Soft soil area film bag sand blowing shortcut composite structure and construction method

Abstract

The invention discloses a soft soil area film bag sand blowing shortcut composite structure and a construction method, and relates to the technical field of highway engineering building construction shortcuts, the technical scheme is that the soft soil area film bag sand blowing shortcut composite structure comprises a film bag sand layer arranged at the bottom and a ballast layer arranged at the top of the film bag sand layer; the film bag sand layer comprises a third film bag sand layer arranged on the original ground or above the water surface, a first film bag sand layer and a second film bag sand layer, wherein the first film bag sand layer and the second film bag sand layer are arranged on the original ground or below the water surface, and the first film bag sand layer and the second film bag sand layer are filled with film bag green sand in a layered mode according to the water depth. The ballast layer is arranged on the top of the third film bag sand layer. The method has the beneficial effects that the working procedures of drainage, desilting, replacement and filling and the like are reduced, the construction period is shortened, the equipment investment and cost are reduced, and rapid forming of the shortcut is achieved. The film bag and the sand are combined to form a high-bearing-capacity compact block, sedimentation is prevented, the maintenance cost is reduced, and smoothness and progress are guaranteed. The mechanical conveying improves the efficiency, reduces the labor intensity, is free of waste, recoverable in sand, and meets the requirements of green sustainable development.

Description

Technical Field

[0001] The present invention relates to the technical field of construction of construction access roads in highway engineering, and particularly relates to a composite structure of a film bag sand blowing access road in soft soil areas and a construction method thereof. Background Art

[0002] During the construction stage of highway engineering, it is often necessary to build construction access roads for the transportation of construction materials and the passage of construction machinery and equipment. As the main transportation route for transport vehicles and construction machinery, the construction access road undertakes a heavy freight volume and plays a very important role in the construction process of the main structure of the highway engineering, and is the "lifeline" of the main structure construction. Currently, most construction access roads are directly filled with crushed stones. When encountering soft soil subgrades such as those with silt and silty soil in rivers or lakes during the construction process, methods such as excavation and replacement, lime mixing improvement, or stone throwing and silt squeezing are usually used for treatment. However, the above methods have problems such as many construction processes, slow construction speed, long construction period, and high construction cost; a large number of large construction machinery and equipment such as excavators, bulldozers, rollers, and mixers need to be invested during the treatment process; after the access road is formed, it is easily affected by water immersion, resulting in easy settlement and damage of the subgrade, frequent maintenance, and high maintenance cost, especially in areas with soft soil subgrades in rivers or lakes. There is an urgent need for an efficient, environmentally friendly, and low-cost rapid construction method for soft soil access roads. Summary of the Invention

[0003] In order to achieve the above-mentioned invention purpose and address the above technical problems, the present invention provides a composite structure of a film bag sand blowing access road in soft soil areas and a construction method thereof.

[0004] Its technical solution is that a composite structure of a film bag sand blowing access road in soft soil areas includes a film bag sand layer arranged at the bottom and a crushed stone layer arranged on top of the film bag sand layer;

[0005] The film bag sand layer includes a film bag sand layer three arranged above the original ground or water surface, and a film bag sand layer one and a film bag sand layer two arranged below the original ground or water surface. The film bag sand layer one and the film bag sand layer two are filled with film bag green sand in layers according to the water depth;

[0006] The crushed stone layer is arranged on top of the film bag sand layer three.

[0007] The thickness of the crushed stone layer is 50 cm;

[0008] The thickness of the film bag sand layer three is 40 cm;

[0009] The thicknesses of both the film bag sand layer one and the film bag sand layer two are 40 cm - 50 cm.

[0010] The thickness and width of the access road structural layer can be adjusted according to the situation of the on-site test section. Generally, below the original ground or water surface, the thickness of each layer should be controlled within 40 cm - 50 cm. The film bag uses 200 g / m 2It is made of a double-layer high-toughness polypropylene reinforced cloth, a polymer geosynthetic material, with the function of one-way drainage and anti-seepage, forming a three-dimensional drainage channel and a constraint system. After the water in the membrane bag is discharged, finally the membrane bag and the sand together form a monolithic stress-dense block with a relatively high bearing capacity, which can effectively resist the erosion of water.

[0011] Based on the construction method of the membrane bag sand blowing access road composite structure described above, it includes the following steps:

[0012] S1. Site preparation

[0013] Clean or relocate sharp obstacles such as tree roots and stones within the construction area to prevent puncturing the membrane bag and causing sand leakage; set a sand storage point every 200 - 500m, and supporting facilities such as a clear water pool, a high-pressure water pump, a sand-water mixing slurry storage pool, a stirrer, a slurry pump, and a sand filling pipeline are arranged;

[0014] S2. Surveying and setting out

[0015] Use GPS or total station to locate the edge line of the access road, and mark the edge line and elevation of the membrane bag on both sides of the access road;

[0016] S3. Laying and fixing the membrane bag

[0017] Lay the membrane bag along the longitudinal axis of the construction access road in the length direction, and strictly control the edge line and elevation of the membrane bag according to the markings of pole-shaped objects such as marking poles or steel pipes; after the membrane bag is laid, fix it firmly through the fixed pull rings on both sides of the bag body to ensure that the bag body does not displace during the sand blowing process;

