Block stone vibration density test system and method

Abstract

The invention relates to a block stone vibration density test system and method, and belongs to the technical field of immersed tunnel foundation construction. The block stone vibration density test system comprises a plurality of groups of test areas, wherein each group of test area comprises a retaining wall, a bottom plate, a cement mixing pile, a block stone layer, sludge, a soil pressure box, a pile top settlement monitoring device and a surface settlement monitoring device; wherein the retaining wall is used for enclosing a test area; the bottom plate is used for bearing the test area and forms a test space with an open top together with the retaining wall; the silt is backfilled in the test space; the cement mixing pile is constructed in the test space; the block stones are laid on the top of the cement stirring pile; the soil pressure boxes are distributed on the tops of the cement stirring piles and soil between the piles. The pile top settlement monitoring device is arranged on the pile top of the cement mixing pile; and the surface settlement monitoring device is arranged above the block stone layer. According to the block stone vibration density test system, vibration density construction parameters suitable for a construction project can be obtained, so that foundation settlement during sinking of an immersed tube is effectively reduced, and the project quality is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of immersed tube tunnel foundation construction, and in particular relates to a block rock vibration compaction test system and method. Background Art

[0002] A rock compaction layer is usually set on the foundation trench of the immersed tube tunnel. The rock compaction layer is composed of rocks of a certain thickness. These rocks are compacted through a compaction process to form a dense layer to ensure the stability and uniformity of the immersed tube bed, thereby ensuring that the bed can bear the weight of the immersed tube and traffic load. Under the compaction layer, cement mixing piles are usually used to reinforce the foundation.

[0003] It is very necessary to conduct a block rock vibration compaction test before sinking the pipe. Through the block rock vibration compaction test, the vibration compaction effect of the block rock cushion layer under different vibration compaction parameters is analyzed, and finally a set of vibration compaction parameters suitable for actual construction is determined to guide the vibration compaction operation. For example, it is necessary to detect the vertical average stress at the top of the cement mixing pile to evaluate the stress of the mixing pile during the block rock vibration compaction to ensure that the mixing pile will not be damaged by the block rock vibration compaction; measure the average settlement of the block rock layer and the deformation modulus of the block rock and cement mixing pile foundation after vibration compaction to evaluate the loose laying thickness of the block rock and the settlement of the foundation when the pipe is sunk.

[0004] Therefore, how to provide a block stone vibration density test method is a technical problem that urgently needs to be solved. Summary of the invention

[0005] In view of the shortcomings in the prior art, the present invention provides a block rock vibration compaction test system and method, which monitors the stress changes and settlement of the top of the cement mixing pile and the soil layer between the piles in real time through the setting of an earth pressure box, a pile top settlement monitoring device and a surface settlement monitoring device, thereby improving the reliability of the test data; and through the setting of multiple groups of test areas, it is possible to obtain vibration compaction construction parameters suitable for the construction project, thereby effectively reducing the foundation settlement during the sinking of the immersed tube and ensuring the quality of the project.

[0006] The present invention provides a block rock vibration compaction test system, comprising: a plurality of test areas, each test area comprising:

[0007] A retaining wall is used to enclose the test area, and the bottom of the retaining wall enters the impermeable layer of the soil layer;

[0008] The bottom plate is used to support the test area and together with the retaining wall form a test space with an open top;

[0009] Silt, which is backfilled into the test space;

[0010] Cement mixing piles are constructed in the test space, and a liquid sludge layer is laid on the top of the cement mixing piles to simulate the residual liquid sludge layer after dredging;

[0011] The block stone layer is laid on top of the cement mixing pile according to the loose laying thickness to be verified;

[0012] Soil pressure boxes are distributed on the top of cement mixing piles and the soil between piles to monitor the stress changes of the soil layers on the top of cement mixing piles and between piles;

[0013] A pile top settlement monitoring device is installed on the top of the cement mixing pile to monitor the settlement of the top of the cement mixing pile;

[0014] The surface settlement monitoring device is arranged above the block rock layer and is used for monitoring the surface settlement.

[0015] This technical solution can monitor the stress changes and settlement of the top of the cement mixing pile and the soil layer between the piles in real time through the setting of earth pressure boxes, pile top settlement monitoring devices and surface settlement monitoring devices, thereby improving the reliability of test data; and can obtain vibration and compaction construction parameters suitable for the construction project through the setting of multiple groups of test areas, thereby effectively reducing the foundation settlement during the sinking of the immersed tube and ensuring the quality of the project.

