Foundation pit bottom rebound monitoring device

Abstract

The utility model discloses a foundation pit bottom springback monitoring device which comprises a measuring rod, a resin grouting pipe and a cement grouting pipe, the measuring rod is arranged in a drill hole formed before a foundation pit is excavated, a resin film bag is fixedly arranged at the lower end of the measuring rod and located at the bottom of the drill hole, the lower end of the resin grouting pipe is communicated with an inner cavity of the resin film bag, and the cement grouting pipe is arranged in the inner cavity of the resin film bag. The lower end of the cement grouting pipe is fixed to the end, close to the resin film bag, of the measuring rod, and the resin grouting pipe and the cement grouting pipe are bundled on the measuring rod and led out of the drill hole through the measuring rod. According to the scheme, the springback amount of the pit bottom in any process of excavation of the foundation pit can be monitored, and therefore real-time and accurate monitoring of the springback amount is achieved; specifically, before a foundation pit is excavated, a ground which is not influenced by excavation of the foundation pit is selected around the foundation pit to serve as a datum point; after a foundation pit is excavated, due to unloading of a soil body, the monitoring device can move upwards along with the soil body, and the springback value of the bottom of the foundation pit can be calculated by measuring the elevation change from the measuring rod to the datum point.

Description

Technical Field

[0001] The utility model relates to the technical field of civil engineering construction, in particular to a foundation pit bottom rebound monitoring device. Background Art

[0002] At present, the following methods are mainly used to monitor the bottom of the foundation pit during foundation pit excavation: one is to install inclinometers around the foundation pit to monitor the displacement of the soil around the foundation pit; one is to use settlement observation points to monitor the settlement of the ground surface near the foundation pit; one is to install stress and strain sensors in the foundation pit support structure or surrounding soil to monitor the stress changes of the support structure and the strain of the soil; these methods can be used alone or in combination. Which monitoring method to choose in actual engineering depends on the specific conditions of the foundation pit.

[0003] However, the above methods also have limitations. When under complex geological conditions, the data of the inclinometer may be disturbed and the monitoring accuracy will be reduced. When the scheme of monitoring surface settlement is used, the surface settlement may appear in the later stage of foundation pit excavation, and it is impossible to reflect the initial condition of pit bottom rebound in time. In addition, surface settlement is caused by many factors and is not necessarily entirely caused by pit bottom rebound. For the monitoring of stress and strain, professional equipment and personnel are required for installation and data interpretation, and the installation and maintenance costs are high. Surface monitoring can only understand the changes in surface settlement around the foundation pit, and cannot know the rebound that may occur at the bottom of the pit during any process of foundation pit excavation. The rebound deformation of the pit bottom at any process of foundation pit excavation cannot be grasped in time at present. Therefore, the rebound monitoring of the pit bottom during foundation pit excavation needs to change this situation technically. Utility Model Content

[0004] In view of the above-mentioned deficiencies in the prior art, the utility model provides a foundation pit bottom rebound monitoring device, which solves the problem that it is difficult to perform rebound detection on the pit bottom during the foundation pit excavation process.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A foundation pit bottom rebound monitoring device is provided, which comprises a measuring rod, a resin grouting pipe and a cement grouting pipe placed in a borehole set before the foundation pit is excavated, a resin film bag is fixedly provided at the lower end of the measuring rod, and the resin film bag is located at the bottom of the borehole, the lower end of the resin grouting pipe is connected to the inner cavity of the resin film bag, the lower end of the cement grouting pipe is fixed to the end of the measuring rod close to the resin film bag, the resin grouting pipe and the cement grouting pipe are bundled on the measuring rod and led out of the borehole through the measuring rod.

[0007] Furthermore, the measuring rod comprises a plurality of sub-measuring rods which are connected in sequence via snap-fit ​​joints.

[0008] Furthermore, both the resin grouting pipe and the cement grouting pipe are flexible hoses, both the resin grouting pipe and the cement grouting pipe are provided with a one-way valve, and both the one-way valves are close to the lower end of the measuring rod.