[0018] S4. Preparation of sand-water mixed slurry

[0019] Set a sand storage area every 200m along the access road, and use a sand and gravel separator to screen the incoming sand and gravel materials; set a sand-water mixed slurry storage pool with a capacity of not less than 25m 3 in the sand storage area, and use a high-pressure water gun to wash the sand into the storage pool to prepare a sand-water mixed slurry; a stirrer is set in the storage pool to mix the sand and water evenly, and control the sand content in the sand-water mixed slurry at 60%. On the one hand, it can prevent uneven mixing of sand and water from blocking the slurry pump or sand pipeline and causing damage to mechanical equipment; on the other hand, it can ensure the sand content and improve the construction efficiency;

[0020] S5. Sand blowing into the membrane bag

[0021] Before sand blowing, manually tie the sand delivery hose firmly to the sand blowing port reserved on the membrane bag. When filling, first moisten the membrane bag, and then use a high-pressure slurry pump to generate hydraulic force to blow the sand-water mixed slurry in the storage pool into the fixed membrane bag, and check the water outlet situation of the membrane bag, and manually level it in time;

[0022] The membrane bag filling is carried out in 2 - 3 times. During the filling process, in order to accelerate the flow and compaction of the sand in the membrane bag, artificial trampling on the top surface of the bag body back and forth is adopted, or a rubber hammer can be used to repeatedly tap and change positions, which can not only promote the rearrangement of particles to be closer but also accelerate the drainage consolidation speed of the bag body; when the slurry begins to overflow from the whole membrane bag, stop filling to prevent the membrane bag from bursting; during the filling process, the surveyors should measure and set the top elevation and slope ratio at any time. When there is a deviation from the design, after the membrane bag is consolidated, it can be filled for the second or multiple times until the design requirements are met;

[0023] Gradually fill the sand material in the order of "near first, far later" and "corners first, center later". When filling to the center of the membrane bag, the fixing ropes at the corners of the membrane bag should be loosened in time to avoid pulling and breaking when the membrane bag sinks; during the filling process, in order to accelerate the flow and consolidation of the sand in the membrane bag, artificial treading treatment is carried out on the sand bag;

[0024] When the filling distance exceeds the capacity of the filling equipment, pressurization and secondary extraction can be adopted; when the height of the sand discharge pipe outlet exceeds the maximum lift of the sand pump, an additional pressurization pump is used;

[0025] After each sand blowing port finishes filling and the sand blowing hose is withdrawn, the sand blowing port must be tied tightly with iron wire or geotextile rope and stuffed into the membrane bag in time; after the sand blowing is completed, the sand material scattered on the surface of the membrane bag should be washed clean;

[0026] After the membrane bag sand filling is completed, wait for the membrane bag sand to secrete water and consolidate; considering the difficulty of drainage in water, artificial trampling combined with high-pressure air guns to blow water is adopted to remove the accumulated water in the bag. At the same time, for every 2 layers of membrane bags filled, secondary drainage is carried out through the ballast of the upper layer;

[0027] S6. Inspection and Re - filling

[0028] After there is no obvious water secretion on the surface of the membrane bag, check the filling fullness of the membrane bag; those that do not meet the requirements should be re - filled in time; in order to ensure the flatness and fullness of the filled bag body, multi - sand - blowing - port filling should be adopted during re - filling;

[0029] S7. Ballast Filling

[0030] After the membrane bag sand reaches the optimum moisture content, carry out ballast filling. Use a grader to level the filler and a roller to level and compact;

[0031] For the large difference in the particle size of the ballast resulting in a large gap between the ballasts, sprinkle fine ballast on the surface of the filling layer to fill the gap, and form a mud - bound macadam road surface during vehicle driving to reduce rainwater infiltration and reduce the damage of the access road;

[0032] S8. Compaction

[0033] Rolling is carried out by a road roller. When rolling, the overlapping width of wheel tracks shall not be less than 1 / 3 of the wheel track width, and covering an operation surface with wheel tracks is regarded as one pass; the longitudinal overlap between the adjacent front and rear sections shall be more than 2m to achieve no missed corners and no dead corners, ensuring uniform rolling; the rolling is carried out in three steps: slow speed for the initial rolling, medium speed for the re-rolling, and fast speed for the final rolling.

[0034] S9. Settlement Observation

[0035] After the ballast paving is completed, settlement observation points are arranged. The observation points are driven into the ground, with the top surface flush with the ground, and marked at the top and around; the elevations of the settlement observation points are measured respectively after the 4th, 5th, and 6th passes of rolling are completed, and records are made.

[0036] After the measurement is completed, data analysis is carried out to see if it meets the requirements of the specification that the average settlement difference is less than 5mm and the standard deviation is less than 3mm; if the requirements are not met, the number of rolling passes needs to be increased until the specification requirements are met.

[0037] In step S2, for the side line of the access road, at intervals of 20m in the straight section and appropriately densified in the curved section, at intervals of 5m or 10m, marker poles or steel pipes and other pile-shaped objects are set on both sides of the access road to mark the side line and elevation of the film bag.

[0038] In step S3, when laying the film bag, it should be noted that the film bag is fully unfolded and laid flat without wrinkles, and the overlapping width at the connection between the film bags shall not be less than 30cm;

[0039] After the film bag is laid, wooden stakes are inserted into the fixed pull rings at intervals of 5m on both sides of the bag body and tied firmly with iron wires and hemp ropes.

