Foundation pit water pumping induced fence deflection evaluation method based on energy method

Abstract

The invention relates to the technical field of foundation pit construction, and particularly discloses a foundation pit water pumping induced fence deflection evaluation method based on an energy method.The method comprises the following steps that foundation pit parameters and enclosure wall body parameters of a target foundation pit before excavation are obtained, and a displacement function curve of an enclosure wall body is established based on the foundation pit parameters and the enclosure wall body parameters before excavation; determining a soil pressure calculation model in a non-limit state based on the displacement function curve of the enclosure wall body; according to the displacement function curve of the enclosure wall body and a soil pressure calculation model, soil pressure work, water pressure work and enclosure wall body bending strain energy are calculated; and calculating a predicted value of the deformation of the enclosure wall body caused by rainfall before excavation based on an energy method of a minimum potential energy principle. According to the method, the deformation condition of the enclosure wall body caused by rainfall before excavation of the foundation pit can be accurately predicted, the problem of inaccurate prediction of a method for inducing deformation of the enclosure structure by rainfall before excavation in the prior art can be solved, and technical support is provided for reasonable construction design.

Description

Technical Field

[0001] The present invention specifically relates to the technical field of foundation pit construction, and in particular is an energy-based method for evaluating foundation pit pumping-induced enclosure deflection. Background Art

[0002] In recent years, my country's economy has developed rapidly. With the continuous advancement of urbanization, many cities have increased their efforts to develop underground space. Projects such as underground commercial areas, underground parking lots and subways have emerged one after another, which has spawned a large number of foundation pit projects. When constructing foundation pits in water-rich areas, due to the high groundwater level, in order to facilitate construction, dewatering operations are usually carried out before excavation to lower the groundwater level. In urban environments, the construction of foundation pit projects is often under complex geological conditions. Many deep foundation pit projects are adjacent to facilities such as high-speed railways, subway tunnels and underground pipe galleries that have been put into use. Therefore, the environmental problems caused by deep foundation pit construction have become one of the topics that need to be urgently addressed in the field of geotechnical engineering.

[0003] In fact, every link of foundation pit construction may lead to deformation of the foundation pit, which is manifested in the deformation of the retaining structure and the settlement of the surface outside the pit. In foundation pit construction in water-rich areas, dewatering before excavation is an indispensable step. Through dewatering, the construction party can check whether the single well pumping capacity of the dewatering well meets the design requirements and obtain the relevant hydrogeological parameters of the underground aquifer. Dewatering before foundation pit excavation lays the foundation for ensuring construction safety and foundation pit stability.

[0004] At present, most of the research focuses on the impact of foundation pit excavation and precipitation on the deformation of retaining structures and surrounding ground settlement. Through the review of abundant literature, it is found that precipitation before foundation pit excavation may indeed cause centimeter-level deformation of retaining structures. However, there is still a lack of relevant data based on theoretical derivation to study the impact of foundation pit excavation or precipitation on the deformation of retaining structures and surrounding strata. The deformation of retaining walls caused by precipitation before excavation is not accurately predicted, which makes the existing foundation pit projects face significant potential risks during the construction process. Therefore, it is necessary to study and analyze the deformation of retaining structures caused by precipitation before foundation pit excavation. Summary of the invention

[0005] The purpose of the present invention is to provide a method for evaluating foundation pit pumping-induced enclosure deflection based on an energy method to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] An energy-based method for evaluating foundation pit pumping-induced enclosure deflection includes the following steps:

[0008] Obtain the foundation pit parameters and retaining wall parameters of the target foundation pit before excavation, and establish a displacement function curve of the retaining wall based on the foundation pit parameters and retaining wall parameters before excavation;

[0009] Determine the soil pressure calculation model under non-limit state based on the displacement function curve of the retaining wall;

[0010] According to the displacement function curve of the retaining wall and the soil pressure calculation model, calculate the soil pressure work, water pressure work and the bending strain energy of the retaining wall;

[0011] The energy method based on the minimum potential energy principle is used to calculate the predicted value of the deformation of the retaining wall caused by precipitation before excavation.

