A simulation method for the effect of the gap time of pile side grouting on the slurry morphology

Abstract

The present invention discloses a simulation method for the effect of the interval time of pile side grouting on the morphology of grout, including: Step 1: Assemble relevant components such as a cavity, a model pile, etc.; Step 2: Fill the cavity with the test soil sample of the (n + 1)-th layer obtained. After the cavity is filled with the test soil sample, cover the top plate at the opening; Step 3: Calculate the effective unit weight of each layer of soil sample; Step 4: Calculate the load Q, apply a force to the top plate according to the calculated load Q, and apply the force in a direction perpendicular to the top plate from above, and the force acts on the test soil sample through the top plate; Step 5: Inject grout into the model pile according to a preset grouting pressure P, and the grout is then injected into the test soil sample through the injection port. After a preset interval time, close the grouting pump to obtain test data. The present invention can effectively simulate the effect of the interval time on the solidification morphology of the grout, so as to obtain test data characterizing the relationship between the interval time and the solidification morphology of the grout.

Description

Technical Field

[0001] The present invention relates to the technical field of slurry liquid form simulation, and specifically to a simulation method for the effect of the gap time of side grouting of piles on the slurry liquid form. Background Art

[0002] Due to the concealment of the post-grouting construction on the side of cast-in-place piles and the complexity of geological conditions, it is impossible for grouting personnel to master the form of the slurry around the pile side, resulting in the final result of on-site grouting often failing to achieve the expected effect. Among them, the cement slurry enters the soil around the pile in a way similar to tree branch bifurcation, including the way of slurry overflow or cross-grouting around, so that it is impossible to form a grouting reinforcement body near the soil around the pile, and then the post-grouting process fails to fully play the role of improving the mud skin on the pile side and the stress relaxation phenomenon of the soil around the pile, enhancing the bearing capacity of the pile foundation and reducing settlement, and cannot achieve the expected effect. This is mainly because during the continuous grouting process, the slurry fails to solidify effectively, causing the slurry to continuously spread outwards. If an effective intermittent time can be set and waiting for the first grouted part to solidify, the formation effect of the grouting slurry can be greatly improved. However, for this defect, the existing technology often relies on the work experience of grouting personnel to grasp the gap time, that is, the empirical value. For example, some specifications give that the gap time should be 30 min - 60 min (minutes), and it is a time suggestion for all regions. Therefore, it is hoped that the specific effect of the gap time on the solidification of the slurry can be simulated, and the relationship between different gap times and the solidification of the slurry can be obtained, so as to accurately carry out grouting with different gap times for different depths and different soil layers, so that grouting can be carried out after the previous grouting has solidified effectively. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a simulation method for the effect of the gap time of side grouting of piles on the slurry liquid form, which can solve the technical problems described in the background art.

[0004] The technical solution for achieving the purpose of the present invention is as follows: A simulation method for the effect of the gap time of side grouting of piles on the slurry liquid form, comprising the following steps:

[0005] Step 1: Assemble a cavity with an opening at the top. A cylindrical model pile is fixedly installed in the cavity, and the model pile is used to simulate the actual pile body. A grouting port is arranged on the side wall of the model pile, and the model pile is connected to a grouting pump in a communicating manner;

[0006] Step 2: Obtain the test soil sample of the (n + 1)-th layer in the depth direction of the target engineering site, where n ≥ 1. Fill the cavity with the obtained test soil sample so that the upper surface of the test soil sample is flush with the opening of the cavity. After the cavity is filled with the test soil sample, cover the opening with a top plate, and the top plate fits on the upper surface of the test soil sample;

[0007] Step 3: Calculate the natural density of each layer of soil sample for the n layers of soil samples above the test soil sample, and obtain the unit weight of soil for each layer of soil sample based on the natural density. Among them, for each layer of soil sample located below the groundwater level, the effective unit weight of the current layer of soil sample is obtained by subtracting the unit weight of water from the unit weight of the current layer of soil sample, so that the effective unit weight of each layer of soil sample located below the groundwater level can be obtained;

[0008] Step 4: Calculate the load Q according to formula ①, apply the calculated load Q to the roof, and apply the force in the direction perpendicular to the roof from above. The force acts on the test soil sample through the roof. Formula ① is as follows:

