Test device and test method for simulating failure mode of cable foundation pit
By using a test device and method to simulate the failure mode of cable foundation pits, and by employing the strength reduction method and centrifuge to simulate foundation pit excavation, the problem of the impact of foundation pit excavation depth on stability was solved. This enabled rapid assessment of the ultimate excavation depth of foundation pits, and reduced test costs and time.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-22
- Publication Date
- 2026-04-14
AI Technical Summary
In existing technologies, the depth of foundation pit excavation affects the stability of the foundation pit, leading to catastrophic consequences such as the collapse of the support structure and ground settlement. Furthermore, traditional methods require multiple experiments to find the limit state, which is cumbersome and costly.
An experimental device simulating the failure mode of cable foundation pits was used. Soil parameters were calculated using the strength reduction method, soil was configured in the model box, and a centrifuge was used to simulate the excavation of the foundation pit. The failure process was observed, and the ultimate failure was triggered by a single test.
It can quickly trigger the ultimate failure state of the foundation pit, reduce testing costs and time, improve evaluation efficiency, and significantly reduce the number of tests.
Smart Images
Figure CN121856522A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of geotechnical engineering testing equipment, and in particular to a testing device and method for simulating cable pit failure modes. Background Technology
[0002] As cities develop towards three-dimensional structures, power utility tunnels and integrated utility tunnels, represented by overhead power line cabling, are emerging in large numbers, requiring the use of open-cut construction methods for a large number of power utility tunnel projects in urban environments.
[0003] The depth of the excavation is one of the most critical factors affecting the stability of the foundation pit. If the foundation pit becomes unstable due to excessive excavation, it may lead to catastrophic consequences such as the collapse of the support structure and the subsidence of the surrounding ground, resulting in huge casualties and economic losses. In addition, the traditional method requires a cumbersome process of conducting multiple tests to find the limit state. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a test apparatus and method for simulating cable pit failure modes.
[0005] To achieve the above-mentioned objectives, the present invention employs the following technical solution: An experimental apparatus for simulating cable pit failure modes includes: a model box; The bottom inner side of the model box is equipped with a deformation device for the support structure inside the foundation pit, and a simulation device for the support structure inside the foundation pit is provided above the deformation device for the support structure inside the foundation pit. After setting up the deformation device for the support structure inside the foundation pit and the simulation device for the support structure inside the foundation pit, the soil is prepared through experiments to completely fill the internal space of the model box. Overload counterweights are provided on the top of the soil and on both sides of the supporting structure simulation device located in the foundation pit.
[0006] According to the test apparatus for simulating cable pit failure modes, the test configuration soil is provided with multiple observation soil layers along the height direction.
[0007] According to the test apparatus for simulating cable pit failure modes, the model box is made of transparent material.
[0008] A test method for a test apparatus simulating cable pit failure modes includes the following steps: The dimensions of the model box are determined based on the preset similarity ratio M and the preset dimensions of the foundation pit; The cohesion c and internal friction angle Φ of the actual soil are obtained, and the safety factor Fs is obtained by strength reduction method based on the preset parameters of the preset foundation pit. Based on the actual soil cohesion c and internal friction angle Φ, as well as the safety factor Fs, the cohesion c0 and internal friction angle Φ0 of the test soil configuration are calculated, and the test soil configuration is placed in the model box. Based on the preset similarity ratio M and the preset dimensions of the foundation pit, determine the dimensions and location of the simulation device for the supporting structure inside the foundation pit; Based on the pre-set overload parameters of the foundation pit, the similarity ratio M, and the acceleration ng when the centrifuge is stable, calculate the overload size and mass of the overload counterweight.
[0009] The centrifuge was used to simulate the excavation of the foundation pit from top to bottom, and to simulate the failure process during the excavation until the foundation pit was destroyed. The excavation depth of the model at the moment of failure was recorded in the model box, and the actual limit excavation depth was calculated based on the similarity ratio.