[0009] Further, the resin film bag is filled with resin slurry through the resin grouting pipe, and the bottom of the borehole is filled with cement slurry for wrapping the resin film bag through the cement grouting pipe.

[0010] Further, the borehole above the cement slurry is filled with coarse sand.

[0011] Furthermore, the bottom of the borehole is lower than the bottom of the foundation pit to be excavated.

[0012] The beneficial effects of the utility model are:

[0013] This solution can monitor the rebound amount of the pit bottom during any process of foundation pit excavation, thereby realizing real-time and accurate monitoring of the rebound amount; specifically, before the foundation pit is excavated, a ground that is not affected by the foundation pit excavation is selected around the foundation pit as a reference point; after the foundation pit is excavated, due to the unloading of the soil, the monitoring device of this solution will move upward with the soil, and the rebound amount of the pit bottom can be calculated by measuring the elevation change from the measuring rod to the reference point; at the same time, in order to prevent the measuring rod from affecting the construction of the foundation pit, the sub-measuring rod above the excavation surface can be removed through the snap joint according to the excavation depth, so as to realize the removal and recovery of the sub-measuring rod, thereby reducing the construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure of the foundation pit bottom rebound monitoring device.

[0015] Figure 2 It is a structural schematic diagram of the implementation of the foundation pit bottom rebound monitoring device.

[0016] Figure 3 Schematic diagram of the local structure at the bottom of the borehole.

[0017] Figure 4 This is a schematic diagram of the structure of the foundation pit bottom rebound monitoring device during excavation.

[0018] Figure 5 This is a schematic diagram of the structure of the foundation pit bottom rebound monitoring device when excavation is completed.

[0019] Among them, 1. drill hole, 2. sub-measuring rod, 3. resin grouting pipe, 4. cement grouting pipe, 5. resin film bag, 6. one-way valve, 7. resin slurry, 8. cement slurry, 9. coarse sand, 10. bottom of foundation pit, 11. excavation surface. DETAILED DESCRIPTION

[0020] The specific implementation methods of the utility model are described below to facilitate technical personnel in this technical field to understand the utility model, but it should be clear that the utility model is not limited to the scope of the specific implementation methods. For ordinary technical personnel in this technical field, as long as various changes are within the spirit and scope of the utility model defined and determined by the attached claims, these changes are obvious, and all utility model creations using the concept of the utility model are protected.

[0021] like Figures 1 to 5 As shown, the pit bottom rebound monitoring device of the present scheme includes a measuring rod, a resin grouting pipe 3 and a cement grouting pipe 4 placed in a borehole 1 set before the foundation pit excavation, wherein the bottom of the borehole 1 is lower than the bottom 10 of the foundation pit to be excavated, a resin film bag 5 is fixedly provided at the lower end of the measuring rod, and the resin film bag 5 is located at the bottom of the borehole 1, the lower end of the resin grouting pipe 3 is connected to the inner cavity of the resin film bag 5, and the lower end of the cement grouting pipe 4 is fixed to the end of the measuring rod close to the resin film bag 5, and the resin grouting pipe 3 and the cement grouting pipe 4 are bundled on the measuring rod and led out of the borehole 1 through the measuring rod.

[0022] The resin film bag 5 of this solution is filled with resin slurry 7 through the resin grouting pipe 3, the bottom of the borehole 1 is filled with cement slurry 8 for wrapping the resin film bag 5 through the cement grouting pipe 4, and the borehole 1 above the cement slurry 8 is filled with coarse sand 9.

