A monitoring device and method for soil uplift at the bottom of a foundation pit

Abstract

The present invention relates to the technical field of foundation pit deformation monitoring, and in particular to a monitoring device and method for soil uplift at the bottom of a foundation pit, comprising a device and method for monitoring soil uplift at the bottom of a foundation pit, which comprises a counterweight block and an anchor rod connected to the counterweight block and serving as a support, wherein the lower part of the anchor rod is driven into bedrock, the counterweight block is embedded in a monitoring device body, and the monitoring device body comprises at least one capacitive monitoring component arranged in a vertical direction; the capacitive monitoring component comprises two vertically arranged fixed-electrode pieces and a monitoring rod, one end of the monitoring rod is vertically provided with a mica piece, and the other end extends out of the counterweight block to follow the up and down movement of the soil, and driven by the monitoring rod, the mica piece enters between the two fixed-electrode pieces to change the capacitance to monitor the movement of the soil; the present invention can achieve real-time measurement, real-time feedback and precise measurement without affecting foundation construction.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit deformation monitoring, and in particular to a monitoring device and method for soil uplift at the bottom of a foundation pit. Background Art

[0002] At present, high-rise buildings are widely used, underground buildings are gradually promoted, and deep foundation pits are also used more and more frequently. The foundation pit refers to the earth pit dug at the design location of the foundation according to the foundation ground elevation and the size of the foundation plane.

[0003] Due to factors such as unloading of the excavation surface caused by excavation of the upper soil, the soil at the bottom of the foundation pit will bulge to a certain extent. The size of the bulge of the soil at the bottom of the foundation pit reflects the stability of the foundation pit to a large extent. When the soil bulge is too large, the foundation pit will become unstable. Therefore, it is very important to measure the bulge of the soil at the bottom of the foundation pit.

[0004] The existing measurement of the soil uplift at the bottom of the foundation pit mainly uses instruments such as levels and total stations to measure the uplift of the test point. Although the detection quantity can be obtained under certain conditions, there are also disadvantages: first, the soil uplift at the bottom of the foundation pit is sometimes fast, and the existing detection method cannot measure it in real time and cannot provide timely feedback; second, after the foundation pit cushion layer is constructed, the cushion layer needs to be destroyed before measurement can be carried out, resulting in adverse consequences such as cushion layer seepage. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a monitoring device and method for the uplift of the soil at the bottom of a foundation pit, which can achieve real-time measurement, real-time feedback and accurate measurement without affecting the foundation construction. In order to achieve the above purpose, the present invention solves it through the following technical solutions:

[0006] In a first aspect, the present invention provides a monitoring device for soil heave at the bottom of a foundation pit, which is buried below the ground at the bottom of the foundation pit and includes a counterweight block and an anchor rod connected thereto and serving as a support, wherein the lower portion of the anchor rod is driven into the bedrock, the counterweight block is embedded in a monitoring device body, and the monitoring device body includes at least one capacitive monitoring component arranged in a vertical direction;

[0007] The capacitance monitoring assembly comprises two vertically arranged fixed-pole pieces and a monitoring rod. A mica piece is vertically provided at one end of the monitoring rod, and a counterweight block is extended from the other end to follow the up and down movement of the soil. Driven by the monitoring rod, the mica piece enters between the two fixed-pole pieces to change the capacitance to monitor the movement of the soil.

[0008] As a further technical solution, the monitoring device body also includes a limiting mechanism for maintaining the monitoring rod in an initial position.

[0009] As a further technical solution, a limiting mechanism is respectively configured above and below the monitoring rod.

[0010] As a further technical solution, the limiting mechanism includes a fixed limiting plate, a movable limiting plate and a limiting rod for controlling the relative movement of the two, and the movable limiting plate can follow the movement of the monitoring rod.

[0011] As a further technical solution, the limit rod is configured with an electric telescopic rod, and the electric telescopic rod drives the limit rod to be inserted and removed to achieve control of the relative movement between the fixed limit plate and the movable limit plate.

