Miniature steel pipe pile embankment landslide reinforcing structure and construction method thereof

Abstract

The invention provides a miniature steel pipe pile embankment landslide reinforcing structure and a construction method thereof. The anti-sliding effect of the miniature steel pipe piles is introduced into a landslide broken line sliding method, reasonable design calculation is provided for the miniature steel pipe piles to solve the side slope problem, the sliding force and the anti-sliding force of the landslide mass above the miniature steel pipe piles are calculated, and after reinforcement of the miniature steel pipe piles, the treated side slope reaches the stable state, and the anti-sliding effect of the miniature steel pipe piles is improved. Parameter indexes such as the wall thickness, the pore-forming diameter, the row number and the spacing of the miniature steel pipe are determined. On the premise of not influencing normal traffic of vehicles on an embankment road above the landslide mass, a proper position is selected on the landslide mass, and the micro steel pipe piles are constructed. The patent achievement of the method can be directly used for guiding engineering practice, the miniature steel pipe pile structure is convenient to construct and small in slope disturbance, and the method has wide application prospects in various slope reinforcement and landslide control in the future and has remarkable economic benefits and social benefits.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, in particular to a micro steel pipe pile embankment landslide reinforcement structure and a construction method thereof, aiming to improve the stability and safety of the embankment slope. Background Art

[0002] The stability of embankment slopes is a key factor in road safety and smooth traffic. In the field of road engineering, the reinforcement of embankment slopes has always been an important and complex issue. Although traditional reinforcement methods, such as soil nail walls and anti-slide piles, can enhance the stability of slopes to a certain extent, these methods often have shortcomings such as complex construction, high costs, and limited reinforcement effects. Especially under complex geological conditions, the limitations of traditional reinforcement methods are particularly prominent, and it is difficult to meet the comprehensive requirements of modern road engineering for slope stability, safety, and economy.

[0003] In view of the limitations of traditional reinforcement methods, the industry has been exploring new slope reinforcement technologies that are more efficient, economical and have significant reinforcement effects. Micro steel pipe pile technology has emerged as the times require. It cleverly combines the grouting method with the micro pile method. By closely combining the micro pile with the grouting body, a new type of reinforcement structure is formed, which can reinforce a part of the sliding body in the landslide into an anti-sliding body, thereby achieving the purpose of effectively controlling the landslide. Micro steel pipe piles have the following advantages and characteristics:

[0004] (1) The micro steel pipe and the cement slurry around it together form a solid micro pile. Multiple micro piles are densely distributed on the sliding body, penetrate the sliding surface and embed into the sliding bedrock to form anchor piles, which have a strong supporting effect on the sliding body and significantly increase the anti-sliding force.

[0005] (2) When the slurry solidifies, its cohesiveness and water absorption can tightly bond the sliding body and the immovable body together to form a diffuse complex. This complex can improve the properties of the sliding zone soil, increase the cohesion and internal friction angle of the soil, thereby increasing the frictional resistance and improving the anti-sliding performance of the rock and soil at the sliding surface.

[0006] (3) The filling and compaction of cement paste can increase the density of rock and soil, reduce porosity, and lower the permeability coefficient. This not only reduces the infiltration of surface water, but also improves the overall stability of the sliding body.

[0007] (4) Micro steel pipe piles can not only reinforce the rock and soil around the piles and improve their lateral resistance, but also reinforce the landslide body, sliding belt and stable rock and soil under the sliding bed around the steel pipes through grouting. This all-round reinforcement effect makes the micro steel pipe piles and the surrounding sliding body, sliding belt and rock and soil under the sliding bed form a solid anti-sliding whole, thereby significantly improving the stability of the slope.

[0008] Although micro steel pipe piles have shown significant advantages in landslide control, their design and calculation system still needs to be further improved. Before using micro steel pipe piles for landslide control construction, it is crucial to determine a series of key parameters, including the diameter of the steel pipe, the wall thickness of the steel pipe, the spacing between piles, and the number of piles. These parameters not only directly affect the effect of landslide control, but also affect the construction cost and safety. In the prior art, no research has been conducted on the parameter design and calculation of micro steel pipe piles. Moreover, during the construction of micro steel pipe piles, how to determine the construction position of micro steel pipe piles, establish a construction platform, and ensure that grouting operations are carried out quickly and effectively is also an urgent problem to be solved. This requires the construction method to be both efficient and to ensure that it does not affect the normal passage of the embankment road. At the same time, it also needs to be able to effectively improve the safety and stability of the embankment part.

[0009] In addition, the traditional micro steel pipe pile adopts an integral steel pipe structure, the bottom end of which is set as a conical closed end, and holes are chiseled on the side wall of the steel pipe. When grouting, the slurry is injected under high pressure from the upper port of the micro steel pipe pile and enters the gap between the steel pipe and the drilled hole through the holes in the steel pipe. Since the steel pipe is made of high-strength steel through curling, welding and other processes, its internal structure is tight and uniform, and it can withstand greater pressure and tension. During the manufacturing process of the existing steel pipe piles, it is necessary to make local cutting or drilling on the steel pipe wall, which will inevitably lead to the destruction of the material continuity of the pipe wall in this area, forming stress concentration points. These stress concentration points are more likely to become the starting point for crack initiation and expansion when subjected to external forces, that is, during the grouting process, thereby reducing the overall bearing capacity of the steel pipe; moreover, chiseling holes may also cause local corrosion of the steel pipe; during the grouting process, the chemical components in the slurry may react with the steel pipe material, especially at the edge of the hole. Due to the destruction of the material structure and the increase in surface area, this reaction may be more intense. In the long run, this may cause corrosion of the steel pipe wall around the hole, further weakening the strength of the steel pipe. Secondly, the quality of the eyelet chiseling process also directly affects the strength and durability of the steel pipe. If the eyelet chiseling process is improper, it may cause damage to the original structure of the steel pipe. For example, the size, shape, and distribution of the eyelets are uneven, or the burrs, cracks and other defects generated during the chiseling process are not effectively dealt with, which will have an adverse effect on the mechanical properties of the steel pipe, and then have an adverse effect on its overall strength; these defects may lead to uneven stress distribution when subjected to force, and accelerate fatigue damage of the steel pipe. Summary of the invention

[0010] In response to some problems existing in the prior art, the present application provides a micro steel pipe pile embankment landslide reinforcement structure and a construction method thereof. The reinforcement structure adopts micro steel pipe piles, and the steel pipe piles do not need to be drilled to carry out efficient grouting, thereby avoiding the impact of drilling on the overall strength of the steel pipe and the fatigue damage caused by it. The present application also proposes an analysis method for the reinforcement mechanism of micro steel pipe piles, and derives the technical parameters required for the design of micro steel pipe piles, which can be directly used to guide engineering practice, thereby reducing construction costs while ensuring the landslide reinforcement effect.

