checking calculation process is as follows:
F Anti-floating ＝F Shearing resistance +F Friction of
F Shearing resistance ＝0.25πd2×fv
F Friction of ＝frb×s
s=π×d×h Groove(s) ×50%
h Groove(s) =10d~15d
Wherein F Shearing resistance is the shear strength (kN) which can be provided by a single fixed dowel bar, F Friction of is the limit friction force (kN) which can be provided by a part of the single fixed dowel bar which enters the buffer groove, d is the diameter (m) of the fixed dowel bar, F v is the design value (kN/m 2) of the shear strength of the single fixed dowel bar, s is the surface area (m 2) of the contact part of the fixed dowel bar positioned in the buffer groove and the buffer groove, 50% of the whole surface area can be obtained, F rb is the friction coefficient between the fixed dowel bar and the inner wall of the buffer groove (kN/m 2);h Groove(s) is the horizontal depth (m) of the fixed dowel bar which is inserted into the buffer groove, N is the total number of the fixed dowel bars of the cyclone well, and the rest are the same;
S3, determining the number N of reserved fixed dowel bars and the depth h Groove(s) of the fixed dowel bars inserted into the buffer grooves, determining the number and horizontal depth of the reserved buffer grooves on the support pile, determining the size of a single reserved buffer groove according to the selected diameter d of the fixed dowel bars, wherein the buffer groove is of a structure with a semicircular upper part and a gradual trapezoid lower part, the diameter of the semicircular upper part is equal to the diameter d of the fixed dowel bars, the width of the upper section of the gradual trapezoid lower part is d, the width of the lower section of the gradual trapezoid is d+10mm, the height of the semicircular area of the buffer groove and the whole gradual trapezoid is 2 d-3 d, the buffer grooves horizontally extend to the depth h Groove(s) in the support pile, and then designing a layout scheme of the buffer grooves according to the vertical interval between two adjacent buffer grooves is 2.5-5.0 m, and the horizontal interval is 1.2-4.8 m;
S4, after the layout parameters of the fixed dowel bars and the buffer grooves are well determined, starting to construct a cyclone well, firstly constructing a foundation pit supporting structure, after the construction of the foundation pit supporting structure is completed, performing foundation pit drainage and earth excavation, excavating to the designed shaft bottom elevation of the cyclone well, starting to construct a main structure of the cyclone well, positioning and paying off the buffer grooves on the supporting pile according to the parameters determined in the steps S1 to S3 before binding the well wall reinforcing steel bars, and performing buffer gouging chisel excavation by using a pneumatic pick or an electric hammer;
S5, after the buffering gouging chisel is dug, binding the corresponding area spiral-flow well wall steel bars, binding the fixed dowel bars, binding the well wall part and the well wall main structure steel bars together, vertically inserting the inserted part into the buffering groove to ensure that the fixed dowel bars are positioned at the semicircular position of the top of the buffering groove, and completing the concrete pouring of the layer of spiral-flow well after the steel bar binding is completed.
According to the technical scheme, steel bars of the support piles are avoided when buffering gouging chisel is carried out in the S4 step, residues and the like in a groove are cleaned up by blowing air compressors or flushing water pipes after the buffering gouging chisel is carried out, smooth insertion of fixed inserted bars is guaranteed, the well wall is firmly bound in the S5 step, the fixed inserted bars are guaranteed not to loosen or move downwards in the concrete pouring process, in the S5 step, in the construction process of the cyclone well, checking calculation is carried out on the dead weight of the constructed cyclone well and the total anti-buoyancy provided by the installed fixed inserted bars at each moment, when the sum of the dead weight of the constructed cyclone well and the total anti-buoyancy provided by the constructed fixed inserted bars is smaller than the buoyancy generated by the constructed cyclone well structure, the sum of the dead weight of the constructed cyclone well and the total anti-buoyancy provided by the constructed fixed inserted bars is guaranteed to be larger than or equal to the buoyancy generated by the constructed cyclone well structure at any moment by adding the fixed bars or replacing large-diameter fixed bars, and the checking calculation process is as follows:
ni＝πDi/li
fs×F Floating device i≤(n1×F Anti-floating 1+...+ni×F Anti-floating i)+Gi
F Floating device i＝γw×Vi
wherein n i is the number of the fixed dowel bars horizontally to a certain layer at a certain time of construction;
d i is the outer diameter of the cyclone well at a certain time of construction, and the unit is m;
l i is the horizontal spacing of fixed dowel bars at a certain time of construction;
f s is an anti-floating safety calculation coefficient, and 1.2 is preferable;
F Floating device i is buoyancy (kN) generated by constructing a cyclone well structure at a certain moment;
f Anti-floating i is the total anti-buoyancy (kN) provided by the construction of a certain moment and horizontally to a certain layer of fixed dowel bars;
G i is the dead weight (kN) of the cyclone well at a certain moment in construction;
Gamma w is the water gravity, 10KN/m 3;
V i is the inner volume of the outer edge contour of the cyclone well, which is constructed at a certain moment and is positioned below the underground water surface, and the unit is m 3.
