Foundation treatment method based on rubble concrete

Abstract

The invention discloses a foundation treatment method based on rubble concrete, which relates to the technical field of building, and comprises the following steps: measuring a setting-out positioning pile position, and preparing wall protection slurry according to the field; excavating ground surface soil at the pile position, burying a steel casing, and drilling by a drilling machine to form a hole; cleaning holes, and hoisting and fixing the steel reinforcement cage which is welded in sections; mounting a concrete guide pipe, and pouring underwater concrete to form a cast-in-place pile; the pile body is maintained, detected and accepted; an interface antifriction material is brushed on the pile body preset section which is accepted and accepted to be qualified, and the pile body preset section corresponds to a rubble concrete filling section; and rubble concrete is poured into the low-lying area of the site to the designed elevation.

Description

Technical Field

[0001] The present invention relates to the field of building technology, in particular to foundation treatment, and specifically to a foundation treatment method based on rubble stone concrete. Background Art

[0002] In the construction industry, cast-in-place pile foundations are the most common type of deep foundation. Under normal circumstances, the piles and soil work together to provide bearing capacity. However, in certain construction scenarios, particularly where space is limited and there are significant elevation differences in the terrain, large-scale rolling machinery cannot be used for construction, making it difficult to guarantee project quality. Consequently, traditional ground treatment and pile foundation construction methods are unable to guarantee both quality and quantity.

[0003] Take the heavy medium workshop project of a mine undertaken by our company as an example. Figure 1 As shown, the construction area is 34m long and 18.5m wide. The distance between the foundations and existing buildings on the east and west sides is only 2 meters, the distance on the south side is 7 meters, and the distance to the waste rock track on the north side is 3 meters. In addition, the ground elevation of a 10-meter-long area on the north side of the site is about 3.6 meters lower than that on the south side. According to the traditional construction process, the low-lying area on the north side should be treated with foundation treatment, that is, backfilled in layers and compacted to the same elevation as the south side before pile foundation construction. However, due to the extremely narrow working space due to the minimum spacing of only 2 meters, large-scale rolling machinery cannot enter the site for operation, resulting in the inability to implement effective layered backfilling and compaction processes. Subsidence is prone to occur, and the quality and reliability of traditional backfilling methods cannot be guaranteed. Summary of the Invention

[0004] In order to solve the problem that large-scale rolling machinery cannot carry out construction, effective layered backfilling and compaction processes cannot be implemented, and pile foundation construction cannot be carried out under conditions of limited space and significant terrain height differences, the present invention provides a foundation treatment method based on rubble concrete.

[0005] The present invention is implemented by the following technologies: The present invention provides a foundation treatment method based on rubble stone concrete, which specifically comprises the following steps: a. Pile foundation construction to the design elevation Measure and lay out the pile position, and configure the retaining wall slurry according to the site; excavate the surface soil at the pile position and bury the steel casing, with the steel casing 0.3m above the construction surface and the vertical deviation of the steel casing ≤1%; drill the hole; clean the hole, lower the segmented welded steel cage and secure it; install the concrete guide pipe and pour underwater concrete to form the bored pile; maintain the pile body and conduct inspection and acceptance; Specifically, the following steps are included: aa, measurement, setting out and stake positioning Determine the center of the pile position on site, set up cross guard piles around the center of the pile position and a radius larger than the pile body, mark and fix them; ab, configure mud If the rock and soil layer is of good viscosity, dry or water drilling technology can be used directly without mud wall protection; If the stratum is loose and prone to collapse or there is groundwater distribution, the hole wall is unstable, and the static mud drilling process is adopted to inject wall protection mud or stabilizing liquid into the hole to protect the wall; the mud technical indicators need to be measured frequently during the drilling process, and the relative density of the wall protection mud should be adjusted at any time according to the needs of the engineering drilling to keep various indicators in compliance with the requirements, so as to avoid the progress being affected by the wall protection mud being too thick, and the hole collapse caused by the wall protection mud being too thin.

