A method for calculating and analyzing ground settlement caused by pipe roof pore-forming disturbance

Abstract

A kind of calculation analysis method based on pipe roof pore-forming disturbance caused ground settlement, comprising: step S1: analysis the deformation mechanism and stress of pipe roof, set up calculation model;Step S2: according to the calculation model and construction condition, obtain tunnel depth and soil structure parameters;Step S3: pipe roof is approximated as small hole tunnel, and Peck formula is used for calculation;Step S4: the Peck formula for calculating ground settlement is used to calculate the ground settlement caused by pipe roof pore-forming disturbance, and multiple pipe roofs are replaced by large circle, and multiple small holes are associated;Step S5: determine the disturbance coefficient between pipe roofs, select measured data fitting;Step S6: considering the bending and compression deformation of pipe roof itself, and corresponding formula is proposed, and the displacement change of pipe roof structure is calculated.The present application can not only obtain the strata loss influence caused by advanced pipe roof pore-forming on upper strata more quickly and simply, but also can calculate the ground settlement caused by stress release when pipe roof pore-forming of shallow-buried tunnel.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of highway tunnel advance pipe shed hole forming technology, and particularly relates to a calculation and analysis method for ground surface settlement caused by pipe shed hole forming disturbance. BACKGROUND

[0002] With the development of national economy and the increase of transportation construction, in the process of highway tunnel construction, the problem of multi-line tunnel underpassing existing structures and buildings often arises. If appropriate engineering measures are not taken in time, the upper structure and buildings are prone to deformation, settlement and even destruction. The existing engineering technology often adopts the pipe shed driving method as one of the tunnel auxiliary construction methods. The pipe shed construction has the characteristics of convenience, high safety, and can effectively reduce the settlement of the ground and the above structures during tunnel excavation, and has a wide application field. However, during the construction of the shallow pipe shed, it is inevitable to cause disturbance to the stratum, and the pipe shed hole forming and laying will cause stratum stress release, soil and water loss, and ground surface settlement.

[0003] A large number of researches and engineering practices have found that the settlement caused by a single pipe shed is very small, and with the increase of the number of pipe sheds, the settlement caused by stress release during hole forming will accumulate, which will affect the total settlement. The ground surface settlement caused by shallow construction in soft stratum is particularly obvious, and has a certain influence on the stratum soil, the structure and buildings on the ground surface. How to accurately calculate the ground surface disturbance caused by the pipe shed driving and the size of the ground surface deformation is very important for the tunnel construction.

[0004] The pipe shed method is mainly used in soft and broken surrounding rock tunnel engineering, such as soft and gravel stratum, soft rock, rock pile and broken zone. However, the supporting mechanism of large pipe shed still needs to be studied, and the deformation law is not clear, so the engineering analogy method is often used in the design. At present, scholars at home and abroad have carried out certain researches on the deformation mechanism of pipe shed. Based on the Pasternak elastic foundation beam theory, the deflection equation and internal force calculation formula of pipe shed are derived. The strain gauge is used to monitor the longitudinal deformation of pipe shed or the ground surface settlement, and the stress characteristics and deformation distribution law of pipe shed in the process of tunnel excavation are analyzed. Based on the mechanical mechanism of pipe shed support in tunnel collapse treatment, a simple and practical mechanical model is established, and the parameters of pipe shed are calculated.

[0005] However, the above researches are mainly aimed at the supporting theoretical mechanism, and there are few calculation and researches on the deformation law of pipe shed in actual engineering and the disturbance of pipe shed hole forming to ground surface settlement. Therefore, how to combine the influence of the disturbance of pipe shed construction to ground surface settlement deformation in actual engineering has become a key and difficult point in tunnel engineering design and construction.

[0006] Therefore, aiming at the problems in the prior art, the designer actively researches and improves based on years of experience in this industry, and thus the application of a calculation and analysis method for ground settlement caused by pipe shed hole-forming disturbance is provided. SUMMARY

[0007] The present application is aimed at the defects in the prior art that the support mechanism of large pipe sheds needs to be researched, the deformation law is not clear, the research on pipe sheds is mostly carried out for support theory mechanism, and the deformation law of pipe sheds in actual engineering and the calculation and research of pipe shed hole-forming disturbance on ground settlement are less.

