Construction method of water-rich round gravel layer foundation pit

Abstract

The application provides a construction method of a water-rich round gravel layer foundation pit, and belongs to the technical field of foundation pit construction. The method comprises the following steps: determining a construction area of the foundation pit; determining a supporting structure of the construction area; based on the time-space effect, layering, segmentation and block excavation of earthwork to excavate the foundation pit and control the change range of the water level outside the pit; setting a plurality of monitoring points in the construction area; obtaining the lateral displacement of the retaining wall, the horizontal displacement of the soil body, the ground settlement behind the retaining wall, the underground water level outside the foundation pit and the axial force of the internal support during the construction process through the plurality of monitoring points; judging whether the deviation degree of any one parameter in the lateral displacement of the retaining wall, the horizontal displacement of the soil body, the ground settlement behind the retaining wall, the underground water level outside the foundation pit and the axial force of the internal support from any one parameter preset threshold value is greater than the preset threshold value; when the deviation degree is greater than the preset threshold value, adjusting through preset measures; when the deviation degree is not greater than the preset threshold value, re-executing the data acquisition through the plurality of monitoring points during the construction process, and reducing the difficulty of the construction of the foundation pit to reach the preset requirement.

Description

Technical Field

[0001] This application relates to the field of foundation pit construction technology, and in particular to a construction method for a water-rich gravel layer foundation pit. Background Technology

[0002] The construction of foundation pits in water-rich gravel layers is quite difficult due to their complex geological environment.

[0003] Current construction methods for foundation pits in water-rich gravel layers involve determining the construction area and obtaining construction parameters from historical construction processes in similar areas. Construction is then based on these historical parameters. After construction is completed, further parameter measurements are taken to ensure the foundation pit meets the required standards.

[0004] However, the matching degree of the construction parameters of the above methods is poor, which makes it difficult for the construction of the foundation pit to meet the preset requirements.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] This application provides a construction method for a water-rich gravel layer foundation pit, which can solve the problem in related technologies where foundation pit construction is difficult to achieve the preset requirements. The technical solution is as follows: According to one aspect of this application, a construction method for a water-rich gravel layer foundation pit is provided for use in a two-way four-lane highway tunnel project, the method comprising: The construction area of ​​the foundation pit is determined, and the construction area includes a first construction section, a second construction section, and a third construction section; The support structure of the construction area is determined as follows: the support structure of the first construction section and the third construction section is a combined retaining wall of bored cast-in-place piles and high-pressure jet grouting piles; the support structure of the second construction section is an interlocking pile retaining wall; and the support structure in the foundation pit is a concrete support and a steel support. Excavation of foundation pits is carried out by layering, segmenting, and block excavation based on spatiotemporal effects; Multiple monitoring points were set up in the construction area; The lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support are obtained through the multiple monitoring points during the construction process. Determine whether any one of the following parameters—lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support—deviations from a preset threshold greater than a preset threshold. When the conditions exist, adjustments are made through preset measures, and the steps of obtaining the lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support during the construction process through the multiple monitoring points are repeated. The preset measures include at least one of the following: reinforcing the support structure, adjusting the excavation depth, the excavation sequence, the parameters of the layers, and grouting.

[0007] Optionally, if none of the above are present, the steps of obtaining the lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support during the construction process through the multiple monitoring points are performed.

[0008] Optionally, multiple monitoring points are set up in the construction area, including: Twenty-eight first inclinometer points were set up in the foundation pit to monitor the lateral displacement of the retaining wall, and twenty-eight second inclinometer points were set up in the deep soil of the foundation pit to monitor the horizontal displacement of the soil. The deep soil is the soil below 5 meters underground. Fifty-six ground settlement monitoring sections are set up around the perimeter of the foundation pit at intervals of 10 meters from the foundation pit. Each section has 5 settlement monitoring points, and the spacing between the 5 settlement monitoring points is 2 meters, 3 meters, 5 meters, 5 meters and 8 meters respectively. 28 groundwater level monitoring points were set up around the perimeter of the foundation pit at intervals of 30 meters from the foundation pit. Seven internal support horizontal axial force detection sections are set inside the foundation pit.

[0009] Optionally, in the construction area, the design speed of the two-way four-lane highway tunnel is 60 kilometers per hour, the total length of the two-way four-lane highway tunnel is 510 meters, the open section of the two-way four-lane highway tunnel is 305 meters, the buried section is 205 meters, the two-way four-lane highway tunnel is constructed using the open-cut method, the excavation width of the foundation pit ranges from 20.4 meters to 30.8 meters, the depth of the foundation pit ranges from 1.8 meters to 11.6 meters, the strata in the construction area include, from top to bottom, fill soil, silty clay, gravel, pebbles, strongly weathered mudstone, and moderately weathered mudstone, the groundwater in the construction area is phreatic water, the groundwater level is in the range of 1 meter to 6.2 meters below the surface, and the annual variation range of the groundwater level is 2 meters.

[0010] Optionally, the first construction section includes the 92-meter to 260-meter section of the highway tunnel, the second construction section includes the 261-meter to 402-meter section of the highway tunnel, and the third construction section includes the 403-meter to 507-meter section of the highway tunnel; In the first construction section, the excavation depth ranges from 1.8 meters to 8 meters. The length of the multiple bored piles and high-pressure jet grouting piles in the first construction section ranges from 6 meters to 10.5 meters. The diameter of each bored pile is 800 mm, and the center-to-center distance between adjacent bored piles is 1000 mm. The diameter of each high-pressure jet grouting pile is 600 mm, and the center-to-center distance between adjacent high-pressure jet grouting piles is 1000 mm. The concrete support includes a C30 concrete block, which is 0.8 meters long and 0.8 meters wide. The steel support includes a steel pipe, which is 609 mm in diameter and 16 mm thick.

[0011] Optionally, in the second construction section, the excavation depth ranges from 8 meters to 11.6 meters. The interlocking pile retaining wall includes multiple interlocking piles with a diameter of 1000 mm and a pile length ranging from 11 meters to 13.5 meters. The center distance between two adjacent interlocking piles is 750 mm. The concrete support includes a C30 concrete block with a length and width of 0.8 meters. The steel support includes two or three steel pipes with a diameter of 609 mm and a wall thickness of 16 mm.

