Construction method of fiber-reinforced curing agent mixing piles suitable for silt foundation pit support

Abstract

This invention relates to the technical field of silt foundation pit support, and discloses a construction method for fiber-reinforced curing agent mixing piles applicable to silt foundation pit support, including the following construction steps: 1) Leveling the construction site and determining the pile positions for the mixing piles; 2) Preparing the fiber-reinforced curing agent, which is a mixture of cement, mineral powder, fly ash, gypsum, polyvinyl alcohol short fibers, and water; 3) Using the mixing drill rod of the grouting pile machine, drilling downwards into the soil at the pile position, while the mixing drill rod drills into the soil layer, the grouting pipe simultaneously sprays the fiber-reinforced curing agent into the soil layer until the mixing drill rod reaches the set depth, and then lifting the mixing drill rod upwards to the set height; while the mixing drill rod is lifted upwards into the soil layer, the mixing drill rod simultaneously drills into the soil layer, and the grouting nozzle of the grouting pipe simultaneously sprays the fiber-reinforced curing agent into the soil layer; 4) Repeating construction step 3) to the set number of times, the fiber-reinforced curing agent mixes with the soil to form a mixing pile.

Description

Technical Field

[0001] This invention patent relates to the technical field of silt foundation pit support, and more specifically, to a construction method for fiber-reinforced curing agent mixing piles applicable to silt foundation pit support. Background Technology

[0002] With urban development, coastal and riverside areas have been extensively developed. These areas often have deep silt layers, poor bearing capacity, high water content, and are prone to deformation, which greatly complicates foundation pit construction.

[0003] In existing technologies, the following methods are commonly used for supporting silt foundation pits:

[0004] (1) Vacuum preloading method. This method is effective for shallow foundation pit excavation in silty areas and has a low cost. The disadvantage is that the construction time is relatively long and it requires long-term preloading.

[0005] (2) Steel sheet pile method. This method is faster to construct and has a lower cost. It is suitable for shallow foundation pit excavation. The disadvantage is that the steel sheet is relatively flexible and the length is relatively shallow, the foundation pit is easy to deform, the water-stopping effect is not good, and the silt will surge back through the bottom of the steel sheet pile because the steel sheet pile is relatively short.

[0006] (3) Mixing pile + anchor cable. This method is commonly used. Its advantages are convenient construction, low cost, good water-stopping effect, and suitable for shallow and medium-sized foundation pits. Its disadvantages are that cement does not solidify easily in silt, resulting in low strength, which can cause foundation pit deformation, and the anchor rods are prone to conflict with municipal road pipelines, etc.

[0007] (4) Underground continuous walls, piles, etc. are effective and suitable for deep foundation pit excavation, but the cost is relatively high. Summary of the Invention

[0008] The purpose of this invention is to provide a construction method for fiber-reinforced curing agent mixing piles suitable for silt foundation pit support, aiming to solve the problems of poor construction effect and low economic efficiency of silt foundation pit support in the prior art.

[0009] This invention is implemented as follows: a construction method for fiber-reinforced curing agent mixing piles applicable to silt foundation pit support includes the following construction steps:

[0010] 1) Level the construction site and determine the pile positions for the mixing piles;

[0011] 2) Prepare a fiber-reinforced curing agent, which is a mixture of cement, mineral powder, fly ash, gypsum, polyvinyl alcohol short fibers and water;

[0012] 3) The mixing drill rod of the grouting pile machine is used to drill into the soil at the pile position. The grouting pile machine is connected to a grouting pipe, and a grouting pump is installed on the grouting pipe. The outer end of the grouting pipe is connected to a grout storage tank, which contains a fiber-reinforced curing agent. The inner end of the grouting pipe extends to the bottom of the mixing drill rod and forms a grouting nozzle.

[0013] During the drilling process of the mixing drill rod in the soil layer, the grouting nozzle of the grouting pipe simultaneously sprays fiber-reinforced curing agent into the soil until the mixing drill rod reaches the set depth, and then lifts the mixing drill rod upward to the set height.

[0014] As the soil layer is lifted upwards, the mixing drill rod simultaneously drills and mixes the soil, and the grouting nozzle of the grouting pipe simultaneously sprays fiber-reinforced curing agent into the soil.

