CN114016495A - Construction method for underground continuous wall system under weak geological conditions in sea reclamation area - Google Patents
Construction method for underground continuous wall system under weak geological conditions in sea reclamation area Download PDFInfo
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- CN114016495A CN114016495A CN202111350453.3A CN202111350453A CN114016495A CN 114016495 A CN114016495 A CN 114016495A CN 202111350453 A CN202111350453 A CN 202111350453A CN 114016495 A CN114016495 A CN 114016495A
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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
- E02D5/18—Bulkheads or similar walls made solely of concrete in situ
- E02D5/187—Bulkheads or similar walls made solely of concrete in situ the bulkheads or walls being made continuously, e.g. excavating and constructing bulkheads or walls in the same process, without joints
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F5/00—Dredgers or soil-shifting machines for special purposes
- E02F5/02—Dredgers or soil-shifting machines for special purposes for digging trenches or ditches
Abstract
The invention discloses a construction method of an underground continuous wall system under the soft geological condition of a sea-filling area, which comprises the following construction steps: measuring and paying off; performing soft foundation treatment, namely performing soft foundation treatment according to the measured and paid-off underground continuous wall linear position; grooving and reinforcing, namely grooving and reinforcing two sides of the linear position of the underground continuous wall; grooving the underground diaphragm wall; manufacturing an underground continuous wall reinforcement cage; hoisting an underground continuous wall reinforcement cage; pouring concrete for the underground continuous wall; backfilling the hollow wall section; in step S2, the soft geological formation within 12m of the underground continuous wall side is subjected to grid type cement mixing pile soft foundation treatment, and the geological formation of the stone-filled layer containing construction waste and disordered miscellaneous filling within 12m of the underground continuous wall side is subjected to grid type single-pipe jet grouting pile soft foundation treatment. The construction method for the underground diaphragm wall system under the weak geological condition of the sea-filling area has the characteristic of high supporting strength, can reduce the construction difficulty, save the construction period and improve the engineering benefit when in application.
Description
Technical Field
The invention relates to a building construction method, in particular to a construction method for an underground continuous wall system under the weak geological condition of a sea reclamation area.
Background
Shenzhen anterior sea comprehensive transportation hub and upper cover property engineering, a north-adjacent double-boundary river road, a south-adjacent peach garden road, an east-adjacent navigation sea road and a west-adjacent listening sea road. The underground railway is positioned between the No. 11 subway line and the deep intercity line of the Guanguan, comprises 6 layers of basements and 8 tower buildings above the basements, and is about 80-100 m in width and about 830m in length. The project has the defects of large foundation pit area, large foundation pit depth, weak geological conditions, complex geological conditions of the sea-filling area, large quantity of engineering piles (about 2 ten thousand piles), and huge earthwork excavation amount (about 230 ten thousand meters)3) And the foundation pit and basements of the bay stations before the subway lines 1#, 5#, and 11# in operation share the support piles, so that the underground foundation pit engineering of the engineering adopts the underground continuous wall as a foundation pit support structure. Due to the complexity and the particularity of the engineering, the existing foundation pit construction process has the defects of high construction difficulty, low construction efficiency, insufficient support strength, long construction period and the like during construction, and the construction cost can be greatly increased.
Therefore, the present invention aims to provide a new technical solution to solve the existing technical drawbacks.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a construction method for an underground continuous wall system under the weak geological condition of a sea-filling area, and the technical defects of high construction difficulty, low construction efficiency, high construction cost, long construction period, insufficient support strength, poor economic benefit and the like existing when the conventional construction process is applied to the project are overcome.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the construction method of the underground continuous wall system used under the weak geological conditions of the sea-filling area comprises the following construction steps:
s1, measuring and setting out, namely measuring and setting out the construction line position of the underground diaphragm wall according to a drawing;
s2, performing soft foundation treatment, namely performing soft foundation treatment according to the measured and laid-out underground continuous wall line position to improve the bearing capacity of a soft stratum;
s3, grooving and reinforcing, namely grooving and reinforcing both sides of the linear position of the underground continuous wall;
s4, grooving the underground continuous wall, and excavating the groove according to the scribed line position of the underground continuous wall;
s5, manufacturing an underground continuous wall reinforcement cage;
s6, hoisting the reinforcement cage of the underground continuous wall;
s7, pouring concrete for the underground continuous wall;
and S8, backfilling the hollow wall section, and backfilling the hollow wall section of the half-section type underground continuous wall part in the underground continuous wall by adopting broken stones.
As an improvement of the technical scheme, in step S2, a soft geological layer within 12m of one side of the underground continuous wall is subjected to grid type cement mixing pile soft foundation treatment;
in step S2, the rockfill geological formation containing construction waste and disordered miscellaneous fill within 12m of one side of the underground continuous wall is subjected to grid type single-pipe jet grouting pile soft foundation treatment.