[0012] As a further solution of the present invention: the foundation pit parameters include the size of the foundation pit, the foundation pit depth and the precipitation depth; the retaining wall parameters include the depth of the retaining wall; the displacement function curve of the retaining wall includes a cantilever deformation curve of the retaining wall and a sinusoidal deformation curve of the retaining wall, the cantilever deformation curve of the retaining wall corresponds to the situation where the top of the retaining wall is unsupported, and the sinusoidal deformation curve of the retaining wall corresponds to the situation where the top of the retaining wall is supported.

[0013] As a further solution of the present invention: when there is no support on the top of the enclosure wall, the cantilever deformation curve of the enclosure wall is:

[0014]

[0015] In the formula, D is the coefficient to be determined, e is the base of the natural logarithm, and z is the calculated depth of the retaining wall without support; H d is the precipitation depth; δ(z) is the wall displacement at depth z without support;

[0016] When the top of the retaining wall is supported, the sinusoidal deformation curve of the retaining wall is:

[0017]

[0018] Where D′ is the coefficient to be determined, δ′(z) is the wall displacement at depth z under support; z' is the calculated depth of the retaining wall under support; H d is the precipitation depth.

[0019] As a further solution of the present invention: when the top of the retaining wall is unsupported, the earth pressure affected by the displacement of the unsupported retaining wall includes the non-limit earth pressure P of the active area. a and the non-limiting earth pressure P in the passive zone p , non-limiting earth pressure in passive zone P p The non-limit earth pressure P in the passive zone above and below the precipitation surface p1and P p2 ,in:

[0020] When there is no support, the non-limit earth pressure in the active area affected by the displacement of the retaining wall is:

[0021]

[0022] In the formula, K 0 is the static earth pressure coefficient, γ′ is the effective weight of the soil; A and B are coefficients; δ(z) is the wall displacement at depth z in the unsupported case;

[0023] The non-limiting earth pressure in the passive zone is:

[0024]

[0025] In the formula, K 0 is the static earth pressure coefficient, γ′ is the effective weight of the soil; A and B are coefficients; γ w is the density of water; δ(z) is the wall displacement at depth z without support.

[0026] As a further solution of the present invention: when the top of the retaining wall is supported, the earth pressure affected by the displacement of the supported retaining wall includes the non-limit earth pressure P of the active area. a ′ and the non-limit earth pressure P in the passive zone p ′, for the non-limit earth pressure P in the passive zone p ′ includes the non-limit earth pressure P in the passive zone above and below the precipitation surface p ' 1 and P p ' 2 ,in:

[0027] The non-limiting earth pressure in the active zone with support is:

[0028]

[0029] In the formula, K 0 is the static earth pressure coefficient, γ′ is the effective weight of the soil; A and B are coefficients; γ w is the density of water; δ′(z) is the wall displacement at depth z under support.

[0030] The non-limiting earth pressure in the passive zone is:

[0031]

[0032] In the formula, K 0 is the static earth pressure coefficient, γ′ is the effective weight of the soil; A and B are coefficients; γ w is the weight of water and δ′(z) is the wall displacement at depth z in the supported case.

[0033] As a further solution of the present invention: when the top of the retaining wall is unsupported, the work done by the earth pressure in the passive zone and the active zone is:

[0034]

[0035] Where: H is the wall depth; P p1 is the passive earth pressure above the precipitation surface; P p2 is the passive earth pressure below the precipitation surface; W p is the work done by the passive earth pressure; W a Work done by active earth pressure;

[0036] When the top of the retaining wall is supported, the work done by the earth pressure in the passive and active zones is:

[0037]

[0038] Among them, W p ′ is the work done by passive earth pressure; W a ′ is the work done by active earth pressure.