[0016] In some of the embodiments, a column hole is opened at the top of the cement mixing pile, and the pile top settlement monitoring device is installed in the column hole.

[0017] This technical solution can not only improve the accuracy of data, but also effectively protect the monitoring device from damage caused by the external environment.

[0018] In some of the embodiments, the pile top settlement monitoring device includes a steel column, a settlement plate and a displacement sensor; wherein the steel column is installed at the bottom of the column hole; the settlement plate is installed at the top of the column hole and clamped on the top of the cement mixing pile; the displacement sensor is arranged between the steel column and the settlement plate, and is fixedly connected to the settlement plate, for monitoring the settlement amount of the settlement plate.

[0019] In some of the embodiments, the pile top settlement monitoring device further includes an acceleration sensor, which is buried between the settlement plate and the cement mixing pile and is used to monitor the vibration frequency.

[0020] In some of the embodiments, the surface settlement monitoring device includes a level and a plurality of observation points arranged on the surface of the block rock layer.

[0021] In some of the embodiments, the block rock vibration compaction test system further includes a support column, which is disposed at the bottom of the test area, and the bottom of the support column penetrates the soil layer into the bearing layer to support the test area.

[0022] Based on the above-mentioned block rock vibration density test system, the present invention further provides a block rock vibration density test method, which adopts the above-mentioned block rock vibration density test system and comprises the following steps:

[0023] Construction of test areas: multiple test areas were constructed, and blocks of the same particle size and gradation were laid in each test area. During construction, the distance between cement mixing piles and the thickness of loose block stones were used as control variables, and a control group and a test group were set up respectively. At the same time, during the construction process, earth pressure boxes and pile top settlement monitoring devices were set on the tops of cement mixing piles in each test area, and earth pressure boxes were set in the block stone layer, and surface settlement monitoring devices were set on the surface of the block stone layer.

[0024] Vibration compaction and monitoring: Start the vibrating hammer for vibration compaction. During the process, the stress changes at the top and between the piles of the cement mixing pile are determined based on the data from each soil pressure box. The pile top settlement monitoring device is used to monitor the pile top settlement data, and the surface settlement monitoring device is used to monitor the surface settlement.

[0025] Deformation modulus test: After the compaction is completed, a flat plate load test is carried out on the surface of the block stone layer, and the load and settlement curve is drawn to obtain the deformation modulus of the block stone layer and the cement mixing pile community.

[0026] Through the construction of multiple test areas and the setting of control and test groups, this technical solution can accurately control the pile spacing of cement mixing piles and the thickness of lycopodii paving, ensure the accuracy and consistency of construction parameters, and thus guide the vibration compaction operations and foundation reinforcement measures in actual construction through detailed monitoring and detection data, thereby improving construction efficiency and project quality.

[0027] In some embodiments, the construction of a single test area includes the following sub-steps:

[0028] Retaining wall construction: Steel sheet piles are set up as retaining walls to form a closed cofferdam. The bottom of the steel sheet piles enters the impermeable layer and the top is at least 1.0m above the ground.

[0029] Excavation of foundation pit: excavation of foundation pit is carried out in the closed cofferdam formed by the retaining wall. During the excavation of foundation pit, the steel sheet piles are supported by surrounding purlins while excavation;

[0030] Bottom plate construction: pour and harden the concrete slab at the bottom of the foundation pit as the bottom plate;

[0031] Cement mixing pile construction: backfill silt in the foundation pit above the bottom plate and carry out cement mixing pile construction in the foundation pit;

[0032] Install the monitoring device on the top of the pile: excavate the soil layer on the top of the cement mixing pile, and install the soil pressure box and the settlement monitoring device on the top of the cement mixing pile;

[0033] Liquid sludge layer laying: Liquid sludge layer is laid on the top of cement mixing piles to simulate the residual sludge residue after silting or desilting;

[0034] Stone layer laying: Use an excavator to lay the stone layers on the top of the cement mixing piles. At the same time, manual labor cooperates with the excavator to simulate the height difference of stone filling. Set up an earth pressure box during the laying process.

[0035] In some of the embodiments, after the cement mixing pile construction step, it is necessary to determine whether the strength of the cement mixing piles in each test area meets the test requirements. When it meets the test requirements, the step of deploying the pile top monitoring device is performed.

[0036] In some of the embodiments, in the test area construction step, the method for setting up the surface settlement monitoring device includes: evenly setting multiple observation points in each group of test areas, and using a level to measure the elevation of each observation point; in the vibration and monitoring steps, using a level to measure the elevation change of the observation point after vibration.