[0011] The purpose of the present invention is to address the above-mentioned problems existing in the prior art and provide a micro steel pipe pile embankment landslide reinforcement structure, including an embankment slope, the reinforcement structure including a working platform constructed in the middle of the embankment slope and a plurality of micro steel pipe piles arranged on the working platform, the working platform being a construction platform formed by excavating the slope surface above the platform and filling the slope surface below the platform in the middle of the embankment slope; the bottom of each micro steel pipe pile extends to at least 2 / 5 of the length of the micro steel pipe pile body below the sliding surface of the embankment slope, the pile top of the micro steel pipe pile is located on the working platform, and the pile tops of the plurality of micro steel pipe piles are connected as a whole by a crown beam; after the construction of the micro steel pipe piles is completed, the embankment slope above the working platform is backfilled to the slope of the original slope;

[0012] The micro steel pipe pile includes a pile body borehole, a steel pipe body and a grouting reinforcement body cast in the steel pipe body and between the steel pipe body and the pile body borehole. The steel pipe body is a hollow pipe structure, and a pipe bottom bracket is provided at the bottom of the steel pipe body; the steel pipe body is placed in the pile body borehole, and a sealing structure is provided between the hole opening of the pile body borehole and the steel pipe body, and an exhaust pipe is provided at the sealing structure. The bottom of the steel pipe body contacts the bottom surface of the pile body borehole through the pipe bottom bracket, and a grouting channel is formed between the bottom surface of the steel pipe body and the pile body borehole; a grouting hose is inserted into the steel pipe body, and the grouting hose extends from the upper pipe opening of the steel pipe body to the bottom of the steel pipe body, and extends into the bottom of the pile body borehole through the grouting channel.

[0013] The preferred technical solution of the present invention is as follows: a drainage ditch is arranged at the top of the embankment slope, and the drainage ditch is located at the edge of the road surface adjacent to the embankment slope; a drainage ditch is arranged at the bottom of the embankment slope; the working platform has a width of 4m to 6m, and is composed of excavation inside the slope and backfilling outside the slope.

[0014] The preferred technical solution of the present invention is as follows: the diameter of the pile body drilling hole is 150-250mm, and the diameter of the steel pipe body is at least 50mm smaller than the diameter of the pile body drilling hole; the steel pipe body is a pipe body structure formed by connecting multiple sections of steel pipes through sleeves, the steel pipe body is inserted into the central axis of the pile body drilling hole, and supporting ear bars are arranged at intervals on both sides of the steel pipe body; the pipe bottom bracket includes two groups of symmetrically arranged U-shaped steel bars, and their openings are welded to the lower pipe mouth of the steel pipe body as a whole.

[0015] The preferred technical solution of the present invention is as follows: the sealing structure uses cement soil to seal the hole within the range of 0.8 to 1.2 soil layers below the surface of the pile body borehole, and an exhaust pipe is inserted during the sealing process, the upper end of the exhaust pipe extends out of the pile body borehole, and the lower end passes through the sealing structure and extends into the pile body borehole; the grouting reinforcement body is a cement slurry reinforcement structure formed by high-pressure grouting through a grouting hose.

[0016] The preferred technical solution of the present invention is as follows: the cross-sectional width of the crown beam is at least 0.1m on both sides of the micro steel pipe pile, and the height is not less than 0.5m. The crown beam is a reinforced concrete structure, with double-layer bidirectional steel bars arranged up and down inside, and frame bars are provided.

[0017] In order to achieve the above technical purpose, the present invention provides a construction method of the above micro steel pipe pile embankment landslide reinforcement structure, and the specific steps are as follows:

[0018] S1. Determine the sliding surface of the embankment slope through geological survey, and calculate the anti-sliding safety stability coefficient F of the embankment slope before treatment based on the broken line sliding method s The calculated anti-sliding force safety stability factor F of the embankment slope before treatment s The value is consistent with the design anti-slip force safety stability factor F that meets the anti-slip requirements. s 'Values ​​are compared in F s Less than F s 'When choosing to use micro steel pipe pile reinforcement structure to reinforce the embankment slope;

[0019] S2. Construct a working platform in the middle of the embankment slope, determine the boundary line of the working platform, excavate and trim the upper and lower slopes of the working platform, level the construction working platform, and backfill the excavated soil on the upper part of the construction working platform to the lower part of the working platform;

[0020] S3. Micro steel pipe piles are constructed on the working platform to reinforce the embankment slope. After the embankment slope is reinforced with micro steel pipe piles, the stability safety factor of the slope increases, which means that the anti-sliding force acting on the slope increases on the original basis. On the basis of the actual anti-sliding force of the embankment slope in step S1, the micro steel pipe piles provide an increased part of the anti-sliding force; based on the above-mentioned broken line sliding method, the calculation expression of the reinforcement effect of micro steel pipe piles on the slope is obtained:

[0021]

[0022] Where: F′ s —Safety and stability coefficient of the design anti-slip force that meets the anti-slip requirements

[0023] m—the number of sliding blocks on the slope above the working platform; j —transfer coefficient;

[0024] Ri —Anti-sliding force of any i-th slope sliding body strip, kN / m;

[0025] R m —The anti-sliding force of the mth slope sliding body strip, kN / m;

[0026] T m —The sliding force of the mth slope sliding body strip, kN / m;

[0027] T i —The sliding force of any i-th slope sliding body strip, kN / m;

[0028] τ1—design value of shear strength of slurry in micro steel pipe pile;

[0029] τ2—the design value of shear strength of the steel tube body in the micro steel tube pile;

[0030] d—diameter of micro steel pipe pile, i.e. the diameter of the hole in the pile body;

[0031] d1—outer diameter of the steel pipe body in the micro steel pipe pile;

[0032] d2—inner diameter of the steel tube in the micro steel tube pile;

[0033] Calculate the sliding force and anti-sliding force of the slope per meter of the slope. Introduce the concept of the number of micro-steel pipe piles N and the spacing S of the micro-steel pipe piles in formula ①. The influence of the number of micro-steel pipe piles N and the spacing S of the micro-steel pipe piles on the anti-sliding force of the piles is as follows:

[0034]

[0035] Where: N—number of rows of micro steel pipe piles;

[0036] S—spacing of micro steel pipe piles;

[0037] S4. According to the requirements of the construction site, select the micro steel pipe pile material that meets the construction requirements. The pile diameter of the micro steel pipe pile is controlled at 150-250mm, and the diameter of the steel pipe body in the micro steel pipe pile is at least 50mm smaller than the diameter of the micro steel pipe pile; the grouting reinforcement of the micro steel pipe pile adopts cement mortar with a label of M10-M30 and a water-cement ratio of 0.4-0.55; and substitute the selected micro steel pipe pile parameters into the formula ② in step S3 to calculate the ratio of the number of rows N of micro steel pipe piles and the spacing S of micro steel pipe piles, and determine the number of rows N of micro steel pipe piles and the spacing S of micro steel pipe piles according to the calculated ratio and the requirements of the construction site; and the bottom of each micro steel pipe pile extends to at least 2 / 5 of the length of the micro steel pipe pile body below the sliding surface of the embankment slope;

[0038] S5. After determining the construction parameters of the micro steel pipe pile, a small drilling rig is used to drill a hole in the pile body on a working platform. The drilling rig is moved so that the center of the drill tool is roughly aligned with the center of the casing. The drill bit is lifted and the drilling rig is moved so that the center of the drill bit is aligned with the pile position.