[0010] Calculate the dimensions of the model box according to the following formula based on the described test method; L1 = (L + K1 * L) / M; W1 = (W + K2 * W) / M; H1 = (H + K3 * H) / M; Where L1 is the length of the model box, W1 is the width of the model box, and H1 is the height of the model box; L is the length of the preset foundation pit, W is the width of the preset foundation pit, and H is the height of the preset foundation pit; K1 is the first proportionality coefficient, K2 is the second proportionality coefficient, and K3 is the third proportionality coefficient.
[0011] Based on the aforementioned test method, the cohesion c0 and internal friction angle Φ0 of the soil in the test configuration are calculated using the following formula: c0 = c / Fs, Φ0 = Φ / Fs.
[0012] According to the aforementioned test method, the dimensions of the simulation device for the internal support structure of the foundation pit are obtained based on the similarity ratio M and the preset parameters of the preset support piles and their internal support structures.
[0013] According to the experimental method described above, the width and length of the simulated foundation pit are obtained based on the similarity ratio. The simulated foundation pit is located at the center of the model box, and the supporting structure simulation device inside the foundation pit is set along the length direction of the simulated foundation pit.
[0014] According to the test method described above, the parameters of the pre-loaded foundation pit include the pre-loaded foundation pit pressure and the pre-loaded foundation pit size.
[0015] According to the test method described above, the overload size of the overload counterweight is calculated by dividing the preset overload size of the foundation pit by the similarity ratio M, and the overload area of the overload counterweight is calculated based on the overload size of the overload counterweight; the preset overload pressure of the foundation pit is the same as the pressure of the overload counterweight; the mass of the overload counterweight is obtained by multiplying the pressure of the overload counterweight by the overload area of the overload counterweight and then dividing by the acceleration ng when the centrifuge is stable.
[0016] Compared with the prior art, the beneficial effects of the present invention include at least the following: Compared with existing theoretical calculation methods and experimental devices, it has the following advantages: This invention calculates the critical soil parameters—namely, the cohesion and internal friction angle of the test soil—using the strength reduction method and directly applies them to the test apparatus, placing the model soil in a vulnerable state. This allows for rapid triggering of the ultimate failure state after excavation in centrifuge testing, enabling observation of the failure depth in a single test and rapid calculation of the actual ultimate excavation depth. This avoids the cumbersome process of multiple tests required by traditional methods to find the ultimate state, greatly improving evaluation efficiency and significantly reducing testing and time costs. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 The principle of the experimental device for simulating cable pit failure modes of the present invention. Figure One ; Figure 2 The principle of the experimental device for simulating cable pit failure modes of the present invention. Figure Two ; In the figure: 1. Model box; 2. Simulation device for the support structure inside the foundation pit; 3. Overload counterweight; 4. Observation soil layer; 5. Deformation device for the support structure inside the foundation pit. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, any other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.
[0020] In the description of this invention, it should be noted that the terms "front," "rear," "inner," "outer," "right," "left," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0022] like Figure 1 or Figure 2 As shown, Embodiment 1 of the present invention provides an experimental device for simulating the failure mode of a cable pit, comprising: a model box 1.
[0023] The bottom inner side of the model box 1 is equipped with a deformation device 5 for the internal support structure of the foundation pit, and a simulation device 2 for the internal support structure of the foundation pit is installed above the deformation device 5. After setting up the deformation device 5 and the simulation device 2, the internal space of the model box 1 is completely filled with soil through experimental configuration. Overload counterweights 3 are provided on the top of the soil and on both sides of the supporting structure simulation device 2 located in the foundation pit.
[0024] Preferably, but not limitingly, the test configuration includes multiple observation soil layers 4 along the height direction.
[0025] By setting multiple soil observation layers 4 along the height direction, the deformation of the corresponding soil layers can be observed.
[0026] Preferably, but not limitingly, the model box 1 is made of a transparent material, such as transparent glass, transparent plastic, etc.
[0027] Preferably, but not limitingly, the pit support structure simulation device 2 may be made of aluminum plate.
[0028] Embodiment 2 of the present invention provides a test method for a test device simulating cable pit failure modes, comprising the following steps: Step S1: Determine the size of model box 1 based on the preset similarity ratio M and the preset size of the foundation pit.
