CN201901875U - Excavation environment controlling and protecting monitoring unit for large-scale ultra-deep foundation pit - Google Patents

Abstract

The utility model relates to a large-scale ultra-deep foundation pit excavation environment control and protection monitoring device, which comprises a display, a data processor, a ground subsidence detector, a pipeline damage detector, an elevated pile foundation displacement detector, a water pressure sensor, earth pressure sensor, the data processor is connected to the display, and the ground subsidence detector, pipeline damage detector, elevated pile foundation displacement detector, water pressure sensor, and earth pressure sensor are respectively connected to the data processor . Compared with the prior art, the utility model has the advantages of high safety to the surrounding environment, effective and reasonable analysis of large-scale ultra-deep foundation pits, and the like.

Description

A large-scale ultra-deep foundation pit excavation environment control and protection monitoring device

technical field

The utility model relates to a monitoring device, in particular to a large-scale ultra-deep foundation pit excavation environment control and protection monitoring device.

Background technique

The foundation pit of the World Expo substation is located in a soft soil area, and it is the first case in Shanghai and even the whole country to excavate a super large foundation pit of more than 30 meters in such a complex surrounding environment. Therefore, how to predict, control and protect the buildings (structures) and pipelines adjacent to the foundation pit has become a difficult and urgent problem to be solved. Corresponding to the urgency of engineering needs, at present, only experience (such as Peck method) can be used to predict the deformation mode of sheet pile or row pile support. Various analysis methods at home and abroad do not yet have a method for calculating, evaluating and controlling the environmental impact of large-scale ultra-deep foundation pit excavation in soft soil areas. Therefore, how to determine the size of the ground deformation for the enclosure structure of the underground diaphragm wall and the coupling of underground drainage conditions And distribution mode, and ensure the safety of the surrounding environment, so as to guide the design and construction has important direct application value.

Engineering Technology Requirements:

(1) The deformation and stability of foundation pit enclosure structure, the deformation analysis of surrounding pipelines, buildings and pile foundations of viaducts are carried out under the comprehensive working conditions of confined water, phreatic precipitation measures, and enclosure structure construction and excavation. and the premise of protection.

(2) The comparison between the measured results and the analysis results of the foundation pit is the basis for determining a reasonable analysis model and calculation method, thus providing a basis for reasonable environmental control and protection in the next construction process of the foundation pit.

Difficulties in implementing the project:

(1) Comprehensive comparison and selection of various research methods at home and abroad to determine the analysis and calculation methods suitable for large-scale ultra-deep foundation pit excavation in soft soil areas;

(2) Using statistical theory and methods, based on variables such as excavation depth of foundation pit, support enclosure structure, precipitation measures and other variables, determine the deformation mode and deformation size of foundation pit under various influencing factors;

(3) Calculation and simulation of the seepage field in the process of precipitation such as confined water and phreatic water;

(4) Stress field simulation caused by earth excavation and its fluid-solid coupling calculation of soil settlement and deformation;

(5) Analysis of the impact of excavation and precipitation on surrounding elevated pile foundations;

(6) Analysis of the impact of excavation and dewatering on surrounding buried pipelines, including three-dimensional deformation, pipeline internal force and safety evaluation criteria.

The existing technology has the following disadvantages: the safety of the surrounding environment is low, and the analysis of large-scale ultra-deep foundation pits cannot be effective and reasonable.

Contents of the invention

The purpose of the utility model is to overcome the above-mentioned defects in the prior art and provide a high security for the surrounding environment, which is effective and reasonable for the analysis of large-scale ultra-deep foundation pit excavation environment control and Protective monitoring device.

The purpose of this utility model can be achieved through the following technical solutions: a large-scale ultra-deep foundation pit excavation environment control and protection monitoring device, characterized in that the device includes a display, a data processor, a ground subsidence detector, a pipeline receiving Damage detector, elevated pile foundation displacement detector, water pressure sensor, earth pressure sensor, the data processor is connected to the display, the ground subsidence detector, pipeline damage detector, elevated pile foundation displacement detector, The water pressure sensor and the earth pressure sensor are respectively connected with the data processor.

The data processor includes a FLAC3D numerical analysis module and a FRWS foundation pit analysis module.