As a further improvement of the technical scheme, when the soft foundation treatment of the grid type cement mixing pile is carried out, the construction method comprises the following construction steps:
s211, measuring and placing the axis of the mixing pile, measuring the axis of the mixing pile along the foundation pit, and grasping the distribution of underground obstacles at the axis position according to the actual situation on site;
s212, axial line excavation: excavating an axial line position according to the distribution condition of the obstacles on site, clearing underground obstacles 2-3m away from the upper part, backfilling and compacting, and reserving a mud groove about one meter deep;
s213, positioning the pile position, re-measuring and setting out the axial line of the stirring pile, and positioning the pile position;
s214, a drilling machine is in place, the mixing pile machine is moved to the pile centering position, and the rack is adjusted to be horizontal and the guide frame is adjusted to be vertical;
s215, preparing cement slurry, wherein the cement is ordinary portland cement with PO42.5MPa, the doping amount of the cement is 68.4kg/m, the water-cement ratio of the cement slurry is 0.4-0.55, and the grouting pressure is kept at 0.40-0.60 MPa;
s216, stirring and sinking, spraying, starting a machine, starting a mortar pump to pump the prepared cement slurry, and enabling the stirring head to rotate, spray and sink along the support;
s217, lifting, spraying and stirring, lifting a drill rod, spraying, and lifting at the same time until the top elevation of the wall body is reached;
s218, repeating the downward stirring and lifting guniting processes once, lifting the stirring head to the designed pile top elevation, lifting the guniting while rotating, sinking and guniting to the designed depth, and lifting the guniting, and lifting the stirring machine out of the ground after the four-stirring and four-spraying processes are completed;
s219, cleaning residual cement slurry in a mortar pump and a pipeline;
s210, shifting to the next pile position for construction;
the effective diameter of the pile mixing pile is 550mm, the pile mixing piles are mutually overlapped by 150mm, the construction interval time of adjacent piles is not more than 2h, and the overlapping time between pile rows is not more than 24 h.
As a further improvement of the technical scheme, when the soft foundation treatment of the grid type cement mixing pile is carried out, if construction waste and an unordered mixed filling stone layer are met, and the local mixing pile is difficult to construct, after design and construction approval, the construction is carried out by using a jet grouting pile, pile positions are released according to a drawing by a professional constructor according to an axis control pile, each pile position is driven into a bamboo strip with the length of 20cm and the width of about 2cm, and a pile number is written, so that the examination and the rechecking can be carried out in time; during grouting, after the grout reaches a grout spraying opening, the grout spraying at the bottom of the pile is not less than 30s, so that the grout can completely reach the end of the pile, and then the grout spraying, stirring and lifting are carried out; when the grout spraying port reaches the elevation of the pile top, stopping lifting, stirring for several seconds, enabling the grout stopping surface to be higher than the designed pile top surface by 0.50m, if grout is stopped due to reasons, sinking the stirrer to be 0.5m below a grout stopping point, and continuing to spray, stir and lift when grout supply is resumed; stopping the stirring drill bit when the stirring drill bit is smaller than 550mm, and timely repairing or replacing the drill bit; quantitatively feeding the cement according to the length of the constructed pile, ensuring the cement consumption per linear meter, checking the residual quantity in the tank or the barrel after the single-pile construction is finished, and timely repairing and driving if the residual quantity exists; the pile-forming depth is marked according to the design requirement and the stratum condition and according to the depth calibrated by a depth meter or a drilling tower on the pile machine, and the depth calibration check is carried out once before the start of work.
As a further improvement of the technical scheme, when the grid type single-pipe jet grouting pile soft foundation treatment is carried out, the method comprises the following construction steps:
s221, a drilling machine is in place, the drilling machine is in place and requires three points of a drill bit, a pile casing center and a drill rod center to be in a line, and the drilling machine is seated firmly and stably;
s222, leading holes to form holes, and forming the holes by using a geological drilling machine or a down-the-hole drilling machine, wherein the diameter of the holes is 80mm, and the diameter of the holes reaches the design depth;
s223, placing the rotary jet grouting pile machine in place, forming a hole for the second time to reach the designed pile bottom elevation, adopting a single-pipe method for rotary jet grouting, enabling the jet pressure of high-pressure cement slurry of the rotary jet grouting pile to be greater than 20MPa, enabling the lifting speed to be 8-10cm/min, adopting P.O.42.5 ordinary portland cement, enabling the water cement ratio to be 1.0, and enabling the cement slurry to be used along with stirring;
s224, the cement consumption of the jet grouting pile per meter is not less than 150 kg;
s225, when the high-pressure injection grouting is finished, quickly pulling out the grouting pipe, and adopting measures such as grouting back or secondary grouting at the original hole position to prevent the grout from solidifying and shrinking to influence the elevation of the pile top;
and S226, moving to the next hole site for construction.
As a further improvement of the technical scheme, when the grid type single-pipe jet grouting pile soft foundation treatment is carried out, the verticality of the drill rod is observed in the drilling process, once the drill rod is found to be inclined, the drilling is stopped, the drill rod is lifted to be vertical to the level surface, and then the drilling is continued; in the construction process, holes are led by adopting an interval jumping method, the hole spacing is less than or equal to 1.5m, and slurry channeling is prevented; after drilling to a designed elevation, sealing the empty top opening by using a sand bag to prevent the empty top opening from being blocked; in the mud circulating system of the construction site, the waste slurry emitting liquid is led into or discharged into a mud pit in time in the construction process, and the sediment is condensed and then is transported to the outside of the site for storage or disposal.