[0039] S6. After the pile body drilling construction is completed, the steel pipe body is inserted into the center, and ear bars are welded to the steel pipe body at a certain interval. The steel pipe body and the bottom of the pile body drilling hole are suspended by a pipe bottom bracket, and the steel pipe bodies are connected by sleeves. Cement soil is used to seal the hole in the soil layer within 0.8 to 1.2 m below the surface of the pile body drilling hole. At the same time, an exhaust pipe is inserted. After the cement soil sealing hole has a certain strength, a grouting hose is inserted into the steel pipe body, and high-pressure grouting is injected into the steel pipe body and the pile body drilling hole;

[0040] S7. After all the micro steel pipe piles are constructed according to steps S5 and S6 and cured, a crown beam is constructed on the top of all the micro steel pipe piles to connect all the micro steel pipe piles together;

[0041] S8. After the construction of the crown beam on the top of the micro steel pipe pile is completed, the upper and lower slopes of the working platform are trimmed to restore the slope gradient to the state before construction; and drainage ditches on the top of the slope and drainage ditches at the bottom of the slope are set.

[0042] A further technical solution of the present invention: the actual anti-sliding force safety stability coefficient F of the embankment slope in step S1 s The value calculation process is as follows:

[0043]

[0044] Where: F s —The anti-sliding safety stability factor Fs value of the embankment slope before treatment;

[0045] θ i —the bottom inclination angle of the i-th slope sliding block, °;

[0046] n—the number of vertical soil strips into which the soil above the sliding surface of the embankment slope is divided by the strip division method, that is, the total number of slope sliding body strips;

[0047] R n —The anti-sliding force of the nth slope sliding body strip, kN / m;

[0048] N n —normal component of the nth slope sliding body strip, kN / m;

[0049] N i —normal component of any i-th slope sliding body strip, kN / m;

[0050] —Internal friction of the strip sliding zone of any i-th slope sliding body, °;

[0051] c i —cohesion of rock and soil on the sliding surface of any i-th slope sliding body strip, kPa;

[0052] l i —The length of the sliding surface of any i-th slope sliding body strip, m;

[0053] T i —The sliding force of any i-th sliding block on the slope, kN / m;

[0054] The parameters in the above calculation formula are the shear strength index of the unreinforced landslide rock and soil obtained from drilling and geological surveys, and the depth of the sliding surface. The stability safety factor Fs, anti-sliding force and sliding force of the unreinforced slope are calculated. The anti-sliding force and sliding force of each block can also be calculated through the Lizheng Geotechnical Commercial Software.

[0055] A further technical solution of the present invention is as follows: In step S3, based on the actual anti-sliding force of the embankment slope in step S1, the micro steel pipe piles provide an additional part of the anti-sliding force, and the design anti-sliding force safety stability factor F that meets the anti-sliding requirements is s The value calculation formula is as follows:

[0056]

[0057] Where: P—anti-sliding force provided by micro steel pipe piles to the slope;

[0058] The shear force that the micro steel pipe pile can withstand is calculated by the stress of the micro steel pipe pile, as shown in formula ⑦:

[0059]

[0060] Where: P 浆体 —The anti-sliding force provided by the slurry in the micro steel pipe piles to the embankment slope;

[0061] P 钢管 —The anti-sliding force provided by the steel tube body in the micro steel tube pile to the embankment slope;

[0062] Based on the above-mentioned broken line sliding method, substitute formula ⑦ into formula ⑥ to obtain formula ① in step S3.

[0063] The preferred technical solution of the present invention is as follows: in step S2, the width of the construction work platform is 4m to 5m, consisting of half of the width excavated inside the slope and half of the width backfilled outside the slope; in step S4, the design value of the slurry shear strength, the design value of the steel pipe shear strength, the diameter of the micropile, the outer diameter of the steel pipe, and the inner diameter of the steel pipe are determined according to the specifications and the commonly used steel pipe sizes on the market; in step S4, the micropile construction adopts the method of skipping hole construction, intermittent construction and increasing the dosage of the accelerating agent to prevent perforation and large-scale loss of slurry along the sand layer.

[0064] The preferred technical solution of the present invention: In step S6, the deviation of the micro steel pipe pile position should be controlled within 20mm, and the verticality deviation of the straight pile should not be greater than 1%. The micro steel pipe pile drilling machine has a hole inclination of less than 1%, a hole depth error of less than 50mm, and a pile diameter error of less than 10mm; three ear bars are welded along the circumference of the steel pipe at intervals of 2 to 3m, three lines form 120°, and the diameter of the ear bars is 8 to 10mm; the bottom of the pipe is welded to the bottom bracket of the pipe to extend by 25 to 30cm, and the diameter of the steel bar is 12 to 18mm; the exhaust pipe is L=1200~1500mmPVC; the high-pressure grouting slurry adopts PO42.5 ordinary silica cement mortar, with a grade of M10~M30, a water-cement ratio of 0.4~0.55, a cement-sand ratio of 1:1~1:3, and the grouting pressure is controlled at 1.5~2.5MPa; in step S7, the cross-sectional size width of the crown beam is 0.1m on both sides of the micro steel pipe pile, and the height is not less than 0.5m. Double-layer bidirectional steel bars of different diameters are arranged on the upper and lower parts of the crown beam, and frame bars are set, molds are made, and concrete is poured. The curing time is not less than 14 days.

[0065] The patent results of this invention can be directly used to guide engineering practice, and provide a more reasonable design calculation for micro steel pipe piles to deal with slope problems. The micro steel pipe pile structure is easy to construct and has little disturbance to the slope. It has broad application prospects in various slope reinforcement and landslide control in the future, and has significant economic and social benefits.

[0066] The micro steel pipe piles in the present invention are flexible in arrangement, have strong adaptability to the strata, can be used alone without additional auxiliary facilities, and further simplify the construction process; the micro steel pipe piles have economic and efficient structural advantages, low cost, good economy, and their reinforcement effect is similar to that of soil nail walls, but with higher cost performance. The micro piles can be embedded in the stable soil layer below the potential sliding surface to a sufficient depth, just like driving a wedge between the sliding body and the sliding bed, and have strong shear resistance, showing a reinforcement effect equivalent to that of general anti-sliding piles.

[0067] The beneficial effects of the present invention are as follows:

[0068] (1) The present invention uses a micro steel pipe pile reinforcement structure to reinforce the embankment slope. According to the characteristics of the embankment slope, it is proposed to construct micro steel pipe piles at a suitable position in the middle of the landslide, and by designing a construction platform, micro equipment is used to construct the steel pipe piles. The embankment slope can be reinforced to prevent slipping without affecting the normal traffic of the landslide embankment road. The entire construction method is convenient and safe, and the required construction site is small, which is particularly suitable for scenes where traditional anti-skid methods are difficult to implement or the cost is high. The construction process does not require large-scale excavation, avoiding the formation of a large open surface, thereby accelerating the construction progress and improving construction safety.