[0040] In step S4, when screening the incoming sand and gravel materials, it is required that the content of particles smaller than 0.075mm in the sand should be less than 15%, preferably less than 10%, and should not agglomerate and concentrate; the content of clay particles smaller than 0.005mm is less than 5%; the organic matter content should be less than 5%; the silt content should be less than 10%; the dry unit weight is not less than 14.5N / m 3 .

[0041] In step S5, the speed and pressure of hydraulic filling should be strictly controlled, and low-flow hydraulic filling is adopted, with the speed controlled at 18 - 22m 3 / h, and the pressure at the pipe orifice is controlled at 0.15 - 0.3MPa;

[0042] The length of a single hydraulic filling operation for the access road is controlled within the range of 50 - 60m, and the single hydraulic filling thickness is controlled at 40cm - 50cm. For the pond section, it is filled in multiple layers according to the water depth;

[0043] To ensure the smooth progress of the construction, a slurry storage pool is set at intervals of 200m.

[0044] In step S7, the filling thickness of ballast is 50 cm, and the loose laying thickness is controlled at 62.5 cm. A 2% cross slope is set on the top surface of the ballast to facilitate drainage. For oversize ballast, manual crushing is required. The ballast used for filling the access road should be medium-quality rock and hard rock, with a proportion of not less than 50%, a compressive strength of not less than 30 MPa, a mud content of not more than 5%, and the particle size controlled within the range of 10 - 15 cm.

[0045] In step S8, the roller used for compaction is a vibration roller with a mass of more than 18 t and adjustable frequency and amplitude. The compaction is carried out by the method of starting slowly and then quickly, with high frequency and low vibration, and the compaction speed is controlled at 2 - 4 km / h.

[0046] The compaction procedure is as follows: static compaction is carried out once at a speed of 2 km / h; weak vibration compaction is carried out twice at a speed of 3 km / h; strong vibration compaction is carried out twice at a speed of 3 km / h; static compaction is carried out once at a speed of 3.5 km / h.

[0047] For the areas where the roller cannot reach the edge of the subgrade, small ramming machines should be used for supplementary compaction. The compaction degree is detected by the method of controlling the settlement difference.

[0048] In step S9, after the ballast paving is completed, four settlement observation points are arranged at each section of every 100 m. The observation points are made of 20-cm-long round steel driven into the ground, with the top surface flush with the ground, and the top and the surrounding are marked with red paint.

[0049] This solution provides a composite access road structure form of film bag sand and ballast in soft soil areas. Above the original ground or water surface, 40 cm of film bag sand and 50 cm thick ballast are used for filling. Below the original ground or water surface, film bag green sand is filled in layers according to the water depth. The thickness and width of the access road structure layer can be adjusted according to the situation of the on-site test section. Generally, the thickness of each layer should be controlled within the range of 40 cm - 50 cm. The film bag green sand used below the original ground or water surface forms a high-bearing-capacity and overall stress-bearing dense block together with the film bag after water seepage consolidation, which can effectively resist water erosion, improve the water stability of the access road, and avoid the problem of repeated maintenance of the access road.

[0050] This solution adopts a set of single-permeable flexible film bag constraint system and corresponding quality control standards: the film bag is made of a double-layer high-tough polypropylene reinforced fabric high-molecular geosynthetic material with a weight of 200 g / m 2 to form a three-dimensional drainage channel for one-way drainage and preventing anti-seepage and a lateral shaping constraint system. A sand blowing port with a diameter of 30 cm is set at every 5 m longitudinally for the film bag, and the number of sand blowing ports in each cross section is controlled within 2. A pull ring is set at every 5 m on both sides to facilitate laying and fixing. The unit area mass of the film bag ≥ 200 g / m 2, the longitudinal breaking strength ≥ 40 kN / m, the transverse breaking strength ≥ 25 kN / m, the longitudinal breaking elongation ≤ 25%, the transverse breaking elongation ≤ 28%, the longitudinal and transverse trapezoidal tearing strength ≥ 0.34 kN, the spherical bursting strength ≥ 3.2 kN, and the vertical permeability coefficient is (1.0 - 9.9) × 10 -3 cm / s.

[0051] This solution determines the optimal ratio of the sand-water mixed slurry: Use a high-pressure water gun to shoot sand into the slurry storage tank to prepare the sand-water mixed slurry. A stirrer is set in the slurry storage tank to mix the sand and water evenly. The sand content in the sand-water mixed slurry should be controlled at 60%. On the one hand, it can prevent the uneven mixing of sand and water from blocking the slurry pump or sand conveying pipe and causing damage to mechanical equipment; on the other hand, it can ensure the sand content, maximize the work efficiency, and improve the construction efficiency.

[0052] This solution studies and applies a sand-water mixed slurry transportation and construction method: Use a high-pressure slurry pump to generate hydraulic force to blow the sand-water mixed slurry in the slurry storage tank into the shaped membrane bag through a sand conveying hose. The sand material drains water and consolidates, and together with the membrane bag, it forms a monolithic and force-bearing dense block with high bearing capacity. The high-pressure slurry pump can provide a stable transportation pressure, ensure the uniform flow of the slurry, avoid the precipitation or stratification of sand grains, and improve the construction quality; the high-pressure slurry pump has a high transportation efficiency and can quickly transport the sand-water mixed slurry into the shaped membrane bag, improving the construction speed; through mechanized transportation, the dependence on manual operation is reduced, the work efficiency is improved, and the labor intensity is reduced; the sand conveying hose uses a rubber hose with a diameter of 160 mm, which is not easily damaged due to bending during construction. The sand conveying hose and the slurry pump are connected by bolts and gaskets to ensure that there is no leakage of the sand-water mixed slurry during transportation. Using the sand-water mixed slurry can reduce the dust generated during transportation and is beneficial to improving the construction environment.

