Method for reinforcing liquefied lateral deformation ground by combining reinforced gravel pile with grouting in different regions

Abstract

The application discloses a method for reinforcing liquefied lateral large-deformation foundation by combined grouting of reinforced gravel pile, which comprises the following steps: step one, field survey is conducted on the slope to determine the dangerous sliding surface before the slope is reinforced; step two, wharf slope top reinforcement: multiple rows of reinforced gravel piles are arranged on the slope top for reinforcement; step three, wharf slope foot reinforcement: underwater grouting equipment is used to conduct grouting reinforcement on the slope foot; step four, reinforcement between adjacent pile foundations of the wharf: remote drilling equipment is used to conduct grouting reinforcement between the adjacent pile foundations of the wharf; and step five, ground penetrating radar is used to recheck the grouting reinforcement effect, the dangerous sliding surface after the slope is reinforced is calculated and determined, and the grouting is ensured to be conducted as required. The method can optimize the overall performance of the high-pile wharf, improve the stability of the wharf slope, reduce the failure risk of the high-pile wharf, and is convenient to operate and reliable in effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rock foundation reinforcement, and relates to a foundation reinforcement method, in particular to a method for reinforcing an inclined liquefied foundation with large lateral deformation by using reinforced gravel piles and combined grouting. BACKGROUND

[0002] High-pile wharfs are widely used in port projects in China due to their unique advantages, but the wharfs located in liquefied inclined sites are prone to large deformation under the action of earthquakes. In the past destructive earthquakes, a large number of high-pile wharf destruction examples have occurred under the condition of soil liquefaction and large lateral deformation. At the same time, many high-pile wharfs were built before the current seismic design code, and the seismic design was not fully considered, so the high-pile wharf does not have enough seismic capacity, which may exacerbate the potential damage. The demolition and reconstruction of high-pile wharfs is a difficult task that requires a lot of time and money. Through a convenient and economical foundation reinforcement method, the seismic performance of the built high-pile wharf is improved, the seismic risk and functional loss are reduced, and certain social benefits are achieved. SUMMARY

[0003] In order to solve the engineering problem that the liquefiable inclined site is prone to large deformation under the action of earthquakes, the application provides a method for reinforcing a liquefied lateral deformation foundation by using reinforced gravel piles and combined grouting in different regions. The method reinforces the slope top, the space between the piles of the wharf, and the slope bottom jointly, the slope top is reinforced by using reinforced gravel piles, the space between the adjacent pile foundations of the wharf is provided with grouting stone bodies, and the slope bottom is provided with a grouting reinforcement body, which jointly bears the slope soil load and the seismic load. By using the method of the application, the stability of the wharf slope can be improved, the failure risk of the high-pile wharf can be reduced, the operation is convenient, and the effect is reliable.

[0004] The purpose of the application is achieved by the following technical scheme:

[0005] A method for reinforcing a liquefied lateral deformation foundation by using reinforced gravel piles and combined grouting in different regions, comprising the following steps:

[0006] Step one, field surveying the slope to determine the dangerous sliding surface before the slope reinforcement;

[0007] Step two, reinforcing the slope top: setting multiple rows of reinforced gravel piles on the slope top for reinforcement;

[0008] Step three, reinforcing the slope foot: using underwater grouting equipment to grout and reinforce the slope foot;

[0009] Step four, reinforcing between the adjacent pile foundations of the wharf: using a remote drilling equipment to grout and reinforce between the adjacent pile foundations of the wharf;

[0010] Step 5: Use ground-penetrating radar to re-inspect the grouting reinforcement effect, calculate and determine the dangerous sliding surface after slope reinforcement, and ensure that grouting is performed as needed.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] This invention presents a method for controlling large lateral deformation of liquefied soil foundations in existing high-pile wharf foundations through regional control. It employs reinforced crushed stone piles to strengthen the liquefied soil foundation behind the wharf, controlling large lateral deformation of the liquefied soil and reducing lateral compression on the piles. Grouting is used to reinforce the weak soil layer between the wharf slope toe and the piles, ensuring that surface liquefied soil cannot pass through the grouting reinforcement zone, reducing soil shear strain, and providing greater lateral restraint and vertical bearing capacity for the high-pile wharf structural system. This significantly improves the seismic performance and overall stability of the wharf pile foundation, achieving the basic goal of earthquake prevention and disaster reduction in wharf engineering, and is worthy of widespread application. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the reinforcement structure of the present invention;

[0014] Figure 2 The diagram shows the layout of reinforced crushed stone piles: (a) triangular grid, (b) square grid.