[0012] Optionally, in the third construction section, the excavation depth ranges from 2.5 meters to 8 meters, the length of the multiple bored piles and high-pressure jet grouting piles in the third construction section ranges from 9.5 meters to 10 meters, and the diameter of each bored pile is 800 mm. The center-to-center distance between adjacent bored piles is 1000 mm. The diameter of each high-pressure jet grouting pile is 600 mm. The center-to-center distance between adjacent high-pressure jet grouting piles is 1000 mm. The concrete support includes a C30 concrete block, the length and width of which are both 0.8 meters. The steel support includes a steel pipe, the diameter of which is 609 mm and the wall thickness is 16 mm.

[0013] Optionally, acquiring the lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support through the multiple monitoring points during construction includes: Acquire the lateral displacement data of the retaining wall obtained from multiple first inclinometer points; Based on the lateral displacement data of the retaining wall, the data of the maximum lateral displacement section is determined. The maximum lateral displacement section is the section where the lateral displacement of the retaining wall is greater than the first lateral displacement threshold. The data of the maximum lateral displacement section includes the lateral displacement values ​​of the retaining wall of multiple first inclinometer points arranged along the depth direction of the foundation pit. The determination of whether any parameter among the following parameters—lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support—deviations from a preset threshold greater than a preset threshold includes: Determine whether the deviation between the lateral displacement data of the maximum lateral displacement section and the preset lateral displacement data is greater than a preset lateral displacement deviation threshold. The preset lateral displacement data includes a preset lateral displacement value composed of the lateral displacement values ​​of the retaining wall formed by multiple first inclination points arranged along the depth direction of the foundation pit. If the deviation is greater than the preset threshold, it is determined that the lateral displacement of the retaining wall is greater than the preset threshold of the lateral displacement of the retaining wall. If the deviation is not greater than the preset threshold, it is determined that the lateral displacement of the retaining wall is not greater than the preset threshold of the lateral displacement of the retaining wall.

[0014] Optionally, determining whether the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is greater than a preset lateral displacement deviation threshold includes: The lateral displacement curve of the maximum lateral displacement segment is obtained based on the lateral displacement data of the maximum lateral displacement segment. The lateral displacement curve of the maximum lateral displacement segment includes a curve composed of multiple lateral displacement values ​​included in the lateral displacement data of the maximum lateral displacement segment. The lateral displacement curve of the preset lateral displacement data is obtained based on the preset lateral displacement data. The lateral displacement curve of the preset lateral displacement data includes a curve composed of multiple preset lateral displacement values ​​included in the preset lateral displacement data. Determine the first fitting rate between the lateral displacement curve of the maximum lateral displacement segment and the lateral displacement curve of the preset lateral displacement data; When the first fitting rate is greater than the first fitting rate threshold, it is determined that the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is greater than the preset lateral displacement deviation threshold. When the fitting rate is less than or equal to the first fitting rate threshold, it is determined that the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is not greater than the preset lateral displacement deviation threshold.

[0015] Optionally, acquiring the lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support through the multiple monitoring points during construction includes: Acquire horizontal displacement data of the soil obtained from multiple second inclinometer points; Based on the soil horizontal displacement data, the soil horizontal displacement data of the maximum soil horizontal displacement segment is determined. The maximum soil horizontal displacement segment is the segment where the soil horizontal displacement is greater than the first soil horizontal displacement threshold. The soil horizontal displacement data of the maximum soil horizontal displacement segment includes the soil horizontal displacement values ​​of multiple second inclinometer points arranged along the depth direction of the foundation pit. The determination of whether any parameter among the following parameters—lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support—deviations from a preset threshold greater than a preset threshold includes: Determine whether the deviation between the horizontal displacement data of the maximum horizontal displacement section and the preset horizontal displacement data of the soil is greater than the preset horizontal displacement deviation. The preset horizontal displacement data of the soil includes the preset horizontal displacement value composed of the horizontal displacement values ​​of the soil at multiple second inclinometer points arranged along the depth direction of the foundation pit. If it is greater than the preset threshold, determine that the horizontal displacement of the soil is greater than the preset threshold of the horizontal displacement of the soil. If it is not greater than the preset threshold, determine that the horizontal displacement of the soil is not greater than the preset threshold of the horizontal displacement of the soil.

[0016] Optionally, determining whether the deviation between the horizontal displacement data of the maximum horizontal displacement segment and the preset horizontal displacement data of the soil is greater than a preset horizontal displacement deviation includes: Based on the soil horizontal displacement data of the maximum soil horizontal displacement segment, the soil horizontal displacement curve of the maximum soil horizontal displacement segment is obtained. The soil horizontal displacement curve of the maximum soil horizontal displacement segment includes a curve composed of multiple soil horizontal displacements included in the soil horizontal displacement data of the maximum soil horizontal displacement segment. Based on the horizontal displacement data of the preset soil, a soil horizontal displacement curve is obtained. The soil horizontal displacement curve of the preset soil includes a curve composed of multiple preset soil horizontal displacement values ​​included in the horizontal displacement data of the preset soil. Determine the second fitting rate between the soil horizontal displacement curve of the maximum soil horizontal displacement segment and the soil horizontal displacement curve of the preset soil horizontal displacement data. When the second fitting rate is greater than the second fitting rate threshold, it is determined that the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is greater than the preset horizontal displacement deviation threshold. When the second fitting rate is less than or equal to the second fitting rate threshold, it is determined that the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is not greater than the preset horizontal displacement deviation threshold.

[0017] The beneficial effects of the technical solutions provided in this application include at least the following: By setting up multiple monitoring points in the construction area and acquiring real-time data on the lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support during construction, this method determines whether any one of these parameters deviates from a preset threshold. If so, adjustments can be made using at least one preset measure, including reinforcing the support structure, adjusting the excavation depth, excavation sequence, and layering parameters, as well as grouting. The process of acquiring the lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support through multiple monitoring points is then repeated. This allows for real-time monitoring and intervention of the foundation pit construction process, making it easier for the foundation pit to meet preset requirements. This method can be applied to the construction of various water-rich gravel layer foundation pits and reduces the difficulty of achieving preset requirements during foundation pit construction. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating a construction method for a water-rich gravel layer foundation pit, as provided in an embodiment of this application. Figure 2 This is a flowchart of another construction method for a water-rich gravel layer foundation pit provided in the embodiments of this application; Figure 3 This is a layout diagram of foundation pit monitoring points provided in an embodiment of this application; Figure 4 This is provided by the embodiments of this application. Figure 3 The lateral displacement curve of the retaining wall formed by the lateral displacement data of the retaining wall obtained from the first six inclinometer points in the middle; Figure 5 This is provided by the embodiments of this application. Figure 3 A deep soil horizontal displacement curve diagram formed by the horizontal displacement data of the soil obtained from the six second inclinometer points. Figure 6 This is provided by the embodiments of this application. Figure 3 The graph shows the change in surface settlement behind the retaining walls over time, formed by the surface settlement data of the two retaining walls.