[0009]

[0010] In the formula, A s is the opening area of the cavity, γ i ′ represents the effective unit weight of the i-th layer of soil sample, γ i ′ = γ i -γ ω , γ ω represents the unit weight of water, γ i represents the unit weight of the i-th layer of soil sample, γ i =ρ i g, ρ i represents the natural density of the i-th layer of soil sample, g represents the acceleration due to gravity, h i represents the thickness of the i-th layer of soil sample, γ n+1 ′ represents the effective unit weight of the test soil sample, h n+1 represents the thickness of the test soil sample;

[0011] Step 5: The grouting pump injects slurry into the model pile at the preset grouting pressure P, and the slurry is then injected into the test soil sample through the injection port. After a preset interval time, the grouting pump is closed and the injection of slurry into the model pile is stopped.

[0012] Observe the solidification degree of the slurry in the test soil sample during the interval from the start of slurry injection to the stop of slurry injection, and obtain the slurry solidification state data, so as to obtain the test data characterizing the relationship between the interval time and the slurry solidification state under the grouting pressure P and the load Q.

[0013] Further, in Step 1, the model pile is arranged along the axial direction of the cavity and is located at the central position of the cavity, that is, on the axis of the cavity.

[0014] Further, a plurality of injection ports are provided on the side wall of the model pile, and the injection ports are spaced apart and installed at different positions of the model pile.

[0015] Further, the grouting pipeline system and the grouting pump form a loop, and the slurry is kept circulating between the grouting pipeline system and the grouting pump.

[0016] Further, after step 5 is completed, step 6 is also included:

[0017] Step 6: Jump to step 2 to obtain a new test soil sample, and then continue to execute steps 2 - 5 several times. In each new step 5, change the grouting pressure P and / or the load and / or the interval time.

[0018] Further, in step 6, the new test soil sample is a soil sample at the same depth or different depths compared to the previous test soil sample.

[0019] Further, when the load is greater than the sum of the weights of the cavity, the test soil sample in the cavity, and the roof plate at the opening of the cavity, a counterweight is loaded on the bottom plate of the cavity.

[0020] Further, in step 6, the grouting pressure P is changed by changing the pressure acting on the grouting pump.

[0021] Further, the cavity is a circular or other regular - shaped structural cavity.

[0022] Further, the model pile is connected to the grouting pump through the grouting pipeline system.

[0023] The beneficial effects of the present invention are as follows: The present invention can effectively simulate the effect of the interval time on the solidification form of the slurry, so as to obtain test data characterizing the relationship between the interval time and the solidification form of the slurry. Based on this test data, it can guide the interval time (i.e., the time period between the current start of grouting and the end of the previous grouting) in the pile - side grouting pouring process at the actual engineering site, and can set the corresponding interval time according to the soil layers at different depths, thereby effectively avoiding the poor solidification of the slurry in the soil layer due to unreasonable interval time, preventing the continuous outward diffusion of the slurry in the soil sample due to ineffective solidification, effectively improving the pile - side mud skin and the stress relaxation phenomenon of the soil around the pile, and enhancing the bearing capacity of the pile foundation and reducing settlement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a structural schematic diagram of the present invention;

[0025] Figure 2 is a structural schematic diagram of the grouting pipeline assembly;

[0026] Figure 3 is a structural schematic diagram after installing the counterweight assembly;

[0027] Figure 4 is a structural schematic diagram after the box body of the counterweight assembly is hidden;

[0028] Figure 5 is a schematic flow chart of the present invention;

[0029] In the figure, 1-threaded part, 2-nut, 3-laminated board, 4-jack, 5-tie rod, 6-grout inlet pipe, 7-grout outlet pipe, 8-model pile, 9-pneumatic box, 10-grout pump, 11-box body, 12-base, 13-foot, 14-timing control switch, 15-control valve, 16-injection port, 17-valve, 18-counterweight frame, 19-counterweight block, 20-top plate. Specific embodiments

[0030] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods:

[0031] As Figures 1 - 5 shown, a simulation method for the effect of the grouting interval time on the slurry liquid state on the side of the pile includes the following steps:

[0032] Step 1: Assemble a cavity with an opening at the top. A cylindrical model pile 8 is fixedly installed in the cavity. The model pile 8 is used to simulate an actual pile body. The model pile 8 is arranged along the axial direction of the cavity and is located at the central position of the cavity, that is, on the axis of the cavity. One or more injection ports 16 are provided on the side wall of the model pile 8, and the injection ports 16 are spaced and installed at different positions of the model pile 8.