[0039] As a further solution of the present invention: when the top of the enclosure wall is unsupported, the work done by the water pressure in the passive zone and the active zone is:

[0040]

[0041] Among them, W pw is the work done by the passive water pressure; W aw Work done for active water pressure;

[0042] When the top of the retaining wall is supported, the work done by the water pressure in the passive and active areas is:

[0043]

[0044] Among them, W p ' w is the work done by the passive water pressure; W a ' w Work done by active water pressure.

[0045] As a further solution of the present invention: the calculation method of the bending strain energy of the enclosure wall is:

[0046]

[0047] Among them: U is the bending strain energy when the top of the wall is unsupported; U′ is the bending strain energy when the top of the wall is supported; E is the elastic modulus of the enclosing wall; I is the section moment of inertia.

[0048] As a further solution of the present invention: a method for calculating the predicted value of the deformation of the retaining wall caused by precipitation before excavation based on the energy method of the minimum potential energy principle comprises the following steps:

[0049] Calculate the total potential energy of the retaining wall, which is the sum of the work done by water pressure, earth pressure and the bending strain energy of the retaining wall.

[0050] The energy method based on the minimum potential energy principle is used to determine the unknown coefficients to obtain the complete displacement function curve of the enclosure wall;

[0051] According to the complete displacement function curve of the retaining wall, the maximum displacement of the retaining wall caused by precipitation before excavation is determined;

[0052] An exponential fitting function is obtained, and based on the relationship between the ratio of any foundation pit width to the foundation pit width of 200 m and the ratio of the maximum displacement of any foundation pit width to the maximum displacement of the foundation pit width of 200 m, the deformation curves of different foundation pit widths under different precipitation depths are determined.

[0053] As a further solution of the present invention: for the case where there is no support on the top of the enclosure wall, the exponential fitting function is:

[0054]

[0055] Where b is the width of any foundation pit, m; b 200 =200m, i.e. 200m width of foundation pit;δ hmax is the maximum displacement of the retaining wall caused by precipitation before excavation of any foundation pit width, m; δ max is the maximum displacement of the retaining wall caused by precipitation before excavation of a 200-meter-wide foundation pit, m;

[0056] The deformation curves of different foundation pit widths under different precipitation depths are:

[0057]

[0058] For the case where there is support on the top of the retaining wall, the exponential fitting function is:

[0059]

[0060] The deformation curves of different foundation pit widths under different precipitation depths are:

[0061]

[0062] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention constructs a deformation curve function of the retaining wall, calculates the work done by the soil pressure in the active area and the soil pressure in the passive area based on the non-limit soil pressure calculation model, calculates the water pressure work in the active area and the water pressure work in the passive area and the bending strain energy of the retaining wall, and finally calculates the predicted value of the deformation of the retaining wall caused by precipitation before excavation based on the principle of minimum potential energy. The present invention can more accurately predict the deformation of the retaining wall caused by precipitation before foundation pit excavation, can solve the problem of inaccurate prediction of the deformation of the retaining structure induced by precipitation before excavation in the prior art, and provides technical support for reasonable construction design. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a flow chart of a method for predicting displacement of retaining structures caused by precipitation before foundation pit excavation in an embodiment of the present invention;

[0064] Figure 2 It is a schematic diagram of a flow chart of calculating the predicted value of displacement of the retaining wall caused by precipitation before excavation by using the energy method based on the minimum potential energy principle in an embodiment of the present invention;

[0065] Figure 3 is a displacement function curve of the enclosing wall in an embodiment of the present invention;

[0066] Figure 4 It is a graph of a quasi-exponential fitting function in an embodiment of the present invention;

[0067] Figure 5 b / b under different precipitation depths in the embodiment of the present invention 200 With δ hmax / δ max Schematic diagram of the relationship between

[0068] Figure 6 b / b under different precipitation depths in the embodiment of the present invention 200 With δ h ' max / δ′ max Schematic diagram of the relationship.