[0020] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0022] Figure 1 This application provides a flowchart of a construction method for a water-rich gravel layer foundation pit, applicable to foundation pits in a two-way four-lane highway tunnel project. The method includes the following steps: Step 101: Determine the construction area of ​​the foundation pit, which includes the first construction section, the second construction section, and the third construction section.

[0023] Step 102: Determine the support structure of the construction area. The support structure of the first and third construction sections is a combination of bored piles and high-pressure jet grouting piles as a water-stop curtain retaining wall. The support structure of the second construction section is an interlocking pile retaining wall. The support structure inside the foundation pit is a concrete support and a steel support.

[0024] Step 103: Excavate the foundation pit by layering, segmenting, and dividing the earthwork based on spatiotemporal effects. During excavation, a longitudinal slope is maintained, and deep wells are used within the pit to drain water, ensuring the water level inside the pit is less than or equal to 1 meter. Furthermore, the fluctuation of the water level outside the pit is controlled; if the fluctuation exceeds a threshold, measures are taken to ensure the safety of the surrounding environment. When excavating the pit to the bottom and constructing the foundation slab, drainage holes are installed at the well points.

[0025] Step 104: Set up multiple monitoring points in the construction area.

[0026] Step 105: Obtain the lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support through multiple monitoring points during the construction process.

[0027] Step 106: Determine whether any one of the following parameters—lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support—deviations from the preset threshold of any one parameter are greater than the preset threshold.

[0028] Step 107: If the condition exists, adjust the condition using preset measures and repeat step 105. The preset measures include at least one of the following: reinforcing the support structure, adjusting the excavation depth, excavation sequence, and layering parameters, and grouting.

[0029] If it does not exist, proceed to step 105.

[0030] In summary, the construction method for water-rich gravel layer foundation pits provided in this application involves setting up multiple monitoring points in the construction area and using these points to acquire real-time data on the lateral displacement of the retaining wall, horizontal displacement of the soil, surface settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support during the construction process. The method determines whether any one of these parameters deviates from a preset threshold greater than a preset threshold. If such deviation exists, reinforcement and support structures can be used to address the issue. The method involves adjusting the excavation depth, excavation sequence, and layering parameters, as well as at least one pre-set measure in grouting. It also involves re-executing the steps of acquiring data from multiple monitoring points during construction, including lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the pit, and axial force of the internal supports. This allows for real-time monitoring of the pit's construction process and real-time intervention and adjustment, making it easier for the pit to meet pre-set requirements. This method can be applied to the construction of various water-rich gravel layer pits and reduces the difficulty of achieving the pre-set requirements.

[0031] Figure 2 This is a flowchart illustrating another construction method for a water-rich gravel layer foundation pit provided in this application embodiment, used for foundation pits in a two-way four-lane highway tunnel project. The method includes the following steps: Step 201: Determine the construction area of ​​the foundation pit, which includes the first construction section, the second construction section, and the third construction section.

[0032] In one exemplary embodiment, in the construction area, the design speed of the two-way four-lane highway tunnel is 60 kilometers per hour, the total length of the two-way four-lane highway tunnel is 510 meters, the open section of the two-way four-lane highway tunnel is 305 meters, and the buried section is 205 meters, wherein the buried section refers to the part of the tunnel main structure that is completely covered by the overlying soil. The two-way four-lane highway tunnel is constructed using the open-cut method. The excavation width of the foundation pit ranges from 20.4 meters to 30.8 meters, and the depth ranges from 1.8 meters to 11.6 meters. The strata in the construction area include, from top to bottom, fill soil, silty clay, gravel, pebbles, strongly weathered mudstone, and moderately weathered mudstone. The groundwater in the construction area is phreatic water, with the groundwater level located between 1 meter and 6.2 meters below the surface. The annual variation range of the groundwater level is 2 meters. The open-cut method is a construction method in which the foundation pit is excavated in the open, and construction is carried out sequentially from bottom to top (foundation slab pouring - side wall pouring - top slab pouring - waterproof layer construction), and then backfilled with soil.

[0033] The foundation pit involved in this application embodiment can be an open-cut tunnel foundation pit, which is an earth and rock pit excavated on the ground during the construction of a tunnel using the open-cut method. The open-cut tunnel foundation pit is the working area for the construction of an open-cut tunnel.

[0034] In one exemplary embodiment, the first construction section includes the 92-meter to 260-meter section of the highway tunnel, the second construction section includes the 261-meter to 402-meter section of the highway tunnel, and the third construction section includes the 403-meter to 507-meter section of the highway tunnel.

[0035] In the first construction section, the excavation depth ranges from 1.8 meters to 8 meters. The length of the multiple bored piles and high-pressure jet grouting piles in the first construction section ranges from 6 meters to 10.5 meters. The diameter of each bored pile is 800 mm, and the center-to-center distance between adjacent bored piles is 1000 mm. The diameter of each high-pressure jet grouting pile is 600 mm, and the center-to-center distance between adjacent high-pressure jet grouting piles is 1000 mm. The concrete support includes a C30 concrete block, which is 0.8 meters long and wide. The steel support includes a steel pipe with a diameter of 609 mm and a wall thickness of 16 mm.

[0036] In the second construction section, the excavation depth ranges from 8 meters to 11.6 meters. The interlocking pile retaining wall consists of multiple interlocking piles with a diameter of 1000 mm and a length ranging from 11 meters to 13.5 meters. The center-to-center distance between two adjacent interlocking piles is 750 mm. The concrete support consists of a C30 concrete block with a length and width of 0.8 meters. The steel support consists of two or three steel pipes with a diameter of 609 mm and a wall thickness of 16 mm.

[0037] Optionally, in the third construction section, the excavation depth ranges from 2.5 meters to 8 meters, the length of the multiple bored piles and high-pressure jet grouting piles in the third construction section ranges from 9.5 meters to 10 meters, and the diameter of each bored pile is 800 mm. The center-to-center distance between adjacent bored piles in the multiple bored piles is 1000 mm. The diameter of each high-pressure jet grouting pile is 600 mm. The center-to-center distance between adjacent high-pressure jet grouting piles in the multiple high-pressure jet grouting piles is 1000 mm. The concrete support includes a C30 concrete block, the length and width of which are both 0.8 meters. The steel support includes a steel pipe, the diameter of which is 609 mm and the wall thickness is 16 mm.