[0033] The model pile 8 is connected to the grout pump 10 through a grouting pipeline system so that the grout pump 10 can inject slurry into the model pile 8.

[0034] Step 2: Obtain the test soil sample of the (n + 1)-th layer in the depth direction of the target engineering site, where n≥1. That is, the soil layer of the target engineering site is divided into n + 1 layers from top to bottom (that is, from the ground surface to the strata), and there are still n layers of soil samples above the test soil sample. The obtained test soil sample is filled into the cavity so that the upper surface of the test soil sample is flush with the opening of the cavity.

[0035] After the cavity is filled with the test soil sample, a top plate 20 is covered at the opening, and the top plate 20 is attached to the upper surface of the test soil sample.

[0036] Step 3: Calculate the natural density of each layer of soil samples of the n layers of soil samples above the test soil sample. Based on the natural density, the unit weight of each layer of soil samples is obtained. Among them, for the effective unit weight of each layer of soil samples located below the groundwater level, the unit weight of the current layer of soil samples minus the unit weight of water is used to obtain the effective unit weight of the current layer of soil samples, so as to obtain the effective unit weight of each layer of soil samples located below the groundwater level.

[0037] Step 4: Calculate the load Q according to Formula ①, apply a force to the top plate 20 according to the calculated load Q, and apply the force in a direction perpendicular to the top plate 20 from above. The force acts on the test soil sample through the top plate 20.

[0038]

[0039] In the formula, A s is the opening area of the cavity, that is, the cross-sectional area of the cavity. For a regular spatial structure of the cavity, such as a cylindrical cavity, it is the cross-sectional area at any position. γ i ′ represents the effective soil unit weight of the i-th layer of soil sample, γ i ′ = γ i -γ w , γ w represents the unit weight of water, usually taken as 10 kN / m 3 , γ i represents the unit weight of the i-th layer of soil sample, γ i = ρ i g, ρ i represents the natural density of the i-th layer of soil sample, g represents the acceleration due to gravity, h i represents the thickness of the i-th layer of soil sample. The thicknesses of each layer of soil sample can be the same or different. h n+1 represents the effective soil unit weight of the test soil sample (that is, the (n + 1)-th layer of soil sample) and represents the thickness of the test soil sample.

[0040] Step 5: The grouting pump 10 grouts the grouting liquid into the model pile 8 through the grouting pipeline assembly according to the preset grouting pressure P, that is, injects the grout. The grout is then injected into the test soil sample through the injection port 16. After a preset interval time, the grouting pump 10 is turned off and the injection of the grout into the model pile 8 is stopped. Observe the setting degree of the grout in the test soil sample during the interval time from the start of grouting to the stop of grouting to obtain the grout setting state data, so as to obtain the relationship between the interval time and the grout setting state under the grouting pressure P and the load Q, that is, the action relationship of the interval time on the grout setting morphology can be simulated. Based on this action relationship, in the subsequent actual engineering construction, specific quantifiable interval time and load are used for grouting on the actual i-th layer of soil at the construction site, so as to ensure that the grout can effectively set within this interval time.

[0041] In an optional embodiment, to avoid the setting of the grout during the period when the injection of the grout into the simulated pile is stopped, the grouting pipeline system and the grouting pump 10 form a loop. The grouting pipeline system includes a grout inlet pipe 6 and a grout outlet pipe 7. The grouting pump 10 injects the grout into the grout inlet pipe 6, and the grout then flows into the grout outlet pipe 7 and finally flows back to the grouting pump 10, circulating continuously, so as to keep the grouting liquid in a flowing state and prevent the grouting liquid from setting.