[0053] The sand blowing speed and pressure of this solution: Adopt low-flow filling, with the speed controlled at 18 - 22 m 3 / h, and the pressure at the pipe orifice is controlled at 0.15 - 0.3 MPa to ensure the construction progress and prevent the damage of the membrane bag caused by excessive sand filling speed and pressure.

[0054] The sand filling sequence of this solution: Gradually fill the sand material in the order of "near first, far later" and "corners first, center later". When filling to the center of the membrane bag, loosen the fixing ropes at the corners of the membrane bag in time to avoid the membrane bag being pulled and broken when it sinks. During the sand filling process, in order to accelerate the flow and consolidation of the sand in the membrane bag, manual trampling treatment is carried out on the sand bag.

[0055] The water drainage and consolidation of this solution: After the membrane bag sand blowing is completed, use the method of manual trampling combined with high-pressure air gun water blowing to drain the accumulated water in the bag. At the same time, every two layers of membrane bags are filled, and secondary drainage is carried out through the ballast of the upper layer.

[0056] The beneficial effects brought by the technical solution provided in the embodiment of the present invention are as follows: The present invention provides a composite structure and construction method of a film bag sand blowing access road in soft soil areas, aiming to solve the problems that in areas involving rivers and lakes, areas with rich groundwater, weak geology, water areas and other soft soil areas, the access roads are prone to settlement damage, frequent maintenance, high construction and maintenance costs, and slow construction progress. This method reduces construction procedures such as drainage, dredging, and replacement filling, shortens the construction period of the access road, reduces the input of construction machinery and equipment, reduces the construction cost, and realizes the rapid formation of the access road; through the film bag, a unidirectional drainage and anti-seepage and lateral restraint system is constructed, combined with the characteristics of the sand being permeable and self-compacting when saturated with water, the water in the film bag is discharged, and finally the film bag and the sand together form an integral force-bearing dense block with a relatively high bearing capacity. After the access road is formed, it can prevent water intrusion, is not prone to settlement damage, solves the problem of repeated maintenance of the access road, and at the same time reduces the maintenance cost, which helps to ensure the smoothness of the access road and the realization of the project progress goal; through the method of high-pressure slurry pump and sand conveying hose, mechanized conveying is realized, reducing the dependence on manual operation, improving work efficiency, and reducing labor intensity; compared with the traditional sand blowing method, less dust is generated during the conveying process, which is beneficial to improving the construction environment; no waste is generated during the construction process, and the sand can be recycled after the access road is used, meeting the ecological and environmental protection requirements of green and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the composite structure of the access road in the embodiment of the present invention.

[0058] Figure 2 It is a schematic diagram of the sand-water slurry preparation system in the embodiment of the present invention.

[0059] Figure 3 It is a schematic diagram of the film bag sand blowing construction in the embodiment of the present invention.

[0060] Among them, the reference numerals are: 1. The first film bag sand layer; 2. The second film bag sand layer; 3. The third film bag sand layer; 4. The crushed stone layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0061] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0062] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0063] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0064] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0065] Example 1

[0066] See Figures 1 to 3 , the present invention provides a composite structure and construction method of a membrane bag sand blowing access road in soft soil areas. A composite structure of a membrane bag sand blowing access road in soft soil areas includes a membrane bag sand layer arranged at the bottom and a stone ballast layer 4 arranged on the top of the membrane bag sand layer;

[0067] The membrane bag sand layer includes a membrane bag sand layer three 3 above the original ground or water surface and a membrane bag sand layer one 1 and a membrane bag sand layer two 2 below the original ground or water surface. The membrane bag sand layer one 1 and the membrane bag sand layer two 2 are filled with membrane bag green sand in layers according to the water depth;

[0068] The stone ballast layer 4 is arranged on the top of the membrane bag sand layer three 3.

[0069] The thickness of the stone ballast layer 4 is 50 cm;

[0070] The thickness of the membrane bag sand layer three 3 is 40 cm;

[0071] The thicknesses of both the membrane bag sand layer one 1 and the membrane bag sand layer two 2 are 40 cm - 50 cm.

[0072] The thickness and width of the access road structural layer can be adjusted according to the situation of the on-site test section. Generally, below the original ground or water surface, the thickness of each layer should be controlled within 40 cm - 50 cm. The membrane bag is made of a double-layer high-tenacity polypropylene reinforced fabric geosynthetic material with a weight of 200 g / m 2 , which has the function of one-way drainage and anti-seepage, forms a three-dimensional drainage channel and restraint system. After the water in the membrane bag is discharged, finally, the membrane bag and the sand together form an overall stress-dense block with high bearing capacity, which can effectively resist the erosion of water.

[0073] A construction method for the composite structure of a membrane bag sand blowing access road in soft soil areas includes the following steps:

[0074] S1. Site preparation

[0075] Clean or remove sharp obstacles such as tree roots and stones within the construction range to prevent puncturing the membrane bag and causing sand leakage; set up a sand storage point every 200 - 500 m, and equip and arrange facilities such as a clean water tank, a high-pressure water pump, a sand-water mixing slurry storage tank, a stirrer, a slurry pump, and a sand filling and conveying pipeline.