[0008] To achieve the purpose of the present application, the present application provides a calculation and analysis method for ground settlement caused by pipe shed hole-forming disturbance, which comprises:

[0009] Step S1 is performed: analyze the deformation mechanism and stress condition of the pipe shed, and set a calculation model;

[0010] Step S2 is performed: according to the calculation model analysis and construction conditions, the tunnel depth and soil layer structure parameters are determined;

[0011] Step S3 is performed: according to the tunnel conditions, a pipe shed deformation calculation model is established, the pipe shed is approximated as a small hole tunnel, and the Peck empirical formula is used for calculation. The ground settlement caused by pipe shed construction disturbance is calculated according to the following formula:

[0012]

[0013] i=K1H1+K2H2+…+K i H i +…+K n H n ,

[0014] In the formula, S x is the settlement of the ground surface on the cross section at a distance x from the axis of the pipe shed;

[0015] S max is the maximum settlement;

[0016] V1 is the stratum loss caused by the pipe shed;

[0017] i is the transverse settlement groove width coefficient, which is the distance between the inflection point of the curve and the origin;

[0018] is the internal friction angle of the tunnel stratum, which is the weighted average value for layered soil;

[0019] Z is the thickness of the overburden soil;

[0020] K i and H i respectively are the transverse settlement trough width factor and the buried depth (m) of the i-th soil layer;

[0021] Step S4 is performed: based on the fact that the distance between the steel pipes is much smaller than the tunnel span, the pipe roof steel pipes of the tunnel arch are simplified as horizontally arranged, the pipe roof above the tunnel is simplified as the same level of small holes by combining the Peck empirical formula, the Peck empirical formula for calculating the ground settlement is used to calculate the ground settlement caused by the pipe roof hole forming disturbance, and a plurality of pipe roofs can be continuously replaced by a large circle, and the Peck empirical formula is combined to preliminarily solve a plurality of small holes:

[0022]

[0023] Step S5 is performed: the disturbance coefficient between the pipe roofs is determined, and the measured data is selected for fitting;

[0024] Step S6 is performed: the disturbance of the pipe roof excavation to the ground soil layer is combined, the bending and compression deformation of the pipe roof itself are further considered, and the corresponding formula is proposed, and the pipe roof structure displacement change can be obtained by calculation, which provides reference and data support for tunnel design.

[0025] Optionally, the calculation model approximates the pipe roof as horizontally arranged.

[0026] Optionally, the soil layer structure parameters include soil layer type, soil layer thickness, elastic modulus, density, Poisson's ratio, internal friction angle and cohesion.

[0027] Optionally, based on the distance between the pipe roofs, the settlement trough curve obtained when fitting the ground settlement approximately conforms to the normal distribution.

[0028] Optionally, the construction method of the pipe roof excavation adopts the bench method or the CRD method.

[0029] Optionally, the tunnel is a horseshoe section.

[0030] In summary, the calculation and analysis method based on the ground settlement caused by the pipe roof hole forming disturbance adopts a theoretical calculation method, which can not only obtain the stratum loss influence of the advanced pipe roof hole forming on the upper stratum more quickly and simply, provide corresponding reliable data support for tunnel engineering design, but also can calculate the ground settlement caused by stress release when the pipe roof hole of the shallow tunnel is formed, and provide reference for corresponding numerical simulation and analysis. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The flow chart of the calculation and analysis method based on the ground settlement caused by the pipe roof hole forming disturbance is shown.

[0032] Figure 2 A pipe roof design chart in an actual tunnel project is shown;

[0033] Figure 3 A Peck formula settlement tank chart is shown;

[0034] Figure 4 A double pipe roof pore-forming settlement tank superimposed chart is shown;

[0035] Figure 5 A multi-pipe roof pore-forming settlement tank chart is shown;

[0036] Figures 6(a) to 6(b) A stress release chart when the pipe roof is pore-formed is shown;

[0037] Figure 7 A comparison chart of the ground surface settlement deformation results caused by the advanced pipe roof calculated by the present application and obtained by the numerical simulation method with the measured results is shown;

[0038] Figure 8 A ground surface settlement deformation result chart caused by the advanced pipe roof calculated by the present application is shown. DETAILED DESCRIPTION

[0039] To explain the technical content, structural features, purposes and effects of the present application in detail, the following will be described in detail in combination with the embodiments and the accompanying drawings.