[0069] (2) The present invention improves the structure of the micro steel pipe, adopts ordinary steel pipe, and welds a special bottom bracket to the bottom of the steel pipe. After the steel pipe is installed in the predetermined borehole, the bottom bracket will play a key supporting role, so that the bottom of the steel pipe and the bottom of the borehole maintain a certain overhead distance. This overhead design effectively avoids the bottom of the steel pipe directly touching the bottom of the hole, thereby eliminating the difficulty of grouting caused by close contact; the structural improvement of the steel pipe pile avoids drilling holes in the steel pipe structure, and there is no need to perform any form of drilling or cutting on the steel pipe, which saves the construction difficulty of the steel pipe pile, reduces the construction cost and time cost, protects the original structure of the steel pipe, avoids damage to the structural integrity of the steel pipe, thereby reducing its bearing capacity and extending the service life of the steel pipe pile; and ensures the efficiency and safety of the grouting process.

[0070] (3) The present invention can construct a spatial frame structure by arranging a connecting beam on the top of the micro steel pipe pile, and together with the soil between the piles, form a composite retaining wall to effectively support the soil behind; the micro steel pipe pile can achieve the effect of crack control and slope stability, and the use of the connecting beam on the pile top makes the connection between each micro steel pipe pile and the rock and soil between the piles tighter, forming an integrated reinforcement system; this integrated reinforcement can effectively control the formation and expansion of tensile cracks in the reinforced area on the slope surface, thereby reducing the adverse effects of tensile crack filling water on slope stability.

[0071] (4) The bottom bracket of the micro steel pipe pile in the present invention is made of high-strength, corrosion-resistant material, and its shape and size are precisely calculated to ensure that it can fit tightly to the bottom of the steel pipe and has a certain load-bearing capacity. The use of the bottom bracket also makes it possible to perform pressure grouting when grouting inside and outside the steel pipe. Due to the presence of the bracket, the grouting slurry can be injected more smoothly through the steel pipe into the medium around the borehole without being affected by the resistance caused by the close contact between the bottom of the steel pipe and the bottom of the hole. This not only improves the grouting efficiency, but also ensures the uniformity and quality of the grouting.

[0072] (5) Based on the calculation of the anti-sliding force safety stability coefficient by the broken line sliding method, this application proposes an analysis method for the reinforcement mechanism of micro steel pipe piles, obtains the technical parameters required for designing micro steel pipe piles, and determines the parameter indicators such as the wall thickness, hole diameter, number of rows, and spacing of micro steel pipes. It plays an important role in guiding engineering practice through theoretical calculation results; it improves the grouting efficiency and overall force coordination of micro steel pipe piles, and can be directly used to guide engineering practice, providing a more reasonable calculation and construction method for micro steel pipe piles to deal with slope problems.

[0073] The micro steel pipe structure of the present invention is easy to construct and has little disturbance to the slope. It has the characteristics of safety, reliability, low cost, short construction period, wide range of use, etc. It has broad application prospects in various slope reinforcement and landslide control, and has significant economic and social benefits. The present invention utilizes micro steel pipe pile technology with its unique reinforcement mechanism and significant reinforcement effect to provide a new solution for the reinforcement of embankment slopes. The construction method of the present invention not only overcomes the limitations of traditional reinforcement methods, but also shows great potential in improving reinforcement efficiency, reducing costs and enhancing reinforcement effects. Through this refined reinforcement method, the present invention not only improves the overall stability of the slope, but also extends the service life of the reinforced structure, providing a strong guarantee for road safety and smooth traffic. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is a schematic diagram of the reinforcement structure of the present invention;

[0075] Figure 2 It is a schematic diagram of the internal structure of the crown beam in the present invention;

[0076] Figure 3 It is a structural schematic diagram of a micro steel pipe pile in the present invention;

[0077] Figure 4 is a schematic diagram of a micro steel pipe pile without grouting in the present invention;

[0078] Figure 5 It is a schematic diagram of the steel pipe structure of the micro steel pipe pile in the present invention;

[0079] Figure 6 It is a simplified diagram of the transfer coefficient method calculation in the present invention;

[0080] Figure 7 1 is a schematic diagram of calculation of the transfer coefficient method in an embodiment of the present invention;

[0081] Figure 8 Schematic diagram of excavation of a construction platform in the embodiment;

[0082] Fig. 9 It is the construction drawing of micro steel pipe pile in the embodiment;

[0083] Fig.10 It is the construction drawing of the crown beam in the embodiment;

[0084] Fig.11 Schematic diagram of the slope restoration in the embodiment.

[0085] In the figure: 1—micro steel pipe pile, 100—pile body drilling hole, 101—steel pipe body, 102—grouting reinforcement body, 103—tube bottom bracket, 104—grouting hose, 105—exhaust pipe, 106—sealing hole structure, 107—support ear reinforcement, 108—connecting sleeve, 2—working platform, 3—embankment slope, 4—crown beam, 400—double-layer bidirectional reinforcement, 5—intercepting ditch, 6—pavement, 7—drainage ditch, 8—backfill slope, 9—slip surface DETAILED DESCRIPTION

[0086] In order to further understand the content, features and effects of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. Figures 1 to 8 The drawings are all of embodiments, which are drawn in a simplified manner and are only used for the purpose of clearly and concisely illustrating the embodiments of the present invention. The technical solutions shown in the following drawings are specific solutions of the embodiments of the present invention and are not intended to limit the scope of the invention claimed for protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0087] A micro steel pipe pile embankment landslide reinforcement structure constructed in the embodiment is specifically as follows Figure 1 and Figure 2 As shown, it includes an embankment slope 3, and the reinforcement structure includes a working platform 2 constructed in the middle of the embankment slope 3 and a plurality of micro steel pipe piles 1 arranged on the working platform 2. The working platform 2 is a construction platform formed by excavating the slope above the platform and filling the slope below the platform in the middle of the embankment slope 3; the pile bottom of each micro steel pipe pile 1 extends to at least 2 / 5 of the length of the micro steel pipe pile body below the sliding surface of the embankment slope 3, the pile top of the micro steel pipe pile 1 is located on the working platform 2, and the pile tops of the plurality of micro steel pipe piles 1 are connected as a whole through a crown beam 4; after the construction of the micro steel pipe piles 1 is completed, the embankment slope 3 above the working platform 2 is backfilled to the slope of the original slope; a drainage ditch 5 is arranged at the top of the embankment slope 3, and the drainage ditch 5 is located at the edge of the road surface 6 adjacent to the embankment slope 3; a drainage ditch 7 is arranged at the bottom of the embankment slope 3; the width of the working platform is 4m to 6m, and it is composed of excavation inside the slope and backfilling outside the slope. The cross-sectional dimension width of the crown beam 4 is at least 0.1m on both sides of the micro steel pipe pile 1, and the height is not less than 0.5m. The crown beam 4 is a reinforced concrete structure, with double-layer bidirectional steel bars arranged up and down inside, and frame bars are provided.

