CN111680383A - Method for predicting additional confining pressure change of lower shield tunnel caused by foundation pit excavation - Google Patents
Method for predicting additional confining pressure change of lower shield tunnel caused by foundation pit excavation Download PDFInfo
- Publication number
- CN111680383A CN111680383A CN202010140265.7A CN202010140265A CN111680383A CN 111680383 A CN111680383 A CN 111680383A CN 202010140265 A CN202010140265 A CN 202010140265A CN 111680383 A CN111680383 A CN 111680383A
- Authority
- CN
- China
- Prior art keywords
- tunnel
- foundation pit
- excavation
- shield tunnel
- lower shield
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Excavating Of Shafts Or Tunnels (AREA)
Abstract
The invention discloses a method for predicting additional confining pressure change of a lower shield tunnel caused by foundation pit excavation, which comprises the following steps of calculating additional load distribution on a tunnel cross section according to an unloading model of the foundation pit excavation; and providing a shield tunnel transverse additional confining pressure change model capable of considering the acting force between the longitudinal deformation rings and obtaining a computing method of the additional confining pressure. The method can predict the change of the lining confining pressure of the lower shield tunnel caused by excavation of the foundation pit, and is suitable for the working condition of the cross shield operation tunnel on the foundation pits with different excavation sizes; theoretical support is provided for stress of the tunnel structure under corresponding working conditions, a full-size shield segment loading test and subway tunnel operation safety; the possibility of overlarge changes of confining pressure and stress is early warned, safety accidents are prevented from being caused, the engineering is prevented and guided, and the construction cost can be saved.
Description
Technical Field
The invention belongs to the technical field of underground engineering, and particularly relates to a prediction method for additional confining pressure change of a lower shield tunnel caused by foundation pit excavation.
Background
With the development of urban rail transit and the development and utilization of underground space, the situation of crossing operation shield tunnels on foundation pit engineering is more and more. When the foundation pit is excavated, the excavation unloading action is directly transmitted to the lower shield tunnel through the soil body from the excavation surface. The tunnel bulges with the soil layer and simultaneously generates large additional load on the tunnel structure. Because the excavation unloading capacity of the foundation pit is large, the unloading effect on the structure can destroy the stress balance of the segment structure, so that deformation and even damage are generated, and the safety of the shield tunnel in operation is greatly influenced. In order to ensure the safe operation of the rail transit line, the subway tunnel has a relatively strict deformation control requirement, so that the research on the influence of the excavation of the foundation pit on the stress deformation of the lower shield tunnel has an important application value. Therefore, a theoretical calculation method for the change of the confining pressure of the lower shield tunnel caused by excavation of the foundation pit needs to be further studied, and theoretical support is provided for subway tunnel operation safety and related full-size structure loading tests.
Such engineering problems have been paid attention at home and abroad, and currently, the main research methods mainly include: statistical analysis of measured data, numerical simulation, theoretical calculation and centrifugal model test. At present, a research result aiming at shield tunnel confining pressure change caused by foundation pit excavation is mainly obtained by finite element simulation and a centrifugal model, and a result obtained by a current common finite element simulation method can only be used as a basis for qualitative judgment, so that a quantitative accurate result is difficult to obtain. Refined numerical simulation has higher requirements on a calculation model and calculation equipment, and needs higher calculation cost. The centrifugal model test needs large-scale supergravity centrifuge, high-precision sensor and model experiment box, and the cost of test research is higher. The theoretical calculation method for shield tunnel confining pressure change caused by the foundation pit is less researched, and especially the achievement of the theoretical calculation method for the additional confining pressure of the lower shield tunnel caused by foundation pit excavation is not reported.
Disclosure of Invention
The invention aims to provide a method for predicting the additional confining pressure change of a lower shield tunnel caused by foundation pit excavation aiming at the defects of the prior art. The tunnel confining pressure obtained by the method is superposed with a normal working condition load combination, and the influence of foundation pit excavation on the lower shield tunnel can be effectively evaluated.
The purpose of the invention is realized by the following technical scheme: a method for predicting additional confining pressure change of a lower shield tunnel caused by foundation pit excavation comprises the following steps:
(1) and establishing a coordinate system at the center o of the foundation pit, wherein the x axis is vertical to the axis of the tunnel, the y axis is parallel to the axis of the tunnel, and the z axis takes the vertical direction as the positive direction.