[0040] Please refer to Figure 1 , Figure 1 A flow chart of the calculation and analysis method of the ground surface settlement caused by the pipe roof pore-forming disturbance based on the present application is shown. The calculation and analysis method of the ground surface settlement caused by the pipe roof pore-forming disturbance comprises:

[0041] Step S1 is performed: the deformation mechanism and stress condition of the pipe roof are analyzed, and a calculation model is set;

[0042] Step S2 is performed: the tunnel depth and soil layer structure parameters are determined according to the calculation model analysis and the construction condition;

[0043] Step S3 is performed: the pipe roof deformation calculation model is established according to the tunnel condition, the pipe roof is approximated as a small hole tunnel, and the Peck empirical formula is used for calculation. The ground surface settlement caused by the pipe roof construction disturbance is calculated according to the following formula:

[0044]

[0045]

[0046]

[0047] i=K1H1+K2H2+…+K i Hi +…+K n H n ,

[0048] S x is the settlement of the ground surface at a distance x from the axis of the pipe roof in cross section;

[0049] S max is the maximum settlement;

[0050] V1is the volume of the ground loss caused by driving the pipe roof;

[0051] i is the lateral settlement trough width coefficient, the distance between the inflection point of the curve and the origin;

[0052] is the internal friction angle of the tunnel stratum, and for layered soil, the weighted average value is taken;

[0053] Z is the thickness of the overburden layer;

[0054] K i and H i are the lateral settlement trough width coefficient and the burial depth (m) of the i-th soil layer, respectively;

[0055] Step S4 is performed: based on the fact that the distance between steel pipes is much smaller than the tunnel span, the pipe roof steel pipes at the arch of the tunnel are simplified as being arranged horizontally, the pipe roof above the tunnel is simplified as being the same level of small holes, the Peck empirical formula for calculating ground settlement is used to calculate the ground settlement caused by the pipe roof hole-forming disturbance, and a plurality of pipe roofs can be continuously replaced by a large circle, and the Peck empirical formula is combined to preliminarily solve a plurality of small holes:

[0056]

[0057] … indicates that the same rule items are omitted.

[0058] Step S5 is performed: the disturbance coefficient between the pipe roofs is determined, and measured data is selected for fitting;

[0059] Step S6 is performed: the disturbance of the pipe roof excavation to the ground surface is combined, further considering the bending and compression deformation of the pipe roof itself, and the corresponding formula is proposed, and through calculation, the displacement change of the pipe roof structure can be obtained, which provides reference and data support for tunnel design.

[0060] In order to more directly disclose the technical scheme of the present application and highlight the beneficial effects of the present application, the calculation and analysis method and principle of ground settlement caused by pipe roof pore-forming disturbance are described in combination with specific embodiments. In the specific embodiments, two layers of pipe roofs are applied to the vaults of the tunnels as advanced support, the length of the tunnels is 120 m, and the construction methods of the tunnels are step method and CRD method respectively. The above-mentioned advanced support structure form, tunnel length, and construction method are only listed and should not be regarded as a limitation on the technical scheme of the present application.

[0061] Please refer to Figure 2 , Figure 2 The pipe roof design diagram in the actual tunnel engineering is shown in FIG. 1. For example, the interval tunnels of the No. 8 and No. 12 subway lines in a certain place in Shandong orthogonally underpass a certain highway with four lanes in both directions. The interval of the No. 8 and No. 12 subway lines is 120 m long, and the north-south direction. The interval of the No. 8 subway line starts from the south side of the end wall of a certain station (commonly built section) and extends to the vertical shaft of the No. 8 and No. 12 subway lines. The design starting and ending mileage is right DK25+300.013~420.013, the length is 120 m, the cross section is horseshoe-shaped, the construction method is step method, and it belongs to a shallow-buried tunnel. The interval plane and longitudinal section are straight sections, and the longitudinal slope of the line is 3‰ after being led out of the station.