[0023] The measuring rod of the present scheme includes a plurality of sub-measuring rods 2 connected in sequence by snap-on joints. When implemented, the top of the uppermost terminal measuring rod 2 can be flush with the port of the borehole 1 or the initial ground of the foundation pit. Before the foundation pit is excavated, a ground point that is not affected by the foundation pit excavation is selected around the foundation pit as a reference point; and the elevation of the top of the uppermost terminal measuring rod 2 and the reference point is measured to be H1. After the foundation pit is excavated, the soil moves upward due to unloading, and the weight of the resin slurry 7 is lighter than that of the soil. Therefore, when the soil is unloaded, the displacement of the resin slurry 7 and the measuring rod can better reflect the amount of rebound at the bottom of the pit.

[0024] This scheme can calculate the rebound amount of the foundation pit bottom by measuring the elevation change from the sub-measuring rod 2 to the reference point; specifically, since the foundation pit is excavated in layers, in order not to affect the construction of the foundation pit excavation, the redundant sub-measuring rods 2 above the foundation pit excavation surface 11 are removed through snap-on joints. At this time, the top of the sub-measuring rod 2 closest to the reference point is at an elevation of H2 with the reference point, and the pit bottom rebound amount ΔH can be calculated by subtracting H1 from H2 and then subtracting the lengths of the removed sub-measuring rods 2.

[0025] Preferably, the resin grouting pipe 3 and the cement grouting pipe 4 are both flexible hoses, and both are provided with a one-way valve 6, and both the one-way valves 6 are close to the lower end of the measuring rod; when the external device fills the resin film bag 5 with resin slurry 7 through the resin grouting pipe 3, and fills the bottom of the borehole 1 with cement slurry 8 through the cement grouting pipe 4, due to the setting of the one-way valve 6, the external device can reversely suck the slurry remaining in the resin grouting pipe 3 and the cement grouting pipe 4, so that when the excavation surface 11 is removed, When the sub-measuring rod 2 is removed, the binding between the resin grouting pipe 3 and the cement grouting pipe 4 and the sub-measuring rod 2 can be released, and the resin grouting pipe 3 and the cement grouting pipe 4 can be coiled and recovered to avoid the resin grouting pipe 3 and the cement grouting pipe 4 being unable to be recovered due to the solidification of the slurry in the pipe; finally, when the foundation pit is dug to the bottom of the pit, the resin grouting pipe 3 and the cement grouting pipe 4 below the one-way valve 6 can be cut off, and when they are used again, the one-way valve 6 can be used as a joint to reconnect a section of the resin grouting pipe 3 and the cement grouting pipe 4.

Claims

1. A foundation pit bottom rebound monitoring device, characterized in that: It includes a measuring rod, a resin grouting pipe and a cement grouting pipe placed in a borehole set before foundation pit excavation. A resin film bag is fixedly provided at the lower end of the measuring rod, and the resin film bag is located at the bottom of the borehole. The lower end of the resin grouting pipe is connected to the inner cavity of the resin film bag, and the lower end of the cement grouting pipe is fixed to the end of the measuring rod close to the resin film bag. The resin grouting pipe and the cement grouting pipe are bundled on the measuring rod and led out of the borehole through the measuring rod.

2. The foundation pit bottom rebound monitoring device according to claim 1 is characterized in that: The measuring rod comprises a plurality of sub-measuring rods which are connected in sequence via snap-fit ​​joints.

3. The foundation pit bottom rebound monitoring device according to claim 1 is characterized in that: The resin grouting pipe and the cement grouting pipe are both flexible hoses, and both the resin grouting pipe and the cement grouting pipe are provided with a one-way valve, and the two one-way valves are both close to the lower end of the measuring rod.

4. The foundation pit bottom rebound monitoring device according to claim 1 is characterized in that: The resin film bag is filled with resin slurry through a resin grouting pipe, and the bottom of the borehole is filled with cement slurry for wrapping the resin film bag through a cement grouting pipe.

5. The foundation pit bottom rebound monitoring device according to claim 4 is characterized in that: The borehole above the cement slurry is filled with coarse sand.

6. The foundation pit bottom rebound monitoring device according to claim 1, characterized in that: The bottom of the borehole is lower than the bottom of the foundation pit to be excavated.

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