Deep foundation pit support structure and its selection method

Abstract

A deep foundation pit support structure and a selection method thereof, comprising: a tough support structure including a tough eyelet, a copper cable, a bearing rod, a damping cylinder and a wire drum, and the copper cable including a bearing cable, an intermediate cable and a traction cable. The defect of the prior art that there is no intelligent derivation method that can comprehensively involve several levels of bending points in the selection of deep foundation pit support structures is effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of deep foundation pit support, and in particular to a deep foundation pit support framework and a selection method thereof. Background Art

[0002] A deep foundation pit refers to a project with an excavation depth of more than 5 meters (including 5 meters), or a project with a depth of less than 5 meters but with particularly complex geological conditions, surrounding environment and underground pipelines.

[0003] Deep foundation pit engineering is:

[0004] (1) Excavation, support and dewatering works for foundation pits (trench) with an excavation depth exceeding 5m (including 5m).

[0005] (2) Although the excavation depth does not exceed 5m, the geological conditions, surrounding environment and underground pipelines are complex, or the excavation and support of foundation pits (trench) may affect the safety of adjacent buildings (structures).

[0006] In terms of deep foundation pit support structure, the ductile support mode has been widely used. However, there is no accurate selection method at present. Since the source of deep foundation pit accidents impacts the ductile support structure, the selection cannot be performed using the analytical method. Therefore, only the interpolation method can be used to select the deep foundation pit support structure.

[0007] However, the impact of deep foundation pit accident sources on the toughness support structure is a momentum impact process with several levels of bending phenomena, including: deep foundation pit accident bending: the deep foundation pit inclination wall style is different, so the deep foundation pit accident source running route, impact power, impact style are intermittent, and there are also curved deep foundation pit accident sources such as stone cracking and soil pouring;

[0008] Material bending: In addition to the load-bearing rod, the copper cable and the tough eyelet are made of tough materials, which will cause high bending strain. The damping cylinder offsets the impact power through the high elastic strain.

[0009] Connection bending: The general isolation component is a flexible ring eye sleeve, which is formed by winding a copper coil. With the impact process, the copper coils are connected, separated, and connected, which is a significant bending connection. At present, there is no intelligent derivation method that can comprehensively involve several levels of bending points in this regard. Therefore, a very accurate bending amount derivation model is given to improve the accuracy of the selection method and improve the focus of the flexible support plan. Summary of the invention

[0010] To solve the above problems, the present invention provides a deep foundation pit support structure and a selection method thereof, which effectively avoids the defect that there is no intelligent derivation method that can comprehensively involve several levels of bending points in the selection of deep foundation pit support structures in the prior art.

[0011] To overcome the deficiencies in the prior art, the present invention provides a solution for a deep foundation pit support structure and a selection method thereof, as follows:

[0012] A deep foundation pit support structure system, comprising:

[0013] The resilient support structure includes resilient eye sleeves, copper cables, load-bearing rods, damping cylinders and wire drums. The copper cables include load-bearing cables, intermediate cables and traction cables.

[0014] A method for selecting a deep foundation pit support structure, comprising:

[0015] S1, identification of deep foundation pit accident indicators;

[0016] S1 includes: constructing an image library of the deep foundation pit inclined wall area through image acquisition, adding an accident library of the deep foundation pit inclined wall constructed by on-site exploration of the deep foundation pit, and identifying deep foundation pit accident indicators, including the location of the deep foundation pit accident source area, the running route of the accident source area, the impact power and the accident impact range;

[0017] S2, executing the selection of the type and component type of the deep foundation pit support structure;

[0018] The S2 includes: according to the deep foundation pit accident model indicators and support requirements, the support impact power A1, the minimum support vertical span A2, and the allowed span A3 for reducing the impact force are determined, and a resilient support structure selection model for resisting stone sliding based on the principle of maximizing efficiency is selected. This model adapts the corresponding component types and material mechanical indicators according to the power offset ratio of each part of the resilient support structure.

[0019] S3, constructing the derivation model 1 with deep foundation pit tilt wall data;

[0020] S3 includes: based on the image library of the deep foundation pit inclined wall area of ​​S1, constructing an overall model integrating the style and size data of the ductile support structure, that is, deriving model 1, the ductile support structure includes a ductile eyelet, a copper cable, a bearing rod, a damping cylinder and a wire drum, and the copper cable includes a bearing cable, an intermediate cable and a traction cable;

[0021] Then the model is cut into a number of square blocks, and the component type, section size, material, boundary, connection and derivation index are set.

[0022] S4, construct the second derivation model with the installation style of the deep foundation pit support structure and the initial internal force;

[0023] The S4 includes: performing initial derivation on the derivation mode 1, including style initiation and internal force initiation, refreshing the style and component internal force of the mode, and setting it to the derivation mode 2.

[0024] S5, constructing the derivation model 3 with the source data of deep foundation pit accident formation;

[0025] The S5 includes: adding a deep foundation pit accident source in the derivation mode two, setting the transmission force when the deep foundation pit accident source and the support structure are connected, and obtaining the derivation mode three.

