CN115688518A - Calculation method for realizing underground pipe gallery displacement control in deep foundation pit construction - Google Patents
Calculation method for realizing underground pipe gallery displacement control in deep foundation pit construction Download PDFInfo
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- CN115688518A CN115688518A CN202211329979.8A CN202211329979A CN115688518A CN 115688518 A CN115688518 A CN 115688518A CN 202211329979 A CN202211329979 A CN 202211329979A CN 115688518 A CN115688518 A CN 115688518A
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Abstract
The invention discloses a calculation method for realizing underground pipe gallery displacement control in deep foundation pit construction, and belongs to the field of civil and architectural engineering construction. The urban underground pipelines are criss-cross, so that the stability of the urban underground pipelines needs to be considered when designing and constructing foundation pit engineering, and the influence of peripheral pipelines needs to be controlled within a certain range. According to the construction method, a two-dimensional mathematical model of the deep foundation pit is established by using Geo-Studio software, the whole process of foundation pit excavation and precipitation construction is simulated, the final construction steps and the method of the foundation pit are optimized and determined, the disturbance of the foundation pit construction to a pipe gallery is reduced to the minimum, and the safety of the pipe gallery in the construction process is greatly improved. The invention is based on the conventional foundation pit construction process, does not need other high special equipment, construction materials and matched professional constructors, does not increase the engineering investment, and has better popularization value.
Description
Technical Field
The invention belongs to the technical field of civil and architectural engineering construction, and particularly relates to a calculation method for realizing underground pipe gallery displacement control in deep foundation pit construction.
Background
With the continuous acceleration of the urbanization process, underground pipelines such as gas, water delivery, pollution discharge, electric power, communication and the like are criss-cross, are important infrastructures for guaranteeing urban operation, and are known as urban 'lifelines'. The construction of urban subways, high-rise buildings and underground business circles needs to excavate foundation pits, and the foundation pits are often adjacent to underground pipelines or even intersect the underground pipelines. Excavation, drainage and support of foundation pit engineering inevitably lead to redistribution of the stress of soil bodies inside and outside the foundation pit, so that the soil bodies deform, and underground pipelines displace and even break, thereby causing great economic loss and adverse social influence. Therefore, the stability of the foundation pit engineering needs to be considered during design and construction, the deformation of municipal pipelines near the foundation pit needs to be controlled within a certain range, the influence factors are complex, and a plurality of difficulties exist in construction.
The urban underground pipeline engineering mostly adopts a pipe-jacking construction process, and the absolute displacement of the pipeline, the settlement difference between every two sections of pipes and the inclination angle have strict requirements. In the actual foundation pit engineering adjacent to or crossed with the pipeline, an additional stress method is often adopted to solve the stress on the pipeline, the foundation pit construction is usually carried out by layered and segmented excavation and synchronous support, the calculation method cannot consider the influence of the whole construction process, and cannot provide a foundation pit construction scheme for guaranteeing the safety of the pipeline, so that technical support is provided for the actual foundation pit construction process.
Disclosure of Invention
(1) Technical problem to be solved
The invention provides a calculation method for realizing underground pipe gallery displacement control in deep foundation pit construction, which overcomes the defects that the existing calculation method takes a foundation as an elastic foundation, cannot simulate complex actual geological conditions, cannot consider the dynamic whole process influence of foundation pit construction, and cannot draw up a foundation pit construction scheme which is practical and effective for controlling the deformation of a pipe gallery according to the calculation result.