As a further improvement of the above technical solution, in step S3, when performing trenching reinforcement, performing a cement mixing pile trenching reinforcement treatment on the weak geological formations on both sides of the underground continuous wall line; and carrying out single-pipe jet grouting pile grooving reinforcement treatment on the geological strata of the rockfill layer containing the building waste and the disordered miscellaneous filling on the two sides of the line position of the underground continuous wall.
As a further improvement of the above technical solution, when performing step S4, the method includes the following steps:
s41, dividing the groove sections, framing the underground diaphragm wall according to a design drawing, and arranging the breadth length according to the design;
s42, lofting the groove section, accurately positioning an underground continuous wall mark on the guide wall according to a design drawing and a control point and a level point provided by a construction unit, and marking the joint position by externally placing 5cm at each side of the ground wall to ensure that the ground wall does not invade the lining;
s43, excavating the groove sections, wherein the excavated groove sections adopt 3 trenching machines which are provided with a sag display instrument and an automatic deviation correcting device;
s44, grooving and entering the rock,
for the region which is difficult to penetrate deep rock filling in the upper rock filling layer, a large-diameter down-the-hole hammer is adopted to guide holes, and sand is used for backfilling and replacement;
s45, measuring and controlling the groove depth, wherein the groove depth is measured by using a calibrated measuring rope, each measuring point is 2 points according to the width of each measuring point, and the depth of the digging groove is controlled according to the elevation of the guide wall so as to ensure the design depth;
s46, testing the groove section, wherein the content of the groove section test comprises the plane position of the groove section, the depth of the groove section, the wall surface verticality of the groove section and the end surface verticality of the groove section, and the method for testing the groove section comprises the following steps: detecting the plane position deviation of the groove section, namely actually measuring the positions of two ends of the groove section by using a measuring hammer, wherein the deviation between an actually measured position line of the two ends and a framing line of the groove section is the plane position deviation of the groove section, detecting the depth of the groove section, and actually measuring the groove bottom depths of the left position and the right position of the groove section by using the measuring hammer, wherein the average depth of the two positions is the depth of the groove section;
and S47, processing corners of the guide wall, and correspondingly placing the guide wall at the corners by 20cm according to the shape of the end face of the grooving machine so as to prevent the lower groove of the reinforcement cage from being obstructed due to insufficient grooving section.
As a further improvement of the above technical means, when performing step S43, the method includes:
s431, perpendicularity control of grooving machine
Before grooving, the flatness of a grooving machine is adjusted by using a vehicle-mounted level gauge, and in the grooving process, a hydraulic grab bucket is provided with a longitudinal deviation correcting device, the state of the grab bucket is detected in real time through a tilt angle sensor and is sent to a processor for processing, and the processor sends a deviation correcting signal to a control oil cylinder to adjust the state of the grab bucket; the wall of the groove can be trimmed back and forth at any time in work, the advanced measuring system is provided, the grab bucket is provided with a touch screen computer measuring system, the excavation depth and the inclination of the hydraulic grab bucket are recorded and displayed, the excavation depth, the lifting speed and the positions in the x and y directions can be accurately displayed on a screen, the inclination measuring precision can reach 0.01 degrees, and the groove wall can be stored by a computer and automatically printed and output;
s432, grooving and excavating sequence
Firstly, the unit groove sections adopt the sequence of firstly digging two sides and then digging the single holes at two ends of the groove sections, or adopt the method of digging a first hole, jumping a distance and then digging a second hole, so that an unearthed partition wall is left between the two single holes, thus the grab bucket can be balanced in force when digging the single holes, the deviation can be effectively corrected, and the perpendicularity of the formed groove is ensured;
secondly, digging a single hole first and then digging a partition wall. Because the length of the hole partition wall is less than the opening length of the grab bucket, the grab bucket can be sleeved on the partition wall to dig, the grab bucket can be balanced in force, the deviation can be effectively corrected, and the verticality of the formed groove is ensured;
thirdly, after the single hole and the hole partition wall are dug to the designed depth, a plurality of buckets are dug in the groove length direction in a sleeved mode, when the grab bucket is used for digging the single hole and the partition wall, concave and convex surfaces formed due to different perpendicularity of the grab bucket forming grooves are repaired to be smooth, and good linearity of the groove section in the transverse direction is guaranteed;
fourthly, when the grab bucket is sleeved and excavated along the length direction of the groove, the grab bucket is lowered to the designed depth of the groove section to excavate and remove the sediment at the bottom of the groove;
s433, trenching and digging
During the grooving process, the grab bucket enters and exits the groove at a slow speed and stably, the deviation is timely corrected according to the verticality of a grooving machine instrument and actual measurement, two-way flashboards are inserted into the guide wall on two sides of the groove section during soil grabbing, so that slurry in the guide wall is not polluted, during grooving, the groove section is prevented from being unstable or locally collapsed due to improper sequence, and when the groove is formed in a soil layer with the possibility of slurry leakage, plugging measures are needed, and sufficient slurry is stored.
As a further improvement of the above technical scheme, in step S6, the dual-crane lifting crane is used for 1 260t and 1 125t crawler cranes, the main hook lifts the top of the steel reinforcement cage, the auxiliary hook lifts the middle of the steel reinforcement cage, and the multiple groups of hoist main hooks and hoist auxiliary hooks work simultaneously, so that the steel reinforcement cage is slowly lifted off the ground, the verticality of the steel reinforcement cage is controlled, the steel reinforcement cage is aligned with the groove section position and slowly enters the groove, and the elevation is controlled. After the steel reinforcement cage is placed to the design elevation, the shoulder pole made of the channel steel is placed on the guide wall.