[0026] S6, running LS-DYNA software for derivation mode 3 to perform the derivation of the deep foundation pit accident formation source and support structure;

[0027] The S6 includes: setting the derivation end time after the maximum impact force is generated to obtain the derivation amount.

[0028] S7, determination of derived quantity.

[0029] The S7 includes: determining the vertical span A4 of the remaining support and the span A5 for alleviating the impact force, and determining whether the bearing force of the eyelet sleeve, the tension of the copper cable, the elongation of the damping tube, and the reliability of the bearing rod meet the set requirements; if it is determined that the set requirements are not met, go to S2 to execute until the set requirements are met.

[0030] Preferably, in S1 and S5, according to the performance of the source of deep foundation pit accidents, the corresponding equivalent accident library or derivation mode three is selected as the model, the sliding stone uses the vibration analysis model, the soil block pouring uses the wave dynamics model, and the sliding debris uses the wave dynamics model; the useless critical amount is set between the equivalent model components of the easy-to-crack stone to simulate the stone cracking bending performance, and the connector set between the block parts when the stone cracks increases the initial force between the block parts. The connector between the block parts can be subjected to a full range of combined force, and the force of the connector between the block parts when cracking is used to simulate the force of the stone when cracking; the amplitude change value A6 of the vertical force between the block parts is:

[0031] A6=A7÷(A8+A9)×A10×A11, where A7 is the vertical force per unit area of ​​the connector; A8 and A9 are the diameters of the adjacent blocks; A10 is the equivalent area of ​​the connector, A10=3.14×(A12) 2 , A12=B(A8,A9)×A13, the B() function takes the smallest value of A8 and A9, A13 is the scaling factor; A11 is the distance between the blocks moving vertically;

[0032] The amplitude variation value A14 of the lateral force between the blocks is:

[0033] A14=(A15×A7)÷(A8+A9)×A10×A16

[0034] Here, A16 is the distance between the blocks due to vertical movement; A15 is the force per unit area of ​​the connector in the lateral direction;

[0035] The amplitude variation value A17 of the bending force between the blocks is:

[0036] A17=A7÷(A8+A9)×A18×A19

[0037] Here, A18 = 3.14 × (A12) 4 ÷4; A19 is the bending radius of the connector;

[0038] The amplitude variation value A20 of the rotational force between the blocks is:

[0039] A20=(A15×A7)÷(A8+A9)×A21×A22

[0040] Here, A21 = 3.14 × (A12) 4 ÷2; A22 is the rotation arc of the connector.

[0041] The damage of the connector between the block parts is controlled by the tensile force A23 and the internal force A24 during damage to simulate the damage of the stone. The control formula is:

[0042] (C(A6))÷A10+(C(A17))×A12÷A18>A23

[0043] (C(A14))÷A10+(C(A20))×A12÷A21>A24

[0044] Here, the C() function takes the absolute value of the value in the brackets;

[0045] The main indicators of the connectors between block parts are: A7, A15, A23 and A24.

[0046] In addition, the different terrain properties of the deep foundation pit inclined wall result in the deep foundation pit accident source and the deep foundation pit inclined wall being in a curved connection. The material indicators of the deep foundation pit inclined wall are set in segments. At the same time, the resistance force per unit area in a constant state and the resistance force per unit area in a moving state between each segment and the deep foundation pit accident source constitute a curved connection.

[0047] Preferably, in S2, different support structures are selected according to the support conditions, including: support for removing and processing rocks that are easy to fall on the inclined wall of the deep foundation pit, support for the deep foundation pit inclined wall with an inclination higher than the set value that is prone to sliding stone accidents, and selecting a tough eyelet and bearing rod structure; support areas where the route of sliding stones is easy to assess and is difficult to collapse, and selecting a copper cable and damping tube support structure.

[0048] Preferably, in S3, several types of bending components are integrated, including: independently connected flexible eyelets equivalent to bending truss components, several azimuthally rotatable load-bearing rods equivalent to truss components, vertically movable copper cables equivalent to cable components, and damping cylinders equivalent to bending damping components.

[0049] Preferably, in S3, the individually connected flexible eyelets are equivalent to a bending truss assembly, including:

[0050] 3-1-1: Framed section: The flexible eyelet is wound by a single ring-shaped copper coil, which is connected into several circles by a wire ring. The framed several-section rod-shaped truss components are used to be equivalent to the ring-shaped copper coil, simulating the elastic segmentation change on the cross-section of the rod-shaped truss component;

[0051] 3-1-2: Bending structure: In the derivation mode 1, several sections of elastic structure modes are used to reflect the forces of several time slices of each copper coil, which include the bending force of the previous time slice and the pulling force of the next time slice;

[0052] 3-1-3: Curved connection: The number of squares cut for each copper coil should ensure that the squares replace the coil body with the set simulation degree, and each copper coil should be used more than 2 4 It is equivalent to a rod-shaped truss component, and each copper coil remains independent and is independently connected.