[0012] As a further technical solution, the monitoring device body also includes a sandwich shell, which seals the fixed pole piece and the mica piece in the counterweight block, the monitoring rod extends through the sandwich shell, and the limiting mechanism is arranged in the sandwich shell.

[0013] As a further technical solution, the limiting mechanism further comprises a fixed plate connected to the fixed limiting plate and a movable plate moving with the movable limiting plate, and the movable plate is vertically slidably connected to the interlayer shell.

[0014] As a further technical solution, the sandwich shell reserves a vertical notch as the moving path of the monitoring rod, and two inner and outer support plates are provided between the monitoring rod and the movable plate, wherein the bottom end of the outer support plate is connected to the junction of the monitoring rod and the notch, and maintains a set inclination angle with the outer inner wall of the sandwich shell.

[0015] As a further technical solution, the support plate is provided with a roller which is rollingly connected to the inner wall of the sandwich shell.

[0016] In a second aspect, the present invention provides a working method of the monitoring device according to the first aspect, comprising the following steps:

[0017] The monitoring device is buried as a whole below the ground at the bottom of the foundation pit. Different numbers of capacitor monitoring components are set according to the monitoring requirements of different soil layers. When buried, the monitoring rod is limited to keep the initial position of the monitoring rod unchanged. When monitoring is needed, the monitoring rod limit is opened to keep it in a free movement state. When the soil moves up and down, the monitoring rod is driven to move. The capacitance changes according to the mica sheet entering between the two fixed poles to monitor the movement of the soil.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) The counterweight block of the present invention forms an integral structure with the bedrock through the anchor rod. During the uplift of the soil, due to the action of the counterweight block, the monitoring device body as a whole does not move with the soil, but only the monitoring rod moves with the soil, thereby achieving accurate measurement of the soil at the bottom of the foundation pit and being able to provide real-time feedback on the size of the uplift displacement. By utilizing the capacitive sensing principle, the measurement accuracy is high. By arranging multiple capacitive monitoring components at different positions of the device, the uplift patterns and changes of soil in different soil layers can be measured.

[0020] (2) The monitoring device of the present invention includes a limiting mechanism for maintaining the monitoring rod in the initial position, that is, before the monitoring device is buried, the monitoring rod is in the initial position and cannot move. By setting the limiting mechanism, the range reduction or inaccurate measurement caused by the movement of the monitoring rod during the burial process can be reduced.

[0021] (3) The monitoring device of the present invention can be pre-buried below the pit bottom ground before the construction of the foundation pit cushion layer, and then the cushion layer is constructed. The soil uplift state can be monitored later without destroying the cushion layer to meet the monitoring requirements, thereby achieving the goal of not affecting the foundation construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their description are used to explain the present invention and do not constitute a limitation of the present invention. It should also be understood that these drawings are shown for simplicity and clarity and are not necessarily drawn to scale. The present invention will now be described and explained with additional features and details through the use of the accompanying drawings, in which:

[0023] Figure 1 The overall structure diagram of the monitoring device in the embodiment of the present invention is shown;

[0024] Figure 2 A schematic diagram of the structure of a measuring device in an embodiment of the present invention is shown;

[0025] Figure 3 A schematic diagram of the structure of a capacitance monitoring component in an embodiment of the present invention is shown;

[0026] Figure 4 A schematic diagram of the structure of a limit assembly in an embodiment of the present invention is shown;

[0027] Figure 5 A schematic diagram of the structure of a support assembly in an embodiment of the present invention is shown.

[0028] In the figure: 1. Monitoring device body; 11. Capacitor monitoring assembly; 111. Fixed electrode; 112. Mica sheet; 113. Monitoring rod; 12. Support assembly; 121. Support plate; 122. Roller; 13. Limit assembly; 131. Electric telescopic rod; 132. Limit rod; 133. Fixed limit plate; 134. Movable limit plate; 135. Movable plate; 136. Fixed plate; 2. Support steel plate; 3. Anchor rod; 4. Bedrock; 5. Counterweight. DETAILED DESCRIPTION

[0029] The technical solutions in typical embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0030] Embodiment 1

