CN116950120A - Pre-jacking system and pre-jacking method for underpinning pile - Google Patents
Pre-jacking system and pre-jacking method for underpinning pile Download PDFInfo
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- 238000009424 underpinning Methods 0.000 title claims abstract description 207
- 238000000034 method Methods 0.000 title claims abstract description 57
- 238000012544 monitoring process Methods 0.000 claims abstract description 74
- 238000010276 construction Methods 0.000 claims abstract description 14
- 230000001105 regulatory effect Effects 0.000 claims abstract description 8
- 238000006073 displacement reaction Methods 0.000 claims description 50
- 230000008569 process Effects 0.000 claims description 23
- 230000003068 static effect Effects 0.000 claims description 19
- 238000004062 sedimentation Methods 0.000 claims description 11
- 238000004458 analytical method Methods 0.000 claims description 7
- 230000001174 ascending effect Effects 0.000 claims description 7
- 238000004364 calculation method Methods 0.000 claims description 4
- 238000012360 testing method Methods 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- 230000001360 synchronised effect Effects 0.000 description 4
- 230000009471 action Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000007405 data analysis Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
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- 230000001276 controlling effect Effects 0.000 description 1
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- 238000013461 design Methods 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
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- 238000010008 shearing Methods 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D27/00—Foundations as substructures
- E02D27/32—Foundations for special purposes
- E02D27/48—Foundations inserted underneath existing buildings or constructions
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D37/00—Repair of damaged foundations or foundation structures
Abstract
The utility model discloses a pre-jacking system and a pre-jacking method for underpinning piles, and relates to the technical field of civil engineering construction. The pre-jacking system comprises a driving system, a monitoring system, a control system, a underpinning beam and a plurality of groups of underpinning devices; the pre-jacking method comprises the following steps: s1, arranging the underpinning pile pre-jacking system; s2, determining a target value of the pre-jacking amount and a theoretical load value; s3, carrying out pre-jacking on the underpinning pile by combining monitoring data of the monitoring system; and S4, when the settlement value of the underpinned pile is monitored to be stable, ending the pre-jacking. According to the utility model, the deformation of the underpinning beam and the deformation of the underpinning device are dynamically regulated and controlled, the settlement of the underpinning beam is monitored in real time through the monitoring system, so that the pre-jacking mode is regulated, the underpinning beam is kept horizontal all the time, cracks on the underpinning beam and the upper structure are prevented, and the stability and the accuracy are improved.
Description
Technical Field
The utility model relates to the technical field of civil engineering construction, in particular to a pre-jacking system and a pre-jacking method for underpinning piles.
Background
The foundation underpinning is a building technology with great difficulty and long construction period, and aims to reinforce, enlarge or shift the existing building, and the underpinning technology is suitable for reinforcing, storey adding or enlarging the existing building, and foundation treatment and foundation reinforcement of the existing building under the influence of building underground engineering, new construction engineering and deep foundation pit excavation. In the underpinning process, the differences in the structural form, the load size, the deformation control requirement (sensitivity to sedimentation and sedimentation difference), the construction space size, the situation of the place where the building is located (topography, ground objects, geological conditions, underground pipelines, underground water levels and the like), the requirement of the structure to be penetrated down and the like are considered, so that the individual difference is large and the difficulty is high.
The active underpinning is to pre-lift the new pile or apply load to the new pile and the underpinning structure by loading the jack before the original pile foundation is cut off, so as to eliminate the partial deformation of the new pile (underpinning pile) and the underpinning structure, and to implement the load transfer step by step in a grading way, so that the deformation of the pile and the structure after the underpinning is controlled in a smaller range. Its advantages are complex operation, long duration and high cost. The existing jacking of the underpinning beam is carried out within the designed maximum jacking force range, jacking is carried out according to the synchronous jacking principle, the jack is used for loading before underpinning, so that the time effect of long-term deformation of the underpinning system is partially eliminated, and in the load conversion process of the upper part, the deformation of the underpinning structure and the upper part is dynamically regulated and controlled by using the jacking device.