The invention has the beneficial effects that: the invention provides a construction method for an underground continuous wall system under the weak geological condition of a sea reclamation area, which can cope with the complex weak geological condition of the sea reclamation area, effectively reduce the construction difficulty, save the construction cost, improve the construction efficiency, effectively shorten the construction period, improve the enough supporting strength during the actual construction and improve the engineering benefit.
To sum up, the construction method for the underground diaphragm wall system under the weak geological condition of the sea-filling area solves the technical defects of high construction difficulty, low construction efficiency, high construction cost, long construction period, insufficient support strength, poor economic benefit and the like when the existing construction process is applied to the project.
Drawings
The invention is further illustrated with reference to the following figures and examples.
FIG. 1 is a schematic flow diagram of the present invention.
Detailed Description
The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings to fully understand the objects, the features, and the effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention. In addition, all the connection/connection relations referred to in the patent do not mean that the components are directly connected, but mean that a better connection structure can be formed by adding or reducing connection auxiliary components according to specific implementation conditions. All technical features in the invention can be interactively combined on the premise of not conflicting with each other, and refer to fig. 1.
The construction method of the underground continuous wall system used under the weak geological conditions of the sea-filling area comprises the following construction steps:
s1, measuring and setting out, namely measuring and setting out the construction line position of the underground diaphragm wall according to a drawing;
s2, performing soft foundation treatment, namely performing soft foundation treatment according to the measured and laid-out underground continuous wall line position to improve the bearing capacity of a soft stratum;
in step S2, the weak geological formation within 12m of one side of the underground continuous wall is subjected to grid type cement mixing pile soft foundation treatment, specifically, the method comprises
S211, measuring and placing the axis of the mixing pile, measuring the axis of the mixing pile along the foundation pit, and grasping the distribution of underground obstacles at the axis position according to the actual situation on site;
s212, axial line excavation: excavating an axial line position according to the distribution condition of the obstacles on site, clearing underground obstacles 2-3m away from the upper part, backfilling and compacting, and reserving a mud groove about one meter deep;
s213, positioning the pile position, re-measuring and setting out the axial line of the stirring pile, and positioning the pile position;
s214, a drilling machine is in place, the mixing pile machine is moved to the pile centering position, and the rack is adjusted to be horizontal and the guide frame is adjusted to be vertical;
s215, preparing cement slurry, wherein the cement is ordinary portland cement with PO42.5MPa, the doping amount of the cement is 68.4kg/m, the water-cement ratio of the cement slurry is 0.4-0.55, and the grouting pressure is kept at 0.40-0.60 MPa;
s216, stirring and sinking, spraying, starting a machine, starting a mortar pump to pump the prepared cement slurry, and enabling the stirring head to rotate, spray and sink along the support;
s217, lifting, spraying and stirring, lifting a drill rod, spraying, and lifting at the same time until the top elevation of the wall body is reached;
s218, repeating the downward stirring and lifting guniting processes once, lifting the stirring head to the designed pile top elevation, lifting the guniting while rotating, sinking and guniting to the designed depth, and lifting the guniting, and lifting the stirring machine out of the ground after the four-stirring and four-spraying processes are completed;
s219, cleaning residual cement slurry in a mortar pump and a pipeline;
s210, shifting to the next pile position for construction;
the effective diameter of the pile mixing pile is 550mm, the pile mixing piles are mutually overlapped by 150mm, the construction interval time of adjacent piles is not more than 2h, and the overlapping time between pile rows is not more than 24 h.
In the process, when the grid type cement mixing pile soft foundation treatment is carried out, if local mixing piles are difficult to construct, after design and construction consent, the rotary spraying pile construction is changed, pile positions are released according to a drawing by a professional constructor according to axis control pile control, bamboo strips with the length of 20cm and the width of 2cm are driven into each pile position, and the pile numbers are written, so that the examination and the rechecking can be carried out in time; during grouting, after the grout reaches a grout spraying opening, the grout spraying at the bottom of the pile is not less than 30s, so that the grout can completely reach the end of the pile, and then the grout spraying, stirring and lifting are carried out; when the grout spraying port reaches the elevation of the pile top, stopping lifting, stirring for several seconds, enabling the grout stopping surface to be higher than the designed pile top surface by 0.50m, if grout is stopped due to reasons, sinking the stirrer to be 0.5m below a grout stopping point, and continuing to spray, stir and lift when grout supply is resumed; stopping the stirring drill bit when the stirring drill bit is smaller than 550mm, and timely repairing or replacing the drill bit; quantitatively feeding the cement according to the length of the constructed pile, ensuring the cement consumption per linear meter, checking the residual quantity in the tank or the barrel after the single-pile construction is finished, and timely repairing and driving if the residual quantity exists; the pile-forming depth is marked according to the design requirement and the stratum condition and according to the depth calibrated by a depth meter or a drilling tower on the pile machine, and the depth calibration check is carried out once before the start of work.