[0015] 4) Repeat the construction step 3) up to the set number of times, and the fiber-reinforced curing agent is mixed with the soil to form a mixing pile.

[0016] Optionally, in construction step 2), the fiber-reinforced curing agent comprises, by weight, 10%~40% cement, 30%~80% mineral powder, 10%~30% fly ash, 5%~30% gypsum and 0.5%~0.7% polyvinyl alcohol short fibers.

[0017] Optionally, in construction step 2), the cement is PO42.5 ordinary Portland cement.

[0018] Optionally, in construction step 2), the mineral powder is S95 grade or higher slag powder.

[0019] Optionally, in construction step 2), the fly ash is low-calcium grade I fly ash.

[0020] Optionally, in construction step 2), the gypsum is dehydrated desulfurized gypsum with a moisture content of less than 1%.

[0021] Optionally, in construction step 2), configuring the fiber-reinforced curing agent includes the following configuration steps:

[0022] 2.1) The cement, mineral powder, fly ash and gypsum are mixed evenly and bagged to form powder, and the polyvinyl alcohol short fibers are stored separately;

[0023] 2.2) The powder is mixed with water to form a slurry. The polyvinyl alcohol short fibers are mixed with a dispersant and then added to water for soaking and stirring to form a fiber solution.

[0024] 2.3) The fiber solution and powder are mixed and stirred to form a fluid fiber-reinforcing curing agent.

[0025] Optionally, in construction step 3), after the mixing drill rod is raised to a set height in the soil layer, the raising of the mixing drill rod is stopped, the mixing drill rod rotates in place for a set time, and during the rotation of the mixing drill rod in place, the grouting nozzle synchronously and continuously sprays fiber-reinforced curing agent into the soil.

[0026] Optionally, the outer periphery of the stirring drill rod is provided with spiral blades, which are arranged to spiral along the axial direction of the stirring drill rod. Along the axial direction of the stirring drill rod, the spiral blades enclose a spiral channel with an outer opening. The spiral channel is formed on the outer periphery of the stirring drill rod and is arranged to spiral in the same direction as the spiral blades.

[0027] The spiral blade has a bottom plate formed at the bottom of the stirring drill rod, and the bottom of the bottom plate is provided with a plurality of downwardly inclined drill teeth, which are spaced apart along the spiral direction of the bottom plate.

[0028] The bottom of the mixing drill rod extends downward to a bottom section, the bottom of which is pointed. The grouting pipe is movably built into the mixing drill rod. The bottom section has a bottom cavity, and the top of the bottom cavity is covered by a mounting plate. The bottom of the grouting pipe passes through the mounting plate, and the mounting plate closes the top of the bottom cavity.

[0029] The bottom section has a bottom spray hole at its bottom and a plurality of side spray hole groups on its side. The plurality of side spray hole groups are arranged at intervals along the circumference of the bottom section. The side spray hole groups are arranged at an angle along the axial direction of the bottom section and are opposite to the spiral direction of the spiral blade. The side spray hole group includes a plurality of side spray holes arranged at intervals along the axial direction of the bottom section.

[0030] In construction step 3), as the mixing drill rod rotates in the soil layer, the spiral blades and drill teeth respectively mix the soil, the fiber-reinforced curing agent sprayed from the grouting nozzle enters the bottom cavity, and the bottom grouting hole and multiple side grouting holes are sprayed onto the soil being mixed, mixing with the soil.

[0031] Optionally, the bottom of the bottom segment is provided with a plurality of strip-shaped bottom teeth, which are arranged at intervals around the bottom segment in the circumferential direction; the inner ends of the bottom teeth are abutted against the outer periphery of the bottom segment, and the outer ends of the bottom segment are arranged inclined upwards.

[0032] The spiral channel is provided with multiple inclined shafts, which extend along the width of the spiral channel and surround the outer periphery of the stirring drill rod. The two ends of the inclined shafts are respectively fixedly connected to the spiral blades, and the inclined shafts are inclined to the axial direction of the stirring drill rod. Multiple rotating sleeves that rotate around the outer periphery of the inclined shafts are provided, and the multiple rotating sleeves are spaced apart along the axial direction of the inclined shafts.