The preferable technical scheme of the invention is that the length of the pile body of the support pile is checked before construction of the foundation pit support structure in the step S4 to meet the pulling-resistant requirement transmitted to the pile body due to the buoyancy of groundwater, so that the sum of the dead weight of the utilized support pile and the limit pulling-resistant force which can be provided by the utilized support pile at any moment is ensured to be larger than or equal to the difference between the buoyancy generated by the constructed cyclone well structure and the dead weight of the constructed cyclone well, and the method comprises the following steps:
fs×F Floating device -G≤(0.5×∑α1j×q1jsi×L1j×πZ1j+G Pile 1)+...+(0.5×∑αij×qijsi×Lij×πZij+G Pile i)
wherein alpha ij is the coefficient of resistance to plucking of the side rock and soil of the j th layer of the ith support pile, q ijsi is the standard value of limiting frictional resistance of the side rock and soil layer of the j th layer of the ith support pile (kPa), L ij is the length (m) of the side rock and soil of the j th layer of the ith support pile, Z ij is the diameter of the side rock and soil pile of the j th layer of the ith support pile, and G Pile i is the dead weight (kN) of the ith support pile.
The buffer gouging chisel is simple in digging operation, low in technological requirement and construction cost, simple in reserved dowel binding operation, low in technological requirement and construction cost, simple in reserved dowel inserting operation into the buffer groove, low in technological requirement and construction cost.
According to the anti-floating structure, through anti-floating design calculation and corresponding elevation and water level observation data of each constructed pair of cyclone wells in the construction process, in the construction process of pouring the walls of the cyclone wells, the height of the underground water level can rise along with the rising of pouring height, the problems of long precipitation period, large depth and large workload in the construction process of the cyclone wells are overcome, the construction precipitation water level requirement and the construction cost of a waterproof curtain in the whole construction process are reduced, the waste of underground water resources are reduced, the corresponding anti-floating measures are carried out by increasing the pit bottom load, the raft thickness, the wall thickness and the like in the construction process, the precipitation construction period and the precipitation strength are shortened, the precipitation and anti-floating extra workload are reduced, the construction cost is reduced, and the support piles are effectively utilized.
According to the invention, when a foundation pit is excavated to the designed bottom elevation and each pair of cyclone well wall reinforcing steel bars are bound, the pile body of the support pile is excavated and a buffer groove is reserved at the top of the buffer groove when each pair of cyclone well wall reinforcing steel bars are bound. The buffer tank lower part is reserved a certain distance to prevent the construction of the cyclone pool from being completed, the post-construction settlement possibly generates pulling crack damage to the well wall, and the support pile is utilized as an anti-floating structure during construction to generate an anti-floating effect.
The invention has simple integral structure, low cost and simple and convenient construction process operation, reduces the precipitation depth and workload in the construction process of the cyclone well, reduces the corresponding anti-floating measures of increasing the pit bottom load, the raft thickness, the well wall thickness and the like in the construction process, shortens the construction period, reduces the construction cost and effectively utilizes the post stage of the support pile.