[0038] Step 202: Determine the support structure for the construction area. The support structure for the first and third construction sections is a combined retaining wall of bored cast-in-place piles and high-pressure jet grouting piles with a water-stop curtain. The support structure for the second construction section is an interlocking pile retaining wall. The support structure within the foundation pit is concrete support and steel support. The high-pressure jet grouting pile water-stop curtain combined retaining wall is a combined retaining wall composed of high-pressure jet grouting piles and a water-stop curtain. The high pressure of the high-pressure jet grouting piles can refer to a pressure range of 20 MPa to 50 MPa.

[0039] In one exemplary embodiment, bored piles serve as vertical bending-resistant retaining structures, resisting lateral earth pressure on the foundation pit; high-pressure jet grouting piles are used to fill the gaps between piles to form a continuous water-stopping curtain, preventing groundwater seepage; interlocking pile retaining walls are formed by alternating interlocking of reinforced concrete piles (Pile A) and plain concrete piles (Pile B) to create a continuous wall that combines soil retention and water-stopping functions. Concrete bracing, also known as concrete support, is a rigid internal support structure used in foundation pit engineering to horizontally connect support piles / walls and form a spatially stable frame, while steel bracing is typically used in combination with concrete bracing to provide flexible support.

[0040] Step 203: Excavate the foundation pit by layering, segmenting and block excavation based on the spatiotemporal effect. During excavation, the soil is sloped longitudinally and deep wells are used to drain water in the foundation pit so that the water level in the foundation pit is less than or equal to 1 meter.

[0041] By employing spatiotemporal effects to excavate earthwork in layers, segments, and blocks for foundation pit excavation, the deformation and surrounding settlement of the foundation pit can be minimized by controlling the unsupported soil exposure time (exposure time) and reducing the single excavation range and depth (spatial scale). Layering is based on the height of the support system to control the vertical direction of the excavated foundation pit. Segmentation is based on the foundation pit length, support spacing, and deformation-sensitive zones to control the horizontal direction of the excavated foundation pit. Blocking further divides a single segment of the foundation pit into smaller units, enabling planar grid control of the excavated foundation pit. In this embodiment, the spatiotemporal effects of layering, segmenting, and block excavation for foundation pit excavation, through refined spatiotemporal dimension cutting, significantly reduce deformation risk and avoid catastrophic accidents.

[0042] Step 204: Control the fluctuation range of water level outside the pit. If any abnormality occurs, take timely measures to ensure the safety of the surrounding environment. When excavating the pit to the bottom and constructing the bottom slab, set up drainage holes at the well point locations.

[0043] Controlling the water level outside the pit and installing drainage holes in the bottom slab can ensure the stability of the foundation pit and the safety of the surrounding environment. For example, a water level monitoring network can be deployed outside the pit to obtain the magnitude of water level changes. When the water level is abnormal, the causes can be analyzed, and corresponding emergency measures can be taken. For instance, if excessive pumping from dewatering wells or curtain leakage causes a sudden drop in water level, remedial measures such as shutting down some dewatering wells, re-injecting water outside the pit, and grouting at leakage points can be implemented. Other methods can also be used to obtain the magnitude of water level changes and take other measures to ensure the safety of the surrounding environment in abnormal situations; this application does not limit these methods.

[0044] Optionally, the drainage hole can be located directly above the dewatering well point in the pit, and is formed through steps such as bottom slab cushion layer, pre-embedded PVC pipe, gravel filter layer filling, geotextile covering, bottom slab reinforcement binding, and concrete pouring. The drainage hole can prevent the bottom slab from being damaged by water pressure and buoyancy, collect residual seepage water under the bottom slab, prevent the cushion layer from bulging, and allow the groundwater level to be observed through the drainage hole while the dewatering wells are gradually closed. The drainage hole can also be formed through other manufacturing steps, which are not limited to the embodiments described in this application.

[0045] Step 205: Set up 28 first inclinometer points in the foundation pit to monitor the lateral displacement of the retaining wall, and set up 28 second inclinometer points in the deep soil of the foundation pit to monitor the horizontal displacement of the soil.

[0046] The deep soil refers to the soil below 5 meters underground. Figure 3 A layout diagram of foundation pit monitoring points is provided for an embodiment of this application, such as... Figure 3 As shown, ZC1~ZC28 are the marking numbers of the first inclinometer point, and SC1~SC28 are the marking numbers of the second inclinometer point.

[0047] Step 206: Set up 56 monitoring sections for ground settlement behind the wall at intervals of 10 meters around the perimeter of the foundation pit.

[0048] Each cross-section is equipped with 5 settlement monitoring points, with the spacing between the 5 monitoring points being 2 meters, 3 meters, 5 meters, 5 meters, and 8 meters, respectively. For example... Figure 3 As shown, DB1-i~DB56-i (i is the measurement point number) are the marking numbers of 56 monitoring sections for ground settlement behind the wall.

[0049] Step 207: Set up 28 groundwater level monitoring points outside the pit at intervals of 30 meters around the pit.

[0050] like Figure 3 As shown, SW1~SW28 are the marking numbers of 28 groundwater level monitoring points outside the pit.

[0051] Step 208: Set up 7 internal support horizontal axial force detection sections inside the foundation pit.

[0052] like Figure 3 As shown, ZL1-m~ZL7-m (m is the number of support layers) are the marking numbers of the 7 internal support horizontal axial force detection sections.

[0053] Step 209: Obtain the lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support through multiple monitoring points during the construction process.

[0054] Step 209 may include: 1.1) Obtain the lateral displacement data of the retaining wall measured from multiple first inclinometer points; Figure 4 This is provided by the embodiments of this application. Figure 3 The lateral displacement curve of the retaining wall, formed by the lateral displacement data of the retaining wall obtained from the first six inclinometer points, is shown in the figure. ZC1~ZC28 are... Figure 3 The marking number of the first inclinometer point in the middle. Figure 4 The graph labeled (a) ZC4 is a curve formed by the data obtained from the first inclinometer point ZC4. Figure 4 The graph labeled (b) ZC8 is a curve formed by the data obtained from the first inclinometer point ZC8. Figure 4 The graph labeled (c) ZC17 is a curve formed by the data obtained from the first inclinometer point ZC17. Figure 4 The graph labeled (d) ZC19 is a curve formed by the data obtained from the first inclinometer point ZC18. Figure 4 The graph labeled (e) ZC21 is a curve formed by the data obtained from the first inclinometer point ZC21. Figure 4 The figure labeled (f) ZC27 is a curve formed by the data obtained from the first inclinometer point ZC27.