[0088] In the embodiment, Figures 3 to 5As shown, the micro steel pipe pile 1 comprises a pile body borehole 100, a steel pipe body 101 and a grouting reinforcement body 102 cast in the steel pipe body 101 and between the steel pipe body 101 and the pile body borehole 100. The steel pipe body 101 is a hollow pipe structure, and a pipe bottom bracket 103 is provided at the bottom of the steel pipe body 101; the steel pipe body 101 is placed in the pile body borehole 100, and a sealing hole structure 1 is provided between the hole opening of the pile body borehole 100 and the steel pipe body 101. 06 is sealed, and an exhaust pipe 105 is provided at the sealing structure 106, the bottom of the steel pipe body 101 is in contact with the bottom surface of the pile body borehole 100 through the pipe bottom bracket 103, and a grouting channel is formed between the bottom surface of the steel pipe body 101 and the pile body borehole 100; a grouting hose 104 is inserted into the steel pipe body 101, and the grouting hose 104 extends from the upper pipe mouth of the steel pipe body 101 to the bottom of the steel pipe body 101, and extends into the bottom of the pile body borehole 100 through the grouting channel. The diameter of the pile body drilling hole 100 is 150-250 mm, and the diameter of the steel pipe body 101 is at least 50 mm smaller than the diameter of the pile body drilling hole 100; the steel pipe body 101 is a pipe body structure formed by connecting multiple sections of steel pipes through a connecting sleeve 108, and the steel pipe body 101 is inserted into the central axis of the pile body drilling hole 100, and supporting ear bars 107 are arranged at intervals on both sides of the steel pipe body 101; the pipe bottom bracket 103 includes two groups of symmetrically arranged U-shaped steel bars, and their openings are welded to the lower pipe mouth of the steel pipe body 101 as a whole. The sealing structure 106 uses cement soil to seal the pile body borehole 100 within the range of 0.8 to 1.2 soil layers below the surface, and inserts an exhaust pipe 105 during the sealing process. The upper end of the exhaust pipe 105 extends out of the pile body borehole 100, and the lower end passes through the sealing structure 106 and extends into the pile body borehole 100; the grouting reinforcement body 102 is a cement slurry reinforcement structure formed by high-pressure grouting through a grouting hose 104.

[0089] The present invention is further described below in conjunction with an embodiment. For a road embankment slope of a certain engineering example, according to drilling and geological surveys, the main strata of the road embankment slope are ① plain fill, ② silty clay containing crushed stone, and ③ 1 fully weathered silty mudstone. The sliding body is in a saturated state, and the saturated gravity is 21.0 kN / m 3 , saturated cohesion 12.0kPa, saturated internal friction angle 13 degrees, anchor body friction resistance 30kPa; the sliding zone strata are mainly ③ fully weathered silty mudstone, saturated cohesion 12.0kPa, saturated internal friction angle 13 degrees; the sliding bed strata are mainly ③1 fully weathered silty mudstone, ③2 strongly weathered silty mudstone, saturated gravity 24.0kN / m 3 , saturated cohesion 150.0kPa, saturated internal friction angle 24 degrees.

[0090] Firstly, the stability safety factor of the embankment slope is calculated according to the broken line sliding method. The calculation principle is as follows: Figure 6 As shown, Figure 6The calculation diagram of the transfer coefficient method is shown in Figure 2. The stability safety factor of the slope is a quantitative value that reflects the stability of the slope. The anti-sliding force safety stability factor F is calculated according to the broken line sliding method. s value,

[0091]

[0092] In the formula: In the formula: F s —Safety stability factor F of the anti-sliding force of the embankment slope before treatment S value;

[0093] θ i —the bottom inclination angle of the i-th slope sliding body strip, °; Ψ j —transfer coefficient;

[0094] n—the number of vertical soil strips into which the soil above the sliding surface of the embankment slope is divided by the strip division method, that is, the total number of slope sliding body strips;

[0095] R i —The anti-sliding force of the i-th slope sliding body strip, kN / m;

[0096] R n —The anti-sliding force of the nth slope sliding body strip, kN / m;

[0097] N n —normal component of the nth slope sliding body strip, kN / m;

[0098] N i —normal component of any i-th slope sliding body strip, kN / m;

[0099] —Internal friction of the strip sliding zone of any i-th slope sliding body, °;

[0100] c i —cohesion of rock and soil on the sliding surface of any i-th slope sliding body strip, kPa;

[0101] l i —The length of the sliding surface of any i-th slope sliding body strip, m;

[0102] T i —The downward force of any i-th sliding block on the slope, kN / m.

[0103] like Figure 7 This is a simplified diagram of the transfer coefficient method calculation of the engineering case in the embodiment. The slope broken line sliding is divided into 6 blocks. The sliding force, anti-sliding force and transfer coefficient of each block are calculated by the Manager Zheng geotechnical analysis software, as shown in the following table:

[0104]

[0105] Substitute the above data into the broken line sliding method to calculate the anti-sliding safety stability factor F s The value is calculated in the formula:

[0106]

[0107] Therefore, the anti-sliding safety stability factor F of the embankment slope before treatment is s If the value does not meet the embankment safety requirements, landslide damage will occur and the embankment landslide needs to be reinforced; therefore, the micro steel pipe piles in the present invention are selected to reinforce the embankment slope. After the embankment slope is reinforced with micro steel pipe piles, the stability safety factor of the slope increases, which means that the anti-sliding moment acting on the slope increases on the original basis. Based on formula ①, the micro steel pipe piles provide an increased part of the anti-sliding moment, and the design anti-sliding force safety stability factor F' that meets the anti-sliding requirements s The numerical calculation formula is as follows:

[0108]

[0109] in:

[0110] F′ s —Safety stability factor of the designed anti-slip force that meets the anti-slip requirements;

[0111] P—the anti-sliding force provided by micro steel pipe piles to the slope;

[0112] m—the number of sliding blocks on the slope above the working platform;

[0113] R i —Anti-sliding force of any i-th slope sliding body strip, kN / m;

[0114] R m —The anti-sliding force of the mth slope sliding body strip, kN / m;

[0115] T m —The sliding force of the mth slope sliding body strip, kN / m;

[0116] T i —The sliding force of any i-th slope sliding body strip, kN / m;

[0117] Stress calculation of micro steel pipe piles The shear force that micro steel pipe piles can withstand is shown in formula ③:

[0118]

[0119] Where: P 浆体 —The anti-sliding force provided by the slurry in the micro steel pipe pile to the slope;

[0120] P 钢管 —The anti-sliding force provided by the steel pipe in the micro steel pipe pile to the slope;

[0121] τ1—design value of shear strength of slurry in micro steel pipe pile;

[0122] τ2—the design value of shear strength of the steel tube body in the micro steel tube pile;

[0123] d—diameter of micro steel pipe pile, i.e. the diameter of the hole in the pile body;

[0124] d1—outer diameter of the steel pipe body in the micro steel pipe pile;

[0125] d2—inner diameter of the steel tube body in the micro steel tube pile;

[0126] On the basis of the above-mentioned broken line sliding method, substituting equation ③ into equation ②, the calculation expression of the reinforcement effect of micro steel pipe piles on the slope is obtained:

[0127]

[0128] Calculate the sliding force and anti-sliding force of the slope per meter of the slope. Introduce the concept of the number of micro-steel pipe piles N and the spacing S of the micro-steel pipe piles in formula ④. Then the influence of the number of micro-steel pipe piles N and the spacing S of the micro-steel pipe piles on the anti-sliding force of the piles is:

[0129]

[0130] Where: N—number of rows of micro steel pipe piles;

[0131] S—spacing between micro steel pipe piles, m.