[0069] Figure 7 Schematic diagram of the structure of an artificial neural network in an embodiment of the present invention. DETAILED DESCRIPTION

[0070] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] See also Figure 1-Figure 6 In an embodiment of the present invention, a method for evaluating the deflection of retaining walls induced by foundation pit pumping based on an energy method is used to predict the deformation of retaining walls using an energy method based on the minimum potential energy principle during the dewatering process before foundation pit excavation, and includes the following steps:

[0072] Step S101, obtaining the foundation pit parameters and the surrounding wall parameters of the target foundation pit before excavation, and establishing a displacement function curve of the surrounding wall based on the foundation pit parameters and the surrounding wall parameters before excavation;

[0073] In step S101 of the embodiment of the present application, the foundation pit parameters of the target foundation pit before excavation include the size of the foundation pit, the foundation pit depth and the precipitation depth; the retaining wall parameters include the depth of the retaining wall; the displacement function curve of the retaining wall includes the cantilever deformation curve of the retaining wall and the sinusoidal deformation curve of the retaining wall. The cantilever deformation curve of the retaining wall corresponds to the situation that the top of the retaining wall is unsupported. In this embodiment, a cantilever support structure is adopted for the situation that the top of the wall is unsupported. The cantilever deformation curve is forward-leaning. The displacement of the retaining wall gradually increases from bottom to top. The maximum displacement occurs at the top of the pile. The cantilever support structure often adopts reinforced concrete pile wall, wooden pile, steel sheet pile and other types. Its mechanism relies on sufficient embedding depth of the pile and the bending resistance of the structure to maintain overall stability and structural safety; the sinusoidal deformation curve of the retaining wall corresponds to the situation that the top of the retaining wall is supported;

[0074] Furthermore, in the embodiment of the application, when the top of the retaining wall is unsupported, the cantilever deformation curve of the retaining wall is:

[0075]

[0076] In the formula, D is the coefficient to be determined, e is the base of the natural logarithm, z is the calculated depth of the retaining wall without support, unit: m; H d is the precipitation depth, unit: m; δ(z) is the wall displacement at depth z without support, unit: m;

[0077] When the top of the retaining wall is supported, the sinusoidal deformation curve of the retaining wall is:

[0078]

[0079] Where D′ is the coefficient to be determined, δ′(z) is the wall displacement at depth z under support, unit: m; z' is the calculated depth of the retaining wall under support, unit: m; H d is the precipitation depth, unit: m.

[0080] Step S102, determining a soil pressure calculation model under a non-limit state based on a displacement function curve of the retaining wall;

[0081] In step S102, the soil pressure calculation model under the non-limit state is divided into the following two cases according to whether there is support on the top of the retaining wall:

[0082] (1) When there is no support on the top of the retaining wall, the earth pressure affected by the displacement of the unsupported retaining wall includes the non-limit earth pressure P in the active area. a and the non-limiting earth pressure P in the passive zone p , for the non-limiting earth pressure P in the passive zone p Due to the different precipitation depths, a piecewise function is used to determine the non-limiting earth pressure P in the passive zone above and below the precipitation surface affected by the displacement of the retaining wall. p1 and P p2 ,in:

[0083] When there is no support, the non-limit earth pressure in the active area affected by the displacement of the retaining wall is:

[0084]

[0085] In the formula, K 0 is the static earth pressure coefficient, γ′ is the effective weight of the soil, unit: kN / m 3 ; A and B are coefficients; δ(z) is the wall displacement at depth z without support;

[0086] The non-limit earth pressure in the passive zone without support is determined by piecewise function:

[0087]

[0088] In the formula, K 0 is the static earth pressure coefficient, γ′ is the effective weight of the soil, unit: kN / m 3 ; A and B are coefficients; γ w is the density of water, kN / m 3 ; δ(z) is the wall displacement at depth z without support.