Chinese patent No. CN201621215285.1 discloses a full-automatic underpinning apparatus for pile foundation, which comprises: the hydraulic lifting device comprises a underpinning pile, a underpinned pile, an underpinned beam, a column holding beam, a hydraulic jack, a stay wire sensor, a hydraulic pump station, a PLC synchronous control system and a static level monitoring device; the underpinning piles are symmetrically arranged on two sides of the underpinned pile, two ends of the underpinning beam are respectively placed on the corresponding underpinned piles and are poured with the underpinned pile, a column-holding beam is arranged, a hydraulic jack is arranged at the lower end of the column-holding beam, the hydraulic jack is sequentially connected with a hydraulic pump station and a PLC synchronous control system, a static level monitoring device is arranged at the upper end of the column-holding beam, and a stay wire sensor is arranged at the middle position of the lower end of the column-holding beam; the whole set of underpinning construction provided by the utility model is all automated, sedimentation monitoring, calculation, transmission and adjustment are all automatically completed by the corresponding devices, the construction efficiency is high, and the labor cost is reduced. However, the control of the specific jacking mode and jacking force is not strictly provided, the operability is poor, the safety problem is easily caused by large errors, and the jacking efficiency is difficult to improve while the jacking accuracy, jacking quality and construction safety are ensured.
The Chinese patent with the patent number of CN202011188882.0 discloses a jacking method of a underpinning beam in pile foundation underpinning construction, wherein a plurality of jacks are arranged between an underpinning pile and the underpinning beam; and then, lifting the underpinning beam by controlling the lifting force of each jack in a mode of multiple times and successive loading until the preset design lifting force is reached, wherein the lifting force of each jack in the next lifting is greater than the lifting force in the previous lifting, and the lifting force of all jacks in each lifting is the same. The method for jacking the underpinning beam can effectively prevent the deformation, displacement and crack generation of the underpinning beam, avoid the overload problem and improve the operability and the construction safety. However, the utility model does not consider the influence of sedimentation monitoring and adjusts the pre-jacking trend in real time.
Therefore, it is necessary to provide a pre-jacking system and a pre-jacking method for underpinning piles, which have high reliability, improve the jacking accuracy and adjust the pre-jacking mode in real time according to the settlement monitoring amount.
Disclosure of Invention
In order to overcome the defects in the prior art, the utility model provides a pre-jacking system and a pre-jacking method for underpinning piles.
The technical scheme adopted by the utility model is as follows:
a pre-jacking system of underpinning piles comprises a driving system, a monitoring system, a control system, underpinning beams and a plurality of groups of underpinning devices;
the underpinning device comprises underpinning piles, the underpinning piles are arranged below the underpinning beam, a plurality of groups of underpinning piles are distributed on two sides of the underpinning beam, and at least 3 jacks are arranged between each underpinning pile and the underpinning beam;
the driving system is connected with the jack and controls the pressure and displacement of the jack;
the monitoring system is electrically connected with the control system, the underpinning beams and the upper parts of the underpinning piles are provided with the monitoring system, and the monitoring systems arranged above the underpinning beams are multiple.
Further, the monitoring system comprises a displacement sensor and a static level, wherein a plurality of displacement sensors and a plurality of static levels are arranged on the upper portion of the underpinning beam, and the displacement sensors and the static levels are uniformly distributed above the underpinning beam.
Further, the plurality of jacks above each underpinning pile are uniformly distributed around the axis of the underpinning pile, and the jacks are perpendicular to the upper surface of the underpinning pile.
Furthermore, the jack adopts a self-locking hydraulic jack, a screw thread is arranged outside the jack, and a detachable clamp is sleeved outside the screw thread.
Further, the driving system adopts a hydraulic system controlled by a PLC
The underpinning pile pre-jacking method utilizes the underpinning pile pre-jacking system of any one of the above to pre-jack the underpinning pile, and specifically comprises the following steps:
s1, arranging a underpinning pile pre-jacking system;
s2, according to load tests and theoretical calculation of the underpinned pile, determining a pre-jacking quantity target value and a theoretical load value by taking the settlement quantity of the underpinned pile as a target value; the settlement amount of the underpinning pile is a determined target value of the pre-jacking amount;
s3, carrying out pre-jacking on the underpinning pile by combining monitoring data of the monitoring system; if the monitoring values of the monitoring points on the underpinning beam are unchanged, continuously performing pre-jacking, and if the monitoring values of part of the monitoring points have an ascending trend, adjusting the pre-jacking progress;
s4, ending the pre-jacking when the sedimentation value of the pile to be underpinned tends to be stable after being monitored;
s5, pile cutting construction is carried out on the original pile.