[0076] S2. Surveying and setting out

[0077] Use GPS or total station to locate the side line of the access road, and mark the side line and elevation of the membrane bag on both sides of the access road;

[0078] S3. Membrane bag laying and fixing

[0079] Lay the membrane bag along the longitudinal axis of the construction access road, and strictly control the side line and elevation of the membrane bag according to the markings of pole-shaped objects such as marker poles or steel pipes; after the membrane bag is laid, fix it firmly through the fixed pull rings on both sides of the bag body to ensure that the bag body does not displace during the sand blowing process;

[0080] S4. Preparation of sand-water mixed slurry

[0081] Set up a sand storage area every 200 m along the access road, and use a sand and stone separator to screen the incoming sand and stone materials; set up a sand-water mixed slurry storage tank with a capacity of not less than 25 m 3 in the sand storage area, and use a high-pressure water gun to wash the sand into the storage tank to prepare a sand-water mixed slurry; install a stirrer in the storage tank to mix the sand and water evenly, and control the sand content in the sand-water mixed slurry at 60%. On the one hand, it can prevent uneven mixing of sand and water from blocking the slurry pump or sand conveying pipe and causing damage to mechanical equipment; on the other hand, it can ensure the sand content and improve the construction efficiency;

[0082] S5. Membrane bag sand blowing

[0083] Before sand blowing, manually tie the sand transportation hose firmly to the sand blowing port reserved on the film bag. When filling, first moisten the film bag, and then use a high-pressure slurry pump to generate hydraulic force to blow the sand-water mixture in the slurry storage tank into the fixed film bag. Check the water discharge condition of the film bag and level it manually in time;

[0084] The film bag filling is carried out in 2 - 3 times. During the filling process, to accelerate the flow and compaction of the sand in the film bag, manually step on the top surface of the bag back and forth, or use a rubber hammer to repeatedly tap and change positions, which can not only promote the rearrangement of particles to be closer but also accelerate the drainage and consolidation speed of the bag body; when the slurry starts to overflow from the entire film bag, stop filling to prevent the film bag from bursting; during the filling process, the surveyors measure and set the top elevation and slope ratio at any time. When there is a deviation from the design, after the film bag is consolidated, it can be filled for the second or multiple times until the design requirements are met;

[0085] Gradually fill the sand material in the order of "near first, then far" and "corners first, then center". When filling to the center of the film bag, loosen the fixing ropes at the corners of the film bag in time to avoid pulling and breaking when the film bag sinks; during the filling process, to accelerate the flow and consolidation of the sand in the film bag, manually step on and press the sand bag;

[0086] When the filling distance exceeds the capacity of the filling equipment, pressurization and secondary extraction can be adopted; when the height of the sand discharge pipe mouth exceeds the maximum lift of the sand pump, an additional pressurization pump is used;

[0087] After each sand blowing port finishes filling and the sand blowing hose is withdrawn, it is necessary to tie the sand blowing port tightly with iron wire or geotextile rope in time and stuff it into the film bag; after sand blowing is completed, wash the sand material scattered on the surface of the film bag;

[0088] After the film bag sand blowing is completed, wait quietly for the film bag sand to secrete water and consolidate; considering the difficulty of drainage in water, adopt the method of manual stepping combined with high-pressure air guns to blow water to remove the accumulated water in the bag. At the same time, for every 2 layers of film bags filled, secondary drainage is carried out through the ballast of the upper layer;

[0089] S6. Inspection and Re - filling

[0090] After there is no obvious water secretion on the surface of the film bag, check the filling fullness of the film bag; those not meeting the requirements should be re - filled in time; to ensure the flatness and fullness of the filled bag body, multi - sand blowing ports should be adopted during re - filling;

[0091] S7. Crushed Stone Filling

[0092] After the film bag sand reaches the optimum moisture content, carry out crushed stone filling. Use a grader to level the filler and a roller to level and compact it;

[0093] For the large difference in the particle size of the crushed stone resulting in a large gap between the crushed stones, sprinkle fine crushed stone on the surface of the filling layer to fill the gap. When the vehicle travels, it forms a mud - bound macadam road surface to reduce rainwater infiltration and reduce the damage of the access road;

[0094] S8. Rolling

[0095] Rolling is carried out by a roller. During rolling, the overlapping width of wheel tracks shall not be less than 1 / 3 of the wheel track width, and one pass is completed when the wheel tracks cover an operation surface; the longitudinal overlap between the adjacent front and rear sections shall be more than 2 m to achieve no missing corners and no dead corners, ensuring uniform rolling; rolling is carried out in three steps: slow initial rolling, medium-speed re-rolling, and fast final rolling.

[0096] S9. Settlement Observation

[0097] After the ballast paving is completed, settlement observation points are arranged. The observation points are driven into the ground, with the top surface flush with the ground, and the top and surrounding areas are marked; the elevations of the settlement observation points are measured respectively after the 4th, 5th, and 6th passes of rolling are completed, and records are made.

[0098] After the measurement is completed, data analysis is carried out to check whether the requirements of the specification are met, that is, the average settlement difference is less than 5 mm and the standard deviation is less than 3 mm; if the requirements are not met, the number of rolling passes needs to be increased until the specification requirements are met.

[0099] In step S2, for the side lines of the access road, in straight sections, a marker pole or a pile-shaped object such as a steel pipe is set on both sides of the access road every 20 m, and in curve sections, it is appropriately densified, every 5 m or 10 m, to mark the side line and elevation of the film bag.