In step S2, the method includes the following steps of performing grid type single-pipe jet grouting pile soft foundation treatment on a rockfill layer geological layer containing construction waste and disordered miscellaneous fillers within a range of 12m on one side of the underground continuous wall, and when performing the grid type single-pipe jet grouting pile soft foundation treatment:
s221, a drilling machine is in place, the drilling machine is in place and requires three points of a drill bit, a pile casing center and a drill rod center to be in a line, and the drilling machine is seated firmly and stably;
s222, leading holes to form holes, and forming the holes by using a geological drilling machine or a down-the-hole drilling machine, wherein the diameter of the holes is 80mm, and the diameter of the holes reaches the design depth;
s223, placing the rotary jet grouting pile machine in place, forming a hole for the second time to reach the designed pile bottom elevation, adopting a single-pipe method for rotary jet grouting, enabling the jet pressure of high-pressure cement slurry of the rotary jet grouting pile to be greater than 20MPa, enabling the lifting speed to be 8-10cm/min, adopting P.O.42.5 ordinary portland cement, enabling the water cement ratio to be 1.0, and enabling the cement slurry to be used along with stirring;
s224, the cement consumption of the jet grouting pile per meter is not less than 150 kg;
s225, when the high-pressure injection grouting is finished, quickly pulling out the grouting pipe, and adopting measures such as grouting back or secondary grouting at the original hole position to prevent the grout from solidifying and shrinking to influence the elevation of the pile top;
and S226, moving to the next hole site for construction.
When the grid type single-tube jet grouting pile soft foundation treatment is carried out, the verticality of the drill rod is observed in the drilling process, once the drill rod is inclined, the drilling is stopped, the drill rod is lifted to be vertical to the level surface, and then the drilling is continued; in the construction process, holes are led by adopting an interval jumping method, the hole spacing is less than or equal to 1.5m, and slurry channeling is prevented; after drilling to a designed elevation, sealing the empty top opening by using a sand bag to prevent the empty top opening from being blocked; in the mud circulating system of the construction site, the waste slurry emitting liquid is led into or discharged into a mud pit in time in the construction process, and the sediment is condensed and then is transported to the outside of the site for storage or disposal.
S3, grooving and reinforcing, namely grooving and reinforcing both sides of the linear position of the underground continuous wall;
in step S3, when performing trenching reinforcement, performing a trenching reinforcement process on the cement mixing pile for the weak geological formations on both sides of the underground continuous wall line; and carrying out single-pipe jet grouting pile grooving reinforcement treatment on the geological strata of the rockfill layer containing the building waste and the disordered miscellaneous filling on the two sides of the line position of the underground continuous wall.
S4, grooving the underground continuous wall, and excavating the groove according to the scribed line position of the underground continuous wall;
when step S4 is performed, it includes the following construction steps:
s41, dividing the groove sections, framing the underground diaphragm wall according to a design drawing, and arranging the breadth length according to the design;
s42, lofting the groove section, accurately positioning an underground continuous wall mark on the guide wall according to a design drawing and a control point and a level point provided by a construction unit, and marking the joint position by externally placing 5cm at each side of the ground wall to ensure that the ground wall does not invade the lining;
s43, excavating the groove sections, wherein the excavated groove sections adopt 3 trenching machines which are provided with a sag display instrument and an automatic deviation correcting device;
s44, grooving and entering the rock,
for the region which is difficult to penetrate deep rock filling in the upper rock filling layer, a large-diameter down-the-hole hammer is adopted to guide holes, and sand is used for backfilling and replacement;
s45, measuring and controlling the groove depth, wherein the groove depth is measured by using a calibrated measuring rope, each measuring point is 2 points according to the width of each measuring point, and the depth of the digging groove is controlled according to the elevation of the guide wall so as to ensure the design depth;
s46, testing the groove section, wherein the content of the groove section test comprises the plane position of the groove section, the depth of the groove section, the wall surface verticality of the groove section and the end surface verticality of the groove section, and the method for testing the groove section comprises the following steps: detecting the plane position deviation of the groove section, namely actually measuring the positions of two ends of the groove section by using a measuring hammer, wherein the deviation between an actually measured position line of the two ends and a framing line of the groove section is the plane position deviation of the groove section, detecting the depth of the groove section, and actually measuring the groove bottom depths of the left position and the right position of the groove section by using the measuring hammer, wherein the average depth of the two positions is the depth of the groove section;
and S47, processing corners of the guide wall, and correspondingly placing the guide wall at the corners by 20cm according to the shape of the end face of the grooving machine so as to prevent the lower groove of the reinforcement cage from being obstructed due to insufficient grooving section.