Further, the concrete method for carrying out pre-jacking on the underpinning pile comprises the following steps:
s301, setting initial pressurization of a jack to be 1Mpa, and locking a stop valve;
s302, installing a displacement sensor and returning to zero;
s303, pressurizing according to 10% of the theoretical load value, recording monitoring data of the displacement sensor and the static level after each pressurizing, analyzing the monitoring data by the control system, and selectively pressurizing according to an analysis result of the monitoring data;
s304, circulating the step S303 until the jack is loaded to 100% of the load theoretical value, closing the stop valve, and installing a clamp on the outer side of the jack.
Further, in step S303, if the monitored values of the monitored points on the underpinning beam are not changed according to the analysis result of the monitored data, repeating step S303, and pressurizing according to 10% of the theoretical load value; if the monitoring value of part of the monitoring points has an ascending trend, closing a stop valve of the jack near the monitoring point, and recording pressure and displacement data at the moment; and simultaneously recording the settlement of the underpinning pile, measuring and reading the settlement rate of the pile top of the underpinning pile, and repeating the step S303 when the settlement rate reaches the relatively stable standard.
Further, the method for measuring and reading the sedimentation rate of the pile top of the underpinning pile comprises the following steps: measuring and reading the settlement of the pile top of the underpinning pile in 5min, 15min, 30min, 45min and 60min after pressurizing, measuring and reading once every 30min after measuring and reading in 60min after pressurizing, and calculating the settlement rate of the pile top of the underpinning pile;
the relative stability standard means that the settlement rate of the pile top of the underpinning pile is less than 0.1mm/h in two continuous hours.
Further, in step S303, the jack needs to maintain the boost load for at least 10 minutes after reaching the boost load set by the boost during each boost.
Further, in step S303, the supercharging is stopped when the following conditions occur during each supercharging:
(1) The underpinning beam is found to generate cracks, and the maximum width of the cracks is larger than 0.15mm;
(2) And the displacement sensor detects pile top displacement of the underpinning pile, and if the maximum value of pile top ascending displacement of the underpinning pile is larger than 1mm or the maximum value of sinking displacement of the underpinning pile is larger than 3mm.
Further, in the pre-jacking process of the underpinning pile, the jacking force of the two ends of the underpinning beam is regulated by adjusting the driving system in combination with the monitoring data of the monitoring system, so that the underpinning beam is always balanced.
Compared with the prior art, the utility model has the beneficial effects that:
1. the underpinning pile pre-jacking system provided by the utility model comprises a driving system, a monitoring system, a control system, an underpinning beam and a plurality of groups of underpinning devices; the monitoring system electrically connected with the control system comprises a plurality of displacement sensors and static leveling gauges which are distributed on the underpinning beam and the underpinning pile, relative settlement displacement of each monitoring point position on the underpinning beam and the underpinning pile can be monitored in real time and transmitted to the control system, and after data analysis is carried out by the control system, the pre-lifting progress of the driving system and the jack can be adjusted in real time.
2. Compared with the prior art, the underpinning pile pre-jacking method provided by the utility model has the advantages that the settlement amount of the underpinning pile is used as the target value, the target value of the pre-jacking amount and the theoretical load value are determined, and the monitoring data of the monitoring system are combined to perform pre-jacking on the underpinning pile. According to the analysis result of the monitoring data, a proper adding mode is selected for boosting, the pre-lifting of the underpinning beam is converted into a double-control process in the actual underpinning process, the pre-lifting force, the original elevation of the bridge body and the underpinning pile and the lifting displacement value are mutually control factors, the stability of system operation is improved, the deformation of the underpinning structure and the upper structure is dynamically regulated and controlled, the bridge structure is prevented from suddenly generating larger upward displacement under the action force of lifting, so that the structure is damaged or deformed, the relative reliability is higher, and the lifting of the underpinning jack meets the displacement control precision of 0.1 mm.
Drawings
Fig. 1 is a block diagram of a underpinning pile pre-jacking system provided by the utility model.
Fig. 2 is a schematic diagram of a method for pre-jacking a underpinning pile.