[0029] Preferably, but not limitingly, the dimensions of model box 1 are calculated according to the following formula; L1 = (L + K1 * L) / M; W1 = (W + K2 * W) / M; H1 = (H + K3 * H) / M; Where L1 is the length of model box 1, W1 is the width of model box 1, and H1 is the height of model box 1; L is the length of the preset foundation pit, W is the width of the preset foundation pit, and H is the height of the preset foundation pit; K1 is the first proportionality coefficient, K2 is the second proportionality coefficient, and K3 is the third proportionality coefficient.
[0030] The value range of K1 is 2 to 3, the value range of K2 is 1.5 to 2, and the value range of K3 is 1.5 to 2.
[0031] Step S2: Obtain the cohesion c and internal friction angle Φ of the actual soil, and obtain the safety factor Fs based on the preset parameters of the preset foundation pit using the strength reduction method.
[0032] Step S3: Calculate the cohesion c0 and internal friction angle Φ0 of the test soil configuration based on the actual soil cohesion c and internal friction angle Φ, as well as the safety factor Fs.
[0033] The safety factor Fs is obtained by strength reduction method, and the cohesion c0 and internal friction angle Φ0 of the soil in the test configuration are calculated by the following formula: c0=c / Fs, Φ0=Φ / Fs.
[0034] For example, if the safety factor Fs is obtained as 1.3 by the strength reduction method, then the cohesion of the soil in the test configuration is c0 = c / 1.3, and the internal friction angle of the soil in the test configuration is Φ0 = Φ / 1.3.
[0035] Step S4: Place the test soil configuration inside the model box 1 and set multiple observation soil layers 4 to divide the test soil configuration inside the model box 1 into multiple layers.
[0036] Step S5: Determine the size and location of the simulation device 2 for the supporting structure inside the foundation pit based on the preset similarity ratio M and the preset size of the foundation pit.
[0037] Preferably, but not limitingly, the dimensions of the simulation device 2 for the support structure inside the foundation pit are obtained according to the similarity ratio M; The width and length of the simulated foundation pit are obtained based on the similarity ratio. The simulated foundation pit is located at the center of the model box 1, and the supporting structure simulation device 2 inside the foundation pit is set along the length direction of the simulated foundation pit.
[0038] Step S6: Calculate the overload size and mass of the overload counterweight 3 based on the preset overload parameters of the foundation pit, the similarity ratio M, and the acceleration ng when the centrifuge is stable.
[0039] Preferably, but not limitingly, the parameters of the pre-loaded pit include the pre-loaded pit pressure and the pre-loaded pit size.
[0040] Further preferred but not restrictive, the overload size of the overload counterweight 3 is calculated by dividing the preset overload size of the foundation pit by the similarity ratio M, and the overload area of the overload counterweight 3 is calculated based on the overload size of the overload counterweight 3; while the preset overload pressure of the foundation pit is the same as the pressure of the overload counterweight 3; by multiplying the pressure of the overload counterweight 3 by the overload area of the overload counterweight 3, and then dividing by the acceleration ng when the centrifuge is stable, the mass of the overload counterweight 3 is obtained.
[0041] For example, the pre-set overload dimensions of the foundation pit are 10m in length and 2m in width; the similarity ratio M is 50; the pre-set overload pressure of the foundation pit is 10kN / m²; and the acceleration of the centrifuge when it is stable is 100g.
[0042] The overload area of the overloaded counterweight 3 is 0.008m². 2 The length is 0.2m and the width is 0.04m.
[0043] The pressure of the overload counterweight 3 is 10 kN / m².
[0044] The pressure of the overload counterweight 3 is 10 kN / m² * 0.008 m. 2 =80N.
[0045] The mass of the overload counterweight 3 is 80 N / (100 g).
[0046] Step S7: A simulation test is conducted using a centrifuge to simulate the excavation conditions of the foundation pit from top to bottom, and to simulate the failure process during the excavation. A high-speed camera is used to record the soil deformation patterns generated during the excavation until the foundation pit fails, and the depth of the foundation pit in model box 1 is recorded.