(2) According to the coordinate system established in the step 1, the unloading of the excavation surface at the bottom of the foundation pit caused by the excavation of the foundation pit at the upper part is calculated, and the distribution of vertical additional stress and horizontal additional stress on the cross section of the shield tunnel at the lower part caused by the unloading of the excavation surface at the bottom of the foundation pit is obtained, and the method specifically comprises the following substeps:
(2.1) the unloading of the excavation surface at the bottom of the foundation pit is uniformly distributed loads vertically upwards at the bottom of the foundation pit, and the unloading p at the bottom of the foundation pit is calculated:
p＝(1-α0)γd (1)
wherein gamma is the soil gravity, the weighted average value of the excavated soil layers above the foundation pit bottom is taken, d is the excavation depth of the foundation pit, α0Is the residual stress factor.
(2.2) according to Mindlin stress solution, taking the excavation surface of the foundation pit bottom as an integral area, and calculating to obtain the vertical additional stress sigma on the cross section of the lower shield tunnel under the excavation unloading of the foundation pit bottomaz(theta, l) and horizontal additional stress sigmaax(θ, l) are respectively:
wherein: theta is the position angle of a calculation point on the cross section of the lower shield tunnel, the upper vertex is 0 DEG, and the angle in the clockwise direction is increased; b is the excavation size of the foundation pit along the x-axis direction; l is the excavation size of the foundation pit along the y-axis direction; d is the excavation depth of the foundation pit; h is the tunnel buried depth; d is the outer diameter of the lower shield tunnel; a is the horizontal distance between the center of the foundation pit and the axis of the tunnel, and l is a corresponding y coordinate value of any point on the axis of the tunnel in the coordinate system; x is the number of1Is a first integral variable, y1Is a second integral variable, σzzFor Mindlin vertical stress solution, σxzIs Mindlin horizontal stress solution.
(3) According to the field monitoring data of the longitudinal deformation of the tunnel, the vertical displacement of the tunnel is combined to obtain the resultant force distribution between the vertical rings of the duct piece, and the method specifically comprises the following substeps:
(3.1) measuring the total vertical displacement w (l) of the tunnel along the longitudinal direction, measuring the displacement caused by the corner between the pipe piece rings, and calculating the vertical inter-ring shearing force Q between the pipe piece ring at the l position and the pipe piece ring at the previous sectionL(l) And the vertical inter-ring shear force Q between the next segment of the pipe sheet ringR(l)：
QL(l)＝(1-j)[w(l-Dt)-w(l)]×ksl(4)
QR(l)＝(1-j)[w(l)-w(l-Dt)]×ksl(5)
Wherein j is the ratio of the displacement caused by the corner between adjacent segment rings to the total vertical displacement, DtIs the width of the segment ring, kslFor the inter-annular shear stiffness of the tunnel, QL(l) With the direction of action being positive, QR(l) With the direction of action being positive downwards.
(3.2) according to QL(l) And QR(l) Obtaining the resultant force F of the vertical ring of the segment received by the segment ring at the position lsz(l)：
Fsz(l)＝QR(l)-QL(l) (6)
(4) According to the vertical additional stress sigma on the cross section of the lower shield tunnel obtained in the step (2.2)az(theta, l) and horizontal directionAdditional stress sigmaax(θ, l), calculating additional load distribution in each direction of different parts on the lower shield tunnel lining:
wherein p isaz(theta, l) is the vertical additional load, p ', lining the upper half of the lower shield tunnel'ax(theta, l) is the horizontal additional load, p ″, of the left side lining of the lower shield tunnelaxAnd (theta, l) is the horizontal additional load of the right side lining of the lower shield tunnel.
And then, establishing a lower shield tunnel lining additional confining pressure change model according to the additional load distribution of different parts on the lower shield tunnel lining in all directions:
wherein, FsxActing as a resultant force between the rings in the horizontal direction, FszIs a resultant force between rings in the vertical direction, Δ qRThe unloading amount of the vertical counter force of the arch bottom is used.
(5) Selecting a calculation section to be analyzed of the lower shield tunnel according to evaluation requirements, leading the additional load on the tunnel lining at the position of the calculation section obtained in the step (4) and the resultant force between the vertical rings of the segments at the position of the calculation section obtained in the step (3) into the additional confining pressure change model of the lower shield tunnel lining established in the step (4), and obtaining the resultant force F between the horizontal rings at the calculation sectionsxAnd the unloading amount delta q of the arch bottom vertical counter forceR。
(6) According to the distribution of additional loads on different parts of the lower shield tunnel lining in all directions and the unloading quantity delta q of the arch bottom vertical counter forceRObtaining the additional confining pressure p of the lower shield tunnel lining after stable deformationar(θ,l)：
Compared with the prior art, the invention has the beneficial effects that:
(1) the method is suitable for the working condition of the foundation pit crossing operation shield tunnel with different excavation sizes and different position relations of the foundation pit;
(2) according to the method, engineering geological hydrological information and design parameters which are necessary for corresponding engineering are adopted in the process of predicting the confining pressure change condition of the lower shield tunnel before foundation pit construction and excavation, and extra exploration and design cost investment is not required.