[0037] Based on the above scheme, the block stone vibration compaction test system in the embodiment of the present invention can monitor the stress changes and settlement of the top of the cement mixing pile and the soil layer between the piles in real time through the setting of the soil pressure box, the pile top settlement monitoring device and the surface settlement monitoring device, thereby improving the reliability of the test data; and can obtain vibration compaction construction parameters suitable for the construction project through the setting of multiple groups of test areas, thereby effectively reducing the foundation settlement during the sinking of the immersed pipe and ensuring the quality of the project. The block stone vibration compaction test method in the embodiment of the present invention can accurately control the pile spacing and block stone loose paving thickness of the cement mixing pile through the construction of multiple groups of test areas and the setting of the control group and the test group, thereby ensuring the accuracy and consistency of the construction parameters, thereby guiding the vibration compaction operation and foundation reinforcement measures in the actual construction through detailed monitoring and detection data, and improving the construction efficiency and project quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0039] Figure 1 It is a structural schematic diagram of a block stone vibration compaction test system in an embodiment of the present invention;

[0040] Figure 2 Schematic diagram of the arrangement of the earth pressure cell of the block rock vibration compaction test system in the embodiment of the present invention;

[0041] Figure 3 It is a schematic diagram of the arrangement of a pile top settlement device of a block rock vibration compaction test system in an embodiment of the present invention;

[0042] Figure 4 for Figure 3 A magnified view of part A;

[0043] Figure 5Flow chart of the block stone vibration compaction test method in an embodiment of the present invention;

[0044] Figure 6 It is a flow chart of the construction of the test area in the block rock vibration compaction test method in the embodiment of the present invention;

[0045] Figure 7 The four test areas set in Example 1;

[0046] Figure 8 The plan layout of the support columns of each group of test areas in Example 1;

[0047] Fig. 9 It is the plan layout diagram of cement mixing piles in each test area in Example 1;

[0048] Fig.10 is a plan view of the earth pressure boxes of each group of test areas in Example 1;

[0049] Fig.11 It is a plan view of the pile top settlement device of each group of test areas in Example 1;

[0050] Fig.12 This is a plan view of the observation points in each group of test areas in Example 1.

[0051] In the figure:

[0052] 1. Retaining wall; 2. Bottom plate; 3. Support column; 4. Cement mixing pile; 5. Block stone layer; 6. Silt; 7. Earth pressure box; 8. Pile top settlement device; 9. Liquid silt layer;

[0053] 801, displacement sensor; 802, acceleration sensor; 803, data collector; 804, steel column; 805, sedimentation plate; 806, flange; 807, observation point. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0056] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] like Figure 1 As shown, in one embodiment of the block rock vibration density test system and method of the present invention, the block rock vibration density test system includes multiple test areas, each test area includes a retaining wall 1, a bottom plate 2, a cement mixing pile 4, a block rock layer 5, silt 6, an earth pressure box 7, a pile top settlement monitoring device 8 and a surface settlement monitoring device; wherein the retaining wall 1 is used to enclose the test area, and the bottom of the retaining wall 1 enters an impermeable layer of the soil layer; the bottom plate 2 is used to bear the test area, and together with the retaining wall 1, forms a test space with an open top; the silt 6 is backfilled in the test space; the cement mixing pile 4 is constructed in the test space, and the top of the cement mixing pile 4 is paved with a liquid silt layer for simulating the residual after dredging; the block rock layer 5 is laid on the top of the cement mixing pile according to the loose laying thickness to be verified; as shown Figure 2 As shown, the soil pressure box 7 is distributed on the top of the cement mixing pile 4 and the soil between the piles, and is used to monitor the stress changes of the soil layer on the top of the cement mixing pile 4 and between the piles; the pile top settlement monitoring device is set on the top of the cement mixing pile 4 to monitor the settlement of the top of the cement mixing pile 4; the surface settlement monitoring device is set above the block stone layer 5 to monitor the surface settlement.

[0058] In the above-mentioned schematic embodiment, by setting up the earth pressure box 7, the pile top settlement monitoring device 8 and the surface settlement monitoring device, the stress changes and settlement of the top of the cement mixing pile 4 and the soil layer between the piles can be monitored in real time, thereby improving the reliability of the test data; and by setting up multiple groups of test areas, the vibration construction parameters suitable for the construction project can be obtained, thereby effectively reducing the foundation settlement during the sinking of the immersed tube and ensuring the quality of the project.