[0062] The No. 12 line is located between the left and right lines of the No. 8 line. The interval of the No. 12 line starts from the south side of the end wall of a certain station (commonly built section) and extends to the vertical shaft of the No. 8 and No. 12 subway lines. The design starting and ending mileage is right DK5+870.013~990.013, the length is 120 m, the cross section is horseshoe-shaped, the construction method is CRD method, and it belongs to a shallow-buried tunnel. The interval plane and longitudinal section are straight sections, and the longitudinal slope of the line is 3‰ after being led out of the station. Two layers of pipe roofs are applied to the vaults of the No. 8 and No. 12 lines as advanced support.

[0063] Please refer to Figures 2 to 8 , and refer to Figure 1 , Figure 2 The pipe roof design diagram in the actual tunnel engineering is shown in FIG. 1. Figure 3 The settlement tank diagram of the Peck formula is shown in FIG. 2. Figure 4 The settlement tank superposition diagram of double-pipe roof pore-forming is shown in FIG. 3.

[0064] Figure 5 The settlement tank diagram of multi-pipe roof pore-forming is shown in FIG. 4. Figures 6(a) to 6(b) The stress release diagram of pipe roof pore-forming is shown in FIG. 5. Figure 7 The comparison diagram of the ground settlement deformation results caused by the advanced pipe roof obtained by the example calculation and the numerical simulation method and the measured results is shown in FIG. 6. Figure 8 The ground settlement deformation result diagram caused by the advanced pipe roof obtained by the calculation of the present application is shown in FIG. 7. The calculation and analysis method of ground settlement caused by the pipe roof construction as advanced support in the tunnel engineering comprises:

[0065] Step S1: analyze the deformation mechanism and stress condition of the pipe roof, and set a calculation model; the calculation model approximates the pipe roof 1 as horizontally arranged.

[0066] Step S2: according to the calculation model analysis and construction conditions, determine the tunnel depth and soil layer structure parameters; the soil layer structure parameters include but are not limited to soil layer type, soil layer thickness, elastic modulus, density, Poisson's ratio, internal friction angle, and cohesion;

[0067] As a specific embodiment, non-limiting enumeration, the geometric parameters and soil parameters of each layer are as follows:

[0068] Table 1 Soil layer parameter table

[0069]

[0070] Step S3: establish a pipe roof deformation calculation model according to the tunnel working condition, and approximate the pipe roof as a small hole tunnel, and calculate by using the Peck empirical formula; the ground settlement caused by the construction disturbance of a single pipe roof is calculated according to the following formula,

[0071]

[0072]

[0073]

[0074] i=K1H1+K2H2+…+K i H i +…+K n H n ,

[0075] In the formula: S x is the settlement of the ground surface on the cross section at a distance x from the axis of the pipe roof;

[0076] S max is the maximum settlement;

[0077] V1 is the stratum loss caused by driving the pipe roof;

[0078] i is the transverse settlement groove width coefficient, the distance between the inflection point of the curve and the origin;

[0079] is the internal friction angle of the tunnel stratum, and for layered soil, the weighted average value is taken;

[0080] Z is the thickness of the overburden layer;

[0081] K i and H i are the transverse settlement groove width coefficient and the buried depth (m) of the i-th soil layer, respectively;

[0082] Step S4 is performed: based on the fact that the distance between the steel pipes is much smaller than the tunnel span, the pipe shed steel pipes of the tunnel arch are simplified as horizontally arranged, the pipe shed 1 above the tunnel is simplified as a same horizontal small hole by combining with the Peck empirical formula, the Peck empirical formula for calculating ground settlement is used to calculate the ground settlement caused by pipe shed hole-forming disturbance, and a plurality of pipe sheds can be continuously replaced by a large circle, and a plurality of small holes are preliminarily solved by using the Peck empirical formula combination.

[0083]

[0084] In the present application, because the distance between the pipe sheds is small, the obtained settlement tank curve still approximately conforms to the normal distribution, so the Peck empirical formula for calculating ground settlement can be used to calculate the ground settlement caused by pipe shed hole-forming disturbance.

[0085] Step S5 is performed: the disturbance coefficient between the pipe sheds is determined, the measured data is selected for fitting, and the pipe shed disturbance calculation value is further obtained.