[0031] like Figure 1-Figure 5 As shown, this embodiment provides a monitoring device for soil uplift at the bottom of a foundation pit, which is buried below the ground at the bottom of the foundation pit and includes a counterweight block 5 and an anchor rod 3 connected thereto and used as a support, the lower part of the anchor rod 3 is driven into the bedrock 4, the counterweight block 5 is embedded in a monitoring device body 1, and the monitoring device body 1 includes at least one capacitive monitoring component 11 arranged in the vertical direction;

[0032] The capacitance monitoring assembly 11 has two vertically arranged fixed pole pieces 111 and a monitoring rod 113. A mica sheet 112 is vertically provided at one end of the monitoring rod 113, and a counterweight block 5 extends from the other end to follow the up and down movement of the soil. Driven by the monitoring rod 113, the mica sheet 112 enters between the two fixed pole pieces 111 to change the capacitance to monitor the movement of the soil.

[0033] like Figure 1 As shown, in this embodiment, the counterweight 5 is a cement pier, which is installed on a supporting steel plate 2, and the supporting steel plate 2 is fixed together with the lower anchor rod 3, and the anchor rod 3 is driven into the bedrock 4. The anchor rod 3 and the soil body bear the force from the upper part. Multiple capacitor monitoring components 11 can be arranged in the vertical direction, depending on the requirements of the monitored soil layer. For example, Figure 3 Only one monitoring device body 1 is provided. Figure 1 and Figure 2 Set two in.

[0034] The counterweight block 5 forms an integral structure with the bedrock 4 through the anchor rod 3. During the uplift of the soil, due to the action of the counterweight block 5, the monitoring device body 1 as a whole does not move with the soil, and only the monitoring rod 113 moves with the soil, thereby achieving accurate measurement of the soil at the bottom of the foundation pit and being able to provide real-time feedback on the size of the uplift displacement. By utilizing the capacitive sensing principle, the measurement accuracy is high, and multiple capacitive monitoring components 11 are arranged at different positions of the device to measure the uplift patterns and changes of soil in different soil layers.

[0035] like Figure 2As shown, the monitoring device body 1 is provided with two vertical shells, one of which is the monitoring shell (left side in the figure) and the other is the sandwich shell (right side in the figure). A fixed pole piece 111 and a mica sheet 112 are provided inside the monitoring shell, and the sandwich shell seals the fixed pole piece 111 and the mica sheet 112 in the counterweight block 5 to ensure that the monitoring element does not contact with the external soil, and the monitoring rod 113 extends through the sandwich shell.

[0036] like Figure 2 and Figure 3 As shown, two fixed-electrode sheets 111 are fixed in the monitoring housing, and there is a gap between the two fixed-electrode sheets 111 for the mica sheet 112 to enter. The mica sheet 112 has a neat shape and a smooth surface. The mica sheet 112 is sandwiched between the two fixed-electrode sheets 111 in the vertical direction. The monitoring rod 113 that moves with the soil is completely stuck in the horizontal direction and can only move vertically.

[0037] In order to reduce the influence on the measurement results, the mica sheet 112 should be initially arranged directly below the two fixed-electrode sheets 111 to ensure that the displacement value can be measured immediately when the soil rises.

[0038] The specific monitoring principle is: the monitoring rod 113 rises with the soil, and the mica sheet 112 fixed on it rises accordingly, and is inserted into the area where the two fixed-electrode sheets 111 overlap each other. The medium in the area changes due to the intervention of the mica sheet 112. The dielectric coefficient of air is 1, while the dielectric coefficient of the mica sheet 112 is 7. The capacitance in the circuit changes immediately, and the oscillation frequency of the oscillator in the circuit also changes. The frequency change is then converted into an amplitude change through a frequency discriminator, and then output after amplification. The capacitance change is obtained through the output data, and then the displacement of the mica sheet 112 is inferred, and the amount of uplift of the soil layer can be known.

[0039] The monitoring device body 1 also includes a limiting mechanism for maintaining the monitoring rod 113 in an initial position, that is, before the monitoring device is buried, the monitoring rod 113 is in the initial position and cannot move. By setting the limiting mechanism, the range reduction or inaccurate measurement caused by the movement of the monitoring rod 113 during the burial process can be reduced.