[0059] It should be noted that the soil pressure box 7 distributed in the soil between the piles is specifically distributed in the soil between the piles at the elevation of the top of the cement mixing pile 4 .

[0060] In some embodiments, Figure 3 As shown, a column hole is opened on the top of the cement mixing pile 4, and a pile top settlement monitoring device is installed in the column hole. Installing the pile top settlement monitoring device in the column hole can not only improve the accuracy of the data, but also effectively protect the monitoring device, avoid damage to it by the external environment, and improve the reliability of the monitoring data.

[0061] In some embodiments, Figure 4 As shown, the pile top settlement monitoring device includes a steel column 804, a settlement plate 805 and a displacement sensor 801; wherein the steel column 804 is installed at the bottom of the column hole; the settlement plate 805 is installed at the top of the column hole and clamped on the top of the cement mixing pile 4; the displacement sensor 801 is arranged between the steel column 804 and the settlement plate 805, and is fixedly connected to the settlement plate 805, and is used to monitor the settlement amount of the settlement plate 805.

[0062] In some embodiments, Figure 4 As shown, the displacement sensor 801 is fixed between the steel column 804 and the sedimentation plate 805 via a flange 806. The outer periphery of the steel column 804 is wrapped with non-woven fabric to increase the friction between the steel column 804 and the wall of the column hole.

[0063] In some embodiments, Figure 4 As shown, the pile top settlement monitoring device 8 also includes an acceleration sensor 802, which is buried between the settlement plate 805 and the cement mixing pile 4 and is used to monitor the vibration frequency.

[0064] In some embodiments, Figure 3 As shown, the pile top settlement monitoring device 8 also includes a collector 803, which is connected to the displacement sensor 801 and the acceleration sensor 802 by wires, respectively, and is used to collect data from the displacement sensor 801 and the acceleration sensor 802. It should be noted that the outside of the wire is wrapped with a high-pressure oil pipe. The high-pressure oil pipe protects the wire to avoid damage to the wire during the vibration compaction process.

[0065] In some embodiments, the surface settlement monitoring device includes a level and a plurality of observation points 807 arranged on the surface of the rock layer 5 .

[0066] In some embodiments, Figure 1 As shown, when the depth of the test area is less than the depth of the site soil layer, the block rock vibration compaction test system also includes a support column 3, which is arranged at the bottom of the test area. The bottom of the support column 3 penetrates the soil layer into the bearing layer to support the test area.

[0067] Based on the above-mentioned block rock vibration test system, Figure 5As shown, the present invention also provides a block rock vibration compaction test method, which adopts the above-mentioned block rock vibration compaction test system, including test area construction, vibration compaction and monitoring, and deformation modulus detection steps; wherein the test area construction steps include: constructing multiple groups of test areas, laying block rock layers 5 with the same particle size distribution in each test area, and using the pile spacing of cement mixing piles 4 and the loose laying thickness of the block rock layer 5 as control variables during construction, and setting a control group and a test group respectively; at the same time, during the construction process, an earth pressure box 7 and a pile top settlement monitoring device 8 are set on the pile top of the cement mixing pile 4 in each test area, and An earth pressure box 7 is set in the layer 5, and a surface settlement monitoring device is set on the surface of the block stone layer 5; the vibration and monitoring steps include: starting a vibrating hammer for vibration, judging the stress changes at the top of the cement mixing pile 4 and between the piles according to the data of each earth pressure box 7 during the process, and using the pile top settlement monitoring device 8 to monitor the pile top settlement data, and using the surface settlement monitoring device to monitor the surface settlement; the deformation modulus detection step includes: after the vibration is completed, a flat plate load test is carried out on the surface of the block stone layer 5, and a load and settlement curve is drawn to obtain the deformation modulus of the block stone layer 5 and the cement mixing pile 4 as a whole.

[0068] In the above-mentioned schematic embodiment, through the construction of multiple groups of test areas and the setting of control groups and test groups, the pile spacing of the cement mixing piles 4 and the loose laying thickness of the block stone layer 5 can be accurately controlled to ensure the accuracy and consistency of the construction parameters, thereby guiding the vibration compaction operation and foundation reinforcement measures in the actual construction through detailed monitoring and detection data, thereby improving the construction efficiency and project quality.