(3) The method can predict the confining pressure change of the lower shield tunnel caused by excavation of the foundation pit, and provides theoretical support for stress of the tunnel structure, a full-size shield segment loading test and subway tunnel operation safety under corresponding working conditions; the possibility of overlarge changes of confining pressure and stress is early warned, safety accidents are prevented from being caused, the engineering is prevented and guided, and the construction cost can be saved.
Drawings
FIG. 1 is a schematic illustration of the effect of excavation of a foundation pit on an underlying shield tunnel;
FIG. 2 is a diagram showing the relationship between the positions of a foundation pit and a shield tunnel;
FIG. 3 is a schematic diagram of redistribution of tunnel confining pressure under the action of additional load of excavation of a foundation pit, wherein (a) is a schematic diagram of a first stage, (b) is a schematic diagram of a second stage, and (c) is a schematic diagram of a third stage;
FIG. 4 is a schematic diagram of the combination of the initial load and the additional load, wherein (a) is a schematic diagram of the combination of the load under the initial working condition of the tunnel, and (b) is a schematic diagram of the additional confining pressure of the tunnel lining after the tunnel is deformed and stabilized;
FIG. 5 is a comparison graph of confining pressure before and after excavation of a foundation pit;
FIG. 6 is a comparison graph of additional confining pressure of a shield tunnel caused by excavation of an upper foundation pit;
fig. 7 is a comparison graph of measured values and calculated values of horizontal additional convergence deformation of a lower tunnel caused by excavation of a foundation pit.
Detailed Description
The invention is further illustrated by the following examples and figures.
Fig. 1 is a schematic diagram showing the influence of excavation of a foundation pit on a lower shield tunnel, and as shown in fig. 1, the lower shield tunnel strides upward in the foundation pit engineering not only causes the axis of the lower shield tunnel to generate longitudinal uplift deformation, but also causes the cross section of a tunnel lining within the influence range to generate overall displacement and ovalization deformation. FIG. 2 is a diagram showing the relationship between the positions of the foundation pit and the shield tunnel, where the upper foundation pit crosses the lower shield tunnel, D is the excavation depth of the foundation pit, h is the buried depth of the tunnel, D is the outer diameter of the lower shield tunnel, and a is the horizontal distance between the center of the foundation pit and the axis of the tunnel, as shown in FIG. 2.
The invention discloses a method for predicting additional confining pressure change of a lower shield tunnel caused by excavation of a foundation pit, which comprises the following steps of:
(1) according to the design data, as shown in fig. 1-2, a coordinate system is established at the center o of the foundation pit, the x-axis is perpendicular to the axis of the tunnel, the y-axis is parallel to the axis of the tunnel, and the z-axis is in the positive direction of the vertical direction.
(2) According to the coordinate system established in the step 1, the unloading of the excavation surface at the bottom of the foundation pit caused by the excavation of the foundation pit at the upper part is calculated, and the distribution of the vertical additional stress and the horizontal additional stress on the cross section of the shield tunnel at the lower part caused by the unloading of the excavation surface at the bottom of the foundation pit is obtained, and the method specifically comprises the following substeps:
(2.1) the unloading of the excavation surface at the bottom of the foundation pit is uniformly distributed loads vertically upwards at the bottom of the foundation pit, and the unloading p at the bottom of the foundation pit is calculated:
p＝(1-α0)γd (1)
wherein gamma is the soil gravity, the weighted average value of the excavated soil layers above the foundation pit bottom is taken, d is the excavation depth of the foundation pit, α0The coefficient can be used for considering the condition that the stress at the bottom of the foundation pit is not completely released.
(2.2) according to Mindlin stress solution, taking the excavation surface of the foundation pit bottom as an integral area, and calculating to obtain the vertical additional stress sigma on the cross section of the lower shield tunnel under the excavation unloading of the foundation pit bottomaz(theta, l) and horizontal additional stress sigmaax(θ, l) are respectively:
wherein: theta is the position angle of a calculation point on the cross section of the lower shield tunnel, the upper vertex is 0 DEG, and the angle in the clockwise direction is increased; b is the excavation size of the foundation pit along the x-axis direction; l is the excavation size of the foundation pit along the y-axis direction; as shown in fig. 2, D is the excavation depth of the foundation pit, h is the buried depth of the tunnel, D is the outer diameter of the shield tunnel below, and a is the horizontal distance between the center of the foundation pit and the axis of the tunnel; l is a y coordinate value corresponding to any point on the tunnel axis in the coordinate system; x is the number of1Is a first integral variable, y1Is a second integral variable, σzzFor Mindlin vertical stress solution, σxzIs Mindlin horizontal stress solution.