(2) Technical scheme
In order to solve the technical problem, the calculation method for realizing underground pipe gallery displacement control in deep foundation pit construction comprises the following steps:
and 5, comprehensively considering the influences of construction process, excavation partition and the like in construction, and optimizing the process with larger displacement, (1) if the pipe gallery floats upwards greatly after the primary foundation pit dewatering and excavation process are completed, the excavation depth of the process can be reduced, or the pumping and drainage strength of the foundation pit is increased, and the water level line is reduced. (2) If the gallery has larger settlement in the primary foundation pit dewatering and excavation process, the excavation depth of the process can be reduced, or the pumping and drainage strength of the foundation pit is reduced, and the water level line is increased. (3) Reasonably selecting an excavation area, or adding auxiliary engineering measures. If the soil bodies on the two sides of the pipe gallery are excavated to the bottom elevation of the foundation pit, the covering soil weight above the pipe gallery is reserved, finally, the covering soil is excavated in a slicing type, and the pipe gallery is prevented from floating upwards by adopting a form of locking a steel beam while excavating;
and 6, optimizing the displacement change of the pipe gallery in each construction process under the construction scheme through model calculation analysis, and continuously correcting until the displacement of the target pipe gallery under the recommended construction scheme is controlled within a range of 10mm, so that the risk of damage to the pipe gallery in construction can be successfully reduced.
Advantageous effects
The invention has the beneficial effects that: the invention provides a calculation method for realizing underground pipe gallery displacement control in deep foundation pit construction. The method has the advantages that a deep foundation pit two-dimensional mathematical model is built by utilizing Geo-Studio software, the whole process of foundation pit excavation and precipitation construction is simulated, the final construction steps and the method of the foundation pit are optimized and determined, the disturbance of the foundation pit construction to a pipe gallery is reduced to the minimum, and the safety of the pipe gallery in the construction process is greatly improved. The invention is based on the conventional foundation pit construction process, does not need other expensive special equipment, construction materials and matched professional constructors, does not increase the engineering investment, and has better popularization value.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
Fig. 1 is a cross plan view of a deep foundation pit and a power pipe gallery of a channel project of a Jinan river in Fuzhou.
Fig. 2 is a cross sectional view of a deep foundation pit and an electric power pipe gallery of the channel engineering of the straight-discharge Minjiang river of the Jinan river in Fuzhou.
FIG. 3 is a two-dimensional mathematical model of a deep foundation pit of the engineering of the Jinan river in Fuzhou City in the straight discharge Minjiang river.
Fig. 4 is a simplified diagram of the excavation process of the foundation pit in the preliminary construction scheme.
Fig. 5 is a simplified view of the final construction scheme for the excavation of the foundation pit.
Fig. 6 is a cloud diagram of displacement changes of the pipe gallery after the final construction scheme process 1 of the foundation pit is completed.
Fig. 7 is a cloud diagram of displacement changes of the pipe gallery after the final construction scheme process 2 of the foundation pit is completed.
Fig. 8 is a cloud view of the displacement change of the pipe gallery after the final construction scheme procedure 3 of the foundation pit is completed.
Fig. 9 is a cloud view of displacement changes of the pipe gallery after the final construction scheme process 4 of the foundation pit is completed.
Fig. 10 is a cloud view of displacement changes of the pipe gallery after the final construction scheme of the foundation pit is completed in step 5.
Fig. 11 is a cloud view of displacement changes of the pipe gallery after the final construction scheme process 6 of the foundation pit is completed.
Fig. 12 is a cloud view of displacement changes of the pipe gallery after the final construction scheme process 7 of the foundation pit is completed.
Fig. 13 is a graph of the results of the foundation pit excavation process and the power pipe gallery settlement value calculation in the construction scheme 1.
FIG. 14 is a diagram of the optimized construction scheme for the excavation process of the foundation pit and the settlement result of the settlement value of the power pipe gallery.
Fig. 15 is a construction process 6 foundation pit excavation process and electric power piping lane settlement result chart.
Detailed Description
The technical solutions in the embodiments of the present invention are further clearly and completely described below with reference to the embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
Example one
The embodiment provides a calculation method for realizing the whole process control of an underground pipe gallery in the deep foundation pit construction, and the embodiment is further detailed by combining the calculation of box culvert deep foundation pit excavation on the tail section of the straight-line Minjiang channel engineering of Jinan river in Fuzhou.
The construction content of the engineering is that a section of water passing box culvert is built on a tailgating road and is connected with a water gate, the water passing box culvert is crossed with a high-voltage cable top pipe of a transformer substation on the tailgating road section, the minimum vertical distance between a pipe gallery and the water passing box culvert is only 0.3m, and the plane section of the engineering is shown in figures 1 and 2. The foundation ditch is planned to excavate to 0m elevation soil layer to the piping lane top and is exposed during the construction period, installs the girder steel in the piping lane top, arranges and crosses water box culvert. The displacement deformation of cable piping lane receives the influence of foundation ditch construction very big.