[0040] Another point needs to be explained. The monitoring device of this embodiment can not only detect the amount of soil uplift, but also monitor the amount of soil subsidence. Two upper and lower mica sheets 112 are set at the end of the monitoring rod 113, and each mica sheet is equipped with a pair of fixed pole sheets 111. The monitoring rod 113 can monitor the displacement whether it rises or falls with the soil. If the soil first rises and then sinks, the movement law of the soil can be monitored by using only the upper fixed pole sheet 111 and the mica sheet 112.

[0041] The monitoring rod 113 is provided with a limit mechanism at the top and bottom to limit the upper and lower positions of the monitoring rod 113 .

[0042] like Figure 4 As shown, the limiting mechanism is arranged in the interlayer shell, and the limiting mechanism includes a fixed limiting plate 133, a movable limiting plate 134 and a limiting rod 132 for controlling the relative movement of the two, and the movable limiting plate 134 can move with the monitoring rod 113; it also includes a fixed plate 136 connected to the fixed limiting plate 133 and a movable plate 135 moving with the movable limiting plate 134, and the movable plate 135 is vertically slidably connected to the interlayer shell.

[0043] The fixed limit plate 133 and the movable limit plate 134 are arranged vertically and staggered, the two plates are fitted, and a limit hole is provided on the side to cooperate with the limit rod 132. The limit rod 132 is equipped with an electric telescopic rod 131, and the electric telescopic rod 131 drives the limit rod 132 to be plugged in and out to realize the control of the relative movement between the fixed limit plate 133 and the movable limit plate 134. Specifically, the electric telescopic rod 131 is externally connected to a controller, and the control signal of the electric telescopic rod and the signal obtained by the capacitance monitoring component 11 are transmitted through the pre-buried cable.

[0044] like Figure 3 and Figure 5 As shown, the sandwich shell reserves a vertical notch as a moving path for the monitoring rod 113, and an inner and outer support plate 121 are provided between the monitoring rod 113 and the movable plate 135, wherein the bottom end of the outer support plate 121 is connected to the junction of the monitoring rod 113 and the notch, and maintains a set inclination angle with the outer inner wall of the sandwich shell. Specifically in this embodiment, as Figure 5 In the direction shown in , the inner support plate 121 is located on the left side, close to the inner wall on the left side, but maintaining a certain gap without friction with the inner wall. The outer support plate 121 is located on the right side, with the bottom end connected to the junction of the monitoring rod 113 and the notch, and maintaining a set inclination angle with the outer inner wall of the sandwich shell, and the inclination angle range is set to 3-5°.

[0045] The reason for setting the inclination angle is that, since a notch is provided on the outside for the monitoring rod 113 to move, the soil has a tendency to enter the sandwich shell through the notch. In order to avoid soil intrusion to the greatest extent, the bottom end of the outer support plate 121 is connected to the junction of the monitoring rod 113 and the notch. At the same time, during the upward movement, the existence of the inclination angle prevents the support plate from contacting and rubbing with the inner wall of the sandwich shell. Therefore, during the upward movement, only friction with the soil is generated, and the friction is small and does not affect the monitoring effect. Therefore, it can avoid soil intrusion to the greatest extent and reduce the friction of the support plate moving upward. If the support plate is set to a vertical setting, although it can avoid contact with the sandwich shell, the soil will invade more than the inclined setting.

[0046] The support plate 121 is provided with a roller 122 which is rollingly connected to the inner wall of the sandwich shell. The corresponding inner wall of the sandwich shell is provided with a track groove which cooperates with the roller 122. The track groove is vertically arranged to play a guiding role.

[0047] Embodiment 2

[0048] This embodiment provides a working method of the monitoring device according to the first embodiment, comprising the following steps:

[0049] The monitoring device is buried as a whole below the ground at the bottom of the foundation pit. Different numbers of capacitor monitoring components 11 are set according to the monitoring requirements of different soil layers. When buried, the monitoring rod 113 is limited to keep the initial position of the monitoring rod 113 unchanged. When monitoring is needed, the monitoring rod 113 is opened to limit its free movement state. When the soil moves up and down, the monitoring rod 113 is driven to move. The capacitance is changed according to the mica sheet 112 entering between the two fixed pole sheets 111 to monitor the movement of the soil.