(3) According to the field monitoring data of the longitudinal deformation of the tunnel, the vertical displacement of the tunnel is combined to obtain the resultant force distribution between the vertical rings of the duct piece, and the method specifically comprises the following substeps:
(3.1) measuring the total vertical displacement w (l) of the tunnel along the longitudinal direction, measuring the displacement caused by the corner between the pipe piece rings, and calculating the vertical inter-ring shearing force Q between the pipe piece ring at the l position and the pipe piece ring at the previous sectionL(l) And the vertical inter-ring shear force Q between the next segment of the pipe sheet ringR(l)：
QL(l)＝(1-j)[w(l-Dt)-w(l)]×ksl(4)
QR(l)＝(1-j)[w(l)-w(l-Dt)]×ksl(5)
Wherein j is the ratio of the displacement caused by the corner between adjacent segment rings to the total vertical displacement, DtIs the width of the segment ring, kslFor the inter-annular shear stiffness of the tunnel, QL(l) With the direction of action being positive, QR(l) With the direction of action being positive downwards.
(3.2) according to QL(l) And QR(l) Obtaining the resultant force F of the vertical ring of the segment received by the segment ring at the position lsz(l)：
Fsz(l)＝QR(l)-QL(l) (6)
(4) As shown in fig. 3, the tunnel confining pressure redistribution diagram under the action of the additional load of the foundation pit excavation is shown, the tunnel confining pressure redistribution diagram is divided into 3 stages, the first stage is shown in fig. 3(a), the foundation pit excavation can cause the vertical additional load p of the upper half part lining of the tunnel belowazAnd horizontal additional loads p 'of left and right side linings'axAnd p ″)axAccording to the vertical additional stress sigma on the cross section of the lower shield tunnel obtained in the step (2.2)az(theta, l) and horizontal additional stress sigmaax(θ, l), calculating additional load distribution in each direction of different parts on the lower shield tunnel lining:
wherein p isaz(theta, l) is the vertical additional load, p ', lining the upper half of the lower shield tunnel'ax(theta, l) is the horizontal additional load, p ″, of the left side lining of the lower shield tunnelaxAnd (theta, l) is the horizontal additional load of the right side lining of the lower shield tunnel.
In the second stage, as shown in fig. 3(b), the tunnel confining pressure balance is broken by the additional load, the tunnel cross section is displaced as a whole, and the longitudinal axis is deformed. Due to the longitudinal non-uniform deformation of the tunnel, relative displacement occurs between adjacent segment rings. Adjacent tube sheet rings connected by longitudinal bolts are mutually constrained and generate an inter-ring acting force.
The third stage is as shown in fig. 3(c), the uninstallation on tunnel upper portion finally can transmit to the bottom through the structure, and the vertical counter force of the arch bottom of tunnel bottom is with partial uninstallation, often will encircle the bottom counter force among the actual structural design and regard as the rectangle load, vertically upwards act on the lining, according to the additional load distribution of different parts in all directions on the shield tunnel lining of below, establish the additional confined pressure change model of shield tunnel lining of below:
wherein, FsxActing as a resultant force between the rings in the horizontal direction, FszIs a resultant force between rings in the vertical direction, Δ qRThe unloading amount of the vertical counter force of the arch bottom is used.
(5) The horizontal displacement of the tunnel below the foundation pit and the horizontal acting force among rings caused by the horizontal displacement are mainly caused by asymmetric unloading of the whole tunnel ring lining in the horizontal direction, and under the condition that longitudinal and transverse stresses are mutually influenced, the key for researching the change of the tunnel surrounding pressure below is to combine the longitudinal acting force among rings on the basis of the transverse stress of the tunnel, so that a calculated section to be analyzed of the shield tunnel below is selected according to an evaluation requirement, the additional load on the tunnel lining at the position of the calculated section obtained in the step (4) and the vertical acting resultant force among rings of the pipe pieces at the position of the calculated section obtained in the step (3) are led into the additional surrounding pressure change model of the shield tunnel lining below established in the step (4), and the horizontal acting resultant force F among rings at the calculated section is obtainedsxAnd the unloading amount delta q of the arch bottom vertical counter forceR。
(6) According to the distribution of additional loads on different parts of the lower shield tunnel lining in all directions and the unloading quantity delta q of the arch bottom vertical counter forceRObtaining the additional confining pressure p of the lower shield tunnel lining after stable deformationar(θ,l)：
It should be noted that the invention is intended to obtain the additional confining pressure of the tunnel lining, and the initial confining pressure can be obtained by combining the loads under the initial working condition of the tunnel. The load combination under the initial working condition of the tunnel considered by the invention is shown in fig. 4 (a). The initial working condition load combination in the figure comprises: (1) self weight g of the lining; (2) covering soil with vertical soil pressure q; (3) lateral active earth pressure pe(ii) a (4) Hydrostatic pressure pw(ii) a (5) Arch bottom counter force qR(ii) a (6) Lateral soil resistance p after deformation of pipe sheet ring under various load effectsk. After the excavation of the foundation pit is completed, the tunnel lining additional confining pressure after the tunnel deformation is stable, which is calculated according to the method of the invention, is shown in fig. 4 (b). And superposing the initial confining pressure and the additional confining pressure to obtain a final tunnel lining confining pressure value, and applying the final tunnel lining confining pressure value to a common revised inertial method or a finite element analysis model to study the internal force and deformation response of the tunnel lining.