[0033] In construction step 3), when the mixing drill rod is rotating, multiple bottom teeth face upwards to mix the soil, and the bottom plate faces downwards to mix the soil. The bottom teeth and the bottom plate clamp and mix the soil in opposite directions. Multiple inclined shafts synchronously mix the soil placed in the spiral channel with the mixing drill rod, and multiple rotating sleeves rotate and mix the soil in the spiral channel.

[0034] Compared with existing technologies, the fiber-reinforced curing agent mixing pile construction method for silt foundation pit support provided by this invention utilizes a grouting pile machine to drill into the soil layer and simultaneously sprays the fiber-reinforced curing agent into the soil layer through a grouting pipe, so that the soil and the fiber-reinforced curing agent are mixed to form a mixing pile. In this way, the use of fiber-reinforced curing agent has the advantages of being economical and environmentally friendly, and having high strength after pile formation. The formula uses a large amount of mineral powder, fly ash, and gypsum, all of which are industrial waste or by-products. It does not require the "two grindings and one burning" in cement production, and makes reasonable resource utilization of solid waste, saving costs and reducing carbon emissions, which is beneficial to the environment.

[0035] The formula uses mineral powder and fly ash, which have a relatively low heat of hydration. The resulting voids are mostly smaller than those in cement, and the hydration products have stronger bonding strength, resulting in higher strength of the solidified soil. The addition of polyvinyl alcohol short fibers effectively hinders the expansion of microcracks and the formation of macrocracks inside the solidified soil, significantly improving the tensile, flexural, impact, and fatigue resistance of the solidified soil. Attached Figure Description

[0036] Figure 1 This is a three-dimensional schematic diagram of the bottom of the stirring drill rod provided by the present invention;

[0037] Figure 2 This is a cross-sectional schematic diagram of the bottom of the stirring drill rod provided by the present invention;

[0038] Figure 3 This is a three-dimensional schematic diagram of the bottom of the stirring drill rod provided by the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0040] The implementation of the present invention will be described in detail below with reference to specific embodiments.

[0041] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0042] Reference Figure 1-3 The image shown is a preferred embodiment of the present invention.

[0043] The present invention provides a construction method for fiber-reinforced curing agent mixing piles suitable for silt foundation pit support, comprising the following construction steps:

[0044] 1) Level the construction site and determine the pile positions for the mixing piles;

[0045] 2) Prepare the fiber-reinforced curing agent, which is a mixture of cement, mineral powder, fly ash, gypsum, polyvinyl alcohol short fibers and water.

[0046] 3) The mixing drill rod 100 of the grout jetting machine is used to drill into the mixing soil downward at the pile position. The grout jetting machine is connected to the grout jetting pipe 10, which is equipped with a grout jetting pump. The outer end of the grout jetting pipe 10 is connected to the grout storage tank, which contains fiber-reinforced curing agent. The inner end of the grout jetting pipe 10 extends to the bottom of the mixing drill rod 100 and forms a grout jetting nozzle.

[0047] During the drilling process of the mixing drill rod 100 in the soil layer, the grouting nozzle of the grouting pipe 10 synchronously sprays fiber-reinforced curing agent into the soil until the mixing drill rod 100 drills to the set depth, and then lifts the mixing drill rod 100 upward to the set height.

[0048] As the soil layer is lifted upwards, the mixing drill rod 100 simultaneously drills and mixes the soil, and the grouting nozzle of the grouting pipe 10 simultaneously sprays fiber-reinforced curing agent into the soil.

[0049] 4) Repeat construction step 3) up to the set number of times to mix the fiber-reinforced curing agent with the soil to form a mixing pile.

[0050] The fiber-reinforced curing agent mixing pile construction method for silt foundation pit support provided above involves drilling into the soil layer using a grouting pile machine and simultaneously spraying the fiber-reinforced curing agent into the soil layer through the grouting pipe 10, so that the soil and the fiber-reinforced curing agent are mixed to form a mixing pile. In this way, the use of fiber-reinforced curing agent has the advantages of being economical and environmentally friendly, and having high strength after pile formation. The formula uses a large amount of mineral powder, fly ash and gypsum, all of which are industrial waste or by-products. It does not require the "two grinding and one burning" process in cement production, and makes reasonable resource utilization of solid waste, saving costs and reducing carbon emissions, which is beneficial to the environment.