Firstly, collecting design data such as a plane arrangement diagram at the intersection of box culverts and a pipe gallery of a planned row tail section, a foundation pit excavation supporting cross section diagram and the like, and data of landform and geomorphic appearance of an engineering area, distribution conditions of rock-soil layers, calculation parameters of each rock-soil layer, distribution conditions of underground water of a site, design of pipelines and operation maintenance.
A two-dimensional mathematical model of a foundation pit and a pipe gallery is established by utilizing Geo-Studio software, a drainage well is arranged, and geotechnical parameters and underground water level are input, wherein the parameters are shown in figure 3. One construction process is defined as one precipitation and one excavation, and the precipitation and excavation construction scheme of the foundation pit is preliminarily formulated as shown in fig. 4. The displacement deformation of the pipe gallery in the scheme is calculated through a Geo-Studio two-dimensional finite element model and is shown in figure 13, when the construction scheme is adopted, the maximum displacement of a single working procedure of the power pipe gallery is 8.0mm, after the accumulated excavation of the foundation pit is 3.0m, the maximum displacement of the pipe gallery reaches 13.0mm, the water level in the foundation pit is reduced by 2.5m at the moment, and the construction scheme has great influence on the deformation and the safety of the pipe gallery in the foundation pit. The rule can be obtained from the calculation result of the scheme: the influence that the soil body received excavation off-load is greater than the influence of tube well precipitation among this engineering, and the produced soil body resilience volume of excavation 1.0 meter soil body is greater than the soil body settlement value that precipitation 1.0 meter leads to, therefore precipitation 1.0m among the construction scheme, the construction scheme of excavation 1.0m going on in turn can lead to the piping lane to have great come-up in the work progress, and the process is more, should optimize.
As shown in fig. 14, the optimization scheme adopts three times of precipitation and three times of excavation from the ground to the overburden layer, wherein precipitation is 1.6m each time, excavation is 1.3m each time, and precipitation and excavation are alternately carried out. And excavating soil bodies on two sides of the covering soil twice, excavating the covering soil again, and installing locking steel beams. The earthing both sides soil body of piping lane top divides twice excavation, before the excavation earthing, reduces electric power piping lane position ground water level to-1.1 m water level. From the calculation results, it can be seen that: the accumulated displacement value after the first three working procedures are finished is not more than 1mm, and the settlement value and the rebound value of the foundation pit reach a good balance state. And after soil bodies on two sides of the covering soil are excavated to the bottom elevation of the box culvert bottom plate, the accumulated displacement of the power pipe gallery in the foundation pit is minus 5.5mm.
In the process 6 of the optimized scheme, the single construction process of the process 6 enables the power pipe gallery to float upwards by 6mm, and the accumulated floating upwards of the power pipe gallery is 0.5mm. For reducing the displacement of the pipe gallery that process 6 caused, under the unchangeable circumstances of other construction processes of keeping, through the measure of the interior precipitation of increase pipe gallery, optimize construction process 6, calculation operating mode and calculation result are as shown in figure 15. Comprehensive analysis shows that when the position of the power pipe gallery is lowered to-1.3 m, the floating value of the pipe gallery in the excavated area of the covering soil is still larger, and when the position of the power pipe gallery is lowered to-1.9 m, the sedimentation value of the pipe gallery below the reserved part of the covering soil is larger, so that the water level below the power pipe gallery is preferably lowered to 1.5 to 1.7m in the process.
After the numerical simulation optimization scheme, the final construction process of the straight-row Fujian river deep foundation pit engineering is as follows:
step 1: the elevation of the original ground is 6.6m, and a thick soil layer of 1.3m is excavated after the precipitation in the foundation pit is 1.6 m. (excavation to 5.3m height at this time)
And a 2 nd step: and excavating a 1.3m thick soil layer after the water in the foundation pit is reduced by 1.6 m. (excavation to 4.0m elevation at this time)
And a 3 rd step: and (4) excavating a 1.3m thick soil layer after continuously lowering water by 1.6m in the foundation pit, and reserving a 1.5m thick cover soil on the top of the pipe gallery. (excavation to 2.7m elevation at this point)
And (4) a step of: and excavating soil bodies on two sides of the reserved covering soil to 1.205 m.