Examples
Taking a tunnel crossing the subway No. 1 line left side in the first stage of an Yanan road-benevolence and road crossing street in Hangzhou city as an example: the excavation size L of the foundation pit plane is 11.4m, B is 14.83m, and the excavation depth d is 8.2 m. The axial buried depth h of the lower shield tunnel is 15.3m, the outer diameter D of the shield tunnel lining is 6.2m, and the ring width DtThe underground water level buried depth is about 1M, the water level fluctuation is small in the construction process, the change of the underground water level is not considered in the calculation, the soil layer distribution and corresponding parameters are shown in table 1, and when the foundation pit excavation unloading is calculated, the residual stress coefficient is α0＝0.3。
Table 1: soil layer distribution and physical and mechanical parameters
And obtaining a soil body related calculation parameter value by adopting a method of taking a weighted average value: heavy gamma (kN/m) of soil3) (ii) a Cohesion C (kPa); internal friction angle Φ (°); poisson's ratio of soil mu. And the horizontal distance l between the tunnel section to be calculated and the excavation center of the foundation pit along the y-axis direction.
According to the method of the invention, the stable deformation tunnel lining additional confining pressure p is obtainedar(θ,l)。
FIG. 5 is a comparison graph of confining pressure before and after excavation of a foundation pit. According to the working conditions of the embodiment, the method can be used for calculating the tunnel confining pressure before the foundation pit is excavated and after the foundation pit is excavated, and the section at the position where l is 0m below the excavation center is taken as an example, as shown in fig. 5. Before the foundation pit is excavated, the water and soil pressure is increased along with the increase of the depth, so that the calculated shield tunnel has the advantages of small upper part and large lower part, and is distributed in bilateral symmetry. The upper apex is 0 deg., and the clockwise angle increases. The change of the ambient pressure is small within the range of 0-90 degrees and is between 218.46kPa and 234.56 kPa. The ambient pressure is gradually increased between 90 degrees and 150 degrees, and the maximum ambient pressure is about 272.45kPa at the temperature of 150 degrees. Because the foundation pit is positioned right above the tunnel in the implementation, the tunnel lining confining pressure calculated according to the theoretical method of the invention is still symmetrically distributed. As shown in fig. 5, after the excavation of the foundation pit, the tunnel confining pressure below the excavation center (i.e., at a position of 0m) is significantly reduced. The confining pressure unloading effect caused by excavation of the foundation pit mainly acts on the vault and the vicinity of the vault bottom of the tunnel lining below. The unloading effect of the tunnel vault (at 0 degree) is the most obvious, and the confining pressure is reduced to 161.92kPa from 218.46kPa before excavation, and is reduced by 25.88%.
Figure 6 is an illustration of the additional confining pressure applied to the segment lining ring at different distances from the excavation center along the shield tunnel direction. As shown, the additional confining pressure is all negative, i.e. excavation of the foundation pit mainly causes the confining pressure of the tunnel lining below to be reduced. The additional confining pressure influence area is mainly near the arch crown and the arch bottom, and the absolute value of the additional confining pressure at the arch waist is smaller. The absolute value of the additional confining pressure at the arch top of the tunnel lining below the center of excavation of the foundation pit (l is 0m) is maximum and is 56.54 kPa. And as the horizontal distance from the excavation center is increased, the absolute value of the additional confining pressure acting on the lower shield tunnel lining is reduced. And in the vicinity of the lower part of the excavation area, the absolute value of the additional confining pressure acting on the upper half part of the shield tunnel lining is larger than that of the lower half part. The difference in additional confining pressure between the upper and lower portions of the lining gradually decreased as the distance from the excavation area increased until the additional confining pressure at the dome and the arch was substantially equivalent at 7.2m from the excavation center (i.e., -7.2 m), which was-22.42 kPa and-21.12 kPa, respectively. As the distance from the excavation center increases further, the absolute value of the additional load on the tunnel lining will be changed to a distribution of the lower size and the upper size.