[0006] ac, excavate the surface soil and bury the steel casing Excavate the surface soil and bury steel casing according to the distribution of geological rock layers. The buried depth of the steel casing is at least 6m. The steel casing is made of 6-8mm steel plate, and the top surface position deviation is no more than 50mm. The clay is backfilled in layers to meet the density requirements to ensure its verticality and prevent mud loss, displacement, and falling; ad, drilling rig drilling into holes Drilling adopts mud wall drilling. If the hole depth is less than 15m, drill directly. During the drilling process, pay attention to the water pressure difference in the hole at any time to prevent quicksand; After the hole reaches the design elevation, the hole depth, hole diameter, verticality and sediment thickness are checked. Among them, the hole depth and hole diameter are not less than the design requirements, the verticality deviation is ≤1%, the sediment thickness meets the design requirements, and the pile position error is ≤50mm.

[0007] ae, clear hole When the relative density of the mud is too high, replace the slurry in the hole to ensure that the sand content of the mud is less than 2%; af, hanging steel cage Use a truck crane to hoist the pre-welded steel cage frame into the hole and weld it into a whole. When welding the two cage sections, the center lines of the upper and lower sections are consistent. The top of the steel cage frame is fixed with a steel pipe frame and a heavy object is placed on it to prevent the steel cage from floating during the concrete pouring process. ag, install concrete pipe and pour into form cast-in-place piles Before installing the conduit, conduct watertight pressure bearing and joint pressure resistance tests to ensure that the conduit is airtight and watertight throughout the entire concrete pouring process. Install the concrete conduit and pour underwater concrete into the concrete conduit. During the pouring process, control the speed at which concrete is placed into the concrete conduit to avoid pouring too quickly, which will cause the upper end of the conduit to be completely sealed and prevent the gas in the middle and lower parts from being discharged, thus forming high-pressure gas. The buried depth of the concrete conduit is maintained at 2-6m, and the slump of the concrete is maintained at 18-22m to form a cast-in-place pile. ah, pile finished product inspection and acceptance After the bored concrete pouring is completed, the pile axis center and pile top elevation are re-measured; after the concrete strength reaches the design requirements, the concrete uniformity and bearing capacity of the pile body are tested.

[0008] It's important to note that the practice of first connecting piles to the designed elevation of the pile top and then filling the height difference area with rubble concrete can lead to negative friction due to differential settlement. This is because the rubble concrete is heavy, resulting in significant settlement after filling and in the post-construction phase. However, the pile foundation is already embedded in a stable bearing layer, with minimal settlement. The rubble concrete's settlement is greater than that of the pile foundation. This differential settlement between the rubble concrete and the pile foundation causes the rubble concrete to drag downward on the pile, creating negative friction. This negative friction significantly reduces the effective bearing capacity of the pile foundation, posing a potential threat to the safety of the superstructure. To address this negative friction, this method employs an interface friction reduction treatment.

[0009] b. Interface friction reduction treatment The interface friction-reducing material is applied to the preset section of the pile body that has passed the acceptance test. The preset section of the pile body corresponds to the rubble stone concrete filling section. The interface friction-reducing material is determined based on the direct shear test of the pile foundation-rubble stone concrete interface. The interface friction-reducing material includes asphalt, polyurethane, and polyurethane mesh cloth. A relative displacement sensor is used to detect the relative displacement between the rubble stone concrete and the pile body. Relative displacement sensors are buried in at least three pile bodies. The relative displacement sensors are arranged along the axial direction, and the spacing between two relative displacement sensors is 1m.

