Time sequence pulse grouting method for stopping settlement of building caused by stratum loss

Abstract

The application discloses a time sequence pulse grouting stop-sinking method for building settlement caused by stratum loss; the method not only carries out targeted numerical calculation simulation and checking treatment on obtained geological information data according to the geological characteristics of stratum loss settlement, so that the accuracy of obtained grouting parameters is obviously improved; and the method also continuously optimizes the grouting parameters in the grouting process, so that the matching degree of the grouting parameters and the geological actual situation is obviously increased, fine regulation and control of the grouting parameters are realized, and the grouting reinforcement effect is further improved; meanwhile, through targeted adjustment of the grouting process and mode inside and outside the building, invalid diffusion and waste of the grout are avoided, and the grouting reinforcement period is obviously shortened, so that the method is suitable for large-scale popularization and application in grouting reinforcement stop-sinking engineering caused by stratum loss.

Description

Technical Field

[0001] This invention relates to the field of reinforcement and settlement control engineering technology, and in particular to a time-sequenced pulse grouting method for stopping settlement of buildings caused by ground loss. Background Technology

[0002] Humans have constructed numerous buildings to meet their survival and living needs, and the geological conditions of these buildings directly impact their lifespan, quality, and safety. Soluble rock strata are a very common geological formation in China, including salt rock, gypsum rock, limestone, and dolomite. Based on their ease of dissolution, they are further classified as easily soluble, moderately soluble, and insoluble rocks. Easily soluble rocks, due to their extremely poor stability, are generally not used for large-scale construction, while insoluble rocks offer the best stability and are the ideal site for large buildings. However, in actual construction, limitations imposed by site conditions, economic factors, environmental considerations, and planning constraints sometimes lead to the construction of large buildings on moderately soluble rock strata. However, due to the relatively poor stability of moderately soluble rocks, as the strata develop, dissolution interlayers may appear, leading to large-scale ground subsidence and severely impacting the safety of the buildings.

[0003] Grouting is currently the most common and effective reinforcement method for preventing settlement. Typically, the grouting rate curve of fissure grouting reinforcement over time can be divided into three stages: The first stage is the void-filling stage, where the grouting volume is generally large, the fissure opening is large, and the duration is long; the second stage is the initial splitting stage, where the grouting volume gradually decreases over time, and the increase in grouting volume gradually decreases, with the decrease being related to the number and strength of the fissures. Adjacent fissures in the fissure group influence each other during grouting, with larger fissures further opening and smaller fissures tending to close, resulting in a reduced diffusion range of grout in micro-fissures or even preventing injection, while creating a large amount of ineffective diffusion in larger fissures; the third stage is the secondary splitting stage, which mainly increases the diffusion range of grout in micro-fissures or allows grout to enter fissures that could not be injected in the early stages. Therefore, the grouting effect is closely related to the degree of crack development. To achieve better grouting reinforcement, it is necessary to monitor the development of cracks in real time and adjust the grouting parameters accordingly to ensure the effective grouting reinforcement.

[0004] However, in practical applications, it has been found that when reinforcing buildings caused by ground loss, especially dissolution interlayers, the spatial distribution of the dissolution interlayers is unknown, and the connectivity and degree of fracture development of the interlayers directly affect the grouting results. As a result, when using conventional grouting methods for reinforcement, there are problems such as poor evaluation of grouting effect, inability to confirm grouting parameters, high grouting difficulty, and poor reinforcement effect. This seriously affects the large-scale application of grouting reinforcement technology in the reinforcement of buildings caused by ground loss, especially dissolution interlayers, and is also detrimental to the safe use of buildings. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing grouting reinforcement technology in the reinforcement of building settlement caused by ground loss, especially dissolution interlayers, which has poor reinforcement effect. A time-sequenced pulse grouting method for stopping settlement of buildings caused by ground loss is proposed.

[0006] To achieve the above objectives, the present invention provides a time-series pulse grouting method for stopping settlement of buildings caused by ground loss, comprising the following steps:

[0007] S1: Grouting holes are set up on both the exterior and interior of the building to be reinforced; while setting up the grouting holes, the conditions inside the grouting holes are observed in real time to obtain geological information data, and the depth and spacing of the grouting holes are adjusted according to the obtained geological information data.

[0008] S2: Use simulation analysis software to perform numerical calculations on geological information data to obtain simulated grouting parameters;

[0009] S3: Verify the simulated grouting parameters to obtain the corrected grouting parameters;

[0010] S4: Grout the grouting holes according to the corrected grouting parameters;

[0011] S5: Repeat steps S2-S4 until grouting reinforcement of all grouting holes is completed.

[0012] Preferably, in step S1, the distance between the grouting holes on the periphery of the building to be reinforced and the building to be reinforced is 5-10m; the grouting holes inside the building to be reinforced are arranged in a quincunx pattern.