Compared with the existing technology, the utility model not only verifies the safety of the foundation pit itself under the design and construction plan of the dewatering excavation, but more importantly, it is expected to judge the surrounding ground settlement, surrounding pipelines and the displacement of the elevated pile foundation during the excavation of the foundation pit The degree of environmental impact such as settlement and settlement provides a direct basis for controlling the safety of the foundation pit project and the controllability of the surrounding environment safety under various excavation conditions in advance. Specifically include: first, the expected evaluation of the safety of each design and construction scheme on the surrounding environment; second, to obtain the main influencing factors on the surrounding environment, and provide matters that need attention in the design and construction; third, based on the comparison of monitoring data, draw a more Reasonable and effective analysis methods for large-scale ultra-deep foundation pits provide analysis basis and experience for future large-scale ultra-deep foundation pits.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Detailed ways

The utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example

As shown in Figure 1, a large-scale ultra-deep foundation pit excavation environment control and protection monitoring device, the device includes a display 1, a data processor 2, a ground subsidence detector 3, a pipeline damage detector 4, an elevated pile foundation Displacement detector 5, water pressure sensor 6, earth pressure sensor 7, data processor 2 connected to display 1, ground subsidence detector 3, pipeline damage detector 4, elevated pile foundation displacement detector 5, water pressure sensor 6, The earth pressure sensors 7 are respectively connected to the data processor 2, and the data processor 2 includes a FLAC3D numerical analysis module and a FRWS foundation pit analysis module.

A large-scale ultra-deep foundation pit excavation environment control and protection method, the steps of the method are as follows:

(1) Comparing the results of various methods for the enclosure structure with the measured values, a reasonable analysis method for determining the deformation of super-large-diameter and super-deep foundation pits is determined:

The deformation of the enclosure structure was analyzed by Clough method (1989), Tongji Qixing retaining structure analysis software FRWS and FLAC3D numerical simulation. The results show that the maximum deformation of the building envelope can be estimated by using appropriate empirical methods, but the deformation value may be overestimated. For the lateral deformation of deep foundation pits, the distribution law and maximum value of the lateral deformation of the enclosure wall given by the current analysis method have higher calculation accuracy than the measured values. As for the vertical displacement of the retaining wall, the calculation results show that when the compressive modulus of the soil is selected to calculate the excavation analysis of the deep foundation pit, the upward vertical displacement of the retaining structure given will be somewhat larger.

(2) Evaluation of the influencing factors of land subsidence under the action of various factors, and a comparative study of the land subsidence obtained by each analysis method and the measured value:

A variety of analysis methods were used to analyze the ground settlement of the foundation pit of the World Expo substation, including three methods provided by Tongji Qixing support structure analysis software FRWS (Peck simplified analysis method, Tongji triangle model and Tongji parabola model), Peck empirical method ( 1969), Clough & Rourke method (1990), Hsieh & Ou method (1998) and FLAC3D three-dimensional numerical analysis method. The results show that the Tongji parabolic model and the Hsieh & Ou method provided by Tongji Venus software FRWS are the closest to the measured values, while the calculated results of FLAC3D are relatively small. The ground subsidence value is slightly smaller.

In terms of the ground settlement model outside the pit, the Tongji parabolic model, the Hsieh & Ou method and FLAC3D are more consistent with the actual situation. The maximum settlement is located at the edge of the foundation pit at a distance of 18m, 17m, and 17m, respectively, while the measured maximum value appears in the range of 15-20m beside the pit Inside. Judging from the impact range of ground subsidence caused by excavation of foundation pit dewatering, the three-dimensional analysis results are in good agreement with the measured values.

The statistical analysis results of foundation pit excavation and precipitation on the enclosure structure and ground subsidence in Shanghai area have strong practicability. Whether it is the lateral deformation of the enclosure structure or the ground subsidence outside the pit, the measured values of this project are all in Shanghai. within the scope of statistical results of deep foundation pits.

(3) Safety analysis of viaduct pile foundation under various working conditions of foundation pit dewatering and excavation:

The pile foundation deformation of the viaduct on the Chengdu North Road side includes two parts: the horizontal displacement and the vertical displacement toward the foundation pit side, and the horizontal displacement is greater than the vertical settlement. In terms of the horizontal displacement distribution of the pile foundation, the displacement of the pile tip is the largest, followed by the pile top. The middle part is the smallest, but the overall displacement difference is within 3mm, and the pile length is 30m, so the bending deformation rate is very small. For each pile foundation in the same cap, as the distance from the foundation pit increases, the deformation gradually decreases. In terms of the force of the pile cap pile foundation, the largest negative bending moment is generated at the pile head. When excavating to the bottom of the pit, the maximum positive bending moment of the pile foundation is 110kN·m, and the maximum negative bending moment is 28kN·m. The measured pile foundation settlement of the viaduct is affected by some other factors so that its distribution law is not obvious, but the overall value is very small, within 5mm, indicating that the excavation of the foundation pit has little effect on the pile foundation of the viaduct.

(4) Determination of pipeline safety evaluation indicators and standards, analysis of pipeline internal force under different deformation distribution modes, and safety evaluation of pipelines under various excavation conditions:

The safety of pipelines is closely related to pipe materials and joints. The safety of the pipeline can be judged by the pipeline structure rotation angle, structural displacement and allowable rotation angle and displacement, pipeline stress (calculated indirectly from pipeline strain) and allowable stress.