[0089] (2) When the top of the retaining wall is supported, the earth pressure affected by the displacement of the supported retaining wall includes the non-limit earth pressure P in the active area. a ′ and the non-limit earth pressure P in the passive zone p ′, for the non-limit earth pressure P in the passive zone p ′, due to the different precipitation depths, a piecewise function is used to determine the non-limiting earth pressure P in the passive zone above and below the precipitation surface affected by the displacement of the retaining wall. p ' 1 and P p ' 2 ,in:

[0090] The non-limiting earth pressure in the active zone with support is:

[0091]

[0092] In the formula, K 0 is the static earth pressure coefficient, γ′ is the effective weight of the soil, unit: kN / m 3 ; A and B are coefficients; γ w is the density of water, kN / m 3 ; δ′(z) is the wall displacement at depth z in the supported case.

[0093] The non-limit earth pressure in the passive zone with support is determined by piecewise function:

[0094]

[0095] In the formula, K 0 is the static earth pressure coefficient, γ′ is the effective weight of the soil, unit: kN / m 3 ; A and B are coefficients; γ w is the density of water, kN / m 3 ; δ′(z) is the wall displacement at depth z in the supported case.

[0096] Step S103, calculating the earth pressure work, water pressure work and bending strain energy of the retaining wall according to the displacement function curve of the retaining wall and the earth pressure calculation model;

[0097] For the work done by earth pressure, when the top of the retaining wall is unsupported, the work done by earth pressure in the passive zone and active zone is:

[0098]

[0099] Where: H is the wall depth, unit: m; P p1 is the passive earth pressure above the precipitation surface, unit: Pa; P p2 is the passive earth pressure below the precipitation surface, unit: Pa; W p is the work done by the passive earth pressure, unit:

[0100] (kN·m) / m; W a is the work done by active earth pressure, unit: (kN·m) / m;

[0101] When the top of the retaining wall is supported, the work done by the earth pressure in the passive and active zones is:

[0102]

[0103] Where Wp′ is the work done by passive earth pressure, unit: (kN·m) / m; W a′ is the work done by active earth pressure, unit: (kN·m) / m.

[0105] For the work done by water pressure, when the top of the retaining wall is unsupported, the work done by water pressure in the passive and active zones is:

[0106]

[0107] Where Wpw is the work done by the passive water pressure, unit: (kN·m) / m; W aw is the work done by active water pressure; unit: (kN·m) / m;

[0108] When the top of the retaining wall is supported, the work done by the water pressure in the passive and active areas is:

[0109]

[0110] Where Wp′w is the work done by the passive water pressure, unit: (kN·m) / m; W a ' w is the work done by the active water pressure, unit: (kN·m) / m;

[0111] In addition, in step S103 of this embodiment, the calculation method of the bending strain energy of the enclosure wall is:

[0112]

[0113] Where: U is the bending strain energy when the top of the wall is unsupported, unit: MPa; U′ is the bending strain energy when the top of the wall is supported, unit: MPa; E is the elastic modulus of the enclosing wall, unit: MPa; I is the section inertia moment, unit: m 4 / m.

[0114] Step S104, calculating the predicted value of the deformation of the retaining wall caused by precipitation before excavation by using the energy method based on the minimum potential energy principle, comprises the following steps:

[0115] S201. Calculate the total potential energy of the retaining wall. The total potential energy of the retaining wall is the sum of the work done by the water pressure, the work done by the earth pressure and the bending strain energy of the retaining wall, where:

[0116] For the case where there is no support on the top of the retaining wall:

[0117] The total potential energy of the enclosure wall system is Π=U+W p -W a +W pw -W aw ;

[0118] Where: U is the bending strain energy when the top of the wall is unsupported, W p is the work done by the passive earth pressure, W ais the work done by active earth pressure, W pw Work done by passive water pressure.