[0055] 1.2) Based on the lateral displacement data of the retaining wall, determine the data of the maximum lateral displacement section. The maximum lateral displacement section is the section where the lateral displacement of the retaining wall is greater than the first lateral displacement threshold. The data of the maximum lateral displacement section includes the lateral displacement values ​​of the retaining wall of multiple first inclinometer points arranged along the depth direction of the foundation pit. like Figure 3 and Figure 4As shown, with the increase of the excavation depth, the lateral displacement of the retaining wall increases significantly, and its distribution curve is shaped like a "bulge". In the early stage of excavation, the lateral earth pressure caused by the unloading of the soil in the pit gradually increases, causing the retaining wall to continuously generate lateral displacement. As the excavation depth increases, the application of internal supports and the constraint effect of the soil at the bottom of the pit on the retaining wall limit the intensification of lateral displacement to a certain extent, so the lateral displacement curve shows a trend of first increasing and then decreasing. The maximum lateral displacement sections at each measuring point are concentrated in the depth of 2 meters to 4 meters, and the maximum lateral displacements are 3.92 mm, 4.06 mm, 4.92 mm, 5.45 mm, 4.64 mm, and 3.55 mm, respectively. This phenomenon is mainly due to the disruption of the stress and strain balance of the original soil layer during the excavation process. With the intervention of internal supports and the gradual exertion of the embedding effect of the soil at the bottom of the pit on the retaining wall, the deformation of the retaining wall is coordinated and the earth pressure behind the wall is dynamically adjusted. Furthermore, as can be seen from step 201, the differences in the length of the retaining wall piles, excavation depth, and number of support layers at each measuring point, as well as the varying geological conditions of the soil layer at the bottom of the pit, lead to significant differences in the distribution of the lateral displacement curves of the retaining wall at each measuring point. The first lateral displacement threshold can be a range of values ​​derived from historical experience data, and this embodiment does not impose such limitations. It should be noted that the various thresholds involved in this embodiment can all be empirical values, such as representative and universally valuable values ​​accumulated by construction units in long-term engineering practice.

[0056] 1.3) Obtain horizontal displacement data of the soil obtained from multiple second inclinometer points; Figure 4 This is provided by the embodiments of this application. Figure 3 The deep soil horizontal displacement curve is formed by the horizontal displacement data of the soil obtained from the six second inclinometer points, where SC1~SC28 are... Figure 3 The marking number of the second inclined plane in the middle, and Figure 4 The graph labeled (a) ZC4 is a curve formed by the data obtained from the second inclinometer point SC4. Figure 4 The graph labeled (b) SC8 is a curve formed by the data obtained from the second inclinometer point SC8. Figure 4 The graph labeled (c) SC17 is a curve formed by the data obtained from the second inclinometer point SC17. Figure 4 The graph labeled (d) SC19 is a curve formed by the data obtained from the second inclinometer point SC18. Figure 4 The graph labeled (e) SC21 is a curve formed by the data obtained from the second inclinometer point SC21. Figure 4 The figure labeled (f) SC27 is a curve graph formed by the data obtained from the second inclinometer point SC27.

[0057] 1.4) Based on the horizontal displacement data of the soil, determine the horizontal displacement data of the section with the maximum horizontal displacement. The section with the maximum horizontal displacement is the section where the horizontal displacement of the soil is greater than the first horizontal displacement threshold. The horizontal displacement data of the section with the maximum horizontal displacement includes the horizontal displacement values ​​of the soil at multiple second inclinometer points arranged along the depth direction of the foundation pit. like Figure 3 and Figure 5 As shown, the horizontal displacement of the deep soil outside the pit increases significantly with the increase of excavation depth, and the distribution curve presents a "bulging" shape. Each measuring point reaches its maximum horizontal displacement when excavated to the bottom slab, with values ​​of 3.66 mm (4 m depth), 4.46 mm (4 m depth), 4.95 mm (5 m depth), 9.55 mm (3.5 m depth), 5.31 mm (3.5 m depth), and 4.48 mm (4 m depth), respectively. The horizontal displacement of the deep soil at measuring points SC17, SC19, and SC21 is higher than that at other measuring points. Comparison reveals that the greater the excavation depth, the greater the maximum value of the horizontal displacement of the deep soil. Furthermore, the location of the maximum horizontal displacement of the deep soil gradually shifts downwards with the excavation depth. This is because the accumulation of excavation depth gradually releases the earth pressure behind the wall, changing the overall stress balance of the soil. Combined with the supporting effect of the internal supports, this causes an increase in the lateral displacement of the soil, which then dynamically adjusts. The first horizontal displacement threshold can be a range of values ​​obtained by summarizing historical experience data; this embodiment does not limit this range.

[0058] 1.5) Obtain surface settlement data behind the retaining wall at multiple settlement monitoring sections.

[0059] The settlement data behind the retaining wall for each settlement monitoring section includes the settlement parameters behind the retaining wall recorded by five settlement monitoring points. Each settlement parameter behind the retaining wall includes a curve showing the change of the settlement value behind the retaining wall recorded by the monitoring point over time.

[0060] Figure 6 This is provided by the embodiments of this application. Figure 3 The graph shows the change in surface settlement behind two retaining walls over time, with DB1~DB56 representing the data. Figure 3 The marking numbers of the 56 surface settlement monitoring sections behind the wall. Figure 6 In the diagram, graph a is a curve graph formed by data labeled DB49, and graph b is a curve graph formed by data labeled DB53. Figure 3 and Figure 6As shown, the surface settlement behind the retaining wall gradually increased as the foundation pit excavation progressed. With the passage of time, the surface settlement gradually stabilized, indicating that the foundation pit excavation stage was the main period of increased surface settlement. The maximum surface settlement range after stabilization was -5.87 mm to -10.22 mm. Furthermore, there were certain differences in surface settlement at different measuring points. Considering the settlement curves of each measuring point, their distribution location, excavation depth, and soil physical properties, these differences were closely related to the distance of the measuring point from the edge of the foundation pit, the distribution of groundwater level, and the application of the support structure. In the initial stage of foundation pit excavation, the surface settlement increased approximately linearly, then gradually slowed down, and finally stabilized. This trend reflects the stress release and redistribution process of the soil during foundation pit excavation. Measuring points DB49 and DB53 showed the above-mentioned pattern relatively completely.

[0061] 1.6) Obtain groundwater level data outside the pit through groundwater level monitoring points outside the pit.