Different settlement displacement modes of pipelines will produce different pipeline internal force distributions. Two deformation modes, normal distribution mode and error compensation function, are used to compare. It is found that the vertical deformation of the pipeline mostly follows the normal distribution mode, while the horizontal deformation and error compensation The function forms are similar, and the comparative analysis shows that the vertical deformation of the pipeline has a more obvious influence on the mechanical properties of the pipeline than the horizontal deformation.

The measured pipeline settlement is affected by the weight of the pipe joint and the transported objects in the pipe, and does not strictly follow the rule that the farther away from the foundation pit, the smaller the settlement. The effect of transporting substances (such as increased weight, etc.). The analysis shows that for relatively flexible pipes, the maximum settlement occurs near the central axis of the foundation pit, and the distribution pattern is close to the calculated value; while for rigid pipes, the maximum settlement does not appear on the central axis of the foundation pit, but is about In the range of 20 to 30m, there are mostly bimodal or single peak distribution phenomena.

For the first time in China, the present invention systematically studies the analysis of the environmental impact and control of ground settlement around the foundation pit, buildings, pipelines and viaduct pile foundations under the construction conditions of super-large diameter and super-deep foundation pit excavation and dewatering construction in soft soil areas , and achieved the following series of innovative achievements in the technical field:

Systematically analyzed foreign representative enclosure structures and ground settlement deformation analysis methods, and simulated the construction excavation process through three-dimensional fluid-solid coupling analysis. Reasonable analysis methods for structures and land subsidence.

The quantitative analysis and evaluation of the impact degree on the surrounding environment of the foundation pit are systematically analyzed under the influence of multiple factors such as the form of the enclosure structure, construction of confined water and phreatic precipitation, overloading of the pit side, and uplift of the pit bottom.

Using the statistical method, the statistical analysis results of foundation pit excavation and precipitation on the surrounding structure and ground subsidence are obtained, which has strong practicability.

Through the passive pile theory and three-dimensional simulation analysis, the safety assessment of the pile foundation of the elevated bridge around the deep foundation pit is carried out.

The standards and evaluation indicators for the safety evaluation of the pipeline around the pit are determined, and two different pipeline distribution patterns are used to determine the size of the internal force of the pipeline and the change process with the excavation of the foundation pit, and the degree of influence on the internal force of the pipeline under different deformation conditions is obtained, and A 3D construction simulation analysis was carried out.

The comparison of the analysis results provided in the early stage with the subsequent actual measurement results shows that the calculation values of the deformation of the enclosure structure, ground settlement around the pit, surrounding buildings, pipelines and viaducts are consistent with the actual measurement values, and it is an ultra-large diameter and ultra-deep foundation pit in soft soil areas The environmental assessment explores a reasonable analysis approach and method, which can be used for reference in the subsequent environmental control of large-scale ultra-deep foundation pits in soft soil areas, and fills the gap in this field in my country.

The invention not only verifies the safety of the foundation pit itself under the design and construction scheme of dewatering excavation, but more importantly, it is expected to judge the degree of environmental impact such as the surrounding ground settlement, the displacement and settlement of the surrounding pipelines and elevated pile foundations during the excavation of the foundation pit, for Provide direct basis for Party A to control in advance the safety of the World Expo Foundation Pit Project under various excavation conditions and the controllability of the safety of the surrounding environment. The specific functions are as follows: first, to predict and evaluate the safety of each design and construction scheme on the surrounding environment; second, to obtain the main influencing factors on the surrounding environment, and to provide matters needing attention in the design and construction; third, to draw conclusions based on the comparison of monitoring data. A more reasonable and effective analysis method for large-scale ultra-deep foundation pits will provide analysis basis and experience for future large-scale ultra-deep foundation pits. Through the implementation of the project, the foundation pit of the Expo substation has been safely excavated to the bottom of the pit, and the surrounding ground settlement, pipelines and elevated pile foundations are all within the expected controllable safety range, ensuring the safety of the surrounding environment and achieving The intended purpose of the project implementation.

Claims (2)

1. A large-scale ultra-deep foundation pit excavation environment control and protection monitoring device is characterized in that the device includes a display, a data processor, a ground subsidence detector, a pipeline damage detector, an elevated pile foundation displacement detector, The water pressure sensor, the earth pressure sensor, the data processor is connected with the display, and the ground subsidence detector, the pipeline damage detector, the elevated pile foundation displacement detector, the water pressure sensor, and the earth pressure sensor are respectively connected with the data processing device connection. 2. A large-scale ultra-deep foundation pit excavation environment control and protection monitoring device according to claim 1, wherein said data processor includes a FLAC3D numerical analysis module and a FRWS foundation pit analysis module.

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