[0010] c. Rubble stone concrete filling: Pour rubble concrete into the low-lying areas of the site to the designed elevation.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a rubble concrete-based foundation treatment method. This method involves constructing cast-in-place piles directly to the designed pile top elevation within existing site conditions. Subsequently, the low-lying area is completely filled with rubble concrete to quickly level the area to the designed ground elevation. The method also measures the shear coefficient of different interface coating materials to determine appropriate anti-friction material coating parameters and the optimal anti-friction material. This method addresses the issue of rubble concrete settling exceeding the pile foundation's self-weight after filling and in the post-construction phase. This method prevents the rubble concrete from dragging the pile downward due to differential settlement, and ensures the effective bearing capacity of the pile foundation through the anti-friction material. Experimental measurements show that the relative displacement between the rubble concrete and the pile foundation is less than 5 mm, effectively addressing the problem of rapidly treating foundations in confined spaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram showing the foundation treatment position in the embodiment. DETAILED DESCRIPTION

[0013] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0014] A foundation treatment method based on rubble stone concrete, taking a new heavy medium workshop project of a mine as an example, specifically includes the following steps: a. Pile foundation construction to the design elevation aa, measurement, setting out and stake positioning Determine the center of the pile position on site, set up cross guard piles around the center of the pile position with a radius larger than the pile body, mark and fix it.

[0015] ab, configure mud If the rock and soil layer is of good viscosity, dry or water drilling technology can be used directly without mud wall protection; If the stratum is loose and prone to collapse or there is groundwater distribution, the hole wall is unstable and a static mud drilling process is used to inject wall protection mud or stabilizing liquid into the hole to protect the wall.

[0016] ac, excavate the surface soil and bury the steel casing Excavate the surface soil and bury steel casing according to the distribution of geological rock layers. The buried depth of the steel casing should be at least 6m, and the top surface position deviation should not exceed 50mm. The clay should be backfilled in layers to meet the density requirements.

[0017] ad, drilling rig drilling into holes The drilling method is mud wall drilling. If the hole depth is less than 15m, direct drilling is carried out.

[0018] After the hole reaches the design elevation, the hole depth, hole diameter, verticality and sediment thickness are checked. The hole depth and hole diameter are not less than the design requirements, the verticality deviation is ≤1%, the sediment thickness meets the design requirements, and the pile position error is ≤50mm.

[0019] ae, clear hole When the relative density of the mud is too high, the slurry in the hole should be replaced to ensure that the sand content of the mud is less than 2%.

[0020] af, hanging steel cage A car crane is used to lift the steel cage frame that has been welded in sections in advance into the hole and weld it into a whole. When the two sections of the cage are welded, the center lines of the upper and lower sections are kept consistent. The top of the steel cage frame is fixed with a cross-shaped frame made of steel pipes and a heavy object is pressed on it.

[0021] ag, install concrete pipe and pour into form cast-in-place piles Before installing the conduit, watertight pressure bearing and joint pressure resistance tests are carried out, and the concrete conduit is installed. Underwater concrete is poured into the concrete conduit. During the pouring process, the speed of concrete being placed into the concrete conduit is controlled, the buried depth of the concrete conduit is maintained at 2~6m, and the slump of concrete is maintained at 18~22m to form a bored pile.

[0022] ah, pile finished product inspection and acceptance After the bored concrete pouring is completed, the pile axis center and pile top elevation are re-measured; after the concrete strength reaches the design requirements, the concrete uniformity and bearing capacity of the pile body are tested.

[0023] b. Interface friction reduction treatment The interface friction-reducing material is applied to the preset section of the pile body that has passed the acceptance test. The preset section of the pile body corresponds to the rubble stone concrete filling section. The interface friction-reducing material is determined based on the direct shear test of the pile foundation-rubble stone concrete interface. A relative displacement sensor is used to detect the relative displacement between the rubble stone concrete and the pile body. Relative displacement sensors are embedded in at least three pile bodies. The relative displacement sensors are arranged along the axial direction, and the spacing between two relative displacement sensors is 1m.