[0062] The groundwater level data obtained from each monitoring point outside the excavation pit includes a curve showing the change in groundwater level over time at that monitoring point. During the excavation pit construction, dewatering measures inside the pit alter the hydraulic gradient balance, leading to seepage of groundwater outside the pit. Over the long term, this causes settlement and deformation of the surrounding soil. To investigate the impact of excavation and dewatering on the groundwater level outside the pit, multiple groundwater level monitoring points can be set up around the perimeter of the pit.

[0063] 1.7) Based on the groundwater level data outside the foundation pit, determine the cumulative change curve of the groundwater level over time and the change curve of the groundwater level rate over time.

[0064] During construction, the cumulative change in groundwater level outside the pit exhibited significant fluctuations over time, particularly at monitoring point SW26, where the cumulative change in groundwater level dropped rapidly in a short period, but did not exceed the monitoring warning value of ±1.0 meter. Furthermore, the cumulative change in groundwater level generally showed two phases: a rapid increase or decrease followed by a gradual stabilization, but the duration of these two phases varied considerably at different monitoring points. The rate of change in groundwater level at each monitoring point fluctuated within ±0.2 m / d, not exceeding the monitoring alarm value of ±0.5 m / d.

[0065] 1.8) The axial force of the internal support is obtained through seven horizontal axial force detection sections of the internal support.

[0066] As the excavation of the foundation pit progressed, the active earth pressure around the pit continued to rise. Under the combined action of lateral loads and internal support structures, the axial force of the supports showed a step-like increase over time, and then gradually stabilized. The range of axial force variation for each support level was as follows: the first support was -381.90~3525.90 kN, the second support was 25.62~512.03 kN, and the third support was 95.76~531.76 kN. The maximum axial forces of the first, second, and third supports were approximately 59.8%, 20.5%, and 21.3% of the design values, respectively, indicating that the design had a high safety margin. A comparison of the axial forces of each layer showed that the axial force of the first concrete support fluctuated more significantly, and the axial force growth could be divided into three stages: rapid growth, slow growth, and stabilization, stabilizing only after 50 days. In contrast, the axial force growth of the second and third steel supports was relatively gradual, with little change after 20 days. As can be seen from the above changes in axial force, the lateral earth pressure load caused by the excavation and unloading of the foundation pit is mainly borne by the first layer of concrete support, while the second and third layers of steel support only bear part of the residual lateral earth pressure and the stress increase caused by the rebound at the bottom of the pit.

[0067] Step 210: Determine whether any one of the following parameters—lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support—deviations from a preset threshold greater than the preset threshold. If none of these parameters exist, proceed to step 209. If they exist, proceed to step 211.

[0068] The preset threshold can be a range of thresholds derived from historical data, and the specific preset threshold is not limited in this embodiment of the application.

[0069] Step 210 includes: 2.1) Determine whether the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is greater than the preset lateral displacement deviation threshold.

[0070] The preset lateral displacement data includes the preset lateral displacement values ​​of the retaining wall composed of the lateral displacement values ​​of multiple first inclinometer points arranged along the depth direction of the foundation pit. When the value is greater than the preset threshold, the lateral displacement of the retaining wall is determined to be greater than the preset threshold. When the value is not greater than the preset threshold, the lateral displacement of the retaining wall is determined to be not greater than the preset threshold.

[0071] 2.2) Based on the lateral displacement data of the maximum lateral displacement segment, the lateral displacement curve of the maximum lateral displacement segment is obtained. The lateral displacement curve of the maximum lateral displacement segment includes a curve composed of multiple lateral displacement values ​​included in the lateral displacement data of the maximum lateral displacement segment. 2.3) Obtain the lateral displacement curve of the preset lateral displacement data based on the preset lateral displacement data. The lateral displacement curve of the preset lateral displacement data includes a curve composed of multiple preset lateral displacement values ​​included in the preset lateral displacement data. 2.4) Determine the first fitting rate between the lateral displacement curve of the maximum lateral displacement segment and the lateral displacement curve of the preset lateral displacement data; The index value is obtained by quantifying the similarity or fit between two curves (lateral displacement curve vs. preset lateral displacement curve). The higher the index value, the closer the actual deformation form is to the preset allowable form; the lower the index value, the greater the difference between the actual deformation form and the preset form.

[0072] 2.5) When the first fitting rate is greater than the first fitting rate threshold, the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is greater than the preset lateral displacement deviation threshold. The first fitting rate threshold can be a pre-set critical value for the degree of curve fitting based on historical data. The specific value is not limited in this embodiment of the application.

[0073] 2.6) When the fitting rate is less than or equal to the first fitting rate threshold, the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data shall not be greater than the preset lateral displacement deviation threshold.

[0074] 2.7) Determine whether the deviation between the horizontal displacement data of the maximum horizontal displacement section and the preset horizontal displacement data of the soil is greater than the preset horizontal displacement deviation.

[0075] The preset horizontal displacement data of the soil includes the preset horizontal displacement values ​​of the soil composed of multiple second inclinometer points arranged along the depth direction of the foundation pit. When the value is greater than the preset threshold, the horizontal displacement of the soil is determined to be greater than the preset threshold. When the value is not greater than the preset threshold, the horizontal displacement of the soil is determined to be not greater than the preset threshold.

[0076] 2.8) Based on the soil horizontal displacement data of the maximum soil horizontal displacement segment, the soil horizontal displacement curve of the maximum soil horizontal displacement segment is obtained. The soil horizontal displacement curve of the maximum soil horizontal displacement segment includes a curve composed of multiple soil horizontal displacements included in the soil horizontal displacement data of the maximum soil horizontal displacement segment. 2.9) Based on the horizontal displacement data of the preset soil, obtain the horizontal displacement curve of the preset soil. The horizontal displacement curve of the preset soil includes a curve composed of multiple horizontal displacement values ​​of the preset soil included in the horizontal displacement data. 2.10) Determine the second fitting rate between the soil horizontal displacement curve of the maximum soil horizontal displacement segment and the soil horizontal displacement curve of the preset soil horizontal displacement data. 2.11) When the second fitting rate is greater than the second fitting rate threshold, the deviation between the soil horizontal displacement data of the maximum soil horizontal displacement segment and the preset soil horizontal displacement data is greater than the preset horizontal displacement deviation threshold. 2.12) When the second fitting rate is less than or equal to the second fitting rate threshold, the deviation between the soil horizontal displacement data of the maximum soil horizontal displacement segment and the preset soil horizontal displacement data shall not be greater than the preset horizontal displacement deviation threshold.