In order to verify the reliability of the method, the initial confining pressure calculated by the theoretical method of the invention, the additional confining pressure caused by the excavation of the upper foundation pit and the acting force between rings are used as load combinations for structural stress analysis in a finite element model. The deformation of the segment rings at different positions can be obtained through calculation, and the horizontal additional convergence deformation measured values of all the ring segments are compared. Fig. 7 is a comparison between the measured value of the horizontal additional convergence deformation of the lower tunnel caused by excavation of the foundation pit and the calculation result in this case. The positive value represents that the shield tunnel segment ring is compressed horizontally and the arch waist is deformed in a radial convergence manner, and the unit is mm. As shown in fig. 7, the horizontal convergence deformation values at the positions of the lower tunnel and the change rules thereof along the longitudinal direction of the tunnel, which are calculated by the method of the present invention, are basically matched with the measured values, so that the reliability of the calculation result of the method of the present invention is verified.
Claims (1)
1. A method for predicting additional confining pressure change of a lower shield tunnel caused by foundation pit excavation is characterized by comprising the following steps:
(1) and establishing a coordinate system at the center o of the foundation pit, wherein the x axis is vertical to the axis of the tunnel, the y axis is parallel to the axis of the tunnel, and the z axis takes the vertical direction as the positive direction.
(2) According to the coordinate system established in the step 1, the unloading of the excavation surface at the bottom of the foundation pit caused by the excavation of the foundation pit at the upper part is calculated, and the distribution of the vertical additional stress and the horizontal additional stress on the cross section of the shield tunnel at the lower part caused by the unloading of the excavation surface at the bottom of the foundation pit is obtained, and the method specifically comprises the following substeps:
(2.1) the unloading of the excavation surface at the bottom of the foundation pit is uniformly distributed loads vertically upwards at the bottom of the foundation pit, and the unloading p at the bottom of the foundation pit is calculated:
p＝(1-α0)γd (1)
wherein gamma is the soil gravity, the weighted average value of the excavated soil layers above the foundation pit bottom is taken, d is the excavation depth of the foundation pit, α0Is the residual stress factor.
(2.2) according to Mindlin stress solution, taking the excavation surface of the foundation pit bottom as an integral area, and calculating to obtain the vertical additional stress sigma on the cross section of the lower shield tunnel under the excavation unloading of the foundation pit bottomaz(theta, l) and horizontal additional stress sigmaax(θ, l) are respectively:
wherein: theta is the position angle of a calculation point on the cross section of the lower shield tunnel, the upper vertex is 0 DEG, and the angle in the clockwise direction is increased; b is the excavation size of the foundation pit along the x-axis direction; l is the excavation size of the foundation pit along the y-axis direction; d is the excavation depth of the foundation pit; h is the tunnel buried depth; d is the outer diameter of the lower shield tunnel; a is the horizontal distance between the center of the foundation pit and the axis of the tunnel, and l is a corresponding y coordinate value of any point on the axis of the tunnel in the coordinate system; x is the number of1Is a first integral variable, y1Is a second integral variable, σzzFor Mindlin vertical stress solution, σxzIs Mindlin horizontal stress solution.
(3) According to the field monitoring data of the longitudinal deformation of the tunnel, the vertical displacement of the tunnel is combined to obtain the resultant force distribution between the vertical rings of the duct piece, and the method specifically comprises the following substeps:
(3.1) measuring the total vertical displacement w (l) of the tunnel along the longitudinal direction, measuring the displacement caused by the corner between the pipe piece rings, and calculating the vertical inter-ring shearing force Q between the pipe piece ring at the l position and the pipe piece ring at the previous sectionL(l) And the vertical inter-ring shear force Q between the next segment of the pipe sheet ringR(l)：
QL(l)＝(1-j)[w(l-Dt)-w(l)]×ksl(4)
QR(l)＝(1-j)[w(l)-w(l-Dt)]×ksl(5)
Wherein j is the ratio of the displacement caused by the corner between adjacent segment rings to the total vertical displacement, DtIs the width of the segment ring, kslFor the inter-annular shear stiffness of the tunnel, QL(l) With the direction of action being positive, QR(l) With the direction of action being positive downwards.
(3.2) according to QL(l) And QR(l) Obtaining the resultant force F of the vertical ring of the segment received by the segment ring at the position lsz(l)：
Fsz(l)＝QR(l)-QL(l) (6)
(4) According to the vertical additional stress sigma on the cross section of the lower shield tunnel obtained in the step (2.2)az(theta, l) and horizontal additional stress sigmaax(θ, l), calculating additional load distribution in each direction of different parts on the lower shield tunnel lining:
wherein p isaz(theta, l) is the vertical additional load, p ', lining the upper half of the lower shield tunnel'ax(theta, l) is the horizontal additional load, p ″, of the left side lining of the lower shield tunnelaxAnd (theta, l) is the horizontal additional load of the right side lining of the lower shield tunnel.