And a 5 th step: lowering the water level in the foundation pit by 0.8m to-0.6 m, covering soil above the excavation pipe gallery, excavating and locking the covering soil in a segmented mode (each segment is 1.0 m) along the direction perpendicular to the water flow direction, locking 1 anti-floating steel beam after earthing each excavation bottom width is 1.0m, performing excavation and locking on the steel beams in the next step after welding and locking, and performing circular construction until all excavation and locking are completed.
And a 6 th step: the soil body outside the jet grouting pile is excavated to 0.1m elevation in a unified mode, and certain degree of precipitation can be considered according to the actual pipe gallery and the stress monitoring condition of the anti-floating steel beam in the process.
The construction is carried out according to the construction procedures, and the displacement of the power pipe gallery can be successfully controlled to be 10mm
Within, reduce the risk that the piping lane destroys.
Claims (1)
1. A calculation method for realizing underground pipe gallery displacement control in deep foundation pit construction is characterized by comprising the following steps:
step 1, collecting design data such as a plane section and the like of a proposed foundation pit, wherein engineering relates to pipeline design, operation and maintenance data;
step 2, collecting the landform, the distribution condition of the geotechnical layers, the calculation parameters of each geotechnical layer and the distribution condition of ground water in the field of the engineering area;
step 3, establishing a two-dimensional finite element model of the longitudinal section of the foundation pit by using Geo-Studio software, preliminarily drawing up a construction scheme for alternately carrying out foundation pit dewatering and excavation, and calculating the displacement deformation value and the accumulated displacement value of the pipe gallery in each time of the foundation pit dewatering and excavation working procedures under the scheme;
step 4, carrying out comparative analysis on the displacement influence of each construction procedure on the pipe gallery obtained by numerical simulation calculation, summarizing the relation between a settlement value caused by precipitation in the foundation and the rebound quantity of the foundation pit caused by excavation, and striving to offset the pipe gallery floating value caused by excavation and the settlement caused by precipitation in the primary precipitation and excavation procedures so as to ensure that the displacement of the pipe gallery is relatively unchanged after the primary precipitation and excavation construction procedure is completed;
step 5, comprehensively considering the influences of construction process, excavation partition and the like in construction, optimizing the process with larger displacement, (1) if the pipe gallery floats upwards greatly after the primary foundation pit dewatering and excavation process is finished, reducing the excavation depth of the process, or increasing the pumping and drainage strength of the foundation pit, reducing the water level line,
(2) if the gallery is greatly settled in the primary foundation pit dewatering and excavation process, the excavation depth of the process can be reduced, or the pumping and drainage strength of the foundation pit can be increased, the water level line can be increased,
(3) reasonably selecting an excavation area, or adding auxiliary engineering measures,
if the soil bodies on the two sides of the pipe gallery are excavated to the bottom elevation of the foundation pit, the covering soil weight above the pipe gallery is reserved, finally, the covering soil is excavated in a slicing type, and the pipe gallery is prevented from floating upwards by adopting a form of locking a steel beam while excavating;
and 6, optimizing the displacement change of the pipe gallery in each construction process under the construction scheme through model calculation analysis, and continuously correcting until the displacement of the target pipe gallery under the recommended construction scheme is controlled within a range of 10mm, so that the risk of damage to the pipe gallery in construction can be successfully reduced.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116906837A (en) * | 2023-09-15 | 2023-10-20 | 上海同济工程咨询有限公司 | State monitoring system and monitoring method for underground pipeline |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116906837A (en) * | 2023-09-15 | 2023-10-20 | 上海同济工程咨询有限公司 | State monitoring system and monitoring method for underground pipeline |
| CN116906837B (en) * | 2023-09-15 | 2023-11-28 | 上海同济工程咨询有限公司 | State monitoring system and monitoring method for underground pipeline |
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