[0053] Preferably, in S3, a plurality of azimuthally rotatable bearing rods are equivalent to a truss assembly, including:

[0054] 3-2-1: Framed section: Use several framed rod-shaped truss components as load-bearing rods to simulate the elastic segmentation changes on the section of the rod-shaped truss components;

[0055] 3-2-2: Bending boundary: The fixed head of the bearing rod can rotate freely vertically at the support, and is restricted in lateral rotation at the support, and the restricted rotation range is [-π / 12,π / 12]. In the boundary setting of the fixed head of the bearing rod, the restriction of vertical rotation is cancelled, and the restricted lateral rotation amplitude of the disc spring connected to the bearing rod is set. The rotation arc of the disc spring - the coordinate of the rotation force is a double broken line of three control points. The control points are the starting point V1 with a horizontal coordinate of zero and a vertical coordinate of zero, the restricted point V2 with a horizontal coordinate of U1 and a vertical coordinate of W1, and the critical point V3 with a horizontal coordinate of U2 and a vertical coordinate of W2. Here, U1 is the critical lateral rotation amplitude.

[0056] Preferably, in S3, the method of equivalently forming the damping cylinder into a bending damping assembly comprises:

[0057] 3-3-1: Bending component: The damping cylinder offsets the impact power through telescopic strain, and is equivalent to the damping unit in the derivation mode 1;

[0058] 3-3-2: Flexural structure: The coordinates of the force-running distance of the damping cylinder are three line segments of four control points, the control points are the starting point V4 with a horizontal coordinate of zero and a vertical coordinate of zero, the operating point V5 with a horizontal coordinate of U3 and a vertical coordinate of W3, the reinforcement point V6 with a horizontal coordinate of U4 and a vertical coordinate of W4, the critical point V7 with a horizontal coordinate of U5 and a vertical coordinate of W5, the line segment from V4 to V5 is the starting area of ​​the damping cylinder expansion and contraction, the line segment from V5 to V6 is the damping extension area, and the line segment from V6 to V7 is the critical reinforcement area.

[0059] Preferably, in S3, the method of forming a cable assembly with a vertically variable copper cable comprises:

[0060] 3-4-1: The middle cable and the load-bearing cable are connected by a wire drum. When the stress inside the middle cable is too high and exceeds the tightening force of the wire drum, the middle cable can be extended. The process of tightening the wire drum and connecting and extending the middle cable is achieved by using a telescopic rod. The force-strain coordinates of the copper cable are three line segments with four control points. The control points are the starting point V8 with a horizontal coordinate of zero and a vertical coordinate of zero, the operating point V9 with a horizontal coordinate of U6 and a vertical coordinate of W6, the blocking point V10 with a horizontal coordinate of U7 and a vertical coordinate of W7, and the critical point V11 with a horizontal coordinate of U8 and a vertical coordinate of W8. The line segment from V8 to V9 is the tightening area, the line segment from V9 to V10 is the connecting movement segment, and the line segment from V10 to V11 is the blocking area;

[0061] 3-4-2: The copper cable is connected to the head of the load-bearing rod for movement. The copper cable in the connected movement area is equalized by a hoop assembly. The obstruction weight at the connection point between the hoop assembly and the head of the load-bearing rod is 15%.

[0062] Preferably, the method for performing initial derivation on derivation mode one in S4 includes: removing the deviation between the zero-stress condition mode and the real mode of the support structure constructed in S3 in terms of shape, size, style and internal force of the structure, and only adding its own weight. In order to efficiently obtain the real shape, size, style and internal force of the system, the overall force of derivation mode two must be increased, and the scaling factor is usually higher than ten.

[0063] The beneficial effects of the present invention are:

[0064] The present invention deduces the bending deep foundation pit accident index, sets the bending materials, bending connection, bending boundary and initial deduction of the support structure, and constructs an intelligent model of a tough support structure that considers several levels of bending. It can achieve the intelligent deduction of the complicated momentum impact process of the deep foundation pit accident source impacting the tough support structure, and achieves the deduction of the complicated process of deep foundation pit accident source impact and tough support, accurately covering several levels of bending points such as high strain and connection separation, and significantly improving the accuracy of support selection. It effectively avoids the defect of the prior art that there is no intelligent deduction method that can comprehensively involve several levels of bending points in the selection of deep foundation pit support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a flow chart of the method for selecting the deep foundation pit support structure of the present invention.

[0066] Figure 2 It is a schematic diagram of the toughness eyelet sleeve of the present invention.

[0067] Figure 3 It is a schematic diagram of the present invention using a plurality of framed rod-shaped truss components equivalent to a circular copper coil.

[0068] Figure 4 It is a schematic diagram of several sections of the telescopic construction mode of the present invention.

[0069] Figure 5 Schematic diagram of the load-bearing bar of the present invention.

[0070] Figure 6 It is a coordinate diagram of the rotational arc-rotational force of the disc spring of the present invention.

[0071] Figure 7 It is a coordinate diagram of the force-running distance of the damping cylinder of the present invention.

[0072] Figure 8 It is a schematic diagram of a copper rope of the present invention.

[0073] Fig. 9 It is an example diagram of performing initial derivation on derivation mode 1 of the present invention.

[0074] Fig.10 It is a schematic diagram of the support range and the trajectory of the sliding stone according to the example of the present invention.

[0075] Fig.11 Schematic diagram of the highest position of splashing according to an example of the present invention.

[0076] Fig.12 It is a schematic diagram of the derived quantities of the example of the present invention.