[0024] c. Rubble stone concrete filling: The rubble concrete was poured into the low-lying areas of the site to the designed elevation. This method shortened the construction period by 11 days compared to the expected time. The new heavy medium workshop was completed ahead of schedule, ensuring the normal production of the mine.

[0025] After monitoring, the on-site controlled displacement was less than 5mm, that is, the relative displacement between the rubble concrete and the pile foundation was less than 5mm, which effectively solved the problem of rapid treatment of foundation in a narrow space.

[0026] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various variations and modifications. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A foundation treatment method based on rubble stone concrete, characterized by: The following steps are involved: a. Pile foundation construction to the design elevation Measure and lay out the pile position, and configure the retaining wall slurry according to the site; excavate the surface soil at the pile position and bury the steel casing, with the steel casing 0.3m above the construction surface and the vertical deviation of the steel casing ≤1%; drill the hole; clean the hole, lower the segmented welded steel cage and secure it; install the concrete guide pipe and pour underwater concrete to form the bored pile; maintain the pile body and conduct inspection and acceptance; b. Interface friction reduction treatment Applying interface friction-reducing material to the preset section of the pile body that has passed the acceptance test, wherein the preset section of the pile body corresponds to the section filled with rough stone concrete; c. Rubble stone concrete filling: Pour rubble concrete into the low-lying areas of the site to the designed elevation.

2. The foundation treatment method based on rubble stone concrete according to claim 1, characterized in that: A relative displacement sensor is used to detect the relative displacement between the rubble concrete and the pile body; relative displacement sensors are buried in at least three pile bodies, the relative displacement sensors are arranged along the axial direction, and the distance between two relative displacement sensors is 1m.

3. The foundation treatment method based on rubble stone concrete according to claim 1, characterized in that: The interface friction-reducing material is determined based on a pile foundation-rubble stone concrete interface direct shear test.

4. The method for foundation treatment based on rubble stone concrete according to claim 1, characterized in that: The interface friction-reducing material includes asphalt, polyurethane, and polyurethane mesh cloth.

5. The method for foundation treatment based on rubble stone concrete according to claim 1, characterized in that: Specifically in step a The following steps are involved: aa, measurement, setting out and stake positioning Determine the center of the pile position on site, set up cross guard piles around the center of the pile position and a radius larger than the pile body, mark and fix them; ab, configure mud If the rock and soil layer is of good viscosity, dry or water drilling technology can be used directly without mud wall protection; If the stratum is loose and prone to collapse or there is groundwater distribution, and the hole wall is unstable, static mud drilling technology is used to inject wall protection mud or stabilizing liquid into the hole to protect the wall; ac, excavate the surface soil and bury the steel casing Excavate the surface soil and bury steel casing according to the distribution of geological rock layers. The steel casing should be buried at a depth of at least 6m, with the top surface position deviation not exceeding 50mm. Then, compact the clay backfill layer by layer to meet the density requirements. ad, drilling rig drilling into holes Drilling adopts mud wall drilling, if the hole depth is less than 15m, drill directly; After the hole reaches the designed elevation, the hole depth, hole diameter, verticality and sediment thickness are checked. 6.ae, Qing Kong When the relative density of the mud is too high, replace the slurry in the hole to ensure that the sand content of the mud is less than 2%; af, hanging steel cage Use a truck crane to lift the steel cage frame that has been welded in sections in advance into the hole and weld it into a whole. Use steel pipes to build a cross frame to fix the top of the steel cage frame and press heavy objects on it. ag, install concrete pipe and pour into form cast-in-place piles Install the concrete pipe and pour underwater concrete into it. During the pouring process, control the speed of concrete into the concrete pipe. Keep the buried depth of the concrete pipe at 2-6m and the slump of the concrete at 18-22m to form a cast-in-place pile. ah, pile finished product inspection and acceptance After the bored concrete pouring is completed, the pile axis center and pile top elevation are re-measured; after the concrete strength reaches the design requirements, the concrete uniformity and bearing capacity of the pile body are tested.

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