[0042] In an alternative embodiment, after step 5 is completed, step 6 is further included:

[0043] Step 6: Jump to step 2 to obtain a new test soil sample. The new test soil sample can be a soil sample from a different depth layer or the same depth layer compared to the previous test soil sample. Then, continue to execute steps 2 to 5 several times, and in each new step 5, change the grouting pressure P and / or the load and / or the interval time. That is, in each new step 5, compared to the previous time, one or more of the grouting pressure P, the load, and the interval time can be changed individually. For example, if the previous grouting pressure P was 10 units and the load was 5 units, then the current grouting pressure is 5 units and the load remains 5 units. Or, if the previous grouting pressure P was 10 units and the load was 5 units, then the current grouting pressure is 5 units and the load is 7 units.

[0044] In another alternative embodiment, when the load is greater than the sum of the weights of the cavity, the test soil sample in the cavity, and the top plate 20 at the opening of the cavity, a counterweight is loaded on the bottom plate of the cavity to bear the load through the counterweight.

[0045] Thus, through multiple tests under different parameters (grouting pressure P, load, interval time), the relationship between the interval time and the slurry solidification state under different grouting pressures P and / or loads can be obtained. Finally, based on these data, the relationship between the grouting pressure P, the load, and the slurry solidification state can be fitted to facilitate better determination of the interval time for grouting at the actual engineering site.

[0046] In this embodiment, a corresponding simulation device is also provided as one of the implementation manners for implementing the above method. The simulation device includes a top plate 20, a jack 4, a tie rod 5, a grouting pipeline system, a pneumatic box 9, a grouting pump 10, a model pile 8, a box body 11, and a base 12. The grouting pipeline system includes a grout inlet pipe 6 and a grout outlet pipe 7. One end of the grout inlet pipe 6 and one end of the grout outlet pipe 7 are both connected to the grouting pump 10. The pneumatic box 9 is connected to the grouting pump 10. The pneumatic box 9 is used to provide pressure to the grouting pump 10 so that the grout can be better driven into the grout inlet pipe 6 through the pressure. The other end of the grout inlet pipe 6 and the other end of the grout outlet pipe 7 are connected and communicate with a grout injection port 16 together. The grout injection port 16 is connected to the inner cavity of the model pile 8. A control valve 15 is installed on the grout injection port 16. The control valve 15 is used to open and close the connection between the grout injection port 16 and the grout inlet pipe 6 and the grout outlet pipe 7. When closed, the grout injection port 16 is tightly closed and not connected to the grout inlet pipe 6 and the grout outlet pipe 7. The grout flows from the grout inlet pipe 6 into the grout outlet pipe 7 and then back to the grouting pump 10, so that the grout circulates between the grouting pump 10 and the grout outlet pipe 7 system, which can prevent the grout from solidifying. When opened, the grout flows from the grout inlet pipe 6 into the grout outlet pipe 7 and the grout injection port 16 respectively. Part of the grout enters the model pile 8 through the grout injection port 16, and the other part of the grout flows back to the grouting pump 10. Of course, when opened, the grout can also only flow to the grout injection port 16, that is, the grout inlet pipe 6 and the grout outlet pipe 7 are tightly closed and not connected at this time. The control valve 15 can be an electromagnetic three-way valve, so that the corresponding path can be selectively opened and closed.

[0047] In an alternative embodiment, a timing control switch 14 is further included. The timing control switch 14 is connected to the control valve 15. The timing control switch 14 is used to open and close the control valve 15 at a fixed time, so that the connection between the grout injection port 16 and the grout inlet pipe 6 and the grout outlet pipe 7 can be opened and closed at a fixed time, and thus the interval time in the above method can be set through the timing control switch 14. Without the timing control switch 14, different interval times can be obtained by manually opening and closing the control valve 15.

[0048] The other ends of the grout inlet pipe 6 and the grout outlet pipe 7 pass through the top plate 20 or are connected to the model pile 8 at the joint of the top plate 20 and the model pile 8. The top plate 20 is arranged at the opening at the top of the box body 11. The top plate 20 is detachably installed at the opening at the top of the box body 11 to facilitate loading of the test soil sample into the inner cavity of the box body 11. The model pile 8 is a cylindrical structure with a cavity. One or more grout injection ports 16 are arranged on the side wall of the model pile 8. The grout injection ports 16 are connected to the inner cavity of the box body 11. The box body 11 can be a circular cylinder or other regular-shaped structures with an inner cavity. For example, the box body 11 is a rectangular box. Correspondingly, the top plate 20 also needs to be set as a rectangle.