[0051] The formula uses mineral powder and fly ash, which have a relatively low heat of hydration. The resulting voids are mostly smaller than those in cement, and the hydration products have stronger bonding strength, resulting in higher strength of the solidified soil. The addition of polyvinyl alcohol short fibers effectively hinders the expansion of microcracks and the formation of macrocracks inside the solidified soil, significantly improving the tensile, flexural, impact, and fatigue resistance of the solidified soil.

[0052] Furthermore, it reduces the amount of mixing pile work. Traditional cement-soil mixing piles have poor bending resistance and usually require the formation of a grid-like gravity retaining wall as a support structure. Fiber-reinforced composite curing agents have high tensile and bending resistance and fewer cracks, which are exactly what gravity retaining walls require. Using fiber-reinforced composite curing agents can significantly reduce the amount of mixing pile work, save material usage, and shorten the construction period and cost.

[0053] Specifically, in construction step 2), the fiber-reinforced curing agent, by weight composition, includes 10%~40% cement, 30%~80% mineral powder, 10%~30% fly ash, 5%~30% gypsum, and 0.5%~0.7% polyvinyl alcohol short fibers.

[0054] Specifically, in construction step 2), the cement is PO42.5 ordinary Portland cement.

[0055] Specifically, in construction step 2), the mineral powder is S95 grade or higher slag powder.

[0056] Specifically, in construction step 2), the fly ash is low-calcium grade I fly ash.

[0057] Specifically, in construction step 2), the gypsum is desulfurized gypsum with a moisture content of less than 1% after dehydration.

[0058] Specifically, in construction step 2), the preparation of the fiber-reinforced curing agent includes the following preparation steps:

[0059] 2.1) Mix cement, mineral powder, fly ash, and gypsum evenly and pack them into bags to form powder. Store polyvinyl alcohol short fibers separately.

[0060] 2.2) Mix the powder with water to form a slurry, mix the polyvinyl alcohol short fibers with a dispersant, and then add water to soak and stir to form a fiber solution;

[0061] 2.3) Mix the fiber solution with the powder to form a fluid fiber-reinforced curing agent.

[0062] Specifically, in construction step 3), after the mixing drill rod 100 is raised to the set height in the soil layer, the raising of the mixing drill rod 100 is stopped, and the mixing drill rod 100 is rotated in place for a set time. During the rotation of the mixing drill rod 100 in place, the grouting nozzle continuously sprays fiber-reinforced curing agent into the soil simultaneously. This ensures that the pile head is uniformly dense.

[0063] The outer periphery of the stirring drill rod 100 is provided with a spiral blade 200. The spiral blade 200 is arranged in a spiral arrangement along the axial direction of the stirring drill rod 100. Along the axial direction of the stirring drill rod 100, the spiral blade 200 surrounds and forms a spiral channel with an outer opening. The spiral channel is formed on the outer periphery of the stirring drill rod 100 and is arranged in the same direction as the spiral blade 200.

[0064] The spiral blade 200 has a bottom plate formed at the bottom of the stirring drill rod 100. The bottom of the bottom plate is provided with a plurality of downwardly inclined drill teeth 210, which are spaced apart along the spiral direction of the bottom plate.

[0065] The bottom of the mixing drill rod 100 extends downward to form a bottom section with a pointed bottom. The grouting pipe 10 is movably built into the mixing drill rod 100. The bottom section has a bottom cavity 103. The top of the bottom cavity 103 is covered by a mounting plate 300. The bottom of the grouting pipe 10 is fixedly passed through the mounting plate 300. The mounting plate 300 closes the top of the bottom cavity 103.

[0066] The bottom section is provided with a bottom spray hole 101, and the side of the bottom section is provided with a plurality of side spray holes 102 groups. The plurality of side spray holes 102 groups are arranged at intervals along the circumference of the bottom section. The side spray holes 102 groups are arranged obliquely along the axial direction of the bottom section and opposite to the spiral direction of the spiral blade 200. The side spray holes 102 groups include a plurality of side spray holes 102 arranged at intervals along the axial direction of the bottom section.