Reference numerals illustrate:
1. a joist is replaced; 2. a jack; 3. a displacement sensor; 4. a static level; 5. a pile cap; 6. a new pile;
7. and (5) original piles.
Detailed Description
In order to make the purpose and technical solution of the embodiments of the present utility model more clear, the technical solution of the present utility model will be clearly and completely described below in connection with the embodiments of the present utility model.
In the description of the present utility model, it should be understood that the terms "length," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present utility model and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a particular orientation, be configured and operated in a particular orientation, and thus should not be construed as limiting the present utility model.
As shown in fig. 1, the utility model provides a underpinning pile pre-jacking system, which comprises a driving system, a monitoring system, a control system, underpinning beams 1 and a plurality of groups of underpinning devices, wherein the underpinning devices are distributed on two sides below the underpinning beams 1, and the underpinning devices on two sides below the underpinning beams 1 are symmetrically arranged.
The underpinning device comprises an underpinning pile, the underpinning pile comprises a new pile 6 and a pile cap 5, the upper part of the new pile 6 is fixedly connected with the pile cap 5, at least 3 jacks 2 are arranged between the pile cap 5 and the underpinning beam 1, and the jacks 2 are arranged between the underpinning beam 1 and the underpinning pile and are used for loading by the jacks 2 before underpinning, so that the time effect of long-term deformation of an underpinning system can be partially eliminated; the jack 2 is preferably a hydraulic jack 2, a stop valve is arranged on the jack 2, and the stop valve is suitable for high-pressure occasions with larger load, belongs to a cut-off valve, and controls the passing and interruption of fluid so as to control the pre-lifting process.
The outer side wall of the jack 2 is provided with a spiral screw thread, and a detachable clamp is fixedly sleeved on the outer side of the spiral screw thread; the clamp is tightly attached to the lower surface of the underpinning beam 1. The clamp cooperates with the spiral thread, and has stronger shearing resistance. The jack 2 selects the self-locking hydraulic jack 2, can realize automatic locking, is used for supporting heavier underpinning beam 1 for a long time, prevents that underpinning beam 1 from dropping suddenly, improves the security of system.
The driving system is connected with the jack 2 and controls the pressure and displacement of the jack 2; preferably, the drive system employs a PLC controlled hydraulic system. The hydraulic system and the hydraulic jack 2 together form a driving execution device of the whole pre-lifting system, and the PLC controls the strength and the speed of the jack 2 in the adjustment of the settlement of the underpinning pile through a pump station in the hydraulic system.
The monitoring system is electrically connected with the control system and comprises a plurality of displacement sensors 3 and a static level 4, the upper wall of the underpinning beam 1 is provided with the plurality of displacement sensors 3 and the static level 4, the plurality of displacement sensors 3 and the static level 4 are uniformly distributed on the upper portion of the underpinning beam 1, and the underpinning pile is also provided with the displacement sensors 3 and the static level 4 for measuring sedimentation values of a plurality of points of the underpinning pile and also for measuring sedimentation values of the upper portion of the underpinning pile. The displacement sensor 3 and the static level 4 can be used for monitoring the relative settlement displacement of the positions of each monitoring point on the underpinning beam 1 and the underpinning pile in real time and transmitting the relative settlement displacement to the control system, and the control system can be used for adjusting the pre-lifting progress of the driving system and the jack 2 in real time after carrying out data analysis.
The control system is also provided with an interactive PC end, and a control interface is arranged on the PC end and contains data such as oil source pressure, displacement and the like. The monitoring system and the driving system are controlled by the control system, and can fully automatically complete synchronous displacement, thereby realizing various functions such as force and displacement control, operation locking, process display, fault alarm and the like.
At least three jacks 2 are arranged on the upper portion of each pile cap 5, the jacks 2 are evenly arranged at intervals around the axis of each pile cap 5, the jacks 2 on each pile cap 5 are arranged into a group, the axes of the jacks 2 in each group are arranged in parallel, and the axes of the jacks 2 are perpendicular to the upper wall of the pile cap 5. The stress between the underpinning pile and the underpinning beam 1 is more balanced, and the stability and safety of jacking can be further improved.
The distance between the underpinning beam 1 and the underpinning pile preferably leaves 500m of jacking space before the jack 2 is installed.