[0013] Preferably, in step S1, the depth of the grouting hole is not less than 5m below the bottom surface of the lost stratum.

[0014] Preferably, in step S1, the spacing between the grouting holes on the periphery of the building to be reinforced is 4 to 8 m; the spacing between the grouting holes inside the building to be reinforced is 8 to 12 m; the spacing between the grouting holes can be determined by comprehensively considering factors such as crack opening, grouting pressure, and grout properties.

[0015] In step S1, the real-time observation methods include one or more of the following: full-section intra-hole television imaging, segmented water pressure test, and borehole acoustic wave. Through multiple observation methods, geological information data can be obtained more accurately and quickly, providing data support for grouting reinforcement.

[0016] In step S1, the geological information data includes at least the stratum type, groundwater level, fracture aperture, fracture location, and groundwater type. The geological information data provides theoretical and data support for the calculation of grouting parameters and is necessary information data to ensure the grouting reinforcement effect.

[0017] In step S2, the simulation analysis software is COMSOL software.

[0018] In step S2, the numerical calculation simulation includes: (1) obtaining the time-normal displacement-crack length relationship curve and the depth-normal displacement-crack length relationship curve respectively; (2) using simulation analysis software to perform orthogonal analysis on the normal displacement, crack length and grouting time in the relationship curve to obtain the simulated grouting parameters.

[0019] The time-normal displacement-crack length relationship curve is: under the same grouting depth and grouting hole radius, but different crack opening conditions, the relationship curve between crack length and crack surface normal displacement as grouting time increases.

[0020] The depth-normal displacement-crack length relationship curve is: under the same crack opening and grouting hole radius, but different grouting depths, the relationship curve between crack length and crack surface normal displacement as grouting time increases.

[0021] In step S2, the simulated grouting parameters include grouting pressure, grouting time, grout type, grout water-cement ratio, setting time, and grouting volume. These grouting parameters are essential data to ensure grouting effectiveness and safety, and are also necessary parameters to guide grouting construction.

[0022] In step S3, the verification process includes: conducting a grouting experiment on a designated grouting hole based on the simulated grouting parameters and observing the effect; and using simulation analysis software to correct the simulated grouting parameters based on the observed grouting effect.

[0023] In step S4, during the grouting process, when grouting and reinforcing the same grouting hole, a top-down, segmented grouting method is adopted.

[0024] During the grouting process, the grouting pressure is calculated and determined according to the following formula:

[0025]

[0026] Where: p c τ is the grouting pressure (MPa); τ is the yield shear force (MPa); r is the distance from any position within the grout migration zone to the center of the grouting hole (m); q is the grouting flow rate (t); b is the crack aperture (m); μ is the viscosity-time function; r t Let p be the slurry diffusion front at time t (m); w This represents the groundwater pressure (MPa).

[0027] Preferably, when grouting is performed in segments, the length of each grouting hole is 3 to 5 meters.

[0028] Preferably, the segmented grouting method includes three stages: grouting, waiting for setting, and re-grouting; the waiting time is determined by numerical simulation analysis results.

[0029] Preferably, during the grouting process, the grouting parameters can be continuously optimized based on the previous grouting results; the specific optimization method refers to the above-mentioned verification process; through continuous optimization of the grouting parameters, the grouting parameters can be better matched with the actual situation, thereby significantly improving the grouting reinforcement effect.

[0030] In step S5, the grouting holes on the periphery of the building to be reinforced are first reinforced by grouting, and then the grouting holes inside the building to be reinforced are reinforced by grouting.

[0031] In step S5, during the grouting reinforcement process, the water-cement ratio of the grout in the grouting holes inside the building to be reinforced is lower than that in the grouting holes outside the building to be reinforced; the water-cement ratio of the grout in the external grouting holes is higher, which on the one hand prevents the grout from spreading too widely and increasing the amount of grouting; on the other hand, it forms a curtain effect, cuts off the dynamic water effect of groundwater, and provides a basis for grouting lifting.

[0032] In step S5, the grouting reinforcement adopts the skip-hole grouting method, that is, grouting is carried out every 1 to 2 grouting holes; the grouting holes at intervals also serve as inspection holes to check the grouting effect, verify the formation loss and grouting information.

[0033] In step S5, when grouting the grouting holes inside the building to be reinforced, a grouting reinforcement sequence from the inside out is adopted.

[0034] This invention discloses a time-series pulse grouting method for stopping settlement in buildings caused by ground loss. It not only performs targeted numerical simulations and verifications on the acquired geological information data based on the geological characteristics of ground loss settlement, thus significantly improving the accuracy of the obtained grouting parameters; but also continuously optimizes the grouting parameters during the grouting process, significantly increasing the matching degree between the grouting parameters and the actual geological conditions, achieving refined control of the grouting parameters, thereby further improving the grouting reinforcement effect; furthermore, through targeted adjustments to the grouting processes and methods inside and outside the building, it avoids ineffective diffusion and waste of grout and significantly shortens the grouting reinforcement period, making it suitable for large-scale application in grouting reinforcement and settlement prevention projects for buildings caused by ground loss.