[0015] Figure 3 The diagram shows the grouting arrangement at the bottom of the slope: (a) triangular grouting, (b) square grouting.

[0016] In the diagram, 1—reinforced crushed stone pile, 2—grouting reinforcement between piles, 3—grouting reinforcement at the slope toe, 4—dangerous sliding surface before reinforcement, and 5—dangerous sliding surface after reinforcement. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0018] This invention provides a method for controlling large lateral deformation of inclined liquefiable foundations by combining reinforced crushed stone piles with grouting in a regional reinforcement manner, such as... Figure 1 As shown, it includes the following steps:

[0019] Step 1: Conduct on-site surveys of the slope, determine the dangerous sliding surface before slope reinforcement through experience and calculations, and determine the specific calculation method for reinforcement through calculation methods.

[0020] Step 2, Wharf Slope Top Reinforcement: Multiple rows of reinforced crushed stone piles are installed at the top of the slope for reinforcement. The reinforced crushed stone piles need to pass through the dangerous sliding surface of the slope. The specific method is as follows: First, determine the reinforcement range of the top of the slope according to the range of the dangerous sliding surface of the slope. Mechanically drill holes in the foundation soil to the design elevation of the bottom of the hole. After the steel cage is placed in, fill it with the specified graded crushed stone.

[0021] Step 3: Reinforcement of the wharf slope bottom: Set up a grouting reinforcement body at the bottom of the slope, that is: use underwater grouting equipment to grout and reinforce the slope toe.

[0022] Step 4: Reinforcement between adjacent pile foundations of the wharf: A grouting stone body connection is set between adjacent pile foundations of the wharf, that is: grouting reinforcement is carried out between adjacent pile foundations of the wharf using remote drilling equipment.

[0023] Step 5: Use ground-penetrating radar to re-inspect the grouting reinforcement effect, and use the Swedish slice method or Bishop method to calculate and determine the dangerous sliding surface after slope reinforcement to ensure that grouting is performed as needed.

[0024] In this invention, the reinforced dangerous sliding surface should be kept away from the dock area.

[0025] In this invention, the top of the high-pile wharf slope is reinforced with reinforced crushed stone piles, such as... Figure 2 As shown, the reinforced crushed stone piles should be arranged in an equilateral triangle or square pattern, and should satisfy the following design formula:

[0026] Arrangement of equilateral triangles:

[0027] Square arrangement:

[0028] In the above formula, s and d are the pile spacing and diameter of the reinforced crushed stone piles, respectively; ξ is the correction factor for ground settlement caused by construction vibration, with a value of 1.1 to 1.2, or 1.0 if not considered; e0 and e1 are the void ratios of the foundation soil before and after foundation treatment, respectively. When designing reinforced crushed stone piles using the above formula, ground settlement caused by the pile driving process is generally not considered.

[0029] In this invention, multiple rows of reinforced crushed stone piles are provided at the top of the slope, and grouting stone bodies are provided between adjacent pile foundations of the wharf to jointly bear the slope soil load and seismic load. Grouting reinforced bodies are provided at the bottom of the slope.

[0030] In this invention, compaction grouting should be used between the piles and at the bottom of the slope of the high-pile wharf. The grout is injected by filling, permeation and compaction. The row spacing of the grouting holes can be 1.5 times the reinforcement radius; the row spacing of the grouting holes can be 1.5 to 1.7 times the reinforcement radius.

[0031] In this invention, the specific arrangement of grouting holes at the bottom of the high-pile wharf slope should be based on the actual site conditions, using an equilateral triangle or a square arrangement, such as...Figure 3 As shown.

[0032] In this invention, finite element analysis software is used to simplify the structure of the grouting reinforcement between piles, establishing a simplified structure for the high-pile wharf. Py springs are installed at the pile unit nodes, with the placement of the Py springs determined based on the actual characteristics of the reinforcement body. Pushover analysis is used to determine whether the reinforcement meets the requirements; if not, the reinforcement body should be strengthened.

[0033] In this invention, the reinforcing crushed stone used in the slope top reinforcement should meet the specified gradation to ensure the rapid dissipation of pore water pressure during an earthquake.

[0034] In this invention, the grouting slurry is made of mineral-based cementitious materials. The material composition is as follows: clay 20-30%, cement 10-20%, hemihydrate gypsum 2-6%, alkali activator 2-6%, slag powder 20-30%, mineral admixture 2-8%, and the balance is water, with a water-cement ratio of 0.8-1.2.