[0132] Micro steel pipe piles were constructed at the end of the third block of the landslide body, and the sliding force and anti-sliding force of the landslide body above the micro steel pipe piles were calculated.

[0133]

[0134] After the reinforcement of the micro steel pipe piles, the treated slope reaches a stable state. At this time, the slope stability safety factor will increase. The anti-sliding force safety stability factor F that meets the safety of the embankment slope is set. s ' is 1.35, the anti-sliding force provided by the micro steel pipe pile to the slope can be calculated:

[0135]

[0136] After analyzing the resistance provided by the micro steel pipe pile to the slope, the pile parameters of the micro steel pipe pile are calculated by inversely calculating the anti-sliding force provided by the micro steel pipe pile to the slope.

[0137] Due to the limited width of the working platform, only light drilling equipment can be placed for drilling, and the commonly used drilling diameter d = 200mm for light drilling equipment is selected. Since the outer diameter of the steel pipe needs to be at least 50mm smaller than the drilling diameter, the steel pipe with an outer diameter of 114mm and an inner diameter of 102mm commonly used in the steel market is selected, the cement mortar is M30, the mortar shear strength design value τ1 = 1.8MPa, and the steel pipe shear strength design value τ2 = 130MPa.

[0138] get:

[0139]

[0140] Therefore, when the number of rows of micro steel pipe piles n = 2 rows, the micro steel pipe pile spacing S = 0.95m. The embedding depth of the micro steel pipe pile below the sliding surface in the landslide should not be less than 1 / 3 of the total length. The bottom depth of the third block of the landslide is about 6m, and the length of the micro steel pipe pile can be set to 12m.

[0141] After the construction parameters are determined, the construction of micro steel pipe piles begins. The specific steps are as follows:

[0142] S1. Excavation diagram of the working platform, as shown below: Figure 8 As shown, the construction platform is measured and laid out: the boundary line of the construction platform is determined to prepare for leveling the construction platform; the upper and lower slopes of the construction platform are excavated and trimmed to level the construction platform. The width of the construction platform is 4m, consisting of a 2m wide excavation inside the slope and a 2m wide backfill outside the slope. The excavated soil on the upper part of the construction platform is backfilled to the lower part of the construction platform.

[0143] S2. Construction of micro steel pipe piles, as follows Fig. 9 As shown; First, put the drilling rig in place: After the drilling rig is set up on the working platform, move the drilling rig so that the center of the drill tool is roughly aligned with the center of the casing, lift the drill bit, and move the drilling rig so that the center of the drill bit is facing the pile position. The pile position deviation should be controlled within 20mm, and the verticality deviation of the straight pile should not be greater than 1%. Drilling: A small drilling rig is used to drill holes, the hole inclination is less than 1%, the hole depth error is less than 50mm, and the pile diameter error is less than 10mm. During the construction of micro piles, perforation and large-scale loss of slurry along the sand layer should be prevented. Measures such as skip hole construction, intermittent construction and increasing the amount of accelerator can be adopted to deal with it; the specific structure of the micro steel pipe pile is as follows Figures 3 to 5 shown.

[0144] Insert and drive 2 rows of grouting micro steel pipe piles 1. To prevent eccentricity, the diameter of the hole of the grouting micro steel pipe pile 1 is 200mm. Insert the steel pipe in the middle and put in the specifications of The steel pipe has three ear bars 2 welded along the circumference of the steel pipe at intervals of 2m, and the three ear bars form a 120° angle. The diameter of the ear bars is 8mm. The ear bars are used to ensure that the micro steel pipe pile maintains a certain safe distance from the side wall of the borehole, so that the cement mortar 6 can be filled between the micro steel pipe pile and the side wall of the borehole, and serve as a protective layer for the micro steel pipe pile to prevent rust. In order to prevent the hole under the steel pipe from being close to the bottom of the hole and causing grouting difficulties, a pipe bottom bracket 4 about 10cm long needs to be welded at the bottom of the pipe. The pipe bottom bracket 4 is welded by a steel bar with a diameter of 12mm and a micro steel pipe pile. The steel bar is U-shaped and has a vertical length of 0.3m, so that the bottom of the steel pipe and the bottom of the borehole are suspended through the pipe bottom bracket 4 to ensure pressure grouting when grouting inside and outside the steel pipe; this measure can avoid drilling holes on the steel pipe structure, and there is no need to use micro piles 1 for grouting of the steel pipe structure, which reduces the time-consuming and labor-intensive construction of drilling holes on the steel pipe and damages the steel pipe structure. When making micro piles with steel pipes, the steel bars should be connected by sleeves as much as possible. Of course, the steel pipe connection can also be welded by inserting a larger steel pipe 3, but butt welding should be avoided as much as possible. Cement soil is used to seal the hole 8 within the soil layer 1.0m below the surface of the steel pipe pile hole, and at the same time, insert L = 1500mmPVC exhaust pipe 7, exhaust the gas in the borehole. After it has a certain strength, the top of the steel pipe is connected to the grouting hose 5 to inject high pressure grouting into the hole. The grouting liquid uses PO42.5 general silicon cement mortar 6, the grade is M30, the water-cement ratio is 0.4-0.45, the cement-sand ratio is 1:1, and the grouting pressure is controlled at 1.5-2.5MPa.

[0145] S3. All micro steel pipe piles are constructed according to the steps of S2. After all micro steel pipe piles are constructed and cured, crown beams are constructed on the tops of all micro steel pipe piles to connect all micro steel pipe piles together. The soil is backfilled on the construction platform to the height of the bottom of the crown beam, and the crown beam steel bars are tied. The cross-sectional size of the crown beam is 900X500mm. The crown beam is arranged with 14mm@150mm diameter steel bars on the top and bottom, double-layer and bidirectional, and the frame bars are 12mm@300mm in diameter. The mold is made, concrete is poured, and the curing time is not less than 14 days. The internal structure of the micro steel pipe pile crown beam is as follows: Figure 2 shown.

[0146] S4. After the construction of the micro steel pipe pile top beam is completed, the upper and lower slopes of the working platform are trimmed to restore the slope gradient to the state before construction; a drainage ditch 5 is set up to intercept nearby surface water, and a drainage ditch 6 at the foot of the slope is built and dredged to divert surface water and prevent it from seeping into the area; specifically, Fig.11 shown.