Drawings
FIG. 1 is a schematic cross-sectional view of the present invention;
FIG. 2 is a schematic top view of the present invention;
FIG. 3 is a schematic view of the anti-floating structure of the present invention;
FIG. 4 is a schematic vertical cross-section of a buffer tank according to the present invention;
FIG. 5 is a schematic transverse cross-sectional view of a buffer tank in accordance with the present invention.
In the figure, 1-a swirl well wall, 2-supporting piles, 3-buffer grooves, 4-fixed dowel bars and 5-swirl wells.
Detailed Description
The invention is further described below with reference to the drawings and examples. Fig. 1 to 5 are drawings of embodiments, which are drawn in a simplified manner, for the purpose of clearly and concisely illustrating embodiments of the present invention. The following technical solutions presented in the drawings are specific to embodiments of the present invention and are not intended to limit the scope of the claimed invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "vertical", "top", "bar diameter d", "2 d-3 d", "10 d-15 d", etc. are based on the directions or positional relationships shown in the drawings, or the directions or positional relationships in which the inventive product is conventionally put in use, or the directions or positional relationships as conventionally understood by those skilled in the art are merely for convenience of describing the present invention and for simplifying the description, and are not intended to indicate or imply that the apparatus or element to be referred to must have a specific direction, be configured and operated in a specific direction, and thus should not be construed as limiting the present invention.
In the description of the present invention, it should also be noted that, unless explicitly stated and limited otherwise, the positions and numbers of the fixing dowels and the corresponding buffer grooves are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements to be referred to must have a specific position and number, and thus should not be construed as limiting the invention. The specific meaning of the above terms in the present invention can be understood by those skilled in the art according to specific circumstances.
The embodiment provides a whirl well construction anti-floating structure, as shown in fig. 1 to 5, anti-floating structure utilizes support stake 2 construction to form in whirl well 5 construction period, includes a plurality of dashpots 3 that dig to form in the side that support stake 2 is adjacent whirl well wall 1 and the fixed dowel 4 of reservation when the ligature of whirl well wall 1 reinforcing bar, dashpot 3 is all equidistantly laid along support stake 2 vertical direction and horizontal direction, and the vertical interval between two adjacent dashpots 3 is mostly 2.5~5.0m, and the horizontal interval is 1.2~4.8m. The buffer grooves 3 horizontally extend into the pile body of the support pile 2 from one surface of the support pile 2 adjacent to the cyclone well wall 1, the vertical section of each buffer groove 3 is semicircular at the top and gradually-changed trapezoidal at the lower part, the semicircular diameter of the top is equal to the diameter d of the fixed dowel bar 4, the width of the upper section of the gradually-changed trapezoidal at the lower part of the buffer groove 3 is d, the width of the lower section of the gradually-changed trapezoidal is d+10mm, the semicircular area of the buffer groove 3 and the overall height of the gradually-changed trapezoidal are 2 d-3 d, and the depth of the buffer groove 3 horizontally extends into the pile body of the support pile 2 is 10 d-15 d. One part of the fixed dowel bar 4 is used as a main bar to be poured into the wall of the cyclone well 5, the other part of the fixed dowel bar is inserted into the corresponding buffer groove 3, and the part inserted into the buffer groove 3 is in a vertical state with the part inserted into the wall 1 of the cyclone well. The fixed dowel bars 4 are inverted L-shaped dowel bars, the vertical parts of the fixed dowel bars are fixed in the cyclone well wall 1 to serve as main bars of the cyclone well wall 1, and the horizontal parts of the fixed dowel bars are horizontally inserted into the buffer grooves 3.