[0100] In step S3, when laying the film bag, it should be noted that the film bag is fully unfolded and laid flat without wrinkles, and the overlapping width at the connection between the film bags shall not be less than 30 cm.

[0101] After the film bag is laid, wooden stakes are inserted into the fixed pull rings at one place every 5 m on both sides of the bag body and tied firmly with iron wires and hemp ropes.

[0102] In step S4, when screening the sand and gravel materials entering the site, it is required that the content of particles with a size less than 0.075 mm in the sand shall be less than 15%, preferably less than 10%, and shall not agglomerate; the content of clay particles with a size less than 0.005 mm shall be less than 5%; the organic matter content shall be less than 5%; the mud content shall be less than 10%; the dry unit weight shall not be less than 14.5 N / m 3 .

[0103] In step S5, the filling speed and pressure should be strictly controlled. Low-flow filling is adopted, with the speed controlled at 18 - 22 m 3 / h, and the pipe outlet pressure is controlled at 0.15 - 0.3 MPa.

[0104] The length of one-time filling operation of the access road is controlled within the range of 50 - 60 m, and the one-time filling thickness is controlled at 40 cm - 50 cm. For the pond section, multi-layer filling is carried out according to the water depth.

[0105] To ensure the smooth progress of construction, a slurry storage pond is set every 200m.

[0106] In step S7, the filling thickness of the crushed stones is 50cm, and the loose laying thickness is controlled at 62.5cm. A 2% cross slope is set on the top surface of the crushed stones for drainage. For the extra-large sized crushed stones, manual crushing is required. The crushed stones used for the filling of the access road should be medium-quality rocks and hard rocks, with a proportion of not less than 50%, and the compressive strength of the rocks should not be less than 30MPa, the mud content should not exceed 5%, and the particle size is controlled within the range of 10 - 15cm.

[0107] In step S8, for the rolling, a vibrating roller with a weight of more than 18t and adjustable frequency and amplitude is selected. The rolling is carried out by the method of slow first and then fast, high frequency and low vibration, and the rolling speed is controlled at 2 - 4km / h;

[0108] The rolling procedure is as follows: static rolling is carried out once at a speed of 2km / h; weak vibration rolling is carried out 2 times at a speed of 3km / h; strong vibration rolling is carried out 2 times at a speed of 3km / h; static rolling is carried out once at a speed of 3.5km / h;

[0109] For the places where the roller cannot reach the edge of the subgrade, small ramming machines should be used for supplementary compaction; the compactness is detected by the method of controlling the settlement difference.

[0110] In step S9, after the crushed stones are paved, 4 settlement observation points are arranged at each cross-section every 100m. The observation points are made of 20cm long round steel driven into the ground, with the top surface flush with the ground, and the top and the surrounding are marked with red paint.

[0111] This scheme provides a composite access road structure form of film bag sand and crushed stones in soft soil areas. Above the original ground or water surface, 40cm of film bag sand and 50cm thick crushed stones are used for filling. Below the original ground or water surface, according to the water depth, film bag green sand is filled in layers. The thickness and width of the access road structural layer can be adjusted according to the situation of the on-site test section. Generally, the thickness of each layer should be controlled within 40cm - 50cm. The film bag green sand used below the original ground or water surface forms a high-bearing-capacity and overall stress-dense block together with the film bag after bleeding and consolidation, which can effectively resist the erosion of water, improve the water stability of the access road, and avoid the problem of repeated maintenance of the access road;

[0112] This scheme adopts a set of single-permeable flexible film bag restraint system and corresponding quality control standards: the film bag is made of a double-layer high-tenacity polypropylene reinforced cloth polymer geosynthetic material of 200g / m 2 to form a three-dimensional drainage channel for one-way drainage and anti-seepage and a lateral shaping restraint system. A sand blowing port with a diameter of 30cm is set every 5m longitudinally for the film bag, and the number of sand blowing ports in each cross-section is controlled within 2. A pull ring is set every 5m on both sides for convenient laying and fixing. The unit area mass of the film bag ≥200g / m 2, the longitudinal breaking strength ≥ 40 kN / m, the transverse breaking strength ≥ 25 kN / m, the longitudinal breaking elongation ≤ 25%, the transverse breaking elongation ≤ 28%, the longitudinal and transverse trapezoidal tearing strength ≥ 0.34 kN, the spherical bursting strength ≥ 3.2 kN, the vertical permeability coefficient (1.0 - 9.9) × 10 -3 cm / s.

[0113] This solution determines the optimal ratio of sand - water slurry: Use a high - pressure water gun to shoot sand into the slurry storage tank to prepare sand - water slurry. A stirrer is set in the slurry storage tank to mix the sand and water evenly. The sand content in the sand - water slurry should be controlled at 60%. On the one hand, it can prevent uneven mixing of sand and water from blocking the mud pump or sand - conveying pipe, causing damage to mechanical equipment; on the other hand, it can ensure the sand content, maximize work efficiency, and improve construction efficiency.