[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.
Claims
1. A test apparatus for simulating cable pit failure modes, characterized in that, include: Model box (1); The bottom inner side of the model box (1) is provided with a foundation pit support structure deformation device (5), and a foundation pit support structure simulation device (2) is provided above the foundation pit support structure deformation device (5); after setting the foundation pit support structure deformation device (5) and the foundation pit support structure simulation device (2), the soil is prepared by test to completely fill the internal space of the model box (1); The top of the soil and the two sides of the supporting structure simulation device (2) in the foundation pit are provided with overload counterweights (3).
2. The test apparatus for simulating cable pit failure modes according to claim 1, characterized in that: The test configuration included multiple observation soil layers (4) along the height direction.
3. The test apparatus for simulating cable pit failure modes according to claim 1, characterized in that: The model box (1) is made of transparent material.
4. A test method for a test apparatus for simulating cable pit failure modes according to any one of claims 1-3, characterized in that, Includes the following steps: The dimensions of the model box (1) are determined based on the preset similarity ratio M and the preset dimensions of the foundation pit; The cohesion c and internal friction angle Φ of the actual soil are obtained, and the safety factor Fs is obtained by strength reduction method based on the preset parameters of the preset foundation pit. Based on the actual soil cohesion c and internal friction angle Φ, as well as the safety factor Fs, the cohesion c0 and internal friction angle Φ0 of the test soil were calculated, and the test soil was placed in the model box (1). Based on the preset similarity ratio M and the preset size of the foundation pit, determine the size and location of the simulation device (2) for the supporting structure inside the foundation pit; Based on the parameters of the pre-set overload of the foundation pit, the similarity ratio M and the acceleration ng when the centrifuge is stable, calculate the overload size and mass of the overload counterweight (3); The centrifuge was used to simulate the excavation conditions of the foundation pit from top to bottom, and the destruction process during the excavation was simulated until the foundation pit was destroyed. The excavation depth of the model at the moment the foundation pit was destroyed in the model box (1) was recorded, and the actual limit excavation depth was calculated based on the similarity ratio.
5. The test method according to claim 4, characterized in that, Calculate the dimensions of the model box (1) according to the following formula; L1 = (L + K1 * L) / M; W1 = (W + K2 * W) / M; H1 = (H + K3 * H) / M; Where L1 is the length of the model box, W1 is the width of the model box, and H1 is the height of the model box; L is the length of the preset foundation pit, W is the width of the preset foundation pit, and H is the height of the preset foundation pit; K1 is the first proportionality coefficient, K2 is the second proportionality coefficient, and K3 is the third proportionality coefficient.
6. The test method according to claim 4, characterized in that, The cohesion c0 and internal friction angle Φ0 of the soil in the test configuration were calculated using the following formula: c0 = c / Fs, Φ0 = Φ / Fs.
7. The test method according to claim 4, characterized in that: The dimensions of the simulation device (2) for the support structure inside the foundation pit are obtained based on the similarity ratio M.
8. The test method according to claim 7, characterized in that: The width and length of the simulated foundation pit are obtained based on the similarity ratio. The simulated foundation pit is located at the center of the model box (1). The simulated support structure device (2) is set along the length of the simulated foundation pit.
9. The test method according to claim 4, characterized in that: The parameters for the pre-loaded pit include the pre-loaded pit pressure and the pre-loaded pit size.
10. The test method according to claim 9, characterized in that: The overload size of the overload counterweight (3) is calculated by dividing the pre-set overload size of the foundation pit by the similarity ratio M, and the overload area of the overload counterweight (3) is calculated based on the overload size of the overload counterweight (3); the pre-set overload pressure of the foundation pit is the same as the pressure of the overload counterweight (3); by multiplying the pressure of the overload counterweight (3) by the overload area of the overload counterweight (3), and then dividing by the acceleration ng when the centrifuge is stable, the mass of the overload counterweight (3) is obtained.