[0069] In some embodiments, Figure 6 As shown, the construction of a single test area includes the steps of retaining wall 1 construction, foundation pit excavation, bottom plate 2 construction, cement mixing pile 4 construction, installation of pile top monitoring device, liquid silt layer laying, and block stone layer 5 laying; wherein, the retaining wall 1 construction step includes: erecting steel sheet piles as retaining wall 1, enclosing to form a closed cofferdam, the bottom of the steel sheet piles enters the impermeable layer, and the top is at least 1.0m above the ground; the foundation pit excavation step includes: excavating the foundation pit in the closed cofferdam enclosed by the retaining wall 1, and when the foundation pit is excavated, the steel sheet piles are supported by purlins while excavating; the bottom plate 2 construction step includes: pouring and hardening the concrete slab at the bottom of the foundation pit as the bottom plate 2; water The construction steps of the mud mixing pile 4 include: backfilling silt 6 in the foundation pit above the bottom plate 2, and constructing the cement mixing pile 4 in the foundation pit; the step of laying out the pile top monitoring device includes: excavating the soil layer on the top of the cement mixing pile 4, and laying out the earth pressure box 7 and the pile top settlement monitoring device 8 on the top of the cement mixing pile 4; the step of laying the liquid silt layer 9 includes: laying the liquid silt layer 9 on the top of the cement mixing pile 4 to simulate the residual silt residue after backsilting or dredging; the step of laying the block stone layer 5 includes: using an excavator to lay the block stone on the top of the cement mixing pile, and manually cooperating with the excavator to simulate the height difference of the block stone filling, and setting the earth pressure box 7 during the laying process.

[0070] In some embodiments, Figure 6 As shown, after the cement mixing pile 4 construction step, it is necessary to determine whether the strength of the cement mixing pile 4 in each test area meets the test requirements. When it meets the test requirements, the step of arranging the pile top monitoring device is carried out.

[0071] In some embodiments, Figure 6 As shown, when the depth of the test area is less than the depth of the site soil layer, the support column 3 is constructed before the retaining wall 1 construction step.

[0072] In some embodiments, in the test area construction step, the method for setting up the surface settlement monitoring device includes: evenly setting multiple observation points 807 in each group of test areas, and using a level to measure the elevation of each observation point 807; in the vibration and monitoring steps, using a level to measure the elevation change of the observation point 807 after vibration.

[0073] Example 1

[0074] Next, Example 1 using the block stone vibration compaction test method and system of the present invention is described. In Example 1, 4 groups of test areas are set up, and the rationality of the vibration compaction construction parameters are evaluated by different cement mixing pile 4 pile spacings and loose laying thickness of the block stone layer 5. The deformation modulus of the block stone layer 5 after vibration compaction is combined to evaluate the influence of the vibration compaction process on the foundation, thereby providing a theoretical basis for obtaining reasonable vibration compaction construction parameters.

[0075] like Figure 7 As shown, the vibration compaction test system in Example 1 includes 4 test areas, which are respectively recorded as C-1, C-2, C-3, and C-4. The size of each test area is 10m*10m. The same number of cement mixing piles 4 are arranged in each test area, and the same number of support columns 3 are arranged at the bottom of each test area. Next, the vibration compaction test process is described, and the vibration compaction test system and vibration compaction test method are explained at the same time:

[0076] 1. Construction of the test area

[0077] The construction of multiple groups of test areas is carried out, and a block stone layer 5 with the same particle size distribution is laid in each test area. During the construction, the pile spacing of the cement mixing piles 4 and the loose laying thickness of the block stone layer 5 are used as control variables, and a control group and a test group are set up respectively; at the same time, during the construction process, an earth pressure box 7 and a pile top settlement monitoring device 8 are set on the pile top of the cement mixing pile 4 in each test area, and an earth pressure box 7 is set in the block stone layer 5, and a surface settlement monitoring device is set on the surface of the block stone layer 5; the specific steps include the following sub-steps.

[0078] (1) Construction of support column 3

[0079] Each test area is provided with support columns 3 of the same number and size. The support columns 3 are constructed with PHC piles, and the pile ends penetrate the soil layer into the bearing layer. The setting of the support columns 3 is calculated according to the tamping plate used for compaction, and it is necessary to ensure that the bottom of the tamping plate is supported by support columns 3 each time the tamping plate is compacted. In this embodiment, 16 support columns 3 are evenly arranged in each test area, and the planar schematic diagram of the support columns 3 is shown in FIG. Figure 8 shown.