And then, establishing a lower shield tunnel lining additional confining pressure change model according to the additional load distribution of different parts on the lower shield tunnel lining in all directions:
wherein, FsxActing as a resultant force between the rings in the horizontal direction, FszIs a resultant force between rings in the vertical direction, Δ qRThe unloading amount of the vertical counter force of the arch bottom is used.
(5) Selecting a calculation section to be analyzed of the lower shield tunnel according to evaluation requirements, leading the additional load on the tunnel lining at the position of the calculation section obtained in the step (4) and the resultant force between the vertical rings of the segments at the position of the calculation section obtained in the step (3) into the additional confining pressure change model of the lower shield tunnel lining established in the step (4), and obtaining the resultant force F between the horizontal rings at the calculation sectionsxAnd the unloading amount delta q of the arch bottom vertical counter forceR。
(6) According to the distribution of additional loads on different parts of the lower shield tunnel lining in all directions and the unloading quantity delta q of the arch bottom vertical counter forceRObtaining the additional confining pressure p of the lower shield tunnel lining after stable deformationar(θ,l)：
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010140265.7A CN111680383B (en) | 2020-03-03 | 2020-03-03 | Method for predicting additional confining pressure change of lower shield tunnel caused by foundation pit excavation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010140265.7A CN111680383B (en) | 2020-03-03 | 2020-03-03 | Method for predicting additional confining pressure change of lower shield tunnel caused by foundation pit excavation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111680383A true CN111680383A (en) | 2020-09-18 |
| CN111680383B CN111680383B (en) | 2023-07-07 |
Family
ID=72451386
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010140265.7A Active CN111680383B (en) | 2020-03-03 | 2020-03-03 | Method for predicting additional confining pressure change of lower shield tunnel caused by foundation pit excavation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111680383B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112597674A (en) * | 2020-12-05 | 2021-04-02 | 福建工程学院 | Method for determining lateral pipeline transverse additional internal force caused by foundation pit excavation |
| CN113111417A (en) * | 2021-04-15 | 2021-07-13 | 交通运输部公路科学研究所 | Additional load calculation method for local removal of tunnel lining |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2209978C1 (en) * | 2002-11-15 | 2003-08-10 | Общество с ограниченной ответственностью "Трансстройтоннель-99" | Method of tunnel construction and device for method embodiment |
| CN101550698A (en) * | 2009-05-05 | 2009-10-07 | 上海隧道工程股份有限公司 | Constructing method for basic pit at the upper part of shield tunnel |
| CN102839674A (en) * | 2012-09-19 | 2012-12-26 | 中国水电顾问集团华东勘测设计研究院 | Foundation pit excavation supporting structure on near end well shield tunnel and construction method of foundation pit excavation supporting structure |
| CN202865850U (en) * | 2012-09-19 | 2013-04-10 | 中国水电顾问集团华东勘测设计研究院 | Near-end shield tunnel foundation pit excavation supporting structure |
| CN106339554A (en) * | 2016-08-29 | 2017-01-18 | 浙江大学城市学院 | Method for caculating displacement of nearby existing subway tunnel due to foundation pit excavation |
| CN109299578A (en) * | 2018-11-20 | 2019-02-01 | 中南大学 | Excavation of foundation pit causes the calculation method of lower sleeping existing shield tunnel protuberance deformation |
| CN110046470A (en) * | 2019-05-13 | 2019-07-23 | 湖南大学 | A kind of shield driving causes ground settlement method for determination of amount after work |
| CN110188413A (en) * | 2019-05-13 | 2019-08-30 | 浙江大学城市学院 | The prediction technique that side shield tunnel confining pressure caused by a kind of excavation of foundation pit changes |
| CN110245401A (en) * | 2019-05-31 | 2019-09-17 | 浙江大学城市学院 | The evaluation method influenced on existing shield tunnel is worn under a kind of shield tunnel |
-
2020
- 2020-03-03 CN CN202010140265.7A patent/CN111680383B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2209978C1 (en) * | 2002-11-15 | 2003-08-10 | Общество с ограниченной ответственностью "Трансстройтоннель-99" | Method of tunnel construction and device for method embodiment |
| CN101550698A (en) * | 2009-05-05 | 2009-10-07 | 上海隧道工程股份有限公司 | Constructing method for basic pit at the upper part of shield tunnel |
| CN102839674A (en) * | 2012-09-19 | 2012-12-26 | 中国水电顾问集团华东勘测设计研究院 | Foundation pit excavation supporting structure on near end well shield tunnel and construction method of foundation pit excavation supporting structure |