[0147] The present invention provides the calculation of micro steel pipe pile reinforcement landslide, determines the key parameters, and guides engineering practice. Micro steel pipe piles are economical and efficient, have excellent reinforcement effect, can construct a spatial frame structure to form a composite retaining structure, have strong shear resistance, are convenient and safe to construct, have strong adaptability, and are particularly suitable for scenes where traditional methods are difficult to construct or costly. At the same time, it can effectively control the formation of cracks, enhance the stability of the slope, form an overall reinforcement system, and reduce adverse effects.

[0148] In summary, the content of the present invention is not limited to the above-mentioned embodiments, and people with insight in the same field can easily propose other embodiments within the technical guiding ideology of the present invention, but such embodiments are all included in the scope of the present invention.

Claims

1. A micro steel pipe pile embankment landslide reinforcement structure, comprising an embankment slope (3), characterized in that: The reinforcement structure comprises an operation platform (2) constructed in the middle of the embankment slope (3) and a plurality of micro steel pipe piles (1) arranged on the operation platform (2); the operation platform (2) is a construction platform formed by excavating the slope surface above the platform and filling the slope surface below the platform in the middle of the embankment slope (3); the pile bottom of each micro steel pipe pile (1) extends to at least 2 / 5 of the length of the micro steel pipe pile body below the sliding surface of the embankment slope (3); the pile top of the micro steel pipe pile (1) is located on the operation platform (2), and the pile tops of the plurality of micro steel pipe piles (1) are connected as a whole via a crown beam (4); after the construction of the micro steel pipe piles (1) is completed, the embankment slope (3) above the operation platform (2) is backfilled to the slope of the original slope surface; The micro steel pipe pile (1) comprises a pile body borehole (100), a steel pipe body (101), and a grouting reinforcement body (102) cast in the steel pipe body (101) and between the steel pipe body (101) and the pile body borehole (100); the steel pipe body (101) is a hollow pipe structure, and a pipe bottom bracket (103) is provided at the bottom of the steel pipe body (101); the steel pipe body (101) is placed in the pile body borehole (100), and a sealing hole structure (103) is provided between the hole opening of the pile body borehole (100) and the steel pipe body (101). 6) sealing, and an exhaust pipe (105) is provided at the sealing structure (106); the bottom of the steel pipe body (101) contacts the bottom surface of the pile body borehole (100) through the pipe bottom bracket (103), and a grouting channel is formed between the bottom surface of the steel pipe body (101) and the pile body borehole (100); a grouting hose (104) is inserted into the steel pipe body (101), and the grouting hose (104) extends from the upper pipe opening of the steel pipe body (101) to the bottom of the steel pipe body (101), and extends into the bottom of the pile body borehole (100) through the grouting channel.

2. The micro steel pipe pile embankment landslide reinforcement structure according to claim 1 is characterized by: A drainage ditch (5) is arranged at the top of the embankment slope (3), and the drainage ditch (5) is located at the edge of the road surface (6) adjacent to the embankment slope (3); a drainage ditch (7) is arranged at the bottom of the embankment slope (3); the working platform has a width of 4m to 6m and is composed of excavation inside the slope and backfill outside the slope.

3. A micro steel pipe pile embankment landslide reinforcement structure according to claim 1 or 2, characterized in that: The diameter of the pile body borehole (100) is 150-250 mm, and the diameter of the steel pipe body (101) is at least 50 mm smaller than the diameter of the pile body borehole (100); the steel pipe body (101) is a pipe structure formed by connecting multiple sections of steel pipes through a connecting sleeve (108), the steel pipe body (101) is inserted into the central axis of the pile body borehole (100), and support ear bars (107) are arranged at intervals on both sides of the steel pipe body (101); the pipe bottom bracket (103) includes two groups of symmetrically arranged U-shaped steel bars, and the openings of the U-shaped steel bars are welded to the lower pipe opening of the steel pipe body (101) as a whole.

4. A micro steel pipe pile embankment landslide reinforcement structure according to claim 1 or 2, characterized in that: The sealing structure (106) uses cement soil to seal the hole in the range of 0.8 to 1.2 soil layers below the surface of the pile body borehole (100), and inserts an exhaust pipe (105) during the sealing process. The upper end of the exhaust pipe (105) extends out of the pile body borehole (100), and the lower end passes through the sealing structure (106) and extends into the pile body borehole (100); the grouting reinforcement body (102) is a cement slurry reinforcement structure formed by high-pressure grouting through a grouting hose (104).

5. A micro steel pipe pile embankment landslide reinforcement structure according to claim 1 or 2, characterized in that: The cross-sectional dimensions of the crown beam (4) are at least 0.1 m wide on both sides of the micro steel pipe pile (1) and not less than 0.5 m in height. The crown beam (4) is a reinforced concrete structure, with double-layer bidirectional steel bars arranged in the upper and lower parts, and frame bars provided.