[0080] (2) Construction of retaining wall 1

[0081] Steel sheet piles are set up as retaining walls 1 to form a closed cofferdam, with the bottom of the steel sheet piles entering the impermeable layer and the top being at least 1.0m above the ground.

[0082] (3) Excavation of foundation pit

[0083] The foundation pit is excavated in the closed cofferdam formed by the retaining wall 1. When the foundation pit is excavated, the steel sheet piles are supported by the surrounding purlins while the excavation is carried out. One section should be excavated and supported. In this embodiment, the surrounding purlins are made of H-shaped steel, and the support is made of steel pipes. The cross braces are welded to the steel sheet piles, and the corbels are welded between the bottom of the surrounding purlins and the steel sheet piles.

[0084] (4) Construction of base plate 2

[0085] The pile heads of the support columns 3 are cut off to ensure that the pile top elevations of the support columns 3 are consistent, and a concrete slab is poured and hardened at the bottom of the foundation pit (the top of the support columns 3) to serve as the bottom plate 2.

[0086] (5) Construction of cement mixing pile 4

[0087] The foundation pit above the bottom plate 2 is backfilled with silt 6, and cement mixing piles 4 are constructed in the foundation pit; the construction parameters of the cement mixing piles 4 in each test area are the same; in this embodiment, the plan layout of the cement mixing piles 4 in each test area is as follows Fig. 9 As shown, the spacing between the four cement mixing piles in the C-1 group test area is 3m×3m, the spacing between the four cement mixing piles in the C-2 group test area is 3m×4m, the spacing between the four cement mixing piles in the C-3 group test area is 3m×5m, and the spacing between the four cement mixing piles in the C-4 group test area is 3m×4m.

[0088] (6) Determine the strength of cement mixing pile 4

[0089] Determine whether the strength of the cement mixing piles 4 in each test area meets the test requirements. If it does, proceed to the step of deploying the pile top monitoring device; if the strength does not meet the test requirements, continue to wait for the strength of the cement mixing piles 4 to increase until it meets the test requirements.

[0090] (7) Installing pile top monitoring device

[0091] The soil layer on the top of the cement mixing pile 4 is excavated, and an earth pressure box 7 and a pile top settlement monitoring device 8 are arranged on the top of the cement mixing pile 4; the relative position of the earth pressure box 7 and the cement mixing pile 4 in each test area is consistent. In this embodiment, Fig.10 As shown, the earth pressure boxes 7 are respectively arranged at the top of one of the uniaxial piles of each cement mixing pile 4, between two cement mixing piles 4, and between four cement mixing piles 4. Specifically, the earth pressure boxes 7 of group C-1 arranged at the top of the cement mixing piles 4 are numbered C-1-1, C-1-2, C-1-3, C-1-4, C-1-5, and C-1-6; the earth pressure boxes 7 of group C-2 arranged at the top of the cement mixing piles 4 are numbered C-2-1, C-2-2, C-2-3, C-2-4, C-2-5, and C-2-6. -2-2, C-2-3, C-2-4, C-2-5, C-2-6; the soil pressure boxes 7 of the C-3 group set on the top of the cement mixing pile 4 are numbered C-3-1, C-3-2, C-3-3, C-3-4, C-3-5, C-3-6; the soil pressure boxes 7 of the C-4 group set on the top of the cement mixing pile 4 are numbered C-4-1, C-4-2, C-4-3, C-4-4, C-4-5, C-4-6. It should also be noted that each soil pressure box 7 is connected to the collector 803 through a wire. Fig.11 As shown, in this embodiment, two groups of pile top settlement monitoring devices 8 are arranged in each test area. Fig.11 , DC1, DC2, DC3, DC4, DC5, DC6, DC7, and DC8 represent the setting points of the settlement plates 805 in each pile top settlement monitoring device 8, and ZM1, ZM2, ZM3, and ZM4 represent the setting points of the acceleration sensors 802 in each pile top settlement monitoring device 8.

[0092] (8) Liquid sludge layer laying

[0093] A liquid sludge layer 9 is laid on the top of the cement mixing pile 4 to simulate the residual sludge after silting or dredging; in this embodiment, a 20 cm liquid sludge layer is laid.

[0094] (9) Paving of stone layer 5

[0095] An excavator is used to lay the stone on the top of the cement mixing pile. At the same time, the excavator is used to simulate the height difference of the stone filling. The filling accuracy is required to be within 25cm. During the laying process, an earth pressure box 7 is set. The setting of the earth pressure box 7 in the stone layer 5 is as follows: Figure 2 As shown, in this embodiment, a block stone layer 5 with a particle size gradation of 15-30 cm is uniformly used. The loose thickness of the block stone layer 5 in the C-1 test area, the C-2 test area, and the C-3 test area is 1.2 m, and the loose thickness of the block stone layer 5 in the C-4 test area is 1.8 m.