[0077] Fig.13 It is a comparison chart of the experimental values ​​and the derived values ​​of the examples of the present invention. DETAILED DESCRIPTION

[0078] The present invention will be preferably described below in conjunction with the accompanying drawings and embodiments.

[0079] like Figure 1-Figure 13 As shown, the deep foundation pit support structure system includes:

[0080] S1, identification of deep foundation pit accident indicators;

[0081] S1 includes: constructing an image library of the deep foundation pit inclined wall area through image acquisition, adding an accident library of the deep foundation pit inclined wall constructed by on-site exploration of the deep foundation pit, and identifying deep foundation pit accident indicators, including the location of the deep foundation pit accident source area, the running route of the accident source area, the impact power and the accident impact range;

[0082] S2, executing the selection of the type and component type of the deep foundation pit support structure;

[0083] The S2 includes: according to the deep foundation pit accident model indicators and support requirements, the support impact power A1, the minimum support vertical span A2, and the allowed span A3 for reducing the impact force are determined, and a resilient support structure selection model for resisting stone sliding based on the principle of maximizing efficiency is selected. This model adapts the corresponding component types and material mechanical indicators according to the power offset ratio of each part of the resilient support structure.

[0084] S3, constructing the derivation model 1 with deep foundation pit tilt wall data;

[0085] S3 includes: based on the image library of the deep foundation pit inclined wall area of ​​S1, constructing an overall model integrating the style and size data of the ductile support structure, that is, deriving model 1, the ductile support structure includes a ductile eyelet, a copper cable, a bearing rod, a damping cylinder and a wire drum, and the copper cable includes a bearing cable, an intermediate cable and a traction cable;

[0086] Then the model is cut into a number of square blocks, and the component type, section size, material, boundary, connection and derivation index are set.

[0087] S4, construct the second derivation model with the installation style of the deep foundation pit support structure and the initial internal force;

[0088] The S4 includes: performing initial derivation on the derivation mode 1, including style initiation and internal force initiation, refreshing the style and component internal force of the mode, and setting it to the derivation mode 2.

[0089] S5, constructing the derivation model 3 with the source data of deep foundation pit accident formation;

[0090] The S5 includes: adding a deep foundation pit accident source in the derivation mode two, setting the transmission force when the deep foundation pit accident source and the support structure are connected, and obtaining the derivation mode three.

[0091] S6, running LS-DYNA software for derivation mode 3 to perform the derivation of the deep foundation pit accident formation source and support structure;

[0092] The S6 includes: setting the derivation end time after the maximum impact force is generated to obtain the derivation amount.

[0093] S7, determination of derived quantity.

[0094] The S7 includes: determining the vertical span A4 of the remaining support and the span A5 for alleviating the impact force, and determining whether the bearing force of the eyelet sleeve, the tension of the copper cable, the elongation of the damping tube, and the reliability of the bearing rod meet the set requirements; if it is determined that the set requirements are not met, go to S2 to execute until the set requirements are met.

[0095] Preferably, in S1 and S5, according to the performance of the source of deep foundation pit accidents, the corresponding equivalent accident library or derivation mode three is selected as the model, for example, the sliding stone uses the vibration analysis model, the soil block pouring uses the wave dynamics model, and the sliding debris uses the wave dynamics model; the useless critical amount is set between the equivalent model components of the easy-to-crack stone to simulate the stone cracking bending performance, and the connector set between the block parts when the stone cracks increases the initial force between the block parts. The connector between the block parts can be subjected to a full range of combined force, and the force of the connector between the block parts when cracking is used to simulate the force of the stone when cracking; the amplitude change value A6 of the vertical force between the block parts is:

[0096] A6=A7÷(A8+A9)×A10×A11, where A7 is the vertical force per unit area of ​​the connector; A8 and A9 are the diameters of the adjacent blocks; A10 is the equivalent area of ​​the connector, A10=3.14×(A12) 2 , A12=B(A8,A9)×A13, the B() function takes the smallest value of A8 and A9, A13 is the scaling factor, usually its value is 1; A11 is the distance between the blocks moving vertically;

[0097] The amplitude variation value A14 of the lateral force between the blocks is:

[0098] A14=(A15×A7)÷(A8+A9)×A10×A16

[0099] Here, A16 is the distance between the blocks due to vertical movement; A15 is the force per unit area of ​​the connector in the lateral direction;

[0100] The amplitude variation value A17 of the bending force between the blocks is:

[0101] A17=A7÷(A8+A9)×A18×A19

[0102] Here, A18 = 3.14 × (A12) 4 ÷4; A19 is the bending radius of the connector;

[0103] The amplitude variation value A20 of the rotational force between the blocks is:

[0104] A20=(A15×A7)÷(A8+A9)×A21×A22

[0105] Here, A21 = 3.14 × (A12) 4 ÷2; A22 is the rotation arc of the connector.

[0106] The damage of the connector between the block parts is controlled by the tensile force A23 and the internal force A24 during damage to simulate the damage of the stone. The control formula is:

[0107] (C(A6))÷A10+(C(A17))×A12÷A18>A23

[0108] (C(A14))÷A10+(C(A20))×A12÷A21>A24

[0109] Here, the C() function takes the absolute value of the value in the brackets;

[0110] The main indicators of the connectors between block parts are: A7, A15, A23 and A24.

[0111] In addition, the different terrain properties of the deep foundation pit inclined wall result in the deep foundation pit accident source and the deep foundation pit inclined wall being in a curved connection. The material indicators of the deep foundation pit inclined wall are set in segments. At the same time, the resistance force per unit area in a constant state and the resistance force per unit area in a moving state between each segment and the deep foundation pit accident source constitute a curved connection.

[0112] Preferably, in S2, different support structures are selected according to the support conditions, including: support for removing and processing rocks that are easy to fall on the inclined wall of the deep foundation pit, support for the deep foundation pit inclined wall with an inclination higher than the set value that is prone to sliding stone accidents, and selecting a tough eyelet and bearing rod structure; support areas where the route of sliding stones is easy to assess and is difficult to collapse, and selecting a copper cable and damping tube support structure.

[0113] Preferably, in S3, several types of bending components are integrated, including: independently connected flexible eyelets equivalent to bending truss components, several azimuthally rotatable load-bearing rods equivalent to truss components, vertically movable copper cables equivalent to cable components, and damping cylinders equivalent to bending damping components.

[0114] Preferably, in S3, the individually connected flexible eyelets are equivalent to a bending truss assembly, including:

[0115] 3-1-1: Framed section: The flexible eyelet is wound by a single ring-shaped copper coil, which is connected into several circles by a wire ring. The framed several-section rod-shaped truss components are used to be equivalent to the ring-shaped copper coil, simulating the elastic segmentation change on the cross-section of the rod-shaped truss component;

[0116] 3-1-2: Bending structure: In the derivation mode 1, several sections of elastic structure modes are used to reflect the forces of several time slices of each copper coil, which include the bending force of the previous time slice and the pulling force of the next time slice;

[0117] 3-1-3: Curved connection: The number of squares cut for each copper coil should ensure that the squares replace the coil body with the set simulation degree. Preferably, each copper coil uses more than 2 4 It is equivalent to a rod-shaped truss component, and each copper coil remains independent and is independently connected.

[0118] Preferably, in S3, a plurality of azimuthally rotatable bearing rods are equivalent to a truss assembly, including:

[0119] 3-2-1: Framed section: Use several framed rod-shaped truss components as load-bearing rods to simulate the elastic segmentation changes on the section of the rod-shaped truss components;

[0120] 3-2-2: Curved Boundary: Figure 5 In it, x, y, and z represent the corresponding joints. The fixed head of the bearing rod can rotate freely vertically at the support, and is restricted in lateral rotation at the support, and the restricted rotation range is [-π / 12,π / 12]. Therefore, the restriction of vertical rotation is cancelled in the boundary setting of the fixed head of the bearing rod, and the restricted lateral rotation amplitude of the disc spring connected to the bearing rod is set. The rotation arc of the disc spring - the coordinate of the rotation force is a double broken line of three control points, and the control points are the starting point V1 with zero horizontal coordinate and zero vertical coordinate, the restricted point V2 with horizontal coordinate U1 and vertical coordinate W1, and the critical point V3 with horizontal coordinate U2 and vertical coordinate W2, where U1 is the critical lateral rotation amplitude.

[0121] Preferably, in S3, the method of equivalently forming the damping cylinder into a bending damping assembly comprises:

[0122] 3-3-1: Bending component: The damping cylinder offsets the impact power through telescopic strain, and is equivalent to the damping unit in the derivation mode 1;

[0123] 3-3-2: Flexural structure: The coordinates of the force-running distance of the damping cylinder can be obtained through experiments. Usually, the coordinates are three line segments of four control points. The control points are the starting point V4 with a horizontal coordinate of zero and a vertical coordinate of zero, the operating point V5 with a horizontal coordinate of U3 and a vertical coordinate of W3, the reinforcement point V6 with a horizontal coordinate of U4 and a vertical coordinate of W4, and the critical point V7 with a horizontal coordinate of U5 and a vertical coordinate of W5. The line segment from V4 to V5 is the starting area of ​​the damping cylinder expansion and contraction, the line segment from V5 to V6 is the damping extension area, and the line segment from V6 to V7 is the critical reinforcement area.

[0124] Preferably, in S3, the method of forming a cable assembly with a vertically variable copper cable comprises:

[0125] 3-4-1: The middle cable and the load-bearing cable are connected by a wire drum. When the stress inside the middle cable is too high and exceeds the tightening force of the wire drum, the middle cable can be extended. The process of tightening the wire drum and connecting and extending the middle cable is achieved by using a telescopic rod. The force-strain coordinates of the copper cable are three line segments with four control points. The control points are the starting point V8 with a horizontal coordinate of zero and a vertical coordinate of zero, the operating point V9 with a horizontal coordinate of U6 and a vertical coordinate of W6, the blocking point V10 with a horizontal coordinate of U7 and a vertical coordinate of W7, and the critical point V11 with a horizontal coordinate of U8 and a vertical coordinate of W8. The line segment from V8 to V9 is the tightening area, the line segment from V9 to V10 is the connecting movement segment, and the line segment from V10 to V11 is the blocking area;

[0126] 3-4-2: The copper cable is connected to the head of the load-bearing rod for movement. The copper cable in the connected movement area is equalized by a hoop assembly. The obstruction weight at the connection point between the hoop assembly and the head of the load-bearing rod is 15%.

[0127] Preferably, the method for performing initial derivation on derivation mode one in S4 includes: removing the deviation between the zero-stress condition mode and the real mode of the support structure constructed in S3 in terms of shape, size, style and internal force of the structure, and only adding its own weight. In order to efficiently obtain the real shape, size, style and internal force of the system, the overall force of derivation mode two must be increased, and the scaling factor is usually higher than ten.

[0128] The present invention can achieve very accurate backtracking and selection of the ductile support structure under high strain, high slippage, connection and separation of strong bending conditions.

[0129] The following is an example illustrating the present invention:

[0130] A deep foundation pit was constructed near a lake, and the inclined wall had the possibility of falling rocks. The main body of the rocks was marble, which had the characteristics of integration, and the rocks were generally flaky and graded. Through image acquisition and construction of an image library of the deep foundation pit inclined wall area, combined with on-site exploration of the deep foundation pit, it was determined that the vertical span of the deep foundation pit accident source was about 100 meters. The method of setting connectors between block parts was used to equate falling rocks. By referring to relevant literature, the main indicators were set as: A6 for 17,000 MPa, A7 for 39%, A23 for 180 MPa, and A24 for 180 MPa. The deep foundation pit inclined wall has a pure stone area and a moss covered area. The resistance per unit area between the stones sliding down in the pure stone area and the deep foundation pit inclined wall in a constant state is 0.3 Newton, and the resistance per unit area in a moving state is 0.25 Newton. The resistance per unit area between the stones sliding down in the moss covered area and the deep foundation pit inclined wall in a constant state is 0.4 Newton, and the resistance per unit area in a moving state is 0.35 Newton. The random collision of the sliding stones and the cracking of the stones make the accident impact range divergent. Through three-dimensional simulation, the accident impact range of the deep foundation pit accident is obtained, and the support range is determined accordingly. The equiphase surface of the highest position of the sliding stones splashing at points E and F is the shortest, which is suitable for the installation of support structures. Point F is closer to the road, and to facilitate the removal operation after the sliding stones are blocked, point F is selected as the location for the installation of the support structure.

[0131] Because the route of the falling rocks is very dense, for such areas, a tough ring eye sleeve and a bearing rod structure are selected as the support structure. The selected impact resistance power is 500 kilowatts, and the vertical span of the bearing rod is 5 meters; for other areas, a copper cable and damping tube support structure is selected; according to relevant standards, the value of A2 is 2.5 meters, and the value of A3 is 9 meters; thus, the support structure selection is as follows:

[0132] The model of the tough eyelet is RXI-025, the model of the load-bearing rod is JC30-00 Jingcheng, the load-bearing cable, the intermediate cable and the traction rope are all Φ32 copper cables made of copper material, the model of the damping cylinder is ZTE, and the coordinates of the force-running distance of the damping cylinder are three line segments of four control points, the control points are the starting point V4 with a horizontal coordinate of zero and a vertical coordinate of zero, the operating point V5 with a horizontal coordinate of one tenth of a meter and a vertical coordinate of fifty kilonewtons, the reinforcement point V6 with a horizontal coordinate of one meter and a vertical coordinate of eighty kilonewtons, and the critical point V7 with a horizontal coordinate of one point one meter and a vertical coordinate of one hundred and twenty kilonewtons; the wire drum connecting the intermediate cable and the load-bearing cable has a starting amount of ten kilonewtons, and the intermediate cable is connected. The movement extension size is one-half meter.

[0133] After executing model construction, cutting grids and starting deduction, deduction model two is obtained. The source of deep foundation pit accidents is introduced into deduction model two, and deduction model three is obtained. The source of deep foundation pit accidents is 1.6 tons of sliding rocks, the impact rate is 25 meters per second, and the impact power is 500 kilowatts.

[0134] It can be deduced that A4 is four meters, which is higher than A2 of 2.5 meters, and A5 is five meters, which is lower than A3 of nine meters. The maximum head force of the bearing rod is 160 kilonewtons, and its critical force is 178 kilonewtons. In addition, the damping cylinder has not been stretched to the critical point, and the damping cylinder at the head of the bearing cable has the highest stretch, but there is still a stretch margin of 0.3 meters. Compared with the experimental value of the set support structure, the deduced deviation of the maximum impact force is less than 1.5 percent. In this way, the structure setting meets the corresponding standards and component judgments, and meets the support selection requirements.

[0135] The present invention has been described above in an illustrative manner using embodiments. It is obvious to those skilled in the art that the present disclosure is not limited to the embodiments described above, and various changes, modifications and updates can be made without deviating from the scope of the present invention.