As shown in fig. 2, the utility model further provides a underpinning pile pre-jacking method, which uses the underpinning pile pre-jacking system to pre-press the underpinning pile, and specifically comprises the following steps:
s1, arranging a underpinning pile pre-jacking system;
firstly pouring the underpinning beam 1 and the original pile 7 together, and then selecting the type of the jack 2 according to actual conditions, wherein in the embodiment, a 500 ton hydraulic jack 2 is selected, the length of the jack 2 is 150mm, the diameter of a base is 210mm, and the stroke is 40mm; in the arrangement process, each underpinning pile is a group, the top of each new pile 6 is provided with a pile cap 5, at least three jacks 2 are uniformly arranged at the upper part of the pile cap 5 at intervals around the axis of the pile cap 5, and a clamp encircling the outside of the screw threads of the jacks 2 is temporarily not installed.
S2, according to load tests and theoretical calculation of the underpinned pile, determining a pre-jacking quantity target value and a theoretical load value by taking the settlement quantity of the underpinned pile as a target value; the settlement amount of the underpinning pile is the determined target value of the pre-lifting amount.
S3, carrying out pre-jacking on the underpinning pile by combining monitoring data of the monitoring system;
the integral pre-jacking process is used for enabling the early-stage settlement amount after the load is converted to the underpinned pile to be stable, pre-jacking is carried out on the underpinned pile, namely, the underpinned pile is pressurized in a mode of increasing 10% of oil source pressure step by step, the pre-jacking is carried out to reach 100% of a theoretical load value, and meanwhile, the state is kept for a certain time until the pre-jacking is finished when the settlement of the underpinned pile is monitored to be stable.
The method for carrying out pre-jacking on the underpinning pile specifically comprises the following steps:
s301, the jack 2 is initially pressurized by 1Mpa, the stop valve is locked, the jack cannot move downwards in the state of locking the stop valve, and the jack can also move upwards;
s302, installing the displacement sensor 3 and returning to zero;
s303, pressurizing according to 10% of the theoretical load value, recording monitoring data of the displacement sensor 3 and the static level 4 after each pressurizing, analyzing the monitoring data by the control system, and pressurizing according to the analysis result of the monitoring data;
determining whether to continue pressurizing according to the analysis result of the monitoring data, wherein the two conditions are as follows:
if the monitoring values of the monitoring points on the underpinning beam 1 are unchanged, repeating the step S303, and pressurizing according to 10% of the theoretical load value;
if the monitoring value of part of the monitoring points has an ascending trend, closing the stop valve of the jack 2 near the monitoring points, and recording the pressure and displacement data when the jack cannot move downwards or upwards under the state of closing the stop valve; simultaneously recording the settlement of the pile foundation, measuring and reading the settlement rate of the pile top of the underpinning pile, and repeating the step S303 when the settlement rate reaches the relatively stable standard;
the method for measuring and reading the sedimentation rate of the pile top of the underpinning pile comprises the following steps: measuring and reading pile top settlement amount in 5, 15, 30, 45 and 60 minutes after pressurization, measuring and reading once every 30 minutes, and calculating the settlement rate of the pile top of the underpinning pile; the relative stability standard means that the settlement rate of the pile tops of the underpinned piles is less than 0.1mm/h for two continuous hours.
S304, the step S303 is circulated until the jack 2 loads 100% of the load theoretical value, the stop valve is closed, and the clamp is installed on the outer side of the jack 2. Plays a supporting role to prevent the underpinning beam 1 from suddenly descending;
and S4, when the settlement value of the underpinned pile is monitored to be stable, ending the pre-jacking.
In the actual underpinning process, the jacking of the underpinning beam 1 is a double-control process, and the jacking force, the original elevation of the bridge body and the pier column and the jacking displacement value are mutually control factors. The bridge structure should be prevented from suddenly being displaced upward greatly under the action of pre-jacking, thereby causing structural damage or deformation. Therefore, load classification is required to be finer in the actual pre-jacking process, the pre-jacking loading process is slow, and informatization construction is adopted to monitor data to guide underpinning jacking. The pre-lifting of the underpinning jack 2 is required to meet the displacement control precision of 0.1 mm. After the whole pre-jacking and jacking process is completed, the stress conversion of the foundation of the jacking bridge pier is realized, so that monitoring for a period of time is carried out after each pre-jacking is finished.