[0049] One end of the jack 4 is connected to the top plate 20, and the other end is connected to the laminated board 3. Multiple jacks 4 can be arranged between the top plate 20 and the laminated board 3, and the jacks 4 are spaced apart from each other.

[0050] The box body 11 is installed on the base 12. A plurality of tie rods 5 are connected between the base 12 and the laminated board 3. The tie rods 5 surround the box body 11, that is, the box body 11 is arranged inside the tie rods 5 that form a complete circle. One end of the tie rod 5 is connected to one end of the base 12. A plurality of feet 13 are connected to the other end of the base 12, and the feet 13 are spaced apart from each other. The other end of the tie rod 5 passes through the laminated board 3 and forms a threaded portion 1 outside the laminated board 3. A nut 2 is threadedly connected to the threaded portion 1, and the lower end of the nut 2 abuts against the upper end surface of the laminated board 3. By rotating the nut 2 to different positions on the threaded portion 1, the tension degree of the tie rod 5 between the laminated board 3 and the base 12 can be adjusted. The nut 2, the tie rod 5, the laminated board 3, the jack 4 and the base 12 form a self-reaction force system. When a force is applied to the laminated board 3 by the jack 4, the reaction force can act on the top of the box body 11, and then act on the test soil sample. Therefore, by adjusting the force applied to the laminated board 3 by the jack 4, the corresponding load can be provided according to the load Q calculated by the above method.

[0051] In one optional embodiment, the base 12 is a magnetic base 12. The base 12 is magnetically connected to the feet 13, and a magnetic switch is arranged on the feet 13. By opening and closing the magnetic switch, the feet 13 can be installed on the magnetic base 12 or detached from the magnetic base 12. That is, a magnetic surface is arranged on the surface of the feet 13 connected to the magnetic base 12, so that by conducting the magnetic switch, the magnetic surface of the feet 13 generates magnetism and adsorbs on the magnetic base 12. Conversely, the magnetism is released and the feet 13 are disconnected from the magnetic base 12.

[0052] In one optional embodiment, a counterweight assembly is connected through the feet 13. The counterweight assembly is detachably installed on the feet 13, so that the counterweight assembly can be loaded according to needs. For example, in the above method, when the load Q is too large and greater than the sum of the total weights of the simulation device except for the grouting pipeline system, the air pressure box 9 and the grouting pump 10, the counterweight assembly can be installed to support better. The counterweight assembly includes a counterweight frame 18 and counterweight blocks 19. The counterweight blocks 19 are installed in the counterweight frame 18, and the counterweight frame 18 is threadedly connected to the feet 13.

[0053] In one optional embodiment, a valve 17 is installed on each of the slurry inlet pipe 6 and the slurry outlet pipe 7 to open and close their respective pipelines.

[0054] The present invention can effectively simulate the action of the interval time on the solidification form of the slurry, so as to obtain test data characterizing the relationship between the interval time and the solidification form of the slurry. Based on this test data, the interval time during the pile side grouting pouring process at the actual engineering site (i.e., the time period between the current start of grouting and the end of the previous grouting) can be guided, and the corresponding interval time can be set according to the soil layers at different depths, so as to effectively avoid the situation that the slurry cannot solidify well in the soil layer due to unreasonable interval time, and avoid the continuous outward diffusion of the slurry in the soil sample due to the failure to solidify effectively. Thus, the pile side mud skin and the stress relaxation phenomenon of the soil around the pile can be effectively improved, the bearing capacity of the pile foundation can be enhanced, and the settlement can be reduced.