Claims

1. A method for selecting a deep foundation pit support structure. It is characterized in that include: S1, through image acquisition, build an image library of the deep foundation pit tilting wall area, plus the accident library of the deep foundation pit tilting wall built by on-site exploration of the deep foundation pit, identify the deep foundation pit accident indicators, including the location of the deep foundation pit accident source area, the running route of the accident source area, the impact power and the accident impact range; S2, based on the accident index and support requirements of deep foundation pits, the support impact power A1, the minimum vertical span of support A2, and the permissible span for mitigating impact force A3 are determined, and a resilient support structure selection model for resisting rock slide based on the principle of maximizing efficiency is adopted. This model adapts the corresponding component types and material mechanical indicators according to the power offset ratio of each part of the resilient support structure; S3, constructing the derivation model 1 with deep foundation pit tilt wall data. The derivation model 1 is to construct an overall model integrating the style and size data of the ductile support structure based on the image library of the deep foundation pit tilt wall area; S4, constructing a second derivation mode with the installation style and initial internal force of the deep foundation pit support structure, wherein the second derivation mode includes performing initial derivation on the first derivation mode, including the style start and the internal force start, and refreshing the style and internal force of the components of the mode; S5, constructing a derivation model 3 with deep foundation pit accident source data, wherein the derivation model 3 includes adding a deep foundation pit accident source to the derivation model 2, and setting the transmission force when the deep foundation pit accident source and the support structure are connected; S6, running LS-DYNA software for derivation mode 3 to perform the derivation of the deep foundation pit accident formation source and support structure; S7, the derivation end time is set after the maximum impact force is generated, and the derivation amount is obtained.

2. The method for selecting a deep foundation pit support structure according to claim 1, It is characterized in that The S3 comprises: a tough support structure including a tough eyelet, a copper cable, a bearing rod, a damping cylinder and a wire drum, and the copper cable includes a bearing cable, an intermediate cable and a traction cable; Then the model is cut into a number of square blocks, and the component type, section size, material, boundary, connection and derivation index are set; The S7 includes: determining the vertical span A4 of the remaining support and the span A5 for alleviating the impact force, and determining whether the bearing force of the eyelet sleeve, the tension of the copper cable, the elongation of the damping tube, and the reliability of the bearing rod meet the set requirements; if it is determined that the set requirements are not met, go to S2 to execute until the set requirements are met.

3. The method for selecting the deep foundation pit support structure according to claim 2, It is characterized in that In S1 and S5, according to the performance of the deep foundation pit accident source, the corresponding equivalent accident library or derivation model three is selected as the model. The sliding stone uses the vibration analysis model, the soil block pouring uses the wave dynamics model, and the sliding debris uses the wave dynamics model; the useless critical amount is set between the equivalent model components of the easy-to-crack stone to simulate the stone cracking bending performance. The connector set between the block parts when the stone cracks increases the initial force between the block parts. The connector between the block parts can withstand a full range of combined forces. The force of the connector between the block parts when cracking is used to simulate the force of the stone when cracking; the amplitude change value A6 of the vertical force between the blocks is: A6=A7÷(A8+A9)×A10×A11, where A7 is the vertical force per unit area of ​​the connector; A8 and A9 are the diameters of the adjacent blocks; A10 is the equivalent area of ​​the connector, A10=3.14×(A12) 2 , A12=B(A8,A9)×A13, the B() function takes the smallest value of A8 and A9, A13 is the scaling factor; A11 is the distance between the blocks moving vertically; The amplitude variation value A14 of the lateral force between the blocks is: A14=(A15×A7)÷(A8+A9)×A10×A16 Here, A16 is the distance between the blocks due to vertical movement; A15 is the force per unit area of ​​the connector in the lateral direction; The amplitude variation value A17 of the bending force between the blocks is: A17=A7÷(A8+A9)×A18×A19 Here, A18=3.14×(A12) 4 ÷4; A19 is the bending radius of the connector; The amplitude variation value A20 of the rotational force between the blocks is: A20=(A15×A7)÷(A8+A9)×A21×A22 Here, A21=3.14×(A12) 4 ÷2; A22 is the rotation arc of the connector.

4. The method for selecting a deep foundation pit support structure according to claim 2, It is characterized in that The damage of the connector between the block parts is controlled by the tensile force A23 and the internal force A24 during damage to simulate the damage of the stone. The control formula is: (C(A6))÷A10+(C(A17))×A12÷A18>A23 (C(A14))÷A10+(C(A20))×A12÷A21>A24 Here, the C() function takes the absolute value of the value in the brackets; The main indicators of the connectors between the blocks are: A7, A15, A23 and A24; In addition, the different terrain properties of the deep foundation pit inclined wall result in the deep foundation pit accident source and the deep foundation pit inclined wall being in a curved connection. The material indicators of the deep foundation pit inclined wall are set in segments. At the same time, the resistance force per unit area in a constant state and the resistance force per unit area in a moving state between each segment and the deep foundation pit accident source constitute a curved connection.

5. The method for selecting a deep foundation pit support structure according to claim 2, It is characterized in that In S2, different support structures are selected according to the support conditions, including: support for removing and processing rocks that are easy to fall on the inclined wall of the deep foundation pit, support for the deep foundation pit where the inclination is higher than the set value and is prone to sliding stone accidents, and the selection of a tough eyelet and bearing rod structure; support areas where the route of sliding stones is easy to assess and is unlikely to cause collapse, and the selection of a copper cable and damping tube support structure.