[0096] (10) Setting up of surface settlement monitoring device

[0097] Multiple observation points 807 are evenly set in each test area, and the elevation of each observation point 807 is measured using a level. In this embodiment, each test area is divided into a 3×3 grid, and observation points 807 are set at the intersection of the grid, and the observation points 807 are numbered. Fig.12 As shown, the observation points 807 in the C-1 group test area are numbered C-CJ-1, C-CJ-2, C-CJ-3, C-CJ-4, C-CJ-5, C-CJ-6, C-CJ-7, C-CJ-8, C-CJ-9, C-CJ-10, C-CJ-11, C-CJ-12, C-CJ-13, C-CJ-14, C-CJ-15, and C-CJ-16.

[0098] 2. Vibration and monitoring

[0099] Record the initial values ​​of each soil pressure box 7 and displacement sensor 801, start the vibrating hammer for compaction, and judge the stress changes of the top and between the piles of the cement mixing pile 4 according to the data of each soil pressure box 7 during the process. After the compaction stops, monitor the data of the soil pressure box 7 for 1 hour; and use the pile top settlement monitoring device 8 to monitor the settlement data of the pile top. Specifically, use the displacement sensor 801 to monitor the settlement data of the settlement plate 805 as the settlement data of the cement mixing pile 4. Use the acceleration sensor 802 to monitor the vibration frequency of the cement mixing pile 4; at the same time, use the level in the surface settlement monitoring device to measure the elevation change of the observation point 807 before and after compaction, and the average settlement value of each observation point 807 is used as the surface settlement of the test area; in this embodiment, each test area uses the data collector 803 to collect the data of each soil pressure box 7, displacement sensor 801 and acceleration sensor 802, and records and analyzes them.

[0100] 3. Deformation modulus detection

[0101] After the compaction is completed, a plate load test is carried out on the surface of the block rock layer 5, and a load and settlement curve is drawn to obtain the deformation modulus of the block rock layer 5 and the cement mixing pile 4. In this embodiment, each test area uses a set of shallow load plates to detect the deformation modulus of the block rock layer 5 and the cement mixing pile 4 in the test area.

[0102] 4. Data analysis and experimental summary

[0103] After the test, the test data will be analyzed to obtain key indicators such as the stress time-history curve of the pile top during the vibration compaction process, the vertical displacement (settlement) of the pile body, the settlement of the block stone layer 5, and the deformation modulus of the block stone layer 5 and the cement mixing pile 4. At the same time, based on the corresponding relationship between the vibration settlement and the deformation modulus, the optimal construction parameter combination under the existing equipment conditions should be finally found, and a test summary report should be written.

[0104] Through the description of multiple embodiments of the block stone vibration density test system and method of the present invention, it can be seen that the block stone vibration density test system and method embodiments of the present invention have at least one or more of the following advantages:

[0105] 1. The block rock vibration compaction test system provided by the present invention can monitor the stress change and settlement of the top of the cement mixing pile 4 and the soil layer between the piles in real time through the arrangement of the earth pressure box 7, the pile top settlement monitoring device 8 and the surface settlement monitoring device, thereby improving the reliability of the test data;

[0106] 2. The block rock vibration compaction test system provided by the present invention obtains vibration compaction construction parameters suitable for the construction project by setting up multiple groups of test areas, thereby effectively reducing the foundation settlement during the sinking of the immersed tube and ensuring the quality of the project;

[0107] 3. The block rock vibration compaction test method provided by the present invention can guide the vibration compaction operation and foundation reinforcement measures in actual construction through detailed monitoring and detection data, thereby improving construction efficiency and project quality.

[0108] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0109] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A rock vibration test system, characterized in that: include: Multiple groups of test areas, each group of test areas includes: A retaining wall is used to enclose the test area, and the bottom of the retaining wall enters the impermeable layer of the soil layer; The bottom plate is used to support the test area and together with the retaining wall form a test space with an open top; Silt, which is backfilled into the test space; Cement mixing piles are constructed in the test space, and a liquid sludge layer is laid on the top of the cement mixing piles to simulate the residual liquid sludge layer after dredging; The block stone layer is laid on top of the cement mixing pile according to the loose laying thickness to be verified; Soil pressure boxes are distributed on the top of cement mixing piles and the soil between piles to monitor the stress changes of the soil layers on the top of cement mixing piles and between piles; A pile top settlement monitoring device is installed on the top of the cement mixing pile to monitor the settlement of the top of the cement mixing pile; The surface settlement monitoring device is arranged above the block rock layer and is used for monitoring the surface settlement.