6. A construction method for the micro steel pipe pile embankment landslide reinforcement structure according to claims 1 to 5, characterized in that The specific steps are as follows: S1. Determine the sliding surface of the embankment slope through geological survey, and calculate the anti-sliding safety stability coefficient F of the embankment slope before treatment based on the broken line sliding method s The calculated anti-sliding force safety stability factor F of the embankment slope before treatment s The value is the design anti-slip force safety stability factor F that meets the anti-slip requirements s 'Values ​​are compared in F s Less than F s 'When choosing to use micro steel pipe pile reinforcement structure to reinforce the embankment slope; S2. Construct a working platform in the middle of the embankment slope, determine the boundary line of the working platform, excavate and trim the upper and lower slopes of the working platform, level the construction working platform, and backfill the excavated soil on the upper part of the construction working platform to the lower part of the working platform; S3. Micro steel pipe piles are constructed on the working platform to reinforce the embankment slope. After the embankment slope is reinforced with micro steel pipe piles, the stability safety factor of the slope increases, which means that the anti-sliding force acting on the slope increases on the original basis. On the basis of the actual anti-sliding force of the embankment slope in step S1, the micro steel pipe piles provide an increased part of the anti-sliding force; based on the above-mentioned broken line sliding method, the calculation expression of the reinforcement effect of micro steel pipe piles on the slope is obtained: Where: F′ s —Safety and stability coefficient of the design anti-slip force that meets the anti-slip requirements m—the number of sliding blocks on the slope above the working platform; j —transfer coefficient; R i —Anti-sliding force of any i-th slope sliding body strip, kN / m; R m —The anti-sliding force of the mth slope sliding body strip, kN / m; T m —The sliding force of the mth slope sliding body strip, kN / m; T i —The sliding force of any i-th slope sliding body strip, kN / m; τ1—design value of shear strength of slurry in micro steel pipe pile; τ2—the design value of shear strength of the steel tube body in the micro steel tube pile; d—diameter of micro steel pipe pile, i.e. the diameter of the hole in the pile body; d1—outer diameter of the steel pipe body in the micro steel pipe pile; d2—inner diameter of the steel tube in the micro steel tube pile; Calculate the sliding force and anti-sliding force of the slope per meter of the slope. Introduce the concept of the number of micro-steel pipe piles N and the spacing S of the micro-steel pipe piles in formula ①. The influence of the number of micro-steel pipe piles N and the spacing S of the micro-steel pipe piles on the anti-sliding force of the piles is as follows: Where: N—number of rows of micro steel pipe piles; S—spacing of micro steel pipe piles; S4. According to the requirements of the construction site, select the micro steel pipe pile material that meets the construction requirements. The pile diameter of the micro steel pipe pile is controlled at 150-250mm, and the diameter of the steel pipe body in the micro steel pipe pile is at least 50mm smaller than the diameter of the micro steel pipe pile; the grouting reinforcement of the micro steel pipe pile adopts cement mortar with a label of M10-M30 and a water-cement ratio of 0.4-0.55; and substitute the selected micro steel pipe pile parameters into the formula ② in step S3 to calculate the ratio of the number of rows N of micro steel pipe piles and the spacing S of micro steel pipe piles, and determine the number of rows N of micro steel pipe piles and the spacing S of micro steel pipe piles according to the calculated ratio and the requirements of the construction site; and the bottom of each micro steel pipe pile extends to at least 2 / 5 of the length of the micro steel pipe pile body below the sliding surface of the embankment slope; S5. After determining the construction parameters of the micro steel pipe pile, a small drilling rig is used to drill a hole in the pile body on a working platform. The drilling rig is moved so that the center of the drill tool is roughly aligned with the center of the casing. The drill bit is lifted and the drilling rig is moved so that the center of the drill bit is aligned with the pile position. S6. After the pile body drilling construction is completed, the steel pipe body is inserted into the center, and ear bars are welded to the steel pipe body at a certain interval. The steel pipe body and the bottom of the pile body drilling hole are suspended by a pipe bottom bracket, and the steel pipe bodies are connected by sleeves. Cement soil is used to seal the hole in the soil layer within 0.8 to 1.2 m below the surface of the pile body drilling hole. At the same time, an exhaust pipe is inserted. After the cement soil sealing hole has a certain strength, a grouting hose is inserted into the steel pipe body, and high-pressure grouting is injected into the steel pipe body and the pile body drilling hole; S7. After all the micro steel pipe piles are constructed according to steps S5 and S6 and cured, a crown beam is constructed on the top of all the micro steel pipe piles to connect all the micro steel pipe piles together; S8. After the construction of the crown beam on the top of the micro steel pipe pile is completed, the upper and lower slopes of the working platform are trimmed to restore the slope gradient to the state before construction; and drainage ditches on the top of the slope and drainage ditches at the bottom of the slope are set.

7. The construction method of a micro steel pipe pile embankment landslide reinforcement structure according to claim 6, characterized in that: The actual anti-sliding force safety stability factor F of the embankment slope in step S1 s The value calculation process is as follows: Where: F s —Safety stability factor F of the anti-sliding force of the embankment slope before treatment s value; θ i —the bottom inclination angle of the i-th slope sliding block, °; n—the number of vertical soil strips into which the soil above the sliding surface of the embankment slope is divided by the strip division method, that is, the total number of slope sliding body strips; R n —The anti-sliding force of the nth slope sliding body strip, kN / m; N n —normal component of the nth slope sliding body strip, kN / m; N i —normal component of any i-th slope sliding body strip, kN / m; —Internal friction of the strip sliding zone of any i-th slope sliding body, °; c i —cohesion of rock and soil on the sliding surface of any i-th slope sliding body strip, kPa; l i —The length of the sliding surface of any i-th slope sliding body strip, m; T i —The sliding force of any i-th sliding block on the slope, kN / m; The parameters in the above calculation formula are the shear strength index of the unreinforced landslide rock and soil obtained from drilling and geological surveys, and the depth of the sliding surface. The stability safety factor Fs, anti-sliding force and sliding force of the unreinforced slope are calculated. The anti-sliding force and sliding force of each block can also be calculated through the Lizheng Geotechnical Commercial Software.

8. The construction method of a micro steel pipe pile embankment landslide reinforcement structure according to claim 6, characterized in that: In step S3, based on the actual anti-sliding force of the embankment slope in step S1, the micro steel pipe piles provide an additional part of the anti-sliding force, and the design anti-sliding force safety stability factor F that meets the anti-sliding requirements is s The value calculation formula is as follows: Where: P—anti-sliding force provided by micro steel pipe piles to the slope; The shear force that the micro steel pipe pile can withstand is calculated by the stress of the micro steel pipe pile, as shown in formula ⑦: Where: P 浆体 —The anti-sliding force provided by the slurry in the micro steel pipe piles to the embankment slope; P 钢管 —The anti-sliding force provided by the steel tube body in the micro steel tube pile to the embankment slope; Based on the above-mentioned broken line sliding method, substitute formula ⑦ into formula ⑥ to obtain formula ① in step S3.

9. The construction method of a micro steel pipe pile embankment landslide reinforcement structure according to claim 6, characterized in that: In step S2, the width of the construction platform is 4m to 6m, consisting of half of the excavation inside the slope and the other half of the backfill outside the slope; in step S4, the design value of the slurry shear strength, the design value of the steel pipe shear strength, the diameter of the micropile, the outer diameter of the steel pipe, and the inner diameter of the steel pipe are determined according to the specifications and the commonly used steel pipe sizes on the market; in step S4, the micropile construction adopts the method of skipping hole construction, intermittent construction and increasing the dosage of the accelerating agent to prevent perforation and large-scale loss of slurry along the sand layer.

10. The construction method of a micro steel pipe pile embankment landslide reinforcement structure according to claim 6, characterized in that: In step S6, the pile position deviation of micro steel pipe pile construction should be controlled within 20mm, and the verticality deviation of straight pile should not be greater than 1%. The micro steel pipe pile drilling rig hole inclination is less than 1%, the hole depth error is less than 50mm, and the pile diameter error is less than 10mm; 3 ear bars are welded along the circumference of the steel pipe every 2 to 3m, and the three lines are 120°. The diameter of the ear bar is 8 to 10mm; the bottom of the pipe is welded to the bottom bracket of the pipe to extend by 25 to 30cm, and the diameter of the steel bar is 12 to 18mm; the exhaust pipe is L=1200~1500mmPVC; the high-pressure grouting slurry adopts PO42.5 ordinary silica cement mortar, with a grade of M10~M30, a water-cement ratio of 0.4~0.55, a cement-sand ratio of 1:1~1:3, and the grouting pressure is controlled at 1.5~2.5MPa; in step S7, the cross-sectional size width of the crown beam is 0.1m on both sides of the micro steel pipe pile, and the height is not less than 0.5m. Double-layer bidirectional steel bars of different diameters are arranged on the upper and lower parts of the crown beam, and frame bars are set, molds are made, and concrete is poured. The curing time is not less than 14 days.

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