The embodiment provides a construction method for constructing an anti-floating structure of a cyclone well, which comprises the following specific steps:
S1, obtaining various construction parameters of support piles and a cyclone well through corresponding project geotechnical engineering investigation reports, construction design drawings of the support piles and the cyclone well and engineering specifications, calculating buoyancy F Floating device generated in the construction process of the cyclone well, calculating the volume of underground water occupied by the cyclone well only by the aid of the outline schematic drawing of the cyclone well and the buried depth condition of underground water, calculating buoyancy of the cyclone well according to Archimedes principle, determining an anti-pulling coefficient alpha of each support pile in each side geotechnical layer, a standard value q si of limit friction resistance of each support pile in each side geotechnical layer and a field anti-floating water level through corresponding project geotechnical engineering investigation reports, obtaining self weight G Pile of each support pile through the support piles and the construction drawings, self weight G of the cyclone well and the design height H of the cyclone well through specification inquiry, obtaining a reserved joint bar and a friction coefficient F rb of the inner wall of a buffer tank, and performing field test to verify parameter rationality, specifically determining a permissible sedimentation value of the cyclone well, obtaining the construction design drawings of the cyclone well structure, and obtaining the inherent water level through the construction drawings, and directly obtaining the design parameters of the cyclone well by the aid of the special design drawings or the construction drawings in the construction process. The diameter d of the fixed dowel bar and the designed shear strength f v of the dowel bar can be obtained according to a factory nameplate of the dowel bar. Firstly, determining the diameter d of a fixed dowel bar, wherein the diameter d of the fixed dowel bar is larger than or equal to the diameter of a main dowel bar of a wall of a cyclone well, and determining the total number N of the fixed dowel bars according to the selected fixed dowel bar by the following formula:
fs×F Floating device ≤N×F Anti-floating +G
wherein f s is an anti-floating safety calculation coefficient, and 1.2 is taken as an ideal value;
F Floating device is buoyancy generated by the cyclone well structure, and the unit is kN;
F Anti-floating provides anti-buoyancy for the single fixed dowel bar, wherein the unit is kN;
g is the dead weight of the cyclone well, and the unit is kN.
S2, determining the horizontal depth of the buffer groove, namely the depth h Groove(s) of the fixed dowel inserted into the buffer groove according to the groundwater anti-floating design calculation and dowel stress checking calculation selected in the S1, wherein the fixed dowel is ensured not to be sheared or sheared bending failure and damage due to insufficient shearing strength, and is not caused by too small relative friction force due to insufficient dowel insertion depth into the buffer groove to generate relative displacement, so that dowel failure and damage or a cyclone well generates floating, and the construction of the cyclone well is influenced, and the checking calculation process is as follows:
F Anti-floating ＝F Shearing resistance +F Friction of
F Shearing resistance ＝0.25πd2×fv
F Friction of ＝frb×s
s=π×d×h Groove(s) ×50%
h Groove(s) =10d~15d
Wherein F Shearing resistance is the shear strength (kN) which can be provided by a single fixed dowel bar, F Friction of is the limit friction force (kN) which can be provided by a part of the single fixed dowel bar which enters the buffer groove, d is the diameter (m) of the fixed dowel bar, F v is the design value (kN/m 2) of the shear strength of the single fixed dowel bar, s is the surface area (m 2) of the contact part of the fixed dowel bar positioned in the buffer groove and the buffer groove, 50% of the whole surface area can be obtained, F rb is the friction coefficient between the fixed dowel bar and the inner wall of the buffer groove (kN/m 2);h Groove(s) is the horizontal depth (m) of the fixed dowel bar which is inserted into the buffer groove), N is the total number of the fixed dowel bars of the cyclone well, and the rest is the same.
S3, determining the number N of reserved fixed dowel bars and the depth h Groove(s) of the fixed dowel bars inserted into the buffer grooves, determining the number and horizontal depth of the reserved buffer grooves on the support pile, determining the size of a single reserved buffer groove according to the selected diameter d of the fixed dowel bars, wherein the buffer groove is of a structure with a semicircular upper part and a gradual-change trapezoid lower part, the diameter of the semicircular upper part is equal to the diameter d of the fixed dowel bars, the width of the upper cross section of the gradual-change trapezoid lower part is d, the width of the lower cross section of the gradual-change trapezoid lower part is d+10mm, the height of the semicircular area of the buffer groove and the total height of the gradual-change trapezoid is 2 d-3 d, the buffer grooves horizontally extend to the depth h Groove(s) in the support pile body, and then designing a layout scheme of the buffer grooves according to the vertical spacing between two adjacent buffer grooves is 2.5-5.0 m, and the horizontal spacing is 1.2-4.8 m.