[0035] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0036] 1. The time-series pulse grouting anti-settlement method of the present invention performs targeted numerical calculation simulation and verification processing on the acquired geological information data based on the geological characteristics of stratum loss and settlement, thereby significantly improving the accuracy of the obtained grouting parameters.

[0037] 2. The time-series pulse grouting anti-settlement method of the present invention continuously optimizes the grouting parameters during the grouting process, which significantly increases the degree of matching between the grouting parameters and the actual geological conditions, and realizes the fine control of the grouting parameters.

[0038] 3. The sequential pulse grouting anti-settlement method of the present invention, through targeted adjustments to the grouting process and method inside and outside the building, not only avoids the ineffective diffusion and waste of grout, but also significantly shortens the grouting reinforcement period.

[0039] 4. The sequential pulse grouting anti-settlement method of the present invention is safe, reliable, has a short construction period, and has a good reinforcement effect. It is suitable for large-scale application in grouting reinforcement and anti-settlement projects where ground loss causes building settlement. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the construction process of Embodiment 1 of the time-sequence pulse grouting method for stopping settlement of buildings caused by ground loss according to the present invention;

[0041] Figure 2 This is a cumulative settlement cloud map of a building in Example 1 of the time-series pulse grouting method for stopping building settlement caused by ground loss according to the present invention;

[0042] Figure 3 This is a schematic diagram of the planar arrangement of grouting holes (grouting holes) in Embodiment 1 of the time-sequenced pulse grouting anti-settlement method for building settlement caused by ground loss of the present invention;

[0043] Figure 4This is a time-normal displacement-fracture length relationship curve in Example 1 of the sequential pulse grouting anti-settlement method for building settlement caused by ground loss of the present invention;

[0044] Figure 5 This is a graph showing the relationship between depth, normal displacement, and crack length along the line in Example 1 of the sequential pulse grouting method for stopping settlement of buildings caused by ground loss according to the present invention. Detailed Implementation

[0045] The present invention will now be described in detail with reference to the accompanying drawings.

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] Example 1

[0048] The total floor area of ​​a certain building is 204,322.27 m². 2 It consists of a high-rise office building A (23 floors), a building B (21 floors), a podium (7 floors, commercial space), and a four-story basement (underground parking and commercial space), with a total underground construction area of ​​77,388 square meters. 2 Building A is a frame-core tube structure, Building B is a frame-shear wall structure, and the podium and basement are frame structures. The main building's foundation is a raft foundation, while the others are independent foundations with waterproof slabs. The foundation bearing layer is moderately weathered mudstone. Construction began in 2012. Cracking due to uneven settlement was discovered in early 2017, and settlement monitoring began in March 2018. The elevation of the bottom of the third basement level was measured, and the design elevation difference was deducted. Assuming the initial elevations were the same at all points, the cumulative settlement difference was calculated. The cumulative settlement difference is significant, with a maximum settlement of 108 mm. The area of ​​maximum settlement is the north side of Building B and the area between Buildings A and B. The settlement cloud map is shown below. Figure 2 As shown. The owner commissioned an appraisal agency to conduct an appraisal. Due to limitations in on-site implementation conditions, exploration boreholes were laid out around the building for geological exploration. The results showed that the site has soluble rock, which is gypsum rock, with dissolution interlayers, the maximum thickness of which is 50cm.

[0049] The present invention employs a time-series pulse grouting method for stopping settlement caused by ground loss in buildings, as described in the present invention. The specific method (construction process diagram shown) is as follows: Figure 1 )as follows:

[0050] S1: Grouting holes are installed both outside and inside the building to be reinforced. Simultaneously, the conditions inside the grouting holes are monitored in real time (full-section intra-hole television imaging, segmented water pressure tests) to obtain geological information data. Based on the obtained stratum type, groundwater level, fracture aperture, fracture location, and groundwater type, the depth and spacing of the grouting holes are adjusted (see Grouting Hole Layout section). Figure 3 );