When performing step S43, the method includes:
s431, perpendicularity control of grooving machine
Before grooving, the flatness of a grooving machine is adjusted by using a vehicle-mounted level gauge, and in the grooving process, a hydraulic grab bucket is provided with a longitudinal deviation correcting device, the state of the grab bucket is detected in real time through a tilt angle sensor and is sent to a processor for processing, and the processor sends a deviation correcting signal to a control oil cylinder to adjust the state of the grab bucket; the wall of the groove can be trimmed back and forth at any time in work, the advanced measuring system is provided, the grab bucket is provided with a touch screen computer measuring system, the excavation depth and the inclination of the hydraulic grab bucket are recorded and displayed, the excavation depth, the lifting speed and the positions in the x and y directions can be accurately displayed on a screen, the inclination measuring precision can reach 0.01 degrees, and the groove wall can be stored by a computer and automatically printed and output;
s432, grooving and excavating sequence
Firstly, the unit groove sections adopt the sequence of firstly digging two sides and then digging the single holes at two ends of the groove sections, or adopt the method of digging a first hole, jumping a distance and then digging a second hole, so that an unearthed partition wall is left between the two single holes, thus the grab bucket can be balanced in force when digging the single holes, the deviation can be effectively corrected, and the perpendicularity of the formed groove is ensured;
secondly, digging a single hole first and then digging a partition wall. Because the length of the hole partition wall is less than the opening length of the grab bucket, the grab bucket can be sleeved on the partition wall to dig, the grab bucket can be balanced in force, the deviation can be effectively corrected, and the verticality of the formed groove is ensured;
thirdly, after the single hole and the hole partition wall are dug to the designed depth, a plurality of buckets are dug in the groove length direction in a sleeved mode, when the grab bucket is used for digging the single hole and the partition wall, concave and convex surfaces formed due to different perpendicularity of the grab bucket forming grooves are repaired to be smooth, and good linearity of the groove section in the transverse direction is guaranteed;
fourthly, when the grab bucket is sleeved and excavated along the length direction of the groove, the grab bucket is lowered to the designed depth of the groove section to excavate and remove the sediment at the bottom of the groove;
s433, trenching and digging
During the grooving process, the grab bucket enters and exits the groove at a slow speed and stably, the deviation is timely corrected according to the verticality of a grooving machine instrument and actual measurement, two-way flashboards are inserted into the guide wall on two sides of the groove section during soil grabbing, so that slurry in the guide wall is not polluted, during grooving, the groove section is prevented from being unstable or locally collapsed due to improper sequence, and when the groove is formed in a soil layer with the possibility of slurry leakage, plugging measures are needed, and sufficient slurry is stored.
S5, manufacturing an underground continuous wall reinforcement cage;
s6, hoisting the reinforcement cage of the underground continuous wall;
and S6, using 1 260t and 1 125t crawler cranes to lift the two cranes, lifting the top of the reinforcement cage by the main hook, lifting the middle of the reinforcement cage by the auxiliary hook, and simultaneously working a plurality of groups of gourd main hooks and gourd auxiliary hooks, so that the reinforcement cage is slowly lifted off the ground, the perpendicularity of the reinforcement cage is controlled, the reinforcement cage is aligned with the groove section to slowly enter the groove, and the elevation is controlled. After the steel reinforcement cage is placed to the design elevation, the shoulder pole made of the channel steel is placed on the guide wall.
S7, pouring concrete for the underground continuous wall;
and S8, backfilling the hollow wall section, and backfilling the hollow wall section of the half-section type underground continuous wall part in the underground continuous wall by adopting broken stones.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The construction method of the underground continuous wall system used under the weak geological conditions of the sea-filling area is characterized by comprising the following construction steps:
s1, measuring and setting out, namely measuring and setting out the construction line position of the underground diaphragm wall according to a drawing;
s2, performing soft foundation treatment, namely performing soft foundation treatment according to the measured and laid-out underground continuous wall line position to improve the bearing capacity of a soft stratum;
s3, grooving and reinforcing, namely grooving and reinforcing both sides of the linear position of the underground continuous wall;
s4, grooving the underground continuous wall, and excavating the groove according to the scribed line position of the underground continuous wall;
s5, manufacturing an underground continuous wall reinforcement cage;
s6, hoisting the reinforcement cage of the underground continuous wall;
s7, pouring concrete for the underground continuous wall;
and S8, backfilling the hollow wall section, and backfilling the hollow wall section of the half-section type underground continuous wall part in the underground continuous wall by adopting broken stones.
2. The construction method for the underground continuous wall system under the weak geological conditions of the reclamation area as recited in claim 1, wherein:
in step S2, performing grid type cement mixing pile soft foundation treatment on the soft geological formation within 12m of one side of the underground continuous wall;
in step S2, the rockfill geological formation containing construction waste and disordered miscellaneous fill within 12m of one side of the underground continuous wall is subjected to grid type single-pipe jet grouting pile soft foundation treatment.
3. The construction method for the underground continuous wall system under the weak geological conditions of the reclamation area as recited in claim 2, wherein: when the soft foundation treatment of the grid type cement mixing pile is carried out, the construction method comprises the following construction steps:
s211, measuring and placing the axis of the mixing pile, measuring the axis of the mixing pile along the foundation pit, and grasping the distribution of underground obstacles at the axis position according to the actual situation on site;
s212, axial line excavation: excavating an axial line position according to the distribution condition of the obstacles on site, clearing underground obstacles 2-3m away from the upper part, backfilling and compacting, and reserving a mud groove about one meter deep;
s213, positioning the pile position, re-measuring and setting out the axial line of the stirring pile, and positioning the pile position;
s214, a drilling machine is in place, the mixing pile machine is moved to the pile centering position, and the rack is adjusted to be horizontal and the guide frame is adjusted to be vertical;
s215, preparing cement slurry, wherein the cement is ordinary portland cement with PO42.5MPa, the doping amount of the cement is 68.4kg/m, the water-cement ratio of the cement slurry is 0.4-0.55, and the grouting pressure is kept at 0.40-0.60 MPa;
s216, stirring and sinking, spraying, starting a machine, starting a mortar pump to pump the prepared cement slurry, and enabling the stirring head to rotate, spray and sink along the support;
s217, lifting, spraying and stirring, lifting a drill rod, spraying, and lifting at the same time until the top elevation of the wall body is reached;
s218, repeating the downward stirring and lifting guniting processes once, lifting the stirring head to the designed pile top elevation, lifting the guniting while rotating, sinking and guniting to the designed depth, and lifting the guniting, and lifting the stirring machine out of the ground after the four-stirring and four-spraying processes are completed;
s219, cleaning residual cement slurry in a mortar pump and a pipeline;
s210, shifting to the next pile position for construction;
the effective diameter of the pile mixing pile is 550mm, the pile mixing piles are mutually overlapped by 150mm, the construction interval time of adjacent piles is not more than 2h, and the overlapping time between pile rows is not more than 24 h.