In step S303, during each pressurization process, the jack 2 needs to maintain the pressurization load for at least 10 minutes after reaching the pressurization load set by the pressurization.
In step S303, in each pressurizing process, if a crack is found to occur in the joist 1, and the maximum width of the crack is greater than 0.15mm, the pressurizing is stopped. The possible cause of the crack is that the lifting force of the jack 2 is uneven, the bridge pier is partially deformed or displaced, if the bridge pier is deformed, the pressurization should be stopped in time, and the crack is processed to prevent the crack from further expanding.
When in the pre-lifting process, the pre-lifting force of the jack 2 is required to be strictly controlled, and the deformation and displacement are monitored in real time, so that the lifting force of each jack 2 reaches a control value, and the deformation of the underpinning beam 1 and the existing bridge pier does not exceed the control value. Therefore, in step S303, during each pressurization process, the displacement sensor 3 detects the pile top displacement of the underpinning pile, and if the maximum value of the pile top rising displacement of the underpinning pile is greater than 1mm or the maximum value of the sinking displacement is greater than 3mm, the pressurization is stopped.
And the driving device is adjusted by combining the monitoring data of the monitoring system, so that the jacking forces at the two ends of the underpinning beam 1 are regulated, the underpinning beam 1 is always balanced, and the PCL automatic control system is utilized to automatically regulate the pressure value input into the system in advance so as to ensure the balance of the jacking forces at the two ends. The deformation of the underpinning structure and the superstructure is dynamically regulated by means of the residual pressure system, in which case the superstructure may be slightly lifted, for example less than 1mm, while the settlement of the new pile 6 is largely eliminated. The method can control the pile position jacking value and the settlement value to be in a tiny control range, is suitable for underpinning engineering with large underpinning load or high structural deformation requirement, and has higher relative reliability.
S5, pile cutting construction
After pile foundation settlement of the underpinning pile is stable and jack 2 locks, static cutting equipment is adopted to cut the obstacle original pile 7, the cutting position of the original pile 7 is at a position 0.5m away from the bottom of the underpinning beam 1, a port with the depth of 100mm and the width of 200mm is firstly opened along the circumference of the pile, in the process, steel bars inside the original pile 7 are continuously cut, in the process, the principle of stripping layer by layer from outside to inside is followed, the fracture height of the broken pile is controlled within a range of 300-500mm, settlement change monitoring is carried out in the process of cutting the original pile 7, the settlement of the underpinning pile is kept within an allowable range, and the lifting value on the pile end of the underpinning pile is controlled to be not more than 1mm and the settlement value is controlled to be not more than 3mm.
The foregoing is a description of embodiments of the utility model, which are specific and detailed, but are not to be construed as limiting the scope of the utility model. 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 utility model, which are all within the scope of the utility model.
Claims (12)
1. The utility model provides a support and change stake jacking system in advance which characterized in that: comprises a driving system, a monitoring system, a control system, a underpinning beam and a plurality of groups of underpinning devices;
the underpinning device comprises underpinning piles, the underpinning piles are arranged below the underpinning beam, a plurality of groups of underpinning piles are distributed on two sides of the underpinning beam, and at least 3 jacks are arranged between each underpinning pile and the underpinning beam;
the driving system is connected with the jack and controls the pressure and displacement of the jack;
the monitoring system is electrically connected with the control system, the underpinning beams and the upper parts of the underpinning piles are provided with the monitoring system, and the monitoring systems arranged above the underpinning beams are multiple.
2. The underpinning pile pre-jacking system of claim 1, wherein: the monitoring system comprises displacement sensors and static leveling instruments, wherein a plurality of displacement sensors and a plurality of static leveling instruments are arranged on the upper portion of the underpinning beam, and the displacement sensors and the static leveling instruments are uniformly distributed above the underpinning beam.
3. The underpinning pile pre-jacking system of claim 1, wherein: the plurality of jacks above each underpinning pile are uniformly distributed around the axis of each underpinning pile, and the jacks are perpendicular to the upper surface of each underpinning pile.
4. A underpinning pile pre-jacking system as claimed in claim 3, wherein: the jack adopts auto-lock hydraulic jack, the jack outside is equipped with the spiral screw thread, the outside cover of spiral screw thread is established detachable clamp.