[0119] For the case where the top of the retaining wall is supported:

[0120] The total potential energy of the enclosure wall system is Π′=U′+W p ′-W a ′+W p ' w -W p ' a ;

[0121] Where: U is the bending strain energy when the top of the wall is unsupported, W p ′ is the work done by passive earth pressure, W a ′ is the work done by active earth pressure, W p ' w Work done by passive water pressure.

[0122] S202, determining the unknown coefficients D and D′ according to the energy method of the minimum potential energy principle, so as to obtain a complete displacement function curve of the enclosure wall;

[0123] In step S202 of the embodiment of the present application, the method for determining the unknown coefficients D and D′ according to the energy method of the minimum potential energy principle is:

[0124] According to the energy method of the minimum potential energy principle, take the first-order derivative when the total potential energy of the enclosing wall is the minimum Find the analytical solution of the unknown coefficient D. The analytical solution of the unknown coefficient D is obtained as follows:

[0125]

[0126] Where: a=B(K 0 α 1 γ′-γ w H d )+1, b=Bα 1 (γ w +K 0 γ′)+1,c=BK 0 α 1 γ′+1;

[0127] According to the energy method of the minimum potential energy principle, take the first-order derivative when the total potential energy of the enclosing wall is the minimum Find the analytical solution of the unknown coefficient D'. The analytical solution of the unknown coefficient D' is obtained as follows:

[0128]

[0129] Where: b 2 =0.086H2 +15.88, b′=γwb 2 2 sin(c′),

[0130] S203, determining the maximum displacement of the retaining wall caused by precipitation before excavation based on the complete retaining wall displacement function curve;

[0131] For the case where there is no support on the top of the retaining wall, the maximum displacement of the retaining wall caused by the precipitation before excavation is:

[0132]

[0133] For the case where the top of the retaining wall is supported, the maximum displacement of the retaining wall caused by the precipitation before excavation is:

[0134]

[0135] S204, obtaining a quasi-exponential fitting function, and determining deformation curves of different foundation pit widths under different precipitation depths based on the relationship between the ratio of any foundation pit width to the foundation pit width of 200 m and the ratio of the maximum displacement of any foundation pit width to the maximum displacement of the foundation pit width of 200 m.

[0136] For the case where there is no support on the top of the retaining wall, the exponential fitting function is:

[0137]

[0138] Where b is the width of any foundation pit, m; b 200 =200m, i.e. 200m width of foundation pit;δ hmax is the maximum displacement of the retaining wall caused by precipitation before excavation of any foundation pit width, m; δ max is the maximum displacement of the retaining wall caused by precipitation before excavation of a 200-meter-wide foundation pit, m;

[0139] The deformation curves of different foundation pit widths under different precipitation depths are:

[0140]

[0141] For the case where there is support on the top of the retaining wall, the exponential fitting function is:

[0142]

[0143] The deformation curves of different foundation pit widths under different precipitation depths are:

[0144]

[0145] The present invention also discloses an early warning method for deformation of a retaining wall, comprising the following steps:

[0146] S301, obtaining monitoring data of the deformation of the retaining wall for at least n days, using the detection data from the 1st day to the (n-1)th day as the sample input of the artificial neural network, using the monitoring data from the 2nd day to the nth day as the expected output value of the artificial neural network, and letting the artificial neural network learn; It should be noted that, in this embodiment, the monitoring data of the deformation of the retaining wall adopts the energy method based on the minimum potential energy principle in step S104 to calculate the predicted value of the deformation of the retaining wall caused by precipitation before excavation;

[0147] S302: After learning is completed, the monitoring data of the nth day is used as sample input to predict the monitoring data of the (n+1)th day to obtain a prediction result;

[0148] S303, comparing the prediction result with the preset monitoring control value, and issuing early warning information according to the comparison result;

[0149] S304, repeat steps S301-S303, and replace the new monitoring data of the deformation of the enclosure wall to train the artificial neural network, use the monitoring data of the (n+1)th day to predict the monitoring data of the (n+2)th day, and choose whether to issue an early warning based on the prediction results.