4. A construction method for an underground diaphragm wall system under weak geological conditions of a reclamation area as recited in claim 3, wherein: when the grid type cement mixing pile soft foundation treatment is carried out, if local mixing piles are difficult to construct, the construction can be carried out by using jet grouting piles instead, pile positions are released according to a drawing by controlling the piles according to an axis, bamboo strips with the length of 20cm and the width of 2cm are driven into each pile position, and the number of the piles is written so as to be convenient for timely inspection and recheck; during grouting, after the grout reaches a grout spraying opening, the grout spraying at the bottom of the pile is not less than 30s, so that the grout can completely reach the end of the pile, and then the grout spraying, stirring and lifting are carried out; when the grout spraying port reaches the elevation of the pile top, stopping lifting, stirring for several seconds, enabling the grout stopping surface to be higher than the designed pile top surface by 0.50m, if grout is stopped due to reasons, sinking the stirrer to be 0.5m below a grout stopping point, and continuing to spray, stir and lift when grout supply is resumed; stopping the stirring drill bit when the stirring drill bit is smaller than 550mm, and timely repairing or replacing the drill bit; quantitatively feeding the cement according to the length of the constructed pile, ensuring the cement consumption per linear meter, checking the residual quantity in the tank or the barrel after the single-pile construction is finished, and timely repairing and driving if the residual quantity exists; the pile-forming depth is marked according to the design requirement and the stratum condition and according to the depth calibrated by a depth meter or a drilling tower on the pile machine, and the depth calibration check is carried out once before the start of work.
5. The construction method for the underground continuous wall system under the weak geological conditions of the reclamation area as recited in claim 2, wherein: when the grid type single-pipe jet grouting pile soft foundation treatment is carried out, the method comprises the following construction steps:
s221, a drilling machine is in place, the drilling machine is in place and requires three points of a drill bit, a pile casing center and a drill rod center to be in a line, and the drilling machine is seated firmly and stably;
s222, leading holes to form holes, and forming the holes by using a geological drilling machine or a down-the-hole drilling machine, wherein the diameter of the holes is 80mm, and the diameter of the holes reaches the design depth;
s223, placing the rotary jet grouting pile machine in place, forming a hole for the second time to reach the designed pile bottom elevation, adopting a single-pipe method for rotary jet grouting, enabling the jet pressure of high-pressure cement slurry of the rotary jet grouting pile to be greater than 20MPa, enabling the lifting speed to be 8-10cm/min, adopting P.O.42.5 ordinary portland cement, enabling the water cement ratio to be 1.0, and enabling the cement slurry to be used along with stirring;
s224, the cement consumption of the jet grouting pile per meter is not less than 150 kg;
s225, when the high-pressure injection grouting is finished, quickly pulling out the grouting pipe, and adopting measures such as grouting back or secondary grouting at the original hole position to prevent the grout from solidifying and shrinking to influence the elevation of the pile top;
and S226, moving to the next hole site for construction.
6. The construction method for the underground continuous wall system under the weak geological conditions of the reclamation area as recited in claim 5, wherein: when the grid type single-tube jet grouting pile soft foundation treatment is carried out, the verticality of the drill rod is observed in the drilling process, once the drill rod is inclined, the drilling is stopped, the drill rod is lifted to be vertical to the level surface, and then the drilling is continued; in the construction process, holes are led by adopting an interval jumping method, the hole spacing is less than or equal to 1.5m, and slurry channeling is prevented; after drilling to a designed elevation, sealing the empty top opening by using a sand bag to prevent the empty top opening from being blocked; in the mud circulating system of the construction site, the waste slurry emitting liquid is led into or discharged into a mud pit in time in the construction process, and the sediment is condensed and then is transported to the outside of the site for storage or disposal.
7. The construction method for the underground continuous wall system under the weak geological conditions of the reclamation area as recited in claim 1, wherein: in step S3, when performing trenching reinforcement, performing a trenching reinforcement process on the cement mixing pile for the weak geological formations on both sides of the underground continuous wall line; and carrying out single-pipe jet grouting pile grooving reinforcement treatment on the geological strata of the rockfill layer containing the building waste and the disordered miscellaneous filling on the two sides of the line position of the underground continuous wall.