S4, after the layout parameters of the fixed dowel bars and the buffer grooves are well determined, constructing a foundation pit supporting structure, after the construction of the foundation pit supporting structure is completed, performing foundation pit drainage and earth excavation, excavating to the designed bottom elevation of the cyclone well, starting construction of a main structure of the cyclone well, positioning and paying off the buffer grooves on the supporting pile before binding the well wall reinforcing steel bars according to the parameters determined in the steps S1 to S3, and performing buffer gouging chisel excavation by using a pneumatic pick or an electric hammer, wherein the reinforcing steel bars of the supporting pile are avoided when the buffer gouging chisel is excavated, cleaning residues and the like in the grooves by using an air compressor after the buffer gouging chisel excavation is completed, ensuring smooth insertion of the fixed dowel bars, and checking the pile length of the supporting pile before the construction of the foundation pit supporting structure meets the anti-pulling requirement of the pile body due to the buoyancy of groundwater, so that the sum of the self weight of the supporting pile to be utilized at any moment and the limit anti-pulling force provided by the supporting pile is greater than or equal to the self weight difference of the constructed cyclone well structure, and the self weight of the constructed cyclone well is specifically as follows:
fs×F Floating device -G≤(0.5×∑α1j×q1jsi×L1j×πZ1j+G Pile 1)+...+(0.5×∑αij×qijsi×Lij×πZij+G Pile i)
wherein alpha ij is the coefficient of resistance to plucking of the side rock and soil of the j th layer of the ith support pile, q ijsi is the standard value of limiting frictional resistance of the side rock and soil layer of the j th layer of the ith support pile (kPa), L ij is the length (m) of the side rock and soil of the j th layer of the ith support pile, Z ij is the diameter of the side rock and soil pile of the j th layer of the ith support pile, and G Pile i is the dead weight (kN) of the ith support pile.
S5, after buffering gouging chisel is excavated, binding the reinforcing steel bars of the wall of the cyclone well in the corresponding area, binding the fixed dowel bars, binding the reinforcing steel bars of the wall of the cyclone well and the main structure of the wall of the well, vertically inserting the inserted part into the buffer groove to ensure that the fixed dowel bars are positioned at the semicircular position at the top of the buffer groove, and completing concrete pouring of the cyclone well after the reinforcing steel bars are bound, wherein the wall of the well is firmly bound to ensure that the fixed dowel bars cannot loosen or move downwards in the concrete pouring process, and the construction layering of the cyclone well carries out concrete pouring, wherein the height of each layer of pouring is about 5m, and in the construction process of the cyclone well, the total anti-buoyancy provided by the dead weight of the cyclone well and the fixed dowel bars installed in each layer is checked, and when the sum of the dead weight of the cyclone well under construction and the total anti-buoyancy provided by the fixed dowel bars under construction is smaller than the buoyancy generated by the cyclone well structure under construction, the sum of the dead weight of the cyclone well under construction and the total anti-buoyancy provided by the fixed dowel bars under construction is ensured to be greater than or equal to the buoyancy generated by the cyclone well structure under construction at any moment under construction is adjusted by adding the fixed dowel bars, and the total anti-buoyancy generated under construction:
ni＝πDi/li
fs×F Floating device i≤(n1×F Anti-floating 1+...+ni×F Anti-floating i)+Gi
F Floating device i＝γw×Vi
wherein n i is the number of the fixed dowel bars horizontally to a certain layer at a certain time of construction;
d i is the outer diameter of the cyclone well at a certain time of construction, and the unit is m;
l i is the horizontal spacing of fixed dowel bars at a certain time of construction;
f s is an anti-floating safety calculation coefficient, and 1.2 is preferable;
F Floating device i is buoyancy (kN) generated by constructing a cyclone well structure at a certain moment;
f Anti-floating i is the total anti-buoyancy (kN) provided by the construction of a certain moment and horizontally to a certain layer of fixed dowel bars;
G i is the dead weight (kN) of the cyclone well at a certain moment in construction;
Gamma w is the water gravity, 10KN/m 3;
V i is the inner volume of the outer edge contour of the cyclone well, which is constructed at a certain moment and is positioned below the underground water surface, and the unit is m 3.