[0051] S2: Numerical simulation of geological information data is performed using COMSOL software. The numerical simulation includes: (1) obtaining the time-normal displacement-fracture length relationship curves respectively. Figure 4 Grouting at a depth of H = 32m and a grouting hole radius r0 of 0.024m, the normal displacement at different positions along the crack length at different times every 20 minutes from 10min to 90min during the grouting process. Five different crack openings (b = 0.40mm, b = 0.45mm, b = 0.50mm, b = 0.55mm, b = 0.60mm) and the relationship curves of depth-normal displacement-crack length were selected. Figure 5 When the crack opening b = 0.50 mm and the grouting hole radius r0 is 0.024 m, the normal displacement at different positions along the crack length at 10 min, 30 min, 50 min, 70 min, and every 20 min during the grouting process. At each time point, three different crack depths, such as 32 m, 37 m, and 42 m, were selected to study their influence on the normal displacement of the crack surface. In the figure, a position point is taken every 1 m along the crack length as the research object, and the point where the normal displacement of the crack surface at a depth of 42 m decays to 0 is taken as the critical point); (2) The normal displacement, crack length, and grouting time in the relationship curve are orthogonally analyzed using simulation analysis software to obtain the simulated grouting pressure, grouting time, grout type, grout water-cement ratio, waiting time, and grouting volume;

[0052] S3: Verify the simulated grouting parameters (conduct grouting experiments on designated grouting holes based on the simulated grouting parameters and observe the effects; use simulation analysis software to correct the simulated grouting parameters based on the observed grouting effects) to obtain the corrected grouting parameters;

[0053] S4: Grout the grouting holes according to the corrected grouting parameters; during the grouting process, when grouting and reinforcing the same grouting hole, adopt the method of top-down, segmented grouting (grouting, waiting for setting and re-grouting);

[0054] S5: Repeat steps S2-S4 until all grouting holes are grouted and reinforced; during the grouting and reinforcement process, first grout the grouting holes on the periphery of the building to be reinforced, and then grout the grouting holes inside the building to be reinforced; the water-cement ratio of the grout in the grouting holes inside the building to be reinforced is less than that in the grouting holes on the periphery of the building to be reinforced; the skip-hole grouting method is used for grouting and reinforcement; when grouting the grouting holes inside the building to be reinforced, the grouting and reinforcement sequence is from the inside out.

[0055] In Embodiment 1 of this invention, the problem of building settlement caused by ground loss was successfully solved, providing technical support for the treatment of differential settlement of buildings, ensuring building safety, saving 6 months of construction time and tens of millions of yuan in construction costs.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A time-series pulse grouting method for stopping settlement of buildings caused by ground loss, characterized in that, Includes the following steps: S1: Grouting holes are set up on the periphery and inside the building to be reinforced; while setting up the grouting holes, the conditions inside the grouting holes are observed in real time to obtain geological information data, and the depth and spacing of the grouting holes are adjusted according to the obtained geological information data; in step S1, the geological information data includes at least the stratum type, groundwater level, fracture aperture, fracture location and groundwater type. S2: Numerical calculation simulation of geological information data is performed using simulation analysis software to obtain simulated grouting parameters; the numerical calculation simulation includes: (1) obtaining the time-normal displacement-fracture length relationship curve and the depth-normal displacement-fracture length relationship curve respectively; (2) performing orthogonal analysis on the normal displacement, fracture length and grouting time in the relationship curve using simulation analysis software to obtain simulated grouting parameters; in step S2, the simulated grouting parameters include grouting pressure, grouting time, grout type, grout water-cement ratio, waiting time and grouting volume; S3: Verify the simulated grouting parameters to obtain the corrected grouting parameters; S4: Grout the grouting holes according to the corrected grouting parameters; In step S4, when grouting the same grouting hole, a top-down, segmented grouting method is adopted during the grouting process. S5: Repeat steps S2-S4 until grouting reinforcement of all grouting holes is completed.

2. The time-series pulse grouting method for preventing settling according to claim 1, characterized in that, In step S1, the distance between the grouting holes on the periphery of the building to be reinforced and the building itself is 5-10m; the grouting holes inside the building to be reinforced are arranged in a quincunx pattern.

3. The time-series pulse grouting method for preventing settling according to claim 1, characterized in that, In step S1, the depth of the grouting hole shall not be less than 5m below the bottom surface of the lost stratum.

4. The time-series pulse grouting method for preventing settling according to claim 1, characterized in that, In step S1, the spacing between the grouting holes on the periphery of the building to be reinforced is 4-8m; the spacing between the grouting holes inside the building to be reinforced is 8-12m.

5. The time-series pulse grouting method for preventing settling according to any one of claims 1-4, characterized in that, In step S5, the grouting holes on the periphery of the building to be reinforced are first reinforced by grouting, and then the grouting holes inside the building to be reinforced are reinforced by grouting.

6. The time-series pulse grouting method for preventing settling according to claim 5, characterized in that, In step S5, during the grouting reinforcement process, the water-cement ratio of the grout in the grouting holes inside the building to be reinforced is less than that in the grouting holes outside the building to be reinforced.

7. The time-series pulse grouting method for preventing settling according to claim 5, characterized in that, In step S5, the grouting reinforcement adopts the skip-hole grouting method; when grouting the grouting holes inside the building to be reinforced, the grouting reinforcement sequence is from the inside out.

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