2. The block stone vibration test system according to claim 1, characterized in that: A column hole is provided at the top of the cement mixing pile, and a pile top settlement monitoring device is installed in the column hole.

3. The block stone vibration test system according to claim 2, characterized in that: The pile top settlement monitoring device includes a steel column, a settlement plate and a displacement sensor; wherein the steel column is installed at the bottom of the column hole; the settlement plate is installed at the top of the column hole and clamped on the top of the cement mixing pile; the displacement sensor is arranged between the steel column and the settlement plate and is fixedly connected to the settlement plate to monitor the settlement amount of the settlement plate.

4. The block stone vibration test system according to claim 3, characterized in that: The pile top settlement monitoring device also includes an acceleration sensor, which is buried between the settlement plate and the cement mixing pile and is used to monitor the vibration density frequency.

5. The block stone vibration test system according to claim 1, characterized in that: The surface settlement monitoring device comprises a level and a plurality of observation points arranged on the surface of the block rock layer.

6. The block stone vibration test system according to claim 1, characterized in that: It also includes a support column, which is arranged at the bottom of the test area. The bottom of the support column penetrates the soil layer into the bearing layer to support the test area.

7. A block rock vibration test method, characterized in that: The block stone vibration density test system according to any one of claims 1 to 6 comprises the following steps: Construction of test areas: multiple test areas were constructed, and blocks of the same particle size and gradation were laid in each test area. During construction, the distance between cement mixing piles and the thickness of loose block stones were used as control variables, and a control group and a test group were set up respectively. At the same time, during the construction process, earth pressure boxes and pile top settlement monitoring devices were set on the tops of cement mixing piles in each test area, and earth pressure boxes were set in the block stone layer, and surface settlement monitoring devices were set on the surface of the block stone layer. Vibration compaction and monitoring: Start the vibrating hammer for vibration compaction. During the process, the stress changes at the top and between the piles of the cement mixing pile are determined based on the data from each soil pressure box. The pile top settlement monitoring device is used to monitor the pile top settlement data, and the surface settlement monitoring device is used to monitor the surface settlement. Deformation modulus test: After the compaction is completed, a flat plate load test is carried out on the surface of the block stone layer, and the load and settlement curve is drawn to obtain the deformation modulus of the block stone layer and the cement mixing pile community.

8. The block stone vibration test method according to claim 7, characterized in that: The construction of a single test area includes the following steps: Retaining wall construction: Steel sheet piles are set up as retaining walls to form a closed cofferdam. The bottom of the steel sheet piles enters the impermeable layer and the top is at least 1.0m above the ground. Excavation of foundation pit: excavation of foundation pit is carried out in the closed cofferdam formed by the retaining wall. During the excavation of foundation pit, the steel sheet piles are supported by surrounding purlins while excavation; Bottom plate construction: pour and harden the concrete slab at the bottom of the foundation pit as the bottom plate; Cement mixing pile construction: backfill silt in the foundation pit above the bottom plate, and carry out cement mixing pile construction in the foundation pit; Install the monitoring device on the top of the pile: excavate the soil layer on the top of the cement mixing pile, and install the soil pressure box and the settlement monitoring device on the top of the cement mixing pile; Liquid sludge layer laying: Liquid sludge layer is laid on the top of cement mixing piles to simulate the residual sludge residue after silting or desilting; Stone layer laying: Use an excavator to lay the stone layers on the top of the cement mixing piles. At the same time, manual labor cooperates with the excavator to simulate the height difference of stone filling. Set up an earth pressure box during the laying process.

9. The block stone vibration test method according to claim 8, characterized in that: After the cement mixing pile construction steps, it is necessary to determine whether the strength of the cement mixing piles in each test area meets the test requirements. When it meets the test requirements, the pile top monitoring device deployment step is carried out.

10. The block stone vibration test method according to claim 7, characterized in that: In the test area construction steps, the method for setting up the surface settlement monitoring device includes: evenly setting multiple observation points in each group of test areas, and using a level to measure the elevation of each observation point; in the vibration and monitoring steps, using a level to measure the elevation change of the observation point after vibration.

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