8. The construction method for the underground continuous wall system under the weak geological conditions of the reclamation area as recited in claim 1, wherein: when step S4 is performed, it includes the following construction steps:
s41, dividing the groove sections, framing the underground diaphragm wall according to a design drawing, and arranging the breadth length according to the design;
s42, lofting the groove section, accurately positioning an underground continuous wall mark on the guide wall according to a design drawing and a control point and a level point provided by a construction unit, and marking the joint position by externally placing 5cm at each side of the ground wall to ensure that the ground wall does not invade the lining;
s43, excavating the groove sections, wherein the excavated groove sections adopt 3 trenching machines which are provided with a sag display instrument and an automatic deviation correcting device;
s44, grooving and entering the rock,
for the region which is difficult to penetrate deep rock filling in the upper rock filling layer, a large-diameter down-the-hole hammer is adopted to guide holes, and sand is used for backfilling and replacement;
s45, measuring and controlling the groove depth, wherein the groove depth is measured by using a calibrated measuring rope, each measuring point is 2 points according to the width of each measuring point, and the depth of the digging groove is controlled according to the elevation of the guide wall so as to ensure the design depth;
s46, testing the groove section, wherein the content of the groove section test comprises the plane position of the groove section, the depth of the groove section, the wall surface verticality of the groove section and the end surface verticality of the groove section, and the method for testing the groove section comprises the following steps: detecting the plane position deviation of the groove section, namely actually measuring the positions of two ends of the groove section by using a measuring hammer, wherein the deviation between an actually measured position line of the two ends and a framing line of the groove section is the plane position deviation of the groove section, detecting the depth of the groove section, and actually measuring the groove bottom depths of the left position and the right position of the groove section by using the measuring hammer, wherein the average depth of the two positions is the depth of the groove section;
and S47, processing corners of the guide wall, and correspondingly placing the guide wall at the corners by 20cm according to the shape of the end face of the grooving machine so as to prevent the lower groove of the reinforcement cage from being obstructed due to insufficient grooving section.
9. The construction method for an underground diaphragm wall system under weak geological conditions in a reclamation area as recited in claim 8, wherein: when performing step S43, the method includes:
s431, perpendicularity control of grooving machine
Before grooving, the flatness of a grooving machine is adjusted by using a vehicle-mounted level gauge, and in the grooving process, a hydraulic grab bucket is provided with a longitudinal deviation correcting device, the state of the grab bucket is detected in real time through a tilt angle sensor and is sent to a processor for processing, and the processor sends a deviation correcting signal to a control oil cylinder to adjust the state of the grab bucket; the wall of the groove can be trimmed back and forth at any time in work, the advanced measuring system is provided, the grab bucket is provided with a touch screen computer measuring system, the excavation depth and the inclination of the hydraulic grab bucket are recorded and displayed, the excavation depth, the lifting speed and the positions in the x and y directions can be accurately displayed on a screen, the inclination measuring precision can reach 0.01 degrees, and the groove wall can be stored by a computer and automatically printed and output;
s432, grooving and excavating sequence
Firstly, the unit groove sections adopt the sequence of firstly digging two sides and then digging the single holes at two ends of the groove sections, or adopt the method of digging a first hole, jumping a distance and then digging a second hole, so that an unearthed partition wall is left between the two single holes, thus the grab bucket can be balanced in force when digging the single holes, the deviation can be effectively corrected, and the perpendicularity of the formed groove is ensured;
secondly, digging a single hole firstly, and then digging a partition wall, wherein the length of the hole partition wall is smaller than that of the grab bucket, so that the grab bucket can be sleeved on the partition wall to dig, the grab bucket can be balanced in force, the deviation can be effectively corrected, and the grooving verticality can be ensured;
thirdly, after the single hole and the hole partition wall are dug to the designed depth, a plurality of buckets are dug in the groove length direction in a sleeved mode, when the grab bucket is used for digging the single hole and the partition wall, concave and convex surfaces formed due to different perpendicularity of the grab bucket forming grooves are repaired to be smooth, and good linearity of the groove section in the transverse direction is guaranteed;
fourthly, when the grab bucket is sleeved and excavated along the length direction of the groove, the grab bucket is lowered to the designed depth of the groove section to excavate and remove the sediment at the bottom of the groove;
s433, trenching and digging
During the grooving process, the grab bucket enters and exits the groove at a slow speed and stably, the deviation is timely corrected according to the verticality of a grooving machine instrument and actual measurement, two-way flashboards are inserted into the guide wall on two sides of the groove section during soil grabbing, so that slurry in the guide wall is not polluted, during grooving, the groove section is prevented from being unstable or locally collapsed due to improper sequence, and when the groove is formed in a soil layer with the possibility of slurry leakage, plugging measures are needed, and sufficient slurry is stored.
10. The construction method for the underground continuous wall system under the weak geological conditions of the reclamation area as recited in claim 1, wherein: and S6, using 1 260t and 1 125t crawler cranes to lift the two cranes, lifting the top of the steel reinforcement cage by the main hook, lifting the middle of the steel reinforcement cage by the auxiliary hook, enabling a plurality of groups of hoist main hooks and auxiliary hooks to work simultaneously, slowly lifting the steel reinforcement cage from the ground, controlling the verticality of the steel reinforcement cage, aligning the groove section to slowly enter the groove and controlling the elevation, placing the steel reinforcement cage to the designed elevation, and placing a shoulder pole made of channel steel on a guide wall.
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