[0077] 2.13) Determine whether the surface settlement data behind the retaining wall at multiple settlement monitoring sections are all greater than the surface settlement threshold behind the retaining wall.

[0078] 2.14) Determine whether the cumulative change curve of groundwater level over time satisfies the preset change curve, and determine whether the change rate of groundwater level over time satisfies the preset change rate curve.

[0079] 2.15) Determine whether the axial forces of the internal supports obtained from the seven internal support horizontal axial force detection sections all meet the internal support axial force threshold.

[0080] Step 211: If the condition exists, adjust it using preset measures and re-execute step 209.

[0081] The pre-planned measures include at least one of the following: reinforcing the support structure, adjusting the excavation depth, excavation sequence, and layering parameters, as well as grouting.

[0082] The lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support were obtained again through multiple monitoring points during the construction process.

[0083] In summary, the construction method for water-rich gravel layer foundation pits provided in this application involves setting up multiple monitoring points in the construction area and using these points to acquire real-time data on the lateral displacement of the retaining wall, horizontal displacement of the soil, surface settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support during the construction process. The method determines whether any one of these parameters deviates from a preset threshold greater than a preset threshold. If such deviation exists, reinforcement and support structures can be used to address the issue. The method involves adjusting the excavation depth, excavation sequence, and layering parameters, as well as at least one pre-set measure in grouting. It also involves re-executing the steps of acquiring data from multiple monitoring points during construction, including lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the pit, and axial force of the internal supports. This allows for real-time monitoring of the pit's construction process and real-time intervention and adjustment, making it easier for the pit to meet pre-set requirements. This method can be applied to the construction of various water-rich gravel layer pits and reduces the difficulty of achieving the pre-set requirements.

[0084] In this application, the term "at least one of A and B" merely describes the relationship between related objects, indicating that three relationships can exist. For example, "at least one of A and B" can represent: A existing alone, A and B existing simultaneously, and B existing alone. Similarly, "at least one of A, B, and C" indicates that seven relationships can exist, representing: A existing alone, B existing alone, C existing alone, A and B existing simultaneously, A and C existing simultaneously, C and B existing simultaneously, and A, B, and C existing simultaneously. Likewise, "at least one of A, B, C, and D" indicates that fifteen relationships can exist, representing: A existing alone, B existing alone, C existing alone, D existing alone, A and B existing simultaneously, A and C existing simultaneously, A and D existing simultaneously, C and B existing simultaneously, D and B existing simultaneously, C and D existing simultaneously, A, B, and C existing simultaneously, A, B, and D existing simultaneously, A, C, and D existing simultaneously, and A, B, C, and D existing simultaneously.

[0085] In this application, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" means two or more, unless otherwise expressly defined.

[0086] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A construction method for a water-rich gravel layer foundation pit, characterized in that, The method for the foundation pit in a two-way four-lane highway tunnel project includes: The construction area of ​​the foundation pit is determined, and the construction area includes a first construction section, a second construction section, and a third construction section; The support structure of the construction area is determined as follows: the support structure of the first construction section and the third construction section is a combined retaining wall of bored cast-in-place piles and high-pressure jet grouting piles; the support structure of the second construction section is an interlocking pile retaining wall; and the support structure in the foundation pit is a concrete support and a steel support. Excavation of foundation pits is carried out by layering, segmenting, and block excavation based on spatiotemporal effects; Multiple monitoring points were set up in the construction area; The lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support are obtained through the multiple monitoring points during the construction process. Determine whether any one of the following parameters—lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support—deviations from a preset threshold greater than a preset threshold. When the conditions exist, adjustments are made through preset measures, and the steps of obtaining the lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit and the axial force of the internal support during the construction process through the multiple monitoring points are repeated. The preset measures include at least one of the following: reinforcing the support structure, adjusting the depth of the excavation, the order of excavation and the parameters of the layers, and grouting. If none of the above are present, the steps of obtaining the lateral displacement of the retaining wall, the horizontal displacement of the soil, the ground settlement behind the retaining wall, the groundwater level outside the foundation pit, and the axial force of the internal support during the construction process through the multiple monitoring points shall be performed. Multiple monitoring points are set up in the construction area, including: Twenty-eight first inclinometer points were set up in the foundation pit to monitor the lateral displacement of the retaining wall, and twenty-eight second inclinometer points were set up in the deep soil of the foundation pit to monitor the horizontal displacement of the soil. The deep soil is the soil below 5 meters underground. Fifty-six ground settlement monitoring sections are set up around the perimeter of the foundation pit at intervals of 10 meters from the foundation pit. Each section has 5 settlement monitoring points, and the spacing between the 5 settlement monitoring points is 2 meters, 3 meters, 5 meters, 5 meters and 8 meters respectively. 28 groundwater level monitoring points were set up around the perimeter of the foundation pit at intervals of 30 meters from the foundation pit. Seven internal support horizontal axial force detection sections are set inside the foundation pit; The acquisition of lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support through the multiple monitoring points during construction includes: Acquire the lateral displacement data of the retaining wall obtained from multiple first inclinometer points; Based on the lateral displacement data of the retaining wall, the data of the maximum lateral displacement section is determined. The maximum lateral displacement section is the section where the lateral displacement of the retaining wall is greater than the first lateral displacement threshold. The data of the maximum lateral displacement section includes the lateral displacement values ​​of the retaining wall of multiple first inclinometer points arranged along the depth direction of the foundation pit. The determination of whether any parameter among the following parameters—lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support—deviations from a preset threshold greater than a preset threshold includes: Determine whether the deviation between the lateral displacement data of the maximum lateral displacement section and the preset lateral displacement data is greater than a preset lateral displacement deviation threshold. The preset lateral displacement data includes a preset lateral displacement value composed of the lateral displacement values ​​of the retaining wall formed by multiple first inclination points arranged along the depth direction of the foundation pit. If the deviation is greater than the preset threshold, it is determined that the lateral displacement of the retaining wall is greater than the preset threshold of the lateral displacement of the retaining wall. If the deviation is not greater than the preset threshold, it is determined that the lateral displacement of the retaining wall is not greater than the preset threshold of the lateral displacement of the retaining wall. Determining whether the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is greater than a preset lateral displacement deviation threshold includes: The lateral displacement curve of the maximum lateral displacement segment is obtained based on the lateral displacement data of the maximum lateral displacement segment. The lateral displacement curve of the maximum lateral displacement segment includes a curve composed of multiple lateral displacement values ​​included in the lateral displacement data of the maximum lateral displacement segment. The lateral displacement curve of the preset lateral displacement data is obtained based on the preset lateral displacement data. The lateral displacement curve of the preset lateral displacement data includes a curve composed of multiple preset lateral displacement values ​​included in the preset lateral displacement data. Determine the first fitting rate between the lateral displacement curve of the maximum lateral displacement segment and the lateral displacement curve of the preset lateral displacement data; When the first fitting rate is greater than the first fitting rate threshold, it is determined that the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is greater than the preset lateral displacement deviation threshold. When the fitting rate is less than or equal to the first fitting rate threshold, it is determined that the deviation between the lateral displacement data of the maximum lateral displacement segment and the preset lateral displacement data is not greater than the preset lateral displacement deviation threshold.