[0067] In construction step 3), as the mixing drill rod 100 rotates in the soil layer, the spiral blade 200 and drill teeth 210 respectively mix the soil. The fiber-reinforced curing agent sprayed from the grouting nozzle enters the bottom cavity 103, and is sprayed into the soil being mixed through the bottom grouting hole 101 and multiple side grouting holes 102, mixing with the soil. In this way, the soil is mixed by the drill teeth 210 and spiral blade 200, and the fiber-reinforced curing agent is sprayed through the side grouting holes 102 and bottom grouting holes, so that the fiber-reinforced curing agent is evenly mixed with the soil. Furthermore, the grouting pipe 10 can be effectively fixed by the mounting plate 300 to prevent the grouting pipe 10 from shifting and causing low grouting efficiency.

[0068] In this embodiment, the bottom of the bottom segment is provided with a plurality of strip-shaped bottom teeth 110, which are arranged around the bottom segment at intervals in the circumferential direction; the inner ends of the bottom teeth 110 are connected to the outer periphery of the bottom segment, and the outer ends of the bottom segment are arranged inclined upwards.

[0069] Multiple inclined shafts 220 are provided in the spiral channel, and the inclined shafts 220 extend along the width direction of the spiral channel. The multiple inclined shafts 220 are arranged around the outer periphery of the stirring drill rod 100. The two ends of the inclined shafts 220 are respectively fixedly connected to the spiral blades 200, and the inclined shafts 220 are inclined to the axial direction of the stirring drill rod 100. Multiple rotating sleeves 230 are sleeved around the outer periphery of the inclined shafts 220, and the multiple rotating sleeves 230 are arranged at intervals along the axial direction of the inclined shafts 220.