[0055] The embodiments disclosed in this specification are only an illustration of the unilateral features of the present invention. The protection scope of the present invention is not limited to this embodiment, and any other functionally equivalent embodiments fall within the protection scope of the present invention. For those skilled in the art, various corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A simulation method for the effect of the grouting interval time on the slurry morphology on the pile side, characterized in that, It includes the following steps: Step 1: Assemble a cavity with an opening at the top. A cylindrical model pile is fixedly installed inside the cavity. The model pile is used to simulate an actual pile. An injection port is provided on the side wall of the model pile, and the model pile is connected to a grouting pump in a communicating manner. Step 2: Obtain a test soil sample from the (n + 1)-th layer in the depth direction of the target engineering site, where n ≥ 1. Fill the cavity with the obtained test soil sample so that the upper surface of the test soil sample is flush with the opening of the cavity. After the cavity is filled with the test soil sample, cover the opening with a top plate, and the top plate fits on the upper surface of the test soil sample. Step 3: Calculate the natural density of each layer of the n layers of soil samples above the test soil sample, and obtain the soil unit weight of each layer of soil samples based on the natural density. Among them, for each layer of soil samples located below the groundwater level, the effective soil unit weight of the current layer of soil samples is obtained by subtracting the unit weight of water from the soil unit weight of the current layer of soil samples, so that the effective soil unit weight of each layer of soil samples located below the groundwater level can be obtained. Step 4: Calculate the load Q according to Formula ①, apply a force to the top plate according to the calculated load Q, and apply the force in a direction perpendicular to the top plate from above. The force acts on the test soil sample through the top plate. Formula ① is as follows: ------① In the formula, is the opening area of the cavity, represents the effective unit weight of the i-th layer of soil sample, , represents the unit weight of water, represents the unit weight of the i-th layer of soil sample, , represents the natural density of the i-th layer of soil sample, g represents the acceleration due to gravity, represents the thickness of the i-th layer of soil sample, represents the effective unit weight of the test soil sample, represents the depth of the test soil sample; Step 5: The grouting pump injects slurry into the model pile according to a preset grouting pressure P. The slurry is then injected into the test soil sample through the injection port. After a preset interval time, close the grouting pump and stop injecting slurry into the model pile. Observe the degree of solidification of the slurry in the test soil sample during the interval time from the start of injecting the slurry to the stop of injecting the slurry, and obtain slurry solidification state data, so as to obtain test data characterizing the relationship between the interval time and the slurry solidification state under the grouting pressure P and the load Q.

2. The simulation method for the effect of the slurry form by the pile side grouting interval time according to claim 1, wherein, In Step 1, the model pile is arranged along the axial direction of the cavity and is located at the central position of the cavity, that is, on the axis of the cavity.

3. The simulation method of the effect of the slurry form by the pile side grouting interval time according to claim 1, wherein A plurality of injection ports are provided on the side wall of the model pile, and the injection ports are installed at different positions of the model pile at intervals.

4. The simulation method of the effect of the slurry form by the pile side grouting interval time according to claim 1, characterized in that The model pile is connected to the grouting pump in a communicating manner through a grouting pipeline system.

5. The simulation method of the effect of the pile side grouting interval time on the slurry form according to claim 4, characterized in that, The grouting pipeline system and the grouting pump form a loop, and the slurry is kept circulating between the grouting pipeline system and the grouting pump.

6. The simulation method of the influence of the grouting interval time on the slurry shape according to claim 1, wherein, After Step 5 is executed, it further includes Step 6: Step 6: Jump to Step 2 to obtain a new test soil sample, and then continue to execute Steps 2 - 5 several times. In each new Step 5, change the grouting pressure P and / or the load and / or the interval time.

7. The simulation method of the slurry morphology affected by the pile side grouting interval time according to claim 6, wherein In Step 6, the new test soil sample is a soil sample at the same depth or different depths compared to the previous test soil sample.

8. The simulation method for the effect of the grouting interval time on the slurry shape according to claim 7, characterized in that When the load is greater than the sum of the weights of the cavity, the test soil sample inside the cavity, and the top plate at the opening of the cavity, a counterweight is loaded on the bottom plate of the cavity.

9. The simulation method of the slurry morphology affected by the pile side grouting interval time according to claim 8, wherein, In Step 6, the grouting pressure P is changed by changing the pressure acting on the grouting pump.

10. The simulation method of the influence of the slurry form by the pile side grouting interval time according to claim 9, wherein, The cavity is a circular or other regularly shaped structural cavity.

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