2. The method according to claim 1, characterized in that, In the construction area, the design speed of the two-way four-lane highway tunnel is 60 kilometers per hour. The total length of the two-way four-lane highway tunnel is 510 meters, with an open section of 305 meters and a buried section of 205 meters. The two-way four-lane highway tunnel is constructed using the open-cut method. The excavation width of the foundation pit ranges from 20.4 meters to 30.8 meters, and the depth of the foundation pit ranges from 1.8 meters to 11.6 meters. The strata in the construction area include, from top to bottom, fill soil, silty clay, gravel, pebbles, strongly weathered mudstone, and moderately weathered mudstone. The groundwater in the construction area is phreatic water, with the groundwater level ranging from 1 meter to 6.2 meters below the surface and an annual variation of 2 meters.

3. The method according to claim 2, characterized in that, The first construction section includes the 92-meter to 260-meter section of the highway tunnel, the second construction section includes the 261-meter to 402-meter section of the highway tunnel, and the third construction section includes the 403-meter to 507-meter section of the highway tunnel; In the first construction section, the excavation depth ranges from 1.8 meters to 8 meters. The length of the multiple bored piles and high-pressure jet grouting piles in the first construction section ranges from 6 meters to 10.5 meters. The diameter of each bored pile is 800 mm, and the center-to-center distance between adjacent bored piles is 1000 mm. The diameter of each high-pressure jet grouting pile is 600 mm, and the center-to-center distance between adjacent high-pressure jet grouting piles is 1000 mm. The concrete support includes a C30 concrete block, which is 0.8 meters long and 0.8 meters wide. The steel support includes a steel pipe, which is 609 mm in diameter and 16 mm thick.

4. The method according to claim 3, characterized in that, In the second construction section, the excavation depth ranges from 8 meters to 11.6 meters. The interlocking pile retaining wall includes multiple interlocking piles with a diameter of 1000 mm and a length ranging from 11 meters to 13.5 meters. The center-to-center distance between any two adjacent interlocking piles is 750 mm. The concrete support includes a C30 concrete block with a length and width of 0.8 meters. The steel support includes two or three steel pipes with a diameter of 609 mm and a wall thickness of 16 mm.

5. The method according to claim 3, characterized in that, In the third construction section, the excavation depth ranges from 2.5 meters to 8 meters. The length of the multiple bored piles and high-pressure jet grouting piles in the third construction section ranges from 9.5 meters to 10 meters. Each bored pile has a diameter of 800 mm, and the center-to-center distance between adjacent bored piles is 1000 mm. Each high-pressure jet grouting pile has a diameter of 600 mm, and the center-to-center distance between adjacent high-pressure jet grouting piles is 1000 mm. The concrete support includes a C30 concrete block, which is 0.8 meters long and wide. The steel support includes a steel pipe with a diameter of 609 mm and a wall thickness of 16 mm.

6. The method according to claim 1, characterized in that, The acquisition of lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support through the multiple monitoring points during construction includes: Acquire horizontal displacement data of the soil obtained from multiple second inclinometer points; Based on the soil horizontal displacement data, the soil horizontal displacement data of the maximum soil horizontal displacement segment is determined. The maximum soil horizontal displacement segment is the segment where the soil horizontal displacement is greater than the first soil horizontal displacement threshold. The soil horizontal displacement data of the maximum soil horizontal displacement segment includes the soil horizontal displacement values ​​of multiple second inclinometer points arranged along the depth direction of the foundation pit. The determination of whether any parameter among the following parameters—lateral displacement of the retaining wall, horizontal displacement of the soil, ground settlement behind the retaining wall, groundwater level outside the foundation pit, and axial force of the internal support—deviations from a preset threshold greater than a preset threshold includes: Determine whether the deviation between the horizontal displacement data of the maximum horizontal displacement section and the preset horizontal displacement data of the soil is greater than the preset horizontal displacement deviation. The preset horizontal displacement data of the soil includes the preset horizontal displacement value composed of the horizontal displacement values ​​of the soil at multiple second inclinometer points arranged along the depth direction of the foundation pit. If it is greater than the preset threshold, determine that the horizontal displacement of the soil is greater than the preset threshold of the horizontal displacement of the soil. If it is not greater than the preset threshold, determine that the horizontal displacement of the soil is not greater than the preset threshold of the horizontal displacement of the soil.

7. The method according to claim 6, characterized in that, The step of determining whether the deviation between the horizontal displacement data of the maximum horizontal displacement segment and the preset horizontal displacement data of the soil is greater than the preset horizontal displacement deviation includes: Based on the soil horizontal displacement data of the maximum soil horizontal displacement segment, the soil horizontal displacement curve of the maximum soil horizontal displacement segment is obtained. The soil horizontal displacement curve of the maximum soil horizontal displacement segment includes a curve composed of multiple soil horizontal displacements included in the soil horizontal displacement data of the maximum soil horizontal displacement segment. Based on the horizontal displacement data of the preset soil, a soil horizontal displacement curve is obtained. The soil horizontal displacement curve of the preset soil includes a curve composed of multiple preset soil horizontal displacement values ​​included in the horizontal displacement data of the preset soil. Determine the second fitting rate between the soil horizontal displacement curve of the maximum soil horizontal displacement segment and the soil horizontal displacement curve of the preset soil horizontal displacement data. When the second fitting rate is greater than the second fitting rate threshold, it is determined that the deviation between the soil horizontal displacement data of the maximum soil horizontal displacement segment and the preset soil horizontal displacement data is greater than the preset horizontal displacement deviation threshold. When the second fitting rate is less than or equal to the second fitting rate threshold, it is determined that the deviation between the horizontal displacement data of the maximum horizontal displacement segment and the preset horizontal displacement data of the soil is not greater than the preset horizontal displacement deviation threshold.

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