6. The method for selecting a deep foundation pit support structure according to claim 2, It is characterized in that In S3, several types of bending components are integrated, including: independently connected flexible eyelets equivalent to bending truss components, bearing rods that rotate in several directions equivalent to truss components, copper cables with vertical movement equivalent to cable components, and damping cylinders equivalent to bending damping components.

7. The method for selecting a deep foundation pit support structure according to claim 2, It is characterized in that In S3, the individually connected flexible eyelets are equivalent to a bending truss assembly, including: 3-1-1: Framed section: The flexible eyelet is wound by a single ring-shaped copper coil, which is connected into several circles by a wire ring. The framed several-section rod-shaped truss components are used to be equivalent to the ring-shaped copper coil, simulating the elastic segmentation change on the cross-section of the rod-shaped truss component; 3-1-2: Bending structure: In the derivation mode 1, several sections of elastic structure modes are used to reflect the forces of several time slices of each copper coil, which include the bending force of the previous time slice and the pulling force of the next time slice; 3-1-3: Curved connection: The number of squares cut for each copper coil should ensure that the squares replace the coil body with the set simulation degree, and each copper coil should be used more than 2 4 It is equivalent to a rod-shaped truss component, and each copper coil remains independent and is independently connected.

8. The method for selecting a deep foundation pit support structure according to claim 2, It is characterized in that In S3, several bearing rods that rotate in different directions are equivalent to a truss assembly, including: 3-2-1: Framed section: Use several framed rod-shaped truss components as load-bearing rods to simulate the elastic segmentation changes on the section of the rod-shaped truss components; 3-2-2: Bending boundary: The fixed head of the bearing rod can rotate freely vertically at the support, and is restricted in lateral rotation at the support, and the restricted rotation range is [-π / 12,π / 12]. In the boundary setting of the fixed head of the bearing rod, the restriction of vertical rotation is cancelled, and the restricted lateral rotation amplitude of the disc spring connected to the bearing rod is set. The rotation arc of the disc spring - the coordinate of the rotation force is a double broken line of three control points, and the control points are the starting point V1 with zero horizontal coordinate and zero vertical coordinate, the restricted point V2 with horizontal coordinate U1 and vertical coordinate W1, and the critical point V3 with horizontal coordinate U2 and vertical coordinate W2. Here, U1 is the critical lateral rotation amplitude.

9. The method for selecting a deep foundation pit support structure according to claim 2, It is characterized in that In S3, the damping cylinder is equivalent to a method of forming a bending damping component, comprising: 3-3-1: Bending component: The damping cylinder offsets the impact power through telescopic strain, and is equivalent to the damping unit in the derivation mode 1; 3-3-2: Flexural structure: The force-running distance coordinates of the damping cylinder are three line segments of four control points, the control points are the starting point V4 with a horizontal coordinate of zero and a vertical coordinate of zero, the operating point V5 with a horizontal coordinate of U3 and a vertical coordinate of W3, the reinforcement point V6 with a horizontal coordinate of U4 and a vertical coordinate of W4, the critical point V7 with a horizontal coordinate of U5 and a vertical coordinate of W5, the line segment from V4 to V5 is the damping cylinder expansion start area, the line segment from V5 to V6 is the damping extension area, and the line segment from V6 to V7 is the critical reinforcement area; In S3, a method for forming a cable assembly with a copper cable having vertical variation, comprising: 3-4-1: The middle cable and the load-bearing cable are connected by a wire drum. When the stress inside the middle cable is too high and exceeds the tightening force of the wire drum, the middle cable can be extended. The process of tightening the wire drum and connecting and extending the middle cable is achieved by using a telescopic rod. The force-strain coordinates of the copper cable are three line segments with four control points. The control points are the starting point V8 with a horizontal coordinate of zero and a vertical coordinate of zero, the operating point V9 with a horizontal coordinate of U6 and a vertical coordinate of W6, the blocking point V10 with a horizontal coordinate of U7 and a vertical coordinate of W7, and the critical point V11 with a horizontal coordinate of U8 and a vertical coordinate of W8. The line segment from V8 to V9 is the tightening area, the line segment from V9 to V10 is the connecting movement segment, and the line segment from V10 to V11 is the blocking area; 3-4-2: The copper cable is connected to the head of the load-bearing rod for movement. The copper cable in the connected movement area is equalized by a hoop assembly. The obstacle weight at the connection between the hoop assembly and the head of the load-bearing rod is 15%; The method for performing initial derivation on derivation mode 1 in S4 includes: removing the zero-stress condition mode of the support structure constructed in S3 and the deviation of the actual mode in shape, size, style and internal force of the structure, and only adding its own weight. In order to efficiently obtain the actual shape, size, style and internal force of the system, the overall force of derivation mode 2 must be increased, and the scaling factor is usually higher than ten.

10. A deep foundation pit support structure system using the deep foundation pit support structure selection method according to any one of claims 1 to 9, It is characterized in that include: The resilient support structure includes resilient eye sleeves, copper cables, load-bearing rods, damping cylinders and wire drums. The copper cables include load-bearing cables, intermediate cables and traction cables.

Images