[0070] In construction step 3), as the mixing drill rod 100 rotates, multiple bottom teeth 110 face upwards to mix the soil, while the bottom plate faces downwards to mix the soil, with the bottom teeth 110 and the bottom plate clamping and mixing the soil in opposite directions. Multiple inclined shafts 220 simultaneously mix the soil placed in the spiral channel along with the mixing drill rod 100, and multiple rotating sleeves 230 rotate and mix the soil in the spiral channel. Thus, during the rotation of the mixing drill rod 100, the inclined shafts 220 can mix the soil around the mixing drill rod 100 and the fiber-reinforced curing agent, and the rotating sleeves 230 can simultaneously mix the surrounding soil and the fiber-reinforced curing agent, promoting uniform and dense mixing and ensuring the quality of the pile formation.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction method for fiber-reinforced curing agent mixing piles applicable to silt foundation pit support, characterized in that, The construction steps include the following: 1) Level the construction site and determine the pile positions for the mixing piles; 2) Prepare a fiber-reinforced curing agent, which is a mixture of cement, mineral powder, fly ash, gypsum, polyvinyl alcohol short fibers and water; 3) The mixing drill rod of the grouting pile machine is used to drill into the soil at the pile position. The grouting pile machine is connected to a grouting pipe, and a grouting pump is installed on the grouting pipe. The outer end of the grouting pipe is connected to a grout storage tank, which contains a fiber-reinforced curing agent. The inner end of the grouting pipe extends to the bottom of the mixing drill rod and forms a grouting nozzle. During the drilling process of the mixing drill rod in the soil layer, the grouting nozzle of the grouting pipe simultaneously sprays fiber-reinforced curing agent into the soil until the mixing drill rod reaches the set depth, and then lifts the mixing drill rod upward to the set height. As the soil layer is lifted upwards, the mixing drill rod simultaneously drills and mixes the soil, and the grouting nozzle of the grouting pipe simultaneously sprays fiber-reinforced curing agent into the soil. 4) Repeat construction step 3) up to the set number of times, and the fiber-reinforced curing agent is mixed with the soil to form a mixing pile; In construction step 2), the fiber-reinforced curing agent, by weight composition, comprises 10%~40% cement, 30%~80% mineral powder, 10%~30% fly ash, 5%~30% gypsum and 0.5%~0.7% polyvinyl alcohol short fibers. In construction step 2), the preparation of the fiber-reinforced curing agent includes the following preparation steps: 2.1) The cement, mineral powder, fly ash and gypsum are mixed evenly and bagged to form powder, and the polyvinyl alcohol short fibers are stored separately; 2.2) The powder is mixed with water to form a slurry. The polyvinyl alcohol short fibers are mixed with a dispersant and then added to water for soaking and stirring to form a fiber solution. 2.3) The fiber solution is mixed and stirred with the powder to form a fluid fiber-reinforcing curing agent; The outer periphery of the stirring drill rod is provided with spiral blades, which are arranged to spiral along the axial direction of the stirring drill rod. Along the axial direction of the stirring drill rod, the spiral blades enclose and form a spiral channel with an outer opening. The spiral channel is formed on the outer periphery of the stirring drill rod and is arranged to spiral in the same direction as the spiral blades. The spiral blade has a bottom plate formed at the bottom of the stirring drill rod, and the bottom of the bottom plate is provided with a plurality of downwardly inclined drill teeth, which are spaced apart along the spiral direction of the bottom plate. The bottom of the mixing drill rod extends downward to a bottom section, the bottom of which is pointed. The grouting pipe is movably built into the mixing drill rod. The bottom section has a bottom cavity, and the top of the bottom cavity is covered by a mounting plate. The bottom of the grouting pipe passes through the mounting plate, and the mounting plate closes the top of the bottom cavity. The bottom section has a bottom spray hole at its bottom and a plurality of side spray hole groups on its side. The plurality of side spray hole groups are arranged at intervals along the circumference of the bottom section and are arranged at an incline along the axial direction of the bottom section. The side spray hole groups include a plurality of side spray holes arranged at intervals along the axial direction of the bottom section. In construction step 3), as the mixing drill rod rotates in the soil layer, the spiral blades and drill teeth respectively mix the soil, and the fiber-reinforced curing agent sprayed from the grouting nozzle enters the bottom cavity, and the bottom grouting hole and multiple side grouting holes spray onto the soil being mixed and stirred. The bottom section has multiple strip-shaped bottom teeth, which are arranged at intervals around the bottom section in the circumferential direction; the inner ends of the bottom teeth are connected to the outer periphery of the bottom section, and the outer ends of the bottom section are arranged inclined upwards. The spiral channel is provided with multiple inclined shafts, which extend along the width of the spiral channel and surround the outer periphery of the stirring drill rod. The two ends of the inclined shafts are respectively fixedly connected to the spiral blades, and the inclined shafts are inclined to the axial direction of the stirring drill rod. Multiple rotating sleeves that rotate around the outer periphery of the inclined shafts are provided, and the multiple rotating sleeves are spaced apart along the axial direction of the inclined shafts. In construction step 3), when the mixing drill rod is rotating, multiple bottom teeth face upwards to mix the soil, and the bottom plate faces downwards to mix the soil. The bottom teeth and the bottom plate clamp and mix the soil in opposite directions. Multiple inclined shafts synchronously mix the soil placed in the spiral channel with the mixing drill rod, and multiple rotating sleeves rotate and mix the soil in the spiral channel.

2. The construction method of fiber-reinforced curing agent mixing piles for silt foundation pit support as described in claim 1, characterized in that, In construction step 2), the cement is PO42.5 ordinary Portland cement.

3. The construction method for fiber-reinforced curing agent mixing piles applicable to silt foundation pit support as described in claim 1, characterized in that, In construction step 2), the mineral powder is S95 grade or higher slag powder.

4. The construction method of fiber-reinforced curing agent mixing piles for silt foundation pit support as described in claim 1, characterized in that, In construction step 2), the fly ash is low-calcium grade I fly ash.

5. The construction method for fiber-reinforced curing agent mixing piles applicable to silt foundation pit support as described in claim 1, characterized in that, In construction step 2), the gypsum is dehydrated desulfurized gypsum with a water content of less than 1%.

6. The construction method for fiber-reinforced curing agent mixing piles applicable to silt foundation pit support as described in any one of claims 1 to 5, characterized in that, In construction step 3), after the mixing drill rod is raised to a set height in the soil layer, the raising of the mixing drill rod is stopped. The mixing drill rod rotates in place for a set time. During the rotation of the mixing drill rod in place, the grouting nozzle continuously sprays fiber-reinforced curing agent into the soil.

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