[0150] like Figure 7 As shown, in the embodiment of the present application, the artificial neural network includes an input layer, a hidden layer and an output layer, wherein the input layer input vector X=(x 1 ,x 2 ,…,x i ,…,x n ) T , where x 0 =-1 is set to introduce a threshold for the hidden layer neurons; the hidden layer output vector is Y = (y 1 ,y 2 ,…,y j ,…,y m ) T , where y 0 = -1 is set to introduce a threshold for the output layer neurons; the output layer output vector O = (o 1 ,o 2 ,…,o k ,…,o l ) T .

[0151] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0152] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for evaluating the deflection of enclosures induced by foundation pit pumping based on energy method, characterized in that: The following steps are involved: Obtain the foundation pit parameters and retaining wall parameters of the target foundation pit before excavation, and establish a displacement function curve of the retaining wall based on the foundation pit parameters and retaining wall parameters before excavation; Determine the soil pressure calculation model under non-limit state based on the displacement function curve of the retaining wall; According to the displacement function curve of the retaining wall and the soil pressure calculation model, calculate the soil pressure work, water pressure work and the bending strain energy of the retaining wall; The energy method based on the minimum potential energy principle is used to calculate the predicted value of the deformation of the retaining wall caused by precipitation before excavation.

2. The energy-based method for evaluating foundation pit pumping-induced enclosure deflection according to claim 1 is characterized in that: The foundation pit parameters include the size of the foundation pit, the depth of the foundation pit and the precipitation depth; the retaining wall parameters include the depth of the retaining wall; the displacement function curve of the retaining wall includes a cantilever deformation curve of the retaining wall and a sinusoidal deformation curve of the retaining wall. The cantilever deformation curve of the retaining wall corresponds to the situation where the top of the retaining wall is unsupported, and the sinusoidal deformation curve of the retaining wall corresponds to the situation where the top of the retaining wall is supported.

3. The method for evaluating the deflection of enclosures induced by foundation pit pumping based on the energy method according to claim 1 is characterized in that: When there is no support on the top of the retaining wall, the cantilever deformation curve of the retaining wall is: In the formula, D is the coefficient to be determined, e is the base of the natural logarithm, and z is the calculated depth of the retaining wall without support; H d is the precipitation depth; δ(z) is the wall displacement at depth z without support; When the top of the retaining wall is supported, the sinusoidal deformation curve of the retaining wall is: Where D′ is the coefficient to be determined, δ′(z) is the wall displacement at depth z under support; z' is the calculated depth of the retaining wall under support; H d is the precipitation depth.

4. The method for evaluating foundation pit pumping-induced enclosure deflection based on energy method according to claim 1 is characterized in that: When there is no support on the top of the retaining wall, the earth pressure affected by the displacement of the unsupported retaining wall includes the non-limit earth pressure P in the active area. a and the non-limiting earth pressure P in the passive zone p , non-limiting earth pressure in passive zone P p The non-limit earth pressure P in the passive zone above and below the precipitation surface p1 and P p2 ,in: When there is no support, the non-limit earth pressure in the active area affected by the displacement of the retaining wall is: Where K0 is the static earth pressure coefficient, γ′ is the effective weight of the soil; A and B are coefficients; δ(z) is the wall displacement at depth z in the unsupported case; The non-limiting earth pressure in the passive zone is: Where K0 is the static earth pressure coefficient, γ′ is the effective weight of the soil; A and B are coefficients; γ w is the density of water; δ(z) is the wall displacement at depth z without support.