[0035] This invention is applicable to high-pile wharves that do not meet seismic performance requirements, and can solve the engineering problem of large deformations easily occurring in liquefiable sloping sites under seismic loading. This invention optimizes the overall performance of high-pile wharves, improves the stability of wharf slopes, and reduces the risk of wharf failure by installing reinforced crushed stone piles, underwater grouting, and inter-pile grouting. It is convenient to operate and reliable in its effectiveness.

Claims

1. A method for reinforcing a liquefied lateral large deformation ground by combined grouting of reinforced gravel piles, characterized in that The method comprises the following steps: Step one, field investigation is conducted on the slope to determine the dangerous sliding surface before slope reinforcement; Step two, wharf slope top reinforcement: multiple rows of reinforced gravel piles are arranged on the slope top for reinforcement; Step three, wharf slope toe reinforcement: underwater grouting equipment is used to conduct grouting reinforcement at the slope toe; Step four, wharf adjacent pile foundation reinforcement: remote drilling equipment is used to conduct grouting reinforcement between adjacent pile foundations of the wharf; Step five, ground penetrating radar is used to recheck the grouting reinforcement effect, and the dangerous sliding surface after slope reinforcement is determined to ensure that grouting is conducted as needed.

2. The method for combined grouting and reinforcing the liquefied lateral large deformation ground by the reinforced stone pile according to claim 1, characterized in that The method for determining the dangerous sliding surface adopts the Swedish slice method or the Bishop method.

3. The method for combined grouting and reinforcing the liquefied lateral large deformation ground by the reinforced stone pile according to claim 1, characterized in that The reinforced gravel piles are arranged in an equilateral triangle arrangement or a square arrangement.

4. The method for combined grouting and reinforcing the liquefied lateral large deformation ground by the reinforced stone pile according to claim 3, characterized in that The arrangement meets the following design formula: Equilateral triangle arrangement: Square arrangement: In the above formula, and are the spacing and diameter of the reinforced gravel pile, respectively; is a correction factor for considering the ground settlement caused by construction vibration, and its value is 1.1-1.2, and is 1.0 when not considered; and are the pore ratios of the ground soil before and after treatment, respectively.

5. The method for combined grouting and reinforced stone pile for reinforcing liquefiable lateral large deformation ground in sub-regional according to claim 1, characterized in that When the wharf slope toe and adjacent pile foundation are reinforced, compaction grouting is used, and the grout is injected in a filling, permeation or compaction manner.

6. The method for combined grouting and reinforcing of the liquefied lateral large deformation ground by the reinforced stone pile according to claim 1 or 5, characterized in that When the wharf slope toe and adjacent pile foundation are reinforced, the row spacing of the grouting holes is 1.5 times the reinforcement radius, and the row spacing of the grouting holes is 1.5-1.7 times the reinforcement radius.

7. The method for combined jet grouting and reinforced stone column for sub-regional reinforcement of liquefiable lateral large deformation ground according to claim 1, characterized in that When the wharf slope toe is reinforced, the grouting holes are arranged in an equilateral triangle arrangement or a square arrangement.

8. The method for combined jet grouting and reinforcement of liquefiable lateral large deformation ground by reinforced rammed aggregate piles according to claim 1, characterized in that When the adjacent pile foundations of the wharf are reinforced, finite element software is used for structure simplification analysis, a simplified structure of the high-pile wharf is established, p-y springs are set at the pile unit nodes, pushover analysis is conducted to determine whether the reinforcement meets the requirements, and if not, the reinforcement body is strengthened.

9. The method for combined jet grouting and reinforced stone column for sub-regional reinforcement of liquefiable lateral large deformation ground according to claim 1, characterized in that When the wharf slope top, slope toe and adjacent pile foundations of the wharf are reinforced, mineral-based cementitious materials are used for grouting.

10. The method for combined grouting and reinforcing the liquefied lateral large deformation ground by the reinforced stone pile according to claim 9, characterized in that The mass ratio of the mineral-based cementitious material is as follows: clay accounts for 20-30%, cement accounts for 10-20%, semi-hydrated gypsum accounts for 2-6%, alkali activator accounts for 2-6%, slag powder accounts for 20-30%, mineral admixture accounts for 2-8%, and the balance is water, and the water-cement ratio is 0.8-1.2.

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