[0114] This solution studies and applies a method for transporting and constructing sand - water slurry: Use a high - pressure mud pump to generate hydraulic force to blow the sand - water slurry in the slurry storage tank into the shaped membrane bag through a sand - conveying hose. The sand material seeps out water and consolidates, forming a monolithic and dense block with high bearing capacity together with the membrane bag. The high - pressure mud pump can provide stable conveying pressure, ensure uniform slurry flow, avoid sand particle precipitation or stratification, and improve the construction quality; the high - pressure mud pump has high conveying efficiency, can quickly transport the sand - water slurry into the shaped membrane bag, improve the construction speed; through mechanized transportation, it reduces the dependence on manual operation, improves work efficiency, and reduces labor intensity; the sand - conveying hose uses a rubber hose with a diameter of 160 mm, which is not easily damaged due to bending during construction. The sand - conveying hose is connected to the mud pump with bolts and gaskets to ensure no leakage of the sand - water slurry during transportation. Using sand - water slurry can reduce the dust generated during transportation and is beneficial to improving the construction environment.

[0115] The sand - blowing speed and pressure of this solution: Adopt low - flow filling, with the speed controlled at 18 - 22 m 3 / h, and the pressure at the pipe outlet is controlled at 0.15 - 0.3 MPa to ensure the construction progress and prevent the membrane bag from being damaged due to excessive sand - blowing speed and pressure.

[0116] The sand - filling sequence of this solution: Gradually fill the sand material in the order of "near first, then far" and "corners first, then center". When filling to the center of the membrane bag, promptly loosen the fixing ropes at the corners of the membrane bag to avoid the membrane bag being torn when sinking. During the filling process, to accelerate the flow and consolidation of sand in the membrane bag, manual trampling treatment is carried out on the sand bag.

[0117] The water seepage and consolidation of this solution: After the membrane bag sand - blowing is completed, use a combination of manual trampling and high - pressure air gun to blow out the water in the bag to remove the accumulated water. At the same time, for every two layers of membrane bags filled, secondary drainage is carried out through the ballast of the upper layer.

[0118] Example 2

[0119] On the basis of Embodiment 1, the composite structure of the membrane bag sand-blowing access road can appropriately adjust the layered thickness under the conditions described in the present invention to achieve the technology of the functions described in the present invention.

[0120] In addition to rubber hoses, other flexible pipes can also be used for the sand transportation hoses.

[0121] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A composite structure of a film bag sand blowing access road in soft soil areas, characterized in that, It includes a sand layer in a membrane bag arranged at the bottom and a crushed stone layer (4) arranged on top of the sand layer in the membrane bag; The sand layer in the membrane bag includes a third sand layer in the membrane bag (3) arranged above the original ground or water surface, and a first sand layer in the membrane bag (1) and a second sand layer in the membrane bag (2) arranged below the original ground or water surface. The first sand layer in the membrane bag (1) and the second sand layer in the membrane bag (2) are filled in layers with green sand in the membrane bag according to the water depth; The crushed stone layer (4) is arranged on top of the third sand layer in the membrane bag (3).

2. The composite structure of the film bag sand-blowing access road in soft soil area according to claim 1, wherein, The thickness of the crushed stone layer (4) is 50 cm; The thickness of the third sand layer in the membrane bag (3) is 40 cm; The thicknesses of both the first sand layer in the membrane bag (1) and the second sand layer in the membrane bag (2) are 40 cm - 50 cm.

3. The construction method of the composite structure of the film bag sand blowing access road in soft soil area according to claim 1, characterized in that, It includes the following steps: S1. Site preparation Clean or relocate sharp obstacles within the construction area to prevent puncturing the membrane bag and causing sand leakage; set up a sand storage point every 200 - 500 m, and configure a clear water tank, a high-pressure water pump, a sand-water mixing slurry storage tank, a stirrer, a slurry pump, and a sand filling pipeline; S2. Surveying and lofting Use GPS or total station to locate the sidelines of the access road, and mark the sidelines and elevation of the membrane bag on both sides of the access road; S3. Laying and fixing the membrane bag Lay the membrane bag along the longitudinal axis of the construction access road in the long direction, and control the sidelines and elevation of the membrane bag according to the marks; After the membrane bag is laid, fix it firmly through the fixed pull rings on both sides of the bag body to ensure that the bag body does not displace during the sand blowing process; S4. Preparation of sand-water mixed slurry A sand storage area is set every 200 m along the access road, and a sand and gravel separator is used to screen the incoming sand and gravel materials; a slurry storage tank for sand-water mixed slurry with a capacity of not less than 25 m 3 is set in the sand storage area. A high-pressure water gun is used to wash the sand into the storage tank to prepare a sand-water mixed slurry; a stirrer is set in the storage tank to mix the sand and water evenly, and the sand content in the sand-water mixed slurry is controlled at 60%; S5. Sand blowing into the membrane bag Before sand blowing, manually tie the sand delivery hose firmly to the sand blowing port reserved on the membrane bag. When blowing and filling, first moisten the membrane bag, and then use a high-pressure slurry pump to generate hydraulic force to blow the sand-water mixed slurry in the slurry storage tank into the fixed membrane bag, and check the water discharge condition of the membrane bag and level it; Sand blowing into the membrane bag; When the entire membrane bag starts to overflow slurry, stop blowing and filling to prevent the membrane bag from bursting; during the blowing and filling process, the surveying personnel should measure and set the top elevation and slope ratio at any time. When there is a deviation from the design, after the membrane bag consolidates, it can be blown and filled twice or multiple times until the design requirements are met; Gradually blow and fill the sand material in the order of "from near to far" and "from the corners to the center"; When the blowing and filling distance exceeds the capacity of the blowing and filling equipment, pressurization and secondary extraction can be adopted; when the height of the sand discharge pipe mouth exceeds the maximum lift of the sand pump, an additional pressurization pump is used; After the sand blowing into the membrane bag is completed, wait for the sand in the membrane bag to secrete water and consolidate; considering the difficulty of drainage in water, adopt the method of manual trampling combined with high-pressure air guns to blow water to remove the accumulated water in the bag. At the same time, for every two layers of membrane bags blown and filled, secondary drainage is carried out through the ballast of the upper layer; S6. Inspection and re-blowing After there is no obvious water secretion on the surface of the membrane bag, check the fullness of the sand blowing into the membrane bag; those that do not meet the requirements should be re-blown in time; to ensure the flatness and fullness of the filled bag body, multi-sand blowing ports should be adopted during re-blowing; S7. Crushed stone filling After the sand in the membrane bag reaches the optimal moisture content, carry out crushed stone filling. Use a grader to level the filler, and use a roller to level and compact it; For the large difference in the particle size of the crushed stone resulting in a large gap between the crushed stones, sprinkle fine crushed stone on the surface of the filling layer to fill the gap, and form a mud-bound crushed stone road surface during vehicle driving to reduce rainwater infiltration and reduce damage to the access road; S8. Compaction Rolling is carried out by a road roller. When rolling, the overlapping width of wheel tracks shall not be less than 1 / 3 of the wheel track width, and covering an operation surface with wheel tracks is regarded as one pass; the longitudinal overlap between the adjacent front and rear sections shall be more than 2m; the rolling is carried out in three steps: slow initial rolling, medium-speed re-rolling, and fast final rolling. S9. Settlement Observation After the ballast is paved, settlement observation points are arranged. The observation points are driven into the ground with the top surface flush with the ground surface, and the top and the surrounding are marked; after the 4th, 5th, and 6th passes of rolling are completed, the elevations of the settlement observation points are measured respectively and records are made. After the measurement is completed, data analysis is carried out to see if it meets the requirements of the specification that the average value of settlement difference is less than 5mm and the standard deviation is less than 3mm; if the requirements are not met, the number of rolling passes needs to be increased until the specification requirements are met.