5. The method for evaluating foundation pit pumping-induced enclosure deflection based on energy method according to claim 1 is characterized in that: When the top of the retaining wall is supported, the earth pressure affected by the displacement of the supported retaining wall includes the non-limit earth pressure P in the active area. a ′ and the non-limit earth pressure P in the passive zone p ′, for the non-limit earth pressure P in the passive zone p ′ includes the non-limit earth pressure P in the passive zone above and below the precipitation surface p ′1 and P p ′2, where: The non-limiting earth pressure in the active zone with support is: Where K0 is the static earth pressure coefficient, γ′ is the effective weight of the soil; A and B are coefficients; γ w is the density of water; δ′(z) is the wall displacement at depth z under support. The non-limiting earth pressure in the passive zone is: Where K0 is the static earth pressure coefficient, γ′ is the effective weight of the soil; A and B are coefficients; γ w is the weight of water and δ′(z) is the wall displacement at depth z in the supported case.

6. The method for evaluating foundation pit pumping-induced enclosure deflection based on energy method according to claim 1 is characterized in that: When the top of the retaining wall is unsupported, the work done by the earth pressure in the passive and active zones is: Where: H is the wall depth; P p1 is the passive earth pressure above the precipitation surface; P p2 is the passive earth pressure below the precipitation surface; W p is the work done by the passive earth pressure; W a Work done by active earth pressure; When the top of the retaining wall is supported, the work done by the earth pressure in the passive and active zones is: Among them, W p ′ is the work done by passive earth pressure; W a ′ is the work done by active earth pressure.

7. The method for evaluating foundation pit pumping-induced enclosure deflection based on energy method according to claim 1 is characterized in that: When the top of the retaining wall is unsupported, the work done by the water pressure in the passive and active zones is: Among them, W pw is the work done by the passive water pressure; W aw Work done for active water pressure; When the top of the retaining wall is supported, the work done by the water pressure in the passive and active areas is: Among them, W p ' w is the work done by the passive water pressure; W a ' w Work done by active water pressure.

8. The method for evaluating the deflection of enclosures induced by foundation pit pumping based on the energy method according to claim 1 is characterized in that: The calculation method of the bending strain energy of the retaining wall is: Among them: U is the bending strain energy when the top of the wall is unsupported; U′ is the bending strain energy when the top of the wall is supported; E is the elastic modulus of the enclosing wall; I is the section moment of inertia.

9. The method for evaluating foundation pit pumping-induced enclosure deflection based on energy method according to claim 1 is characterized in that: The method for calculating the predicted value of the deformation of the retaining wall caused by precipitation before excavation by the energy method based on the minimum potential energy principle includes the following steps: Calculate the total potential energy of the retaining wall, which is the sum of the work done by water pressure, earth pressure and the bending strain energy of the retaining wall. The energy method based on the minimum potential energy principle is used to determine the unknown coefficients to obtain the complete displacement function curve of the enclosure wall; According to the complete displacement function curve of the retaining wall, the maximum displacement of the retaining wall caused by precipitation before excavation is determined; An exponential fitting function is obtained, and based on the relationship between the ratio of any foundation pit width to the foundation pit width of 200 m and the ratio of the maximum displacement of any foundation pit width to the maximum displacement of the foundation pit width of 200 m, the deformation curves of different foundation pit widths under different precipitation depths are determined.

10. The energy-based method for evaluating foundation pit pumping-induced enclosure deflection according to claim 9 is characterized in that: For the case where there is no support on the top of the retaining wall, the exponential fitting function is: Where b is the width of any foundation pit, m; b 200 =200m, i.e. 200m width of foundation pit;δ hmax is the maximum displacement of the retaining wall caused by precipitation before excavation of any foundation pit width, m; δ max is the maximum displacement of the retaining wall caused by precipitation before excavation of a 200-meter-wide foundation pit, m; The deformation curves of different foundation pit widths under different precipitation depths are: For the case where there is support on the top of the retaining wall, the exponential fitting function is: The deformation curves of different foundation pit widths under different precipitation depths are:

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