The invention is further described by combining a concrete embodiment, wherein the embodiment is a steel-making unit cyclone well of a certain steel factory, the outer diameter of the outer cylinder wall of the cyclone well is 35.2m, the inner diameter of the outer cylinder wall is 32m, the wall thickness of the outer cylinder wall is 1.6m, the depth of the outer cylinder wall is 35.2m, the stable burial depth of the underground water level actually measured in the construction period is 9.50m, the cyclone well is constructed by adopting a forward construction method, the construction height of each cyclone well is 5.0m, the foundation pit support of the cyclone well adopts concrete row piles, the pile diameter is 1.0m, the pile length is 28.0m, 90 support piles are totally arranged, the top of the cyclone well is provided with reinforced concrete crown beams, the cyclone well is uniformly arranged along the outer side of the cylinder wall, and the center distance between two adjacent piles is 1.2m.
The project dowel bar is made of threaded reinforcing steel bars with the brand number of HRB400 and the diameter of 40mm, one bar planting point is arranged at every 1 support pile on the horizontal interval, 45 steel bar planting points are counted in a single circle, the vertical interval is 5m consistent with the construction height of each steel bar, 7 steel bar planting points are counted in total, and the total number of the steel bar planting points is 315. The depth of the embedded bars extending into the buffer groove is 15 times of the embedded bar diameter of 600mm, the friction coefficient of the embedded bars and reinforced concrete is 0.7, and the design of groundwater anti-floating and the stress of the reinforced bars are proved as follows:
N=45×7=315 roots
F Floating device ＝γw×V＝10*3.14*17.62*(35.2-9.5)=249970.1kN
F Shearing resistance ＝0.25πd2×fv＝0.25*3.14*0.042*400*1000=502.4kN
F Friction of ＝frb×s=0.7*400*3.14*0.04*0.3*50%=5.2kN
G=3.14*(17.62-162)*35.2*25=148549.6kN
F Anti-floating =315*(502.4+5.2)=159894.0kN
F Anti-floating +G=159894+148549.6=308443.6kN
F Floating device *1.2=249970.1*1.2=299964.1kN
308443.6KN >299964.1kN, and the groundwater anti-floating design and the steel bar stress checking calculation meet the requirements.
According to the geological survey data and the construction record of the supporting piles, the pulling-resistant requirement of the supporting piles of the project is checked and calculated, and the concrete steps are as follows.
Maximum anti-buoyancy force required to be provided by the support piles is 1.2 x 249970.1-148549.6 = 151414.5kN
Single support piles can provide a pullout resistance of 3.14 x 0.5 x 28 x 24+0.3 x 5000= 2027.5kN;
The top of the supporting pile is provided with a reinforced concrete crown beam, and the total pulling resistance provided by the corresponding supporting pile group is 90 x 2027.5= 182475kN according to the whole consideration
182475Kn >151414.5kn, the anti-pulling checking calculation of the support pile meets the requirements.
According to the embodiment, the anti-floating is performed by utilizing the support piles during construction of the cyclone well, theoretical calculation is feasible, and on-site application tests prove that on-site underground water is dynamically adjusted, the height of the underground water drop head of the site is synchronously increased while the construction of the cyclone well is carried out upwards along with the construction of the cyclone well, the underground water is ensured to be 0.5m below the current construction working face, the workload of pumping and draining the underground water can be greatly reduced, the underground water pumping and draining can be expected to be avoided from being nearly 100 trilateral in the construction period of the project, meanwhile, the anti-floating piles/the anti-floating anchors are not arranged in the project, or the self weight is increased by deliberately increasing the wall thickness of the cyclone well, and the like, the anti-floating cost is saved by only utilizing the support piles of the cyclone well and adopting the structure and the corresponding construction method, the on-site monitoring data is not abnormal, and the project is finished in the main construction and the project is to be put into production.
The foregoing description is of one embodiment of the invention and is thus not to be taken as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of the invention should be assessed as that of the appended claims.
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