4. The construction method of the composite structure of the film bag sand blowing access road in soft soil area according to claim 3, characterized in that In step S2, for the side lines of the access road, at intervals of 20m in the straight section and appropriately densified in the curve section, at intervals of 5m or 10m, flagpoles or steel pipe piles are set on both sides of the access road to mark the side lines and elevations of the film bags.

5. The construction method of the composite structure of the film bag sand-blowing access road in soft soil area according to claim 4, characterized in that, In step S3, the overlapping width at the connection between the film bags shall not be less than 30cm. After the film bags are laid, wooden stakes are inserted into the fixed pull rings at intervals of 5m on both sides of the bag body and tied firmly.

6. The construction method of the composite structure of the film bag sand blowing access road in soft soil area according to claim 5, characterized in that, In step S4, when screening the incoming sand and gravel, it is required that the content of particles smaller than 0.075 mm in sand should be less than 15%, preferably less than 10%, and should not agglomerate and concentrate; the content of clay particles smaller than 0.005 mm should be less than 5%; the organic matter content should be less than 5%; the mud content should be less than 10%; the dry unit weight should not be less than 14.5 N / m 3 .

7. The construction method of the composite structure of the film bag sand-blowing access road in soft soil area according to claim 6, characterized in that, In step S5, control the speed and pressure of hydraulic filling, and adopt low-flow hydraulic filling with the speed controlled at 18-22m 3 / h and the pressure at the pipe orifice controlled at 0.15-0.3 MPa; The length of a single dredging operation for the access road is controlled within the range of 50 - 60m, the single dredging thickness is controlled at 40cm - 50cm, and the pond section is dredged in multiple layers according to the water depth. A slurry storage pond is set at intervals of 200m.

8. The construction method of the composite structure of the film bag sand blowing access road in soft soil area according to claim 7, characterized in that, In step S7, the thickness of the ballast filling is 50cm, and the loose laying thickness is controlled at 62.5cm. A 2% cross slope is set on the top surface of the ballast for drainage; for the oversize ballast, manual crushing is required. The ballast used for the access road filling requires that the proportion of medium-quality rock and hard rock is not less than 50%, and the compressive strength of this rock is not less than 30MPa, the mud content shall not exceed 5%, and the particle size is controlled within the range of 10 - 15cm.

9. The construction method of the composite structure of the film bag sand blowing access road in soft soil area according to claim 8, characterized in that, In step S8, the road roller used for rolling is a vibration road roller with a mass of more than 18t and adjustable frequency and amplitude. The rolling is carried out by the method of slow first and then fast, high frequency and low vibration, and the rolling speed is controlled at 2 - 4km / h. The rolling procedure is as follows: static rolling is carried out at a speed of 2km / h for 1 pass; weak vibration rolling is carried out at a speed of 3km / h for 2 passes; strong vibration rolling is carried out at a speed of 3km / h for 2 passes; static rolling is carried out at a speed of 3.5km / h for 1 pass. For the places where the road roller cannot reach the edge of the subgrade, small ramming machines shall be used for supplementary compaction; the compactness is detected by the method of controlling the settlement difference.

10. The construction method of the composite structure of the film bag sand blowing access road in soft soil area according to claim 9, characterized in that, In step S9, after the ballast is paved, according to one cross-section every 100m, 4 settlement observation points are arranged for each cross-section. The observation points are driven into the ground with 20cm-long round steel, and the top surface is flush with the ground surface.

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