[0050] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A monitoring device for soil uplift at the bottom of a foundation pit, It is characterized in that The device is buried below the ground at the bottom of the foundation pit, and includes a counterweight block and an anchor rod connected thereto and used as a support, wherein the lower part of the anchor rod is driven into the bedrock, and the counterweight block is embedded with a monitoring device body, and the monitoring device body includes at least one capacitive monitoring component arranged in a vertical direction; The capacitance monitoring assembly comprises two vertically arranged fixed-pole pieces and a monitoring rod, one end of the monitoring rod is vertically provided with a mica piece, and the other end extends out of the counterweight block to move up and down with the soil, and driven by the monitoring rod, the mica piece enters between the two fixed-pole pieces to change the capacitance to monitor the movement of the soil; The monitoring device body also includes a limit mechanism for maintaining the monitoring rod in an initial position; the limit mechanism includes a fixed limit plate, a movable limit plate and a limit rod for controlling the relative movement of the two, and the movable limit plate can move with the monitoring rod; the limit rod is equipped with an electric telescopic rod, and the electric telescopic rod drives the limit rod to be pulled out and inserted to realize the control of the relative movement between the fixed limit plate and the movable limit plate; The two fixed-pole pieces are fixed in the monitoring housing, and there is a gap between the two fixed-pole pieces for the mica piece to enter; the mica piece has a neat shape and a smooth surface, and the mica piece is clamped between the two fixed-pole pieces in the vertical direction, and the monitoring rod that moves with the soil is completely stuck in the horizontal direction and only moves vertically; The mica sheet is initially set just below the two fixed-pole sheets to ensure that the displacement value is measured immediately when the soil rises; The specific monitoring principle is as follows: the monitoring rod rises with the soil, and the mica sheet fixed on it rises accordingly, and is inserted into the area covered by the two fixed-electrode sheets. The medium in the area changes, and the capacitance in the circuit changes immediately, and the oscillation frequency of the oscillator in the circuit also changes. Then, the frequency change is converted into amplitude change through the frequency discriminator, and then output after amplification. The capacitance change is obtained through the output data, and then the displacement of the mica sheet is inferred, and the uplift of the soil layer is known; The monitoring device body further comprises an interlayer shell, the interlayer shell seals the fixed pole piece and the mica piece in the counterweight block, the monitoring rod extends through the interlayer shell, and the limiting mechanism is arranged in the interlayer shell; The limiting mechanism further comprises a fixed plate connected to the fixed limiting plate and a movable plate following the movable limiting plate, wherein the movable plate is vertically slidably connected to the interlayer shell; The sandwich shell reserves a vertical notch as a moving path for the monitoring rod, and an inner and outer support plate is provided between the monitoring rod and the movable plate, wherein the bottom end of the outer support plate is connected to the junction of the monitoring rod and the notch, and maintains a set inclination angle with the outer inner wall of the sandwich shell; The support plate is provided with a roller which is rollingly connected with the inner wall of the sandwich shell, and a track groove which cooperates with the roller is provided on the corresponding inner wall of the sandwich shell. The track groove is vertically arranged to play a guiding role.

2. A monitoring device for soil heave at the bottom of a foundation pit as claimed in claim 1, It is characterized in that The monitoring rod is respectively provided with a limiting mechanism at the top and the bottom.

3. The working method of the monitoring device according to any one of claims 1 to 2, It is characterized in that The following steps are involved: The monitoring device is buried as a whole below the ground at the bottom of the foundation pit. Different numbers of capacitor monitoring components are set according to the monitoring requirements of different soil layers. When buried, the monitoring rod is limited to keep the initial position of the monitoring rod unchanged. When monitoring is needed, the monitoring rod limit is opened to keep it in a free movement state. When the soil moves up and down, the monitoring rod is driven to move. The capacitance changes according to the mica sheet entering between the two fixed poles to monitor the movement of the soil.

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