[0086] Step S6 is performed: the whole tunnel model is established according to the actual project, the finite difference software FLAC3D is used for calculation, and the numerical simulation result without considering the pipe shed disturbance, the field measured result, and the numerical simulation result considering the pipe shed disturbance are obtained.

[0087] Through comprehensive data analysis, it can be obtained that the influence of the pipe shed disturbance on the ground settlement caused by tunnel excavation cannot be ignored, the influence of the stress release of the advanced pipe shed hole-forming on the ground settlement can be clearly obtained by using the present application, and the tunnel engineering design has an unnegligible effect.

[0088] In summary, the present application adopts a theoretical calculation method based on the calculation and analysis method of the ground settlement caused by pipe shed hole-forming disturbance, can more quickly and simply obtain the influence of the advanced pipe shed hole-forming on the ground loss of the upper stratum, provide corresponding reliable data support for the tunnel engineering design, and can calculate the ground settlement caused by the stress release of the pipe shed hole-forming of the shallow-buried tunnel, and provide a reference for corresponding numerical simulation and analysis.

[0089] Those skilled in the art should understand that various modifications and variations can be made to the present application without departing from the spirit or scope of the present application. Thus, if any modification or variation falls within the scope of the appended claims and their equivalents, it is considered that the present application covers these modifications and variations.

Claims

1. A method for calculating and analyzing ground settlement caused by pipe roof pore-forming disturbance, characterized in that, The calculation analysis method based on the pipe roof hole-forming disturbance causing ground settlement comprises the following steps: Step S1: analyze the deformation mechanism and stress condition of the pipe roof, and set a calculation model; Step S2: according to the calculation model analysis and construction conditions, determine the tunnel burial depth and soil layer structure parameters; Step S3: according to the tunnel working condition, establish a pipe roof deformation calculation model, and approximate the pipe roof as a small hole tunnel, and calculate by using the Peck empirical formula, and the ground settlement caused by the pipe roof construction disturbance is calculated according to the following formula: i = K1H1+ K2H2+... + K j H j +... + K n H n , wherein: S x is the settlement of the ground at a distance x from the axis of the pipe roof in cross section; S max For maximum sedimentation; V1 is the stratum loss caused by the pipe roof; i is the transverse settlement groove width coefficient, the distance between the curve inflection point and the origin; For the tunneling formation internal friction angle, the weighted average value is taken for the layered soil; Z is the overburden thickness; K j and H j are the lateral settlement tank width factor and the embedment of the jth soil layer, respectively, in meters. Step S4: based on the fact that the distance between the steel pipes is much smaller than the tunnel span, the pipe roof steel pipes at the arch part of the tunnel are simplified as horizontal arrangement, the pipe roof above the tunnel is simplified as the same horizontal small hole, the Peck empirical formula for calculating the ground settlement is applied to calculate the ground settlement caused by the pipe roof hole-forming disturbance, and a plurality of pipe roofs are continuously replaced by a large circle, and the Peck empirical formula is combined to preliminarily solve a plurality of small holes: Step S5: determine the disturbance coefficient between the pipe roofs, and select the measured data for fitting; Step S6: combine the pipe roof excavation disturbance to the ground soil layer, further consider the bending and compression deformation of the pipe roof, and propose the corresponding formula, and the pipe roof structure displacement change can be obtained by calculation, which provides reference and data support for the tunnel design.

2. The method for calculating and analyzing ground settlement based on pipe roof pore-forming disturbance according to claim 1, characterized in that, The calculation model approximates the pipe roof as horizontal arrangement.

3. The method of claim 1, wherein the method is characterized by: The soil layer structure parameters include soil layer type, soil layer thickness, elastic modulus, density, Poisson's ratio, internal friction angle and cohesion.

4. The method of claim 1, wherein the method is characterized by: Based on the distance between the pipe roofs, the settlement groove curve obtained when fitting the ground settlement approximately conforms to the normal distribution.

5. The method for calculating and analyzing ground settlement based on pipe roof pore-forming disturbance according to claim 1, characterized in that, The pipe roof excavation construction method adopts the bench method or the CRD method.

6. The method for calculating and analyzing ground settlement based on pipe roof pore-forming disturbance according to claim 1, wherein, The tunnel is a horseshoe-shaped section.

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