5. The underpinning pile pre-jacking system of claim 1, wherein: the driving system adopts a hydraulic system controlled by a PLC.
6. A pre-jacking method for underpinning piles is characterized by comprising the following steps of: a underpinning pile pre-jacking method by using the underpinning pile pre-jacking system according to any one of claims 1 to 5, comprising the following steps:
s1, arranging a underpinning pile pre-jacking system;
s2, according to load tests and theoretical calculation of the underpinned pile, determining a pre-jacking quantity target value and a theoretical load value by taking the settlement quantity of the underpinned pile as a target value; the settlement amount of the underpinning pile is a determined target value of the pre-jacking amount;
s3, carrying out pre-jacking on the underpinning pile by combining monitoring data of the monitoring system; if the monitoring values of the monitoring points on the underpinning beam are unchanged, continuously performing pre-jacking, and if the monitoring values of part of the monitoring points have an ascending trend, adjusting the pre-jacking progress;
s4, ending the pre-jacking when the sedimentation value of the pile to be underpinned tends to be stable after being monitored;
s5, pile cutting construction is carried out on the original pile.
7. The underpinning pile pre-jacking method according to claim 6, wherein the method comprises the following steps: the concrete method for carrying out pre-jacking on the underpinning pile comprises the following steps:
s301, setting initial pressurization of a jack to be 1Mpa, and locking a stop valve;
s302, installing a displacement sensor and returning to zero;
s303, pressurizing according to 10% of the theoretical load value, recording monitoring data of the displacement sensor and the static level after each pressurizing, analyzing the monitoring data by the control system, and pressurizing according to an analysis result of the monitoring data;
s304, circulating the step S303 until the jack is loaded to 100% of the load theoretical value, closing the stop valve, and installing a clamp on the outer side of the jack.
8. The underpinning pile pre-jacking method according to claim 7, wherein the method comprises the following steps: in the step S303, if the monitoring values of the monitoring points on the underpinning beam are unchanged according to the analysis result of the monitoring data, repeating the step S303, and pressurizing according to 10% of the theoretical load value; if the monitoring value of part of the monitoring points has an ascending trend, closing a stop valve of the jack near the monitoring point, and recording pressure and displacement data at the moment; and simultaneously recording the settlement of the underpinning pile, measuring and reading the settlement rate of the pile top of the underpinning pile, and repeating the step S303 when the settlement rate reaches the relatively stable standard.
9. The underpinning pile pre-jacking method according to claim 8, wherein the method comprises the following steps: the method for measuring and reading the sedimentation rate of the pile top of the underpinning pile comprises the following steps: measuring and reading the settlement of the pile top of the underpinning pile in 5min, 15min, 30min, 45min and 60min after pressurizing, measuring and reading once every 30min after measuring and reading in 60min after pressurizing, and calculating the settlement rate of the pile top of the underpinning pile;
the relative stability standard means that the settlement rate of the pile top of the underpinning pile is less than 0.1mm/h in two continuous hours.
10. The underpinning pile pre-jacking method according to claim 7, wherein the method comprises the following steps: in step S303, during each pressurization process, the jack needs to maintain the pressurization load for at least 10 minutes after reaching the pressurization load set by the pressurization.
11. The underpinning pile pre-jacking method according to claim 7, wherein the method comprises the following steps: in step S303, the supercharging is stopped every time the following occurs during the supercharging:
(1) The underpinning beam is found to generate cracks, and the maximum width of the cracks is larger than 0.15mm;
(2) And the displacement sensor detects pile top displacement of the underpinning pile, and if the maximum value of pile top ascending displacement of the underpinning pile is larger than 1mm or the maximum value of sinking displacement of the underpinning pile is larger than 3mm.
12. The underpinning pile pre-jacking method according to claim 6, wherein the method comprises the following steps: in the pre-jacking process of the underpinning pile, the jacking force of the two ends of the underpinning beam is regulated by adjusting the driving system by combining the monitoring data of the monitoring system, so that the underpinning beam is always balanced.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310834743.8A CN116950120A (en) | 2023-07-07 | 2023-07-07 | Pre-jacking system and pre-jacking method for underpinning pile |
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