| CN202865850U (en) * | 2012-09-19 | 2013-04-10 | 中国水电顾问集团华东勘测设计研究院 | Near-end shield tunnel foundation pit excavation supporting structure |
| CN106339554A (en) * | 2016-08-29 | 2017-01-18 | 浙江大学城市学院 | Method for caculating displacement of nearby existing subway tunnel due to foundation pit excavation |
| CN109299578A (en) * | 2018-11-20 | 2019-02-01 | 中南大学 | Excavation of foundation pit causes the calculation method of lower sleeping existing shield tunnel protuberance deformation |
| CN110046470A (en) * | 2019-05-13 | 2019-07-23 | 湖南大学 | A kind of shield driving causes ground settlement method for determination of amount after work |
| CN110188413A (en) * | 2019-05-13 | 2019-08-30 | 浙江大学城市学院 | The prediction technique that side shield tunnel confining pressure caused by a kind of excavation of foundation pit changes |
| CN110245401A (en) * | 2019-05-31 | 2019-09-17 | 浙江大学城市学院 | The evaluation method influenced on existing shield tunnel is worn under a kind of shield tunnel |
Non-Patent Citations (1)
| Title |
|---|
| 魏纲 等: "基坑开挖引起的旁侧盾构隧道横向受力变化研究", 《岩土力学》, vol. 41, no. 2, pages 635 - 644 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112597674A (en) * | 2020-12-05 | 2021-04-02 | 福建工程学院 | Method for determining lateral pipeline transverse additional internal force caused by foundation pit excavation |
| CN112597674B (en) * | 2020-12-05 | 2022-07-08 | 福建工程学院 | Method for determining lateral pipeline transverse additional internal force caused by foundation pit excavation |
| CN113111417A (en) * | 2021-04-15 | 2021-07-13 | 交通运输部公路科学研究所 | Additional load calculation method for local removal of tunnel lining |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111680383B (en) | 2023-07-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111753363A (en) | Foundation pit side shield tunnel confining pressure change calculation method considering foundation pit support structure deformation and space effect | |
| CN110188413B (en) | Method for predicting lateral shield tunnel confining pressure change caused by foundation pit excavation | |
| Huang et al. | Exploring the three-dimensional response of a water storage and sewage tunnel based on full-scale loading tests | |
| CN107330194B (en) | Numerical simulation analysis method for influence of shield tunnel excavation on adjacent pile group foundation | |
| CN104652448B (en) | A kind of Pit imbalance support design method | |
| CN107301305B (en) | Modeling method for realizing structural mechanical property of three-dimensional loaded duct piece | |
| CN113360985B (en) | High-precision prediction method for longitudinal deformation of existing shield tunnel caused by penetration of newly-built tunnel | |
| CN111680383A (en) | Method for predicting additional confining pressure change of lower shield tunnel caused by foundation pit excavation | |
| Waclawik et al. | Stress-state monitoring of coal pillars during room and pillar extraction | |
| Zhang et al. | ‘Standing’full-scale loading tests on the mechanical behavior of a special-shape shield lining under shallowly-buried conditions | |
| Weng et al. | Research on subway shield tunnel induced by local water immersion of collapsible loess | |
| Wang et al. | Analysis of deep foundation pit construction monitoring in a metro station in Jinan city | |
| CN116150843A (en) | Design method for active control support of deep buried tunnel by considering rotation of surrounding rock stress main shaft | |
| CN110046470A (en) | A kind of shield driving causes ground settlement method for determination of amount after work | |
| CN115809498A (en) | Longitudinal deformation calculation method for existing line penetrating through deep-buried shield tunnel | |
| CN109087028A (en) | Karst strata metro construction shield machine section risk evaluating method and system | |
| Ying et al. | An efficient method for evaluating the ground surface settlement of Hangzhou metro deep basement considering the excavation process | |
| Yan et al. | Field study on deformation and stress characteristics of large open caisson during excavation in deep marine soft clay | |
| WO2024139683A1 (en) | Active support force calculation method and system for tunnel passing under existing structure | |
| Zhou et al. | Analysis and treatments of primary support failure in large-span tunnel under a soft-hard interbedded surrounding rock mass | |
| Wang et al. | Field monitoring of a subsea shield tunnel during standpipe lifting | |
| Xie et al. | Analytical Solution for the Steady‐State Karst Water Inflow into a Tunnel | |
| CN117556493A (en) | Tunnel blasting damage judging method based on large-scale network topology optimization design | |
| CN114329680A (en) | Stability evaluation method for ore pillar dam body of underground reservoir in mining area and application of stability evaluation method | |
| Zhou et al. | Mechanical response of supporting structure of closely spaced super large span twin tunnels |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |