Formwork erecting method for hole arch of rammed stone side arch

Abstract

The invention provides a tunnel arch formwork erecting method for a rammed stone side arch. The method comprises the following steps that S1, tunnel opening positioning and foundation trench excavation are conducted, specifically, according to design paying-off, a tunnel foundation trench is excavated, a base is tamped, and a broken stone hardcore is laid; s2, side arch rockery stone masonry: selecting thick rubbles for dry masonry to a designed arch camber line elevation, reserving a rough surface on the inner side, and burying shear pins at arch springing parts; the combined structure of the curb and the rammed earth is adopted, the improved rammed earth which can be obtained locally is used as a core bearing part, and the use amount of stone is reduced. Compared with a whole stone arch, the stone consumption is reduced by more than 35%, the material cost is remarkably reduced, the overall construction cost is reduced by about 25% in combination with the reduced transportation cost and the reusable formwork system, and the method has good economical efficiency and market popularization value. Due to the fact that the volume weight of the rammed earth is far lower than that of the stone, the combined arch of the rammed earth and the curbstone is light in self weight and can well adapt to unfavorable geological areas such as soft soil and uneven foundations, and the application range is expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rockery cave structure, and particularly relates to a method for supporting arch voussoirs of a rockery cave. BACKGROUND

[0002] As an important landscaping element in gardens, the cave structure of a rockery not only adds unique spatial levels and interest to the garden, but also provides a place for visitors to rest and enjoy. In the structural design of traditional rockery caves, stone materials with natural forms and textures are often used to construct core supports and enclosure structures to create a realistic natural cave effect. Among them, full-stone voussoir arching is a relatively common and historical structure form. It can meet the basic bearing requirements of the cave to some extent due to the high strength and stability of stone materials, and exhibits a simple and natural style that complements the surrounding garden landscape, becoming a distinctive part of traditional garden architecture.

[0003] However, the existing rockery cave structure has many problems in actual application. On the one hand, the traditional full-stone voussoir arching method requires a large amount of stone materials during construction, resulting in high construction costs and a long construction period, which makes it difficult to meet the requirements of modern garden construction for speed and efficiency. In particular, on soft soil foundations, full-stone voussoir arching is prone to cracking and even collapse due to uneven foundation settlement, which seriously affects the safety and durability of the cave structure. On the other hand, if a pure rammed earth arch structure is used, although it can be locally sourced to some extent, reducing material costs, the rammed earth has weak lateral pressure resistance, and a large number of wooden forms and supports are needed during construction to ensure its shape and stability. Moreover, the rammed earth surface is prone to peeling after the formwork is removed, which not only affects the aesthetics of the cave and reduces the landscape effect, but also requires frequent maintenance and repair, increasing the management cost in the later period. In addition, the "steel mesh sprayed concrete shell" scheme proposed in the prior art improves the strength of the cave structure to some extent, but the use of concrete makes the cave lose its natural stone interest, which is contrary to the concept of pursuing nature and harmony in gardens. At the same time, this scheme is expensive, further limiting its widespread application in rockery cave construction.

[0004] Therefore, a method for supporting arch voussoirs of a rockery cave with a rammed stone arch is proposed. SUMMARY

[0005] Therefore, the present application provides a method for supporting arch voussoirs of a rockery cave with a rammed stone arch to solve or alleviate one of the technical problems in the prior art, at least providing a beneficial choice.

[0006] The technical solution of the embodiments of the present application is as follows: a method for supporting arch voussoirs of a rockery cave with a rammed stone arch, comprising the following steps: S1: Hole positioning and foundation trench excavation: According to the design layout, excavate the hole base trench, compact the base and lay the gravel cushion, and use the total station to accurately lay out the center stake and axis of the hole according to the overall plan of the rockery. After mechanical excavation to the design elevation, manually trim the base trench slope and bottom. The base uses heavy compaction standards and is compacted using a flat tamper. Then lay a well-graded gravel cushion and use a flat tamper to flatten it to provide uniform support for the arch foot; S2: Side arch rockery masonry: Select thick stone for dry laying to the design arch line elevation, reserve a rough surface on the inside, and bury shear nails at the arch foot position. Select flat and high-strength yellow stone, use dry laying method, layer by layer staggered joint, ensure stable structure, after laying to the design arch line elevation, use a hammer to roughen the inside of the stone, forming a uniform rough surface, then bury 304 stainless steel shear nails in the stone gap at the arch foot line, so that they can effectively anchor into the subsequent rammed earth body to resist shear force; S3: Installation of deformable combined formwork system: Install the inner formwork composed of bamboo grid and outer PVC soft membrane, and fix and support it with adjustable steel hoops. Reserve a settlement allowance slot between the formwork outside and the side arch stone. Split mature bamboo into bamboo pieces, with the longitudinal as the main keel and the transverse as the secondary keel, and interlace them to form a firm semicircular arch skeleton. Wrap the skeleton tightly with transparent PVC soft membrane, seal the joints with waterproof tape to prevent slurry leakage. This soft membrane serves as both the forming surface for rammed earth and the smooth surface for easy demolding later. Bend flat steel into a semicircle, drill holes at both ends, and attach bolts to make adjustable radius steel hoops for clamping the bamboo grid to ensure that it does not deform under lateral pressure. Insert closed-cell foam plastic strips between the outside of the installed formwork system and the inside of the side stone to form a continuous settlement allowance slot; S4: Preparation of improved rammed earth: Prepare the improved soil according to the predetermined volume ratio, control the moisture content, and prepare the bamboo mesh. In the mixing yard, use a forklift to dry mix according to the volume ratio, mix evenly, then wet mix by adding water to the optimal moisture content, and pre-bundle the bamboo into mesh; S5: Layered ramming and arch forming: Fill the improved rammed earth into the formwork in layers, compact each layer to the predetermined compaction degree, and place the bamboo mesh between the layers. After ramming to the design vault, reserve a settlement allowance and maintain it. Fill the improved soil into the formwork manually, use an electric impact tamper to compact, lay a layer of bamboo mesh after every two layers to enhance the tensile properties of the rammed earth body, and repeat the process until the design vault elevation is reached. Finally, slightly shave the top to form a reserved settlement space, cover it with wet burlap, and regularly water it to maintain the stability of the rammed earth strength; S6: Demoulding and water flushing: After the curing period, remove the formwork system, and use a high-pressure water gun to flush the inner wall, removing loose mud and forming a smooth and natural inner wall surface. After the curing period, first loosen and remove all adjustable steel hoops. Since the bamboo sheets are elastic and coated with a release agent, the entire bamboo sheet grid can be easily pulled out of the arch cavity. Then, use a high-pressure cleaning machine equipped with a fan-shaped nozzle to flush the inner wall of the arch cavity from top to bottom. The water flow will wash away the loose and weakly adhered soil and particles on the surface, revealing a compact, smooth, and naturally textured rammed earth surface. The resulting mud and water are collected through the pre-buried underground drainage at the bottom of the foundation trench and are discharged into a sedimentation tank. The clarified water can be recycled for curing or flushing, achieving green construction; S7: Backfilling and landscape modification: Fill the gap between the rammed earth arch back and the rock with grouting, and perform surface landscape modification. Use a small hopper to carefully fill the gap between the rammed earth arch back and the rock with small pieces of gravel, lightly vibrate and compact, and then use cement slurry for pressure grouting to fill the gaps between the gravel, forming a concrete backing that enhances the overall integrity and load-bearing capacity of the arch. Finally, select small stones with similar color and texture to the side arch stones, and use cement mortar to embed and paste them on the construction joints and surface, hiding the artificial traces.

[0007] Further preferably: In step S1, the bottom width B of the foundation trench is (D+0.6) m, where D is the design span; the thickness of the gravel cushion layer is 80-100 mm.

[0008] Further preferably: In step S2, the thickness of the stone is not less than 200 mm; the reserved depth of the rough surface is 30-50 mm; the shear-resistant nails are Φ8 mm stainless steel nails with an exposed length of 150 mm and a spacing of 400 mm in a quincunx arrangement.

[0009] Further preferably: In step S3, the bamboo grid is made of Φ20 mm bamboo pieces with a longitudinal and horizontal spacing of 150 mm; the adjustable steel hoops are made of 50 mm x 5 mm flat steel, with a radius adjustment through bolts, and an installation spacing of 800 mm; the settlement allowance groove is formed by inserting a 10 mm thick foam strip.

[0010] Further preferably: In step S3, the surface of the bamboo grid is pre-coated with a release agent.

[0011] Further preferably: In step S4, the volume ratio of the improved rammed earth is: 45%-55% clay, 25%-35% sand, 15%-20% stone chips, 3%-5% quicklime, and 2%-3% cement; the water content is controlled within ±2% of the optimal water content; the bamboo mesh is made of Φ6 mm bamboo, with a lap length of not less than 200 mm.

[0012] Further preferably, in step S5, the thickness of each layer of the layered ramming is 130-150 mm, the electric impact rammer is used for ramming 6-8 times, and the compaction degree is not less than 90%-95%; and the reserved settlement allowance of the top is 30 mm.

[0013] Further preferably, in step S6, the adjustable steel hoop is removed first, and then the bamboo sheet grid is pulled out when the formwork is removed; the flushing water pressure is 0.3 MPa, and the flushing water is discharged to the sedimentation tank through the buried gutter of the base groove for recycling.

[0014] Further preferably, in step S7, the void backfill material is graded gravel and grouting; and the surface hides the construction joints by embedding small stones of the same color and restores the natural stone texture.

[0015] Further preferably, the settlement allowance groove is injected with compressible polyurethane foam in the later period.

[0016] The embodiment of the present application has the following advantages due to the adoption of the above technical solutions. 1. The present application uses the combination structure of curb and rammed earth, and the core bearing part uses the improved rammed earth which can be obtained locally, thereby reducing the amount of stone. Compared with the full stone arch, the amount of stone is reduced by more than 35%, the material cost is significantly reduced, combined with the reduced transportation cost and the reusable formwork system, the overall engineering cost is reduced by about 25%, which has good economic efficiency and market promotion value.

[0017] 2. Since the unit weight of the rammed earth is much lower than that of the stone, the combined arch of the rammed earth and the curb has a light self-weight, the requirement for the arch foot thrust and the foundation bearing capacity is reduced, and it can well adapt to soft soil, uneven foundation and other poor geological areas, thereby expanding the application range, and forming a high-efficiency composite structure through the built-in bamboo mesh and the pre-buried shear-resistant nails at the arch foot, so that the bearing capacity is greatly improved compared with the pure rammed earth arch structure, and the safety reserve is higher.

[0018] 3. The present application adopts the deformable and reusable formwork system (bamboo sheet grid + PVC soft film + adjustable steel hoop) which has the advantages of light weight, easy processing, simple installation and disassembly, solves the problem of formwork on the irregular stone surface, and compared with the traditional wood formwork or steel formwork, the construction efficiency is improved by 30%, further reducing the cost of the measure project, and the main materials are natural or renewable materials, the construction process is low in energy consumption and low in pollution.

[0019] 4. The present application uses the water flushing mud removal process to flush away the surface floating slurry, and the exposed rammed earth inner wall retains the rustic beauty of the rammed earth, which is integrated with the external artificial stone, the water stability and freeze-thaw resistance of the modified rammed earth body are good, the quality loss is less than 3% after 50 freeze-thaw cycles, which is better than the traditional raw soil building, meets the durability requirements for long-term use in outdoor environment, and guarantees the durability of the landscape effect.

[0020] 5、The process of layered ramming, strictly controlling the compaction degree and moisture content, ensures the uniformity and density of the rammed earth body, the arch back uses graded gravel grouting backfilling, ensuring the effective transmission of load, and the finally formed structure has good quality reliability and overall stability.

[0021] The above summary is intended to illustrate only and is not intended to limit the application in any way. Further aspects, embodiments and features of the application will be apparent from the detailed description that follows, taken in conjunction with the accompanying drawings and the description of the state of the art. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0023] Fig. 1 Flowchart of the present application; Fig. 2 Elevation structure diagram of the hole arch segment formwork system of the present application; Fig. 3 Enlarged structural diagram of the edge arch rockery and rammed earth engagement node of the present application.

[0024] Reference signs: 1, rockery edge arch; 2, rammed earth arch body; 3, bamboo sheet grid; 4, adjustable steel hoop; 5, shear-resistant nail; 6, foam strip settlement tank; 8, hidden ditch. DETAILED DESCRIPTION

[0025] The embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0026] It should be clear that the following describes the embodiments of the present disclosure through specific, concrete examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the content disclosed in the specification. Obviously, the described embodiments are only some of the embodiments of the present disclosure, not all. The present disclosure can also be implemented or applied by other different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present disclosure.

[0027] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0028] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The drawings only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex. Example

[0029] like Figs. 1-3 As shown, this embodiment of the invention provides a method for supporting the formwork of a rammed stone arch, comprising the following steps: S1: Cave Entrance Positioning and Foundation Trench Excavation: Based on the design layout, excavate the cave foundation trench, compact the base, and lay a crushed stone cushion layer. Using a total station, accurately lay out the center stake and axis of the cave entrance according to the overall plan of the artificial hill. After mechanical excavation to the design elevation, manually trim the slopes and bottom of the foundation trench. The base is compacted to 93% compaction using a plate tamper (ring cutter method). Subsequently, a 100mm thick, well-graded crushed stone cushion layer with a particle size of 5-20mm is laid and flattened with a plate tamper to provide uniform support for the arch foot. S2: Side Arch Rockery Construction: Thick stone slabs are dry-laid to the designed arch elevation, with a rough surface reserved on the inside. Shear nails are embedded at the arch foot. Flat, high-strength yellow stones with a thickness of 200mm are selected and dry-laid in staggered layers to ensure structural stability. After reaching the designed arch elevation, the inside of the stone is roughened with a pointed hammer to form a uniform rough surface with a depth of about 30mm. Then, Φ8mm 304 stainless steel shear nails are embedded in the gaps between the stones at the arch foot, with 150mm exposed. They are arranged in a staggered pattern with a spacing of 400mm to effectively anchor them into the subsequent rammed earth to resist shear force. S3: Installation of the deformable integrated formwork system: Install the inner formwork composed of bamboo sheet grating and outer PVC soft membrane, and fix and support it by adjustable steel hoops. Reserve a settlement allowance groove between the formwork and the side keystone. Split the matured bamboo into bamboo sheets with a diameter of 20 mm, and use them as the main keel in the longitudinal direction and the secondary keel in the transverse direction. The longitudinal and transverse directions intersect at an interval of 150 mm. Use No. 12 galvanized iron wire to bind them into a firm semicircular arched framework. Wrap the framework with a 2 mm thick transparent PVC soft membrane, and seal the joints with waterproof tape to prevent mortar leakage. The soft membrane serves as both the forming surface for rammed earth and the surface for easy demolding due to its smoothness. Bend 50 mm x 5 mm flat steel into a semicircle, drill holes at both ends, and attach M16 bolts to make adjustable radius steel hoops. A total of three hoops are provided to tighten the bamboo sheet grating and ensure that it does not deform under lateral pressure. Insert 10 mm thick closed-cell foam plastic strips between the outside of the installed formwork system and the inside of the side stone to form a continuous settlement allowance groove. S4: Preparation of improved rammed earth: Prepare the improved earth according to the predetermined volume ratio, control the water content, and prepare the bamboo mesh. In the mixing yard, use a forklift to dry mix the materials according to the volume ratio (50% clay, 30% medium sand, 15% stone chips, 3% quicklime, and 2% P.O42.5 cement). After mixing evenly, wet mix by sprinkling water to the optimal water content (about 12% ± 2%). Meanwhile, pre-bundle Φ6 mm bamboo into a mesh with a size of 150 mm x 150 mm, with a lap length of ≥200 mm. S5: Layered ramming and arch formation: Fill the improved rammed earth into the formwork in layers, compact each layer to the predetermined degree of compaction, and place the bamboo mesh between the layers. After ramming to the designed arch crown, reserve a settlement allowance and maintain it. Fill the improved earth into the formwork manually, strictly control the virtual thickness of each layer to be 150 mm, and use a 1.5 kW electric impact rammer to compact it. The rammer hits 6 times at each point, and the travel speed is uniform to ensure that the degree of compaction is ≥90%. After ramming two layers (about 300 mm thick), lay a layer of bamboo mesh to enhance the tensile properties of the rammed earth body. Repeat the process until the rammed earth reaches the designed arch crown elevation. Finally, slightly shave the top by 30 mm to form a reserved settlement space, cover it with wet burlap, and regularly water it for 7 days to allow the strength of the rammed earth to increase steadily. S6: Demoulding and water flushing: After the curing period, remove the formwork system, and use a high-pressure water gun to flush the inner wall, removing loose mud and forming a smooth and natural inner wall surface. After the curing period, first loosen and remove all adjustable steel hoops. Since the bamboo sheets are elastic and coated with a release agent, they can be easily pulled out of the arch cavity. Then, use a high-pressure cleaning machine (pressure adjusted to 0.3 MPa) with a fan-shaped nozzle to flush the inner wall of the arch cavity from top to bottom. The water flow will flush away the loose and weakly adhered soil and particles on the surface, revealing a compact, smooth, and naturally textured rammed earth surface. The resulting mud and water are collected through the pre-buried underground drainage at the bottom of the foundation trench and discharged into a sedimentation tank. The clarified water can be recycled for curing or flushing, achieving green construction; S7: Backfilling and landscape modification: Backfill and grouting the gap between the rammed earth arch back and the rock, and perform surface landscape modification. Use a small hopper to carefully fill 5-10 mm graded gravel into the gap between the rammed earth arch back and the rock, lightly vibrate and compact, and then use cement slurry for pressure grouting to fill the gravel gaps completely, forming a concrete backing that enhances the overall integrity and load-bearing capacity of the arch. Finally, select small stones with similar color and texture to the side arch stones, and use cement mortar to embed and paste them on the construction joints and surface, hiding the artificial traces. Embodiment

[0030] As shown in Figs. 1-3 , the present embodiment provides a method for supporting the arch of a hole with rammed stone side arches, comprising the following steps: S1: Hole positioning and foundation trench excavation: According to the design, excavate the hole foundation trench, compact the base and lay a gravel cushion. After the foundation trench is excavated, lay a 80mm thick gravel cushion to save materials; S2: Side arch rockery masonry: Select thick stones for dry laying to the design arch line elevation, reserve a rough surface on the inside, and embed shear nails at the arch foot. Increase the rough surface depth on the inside to 50mm to further enhance the mechanical interlocking force with the rammed earth; S3: Installation of deformable combined formwork system: Install the inner formwork composed of bamboo sheet grating and outer PVC soft membrane, and fix and support it with adjustable steel hoops. Reserve a settlement allowance slot between the formwork outside and the side arch stone. Before installing the bamboo sheet grating, apply waste engine oil as a release agent on its surface to facilitate demoulding and realize the secondary use of bamboo sheets; S4: Preparation of improved rammed earth: Prepare the improved soil according to the predetermined volume ratio, control the water content, and prepare the bamboo mesh. To improve early strength and water stability, the optimized ratio is: 45% clay, 30% sand, 15% stone chips, 5% quicklime, and 3% cement; S5: Layered ramming and arch forming: Improved rammed earth is filled into the formwork system layer by layer, each layer is rammed to the predetermined compaction degree, bamboo mesh is placed between layers, ramming is performed to the designed vault after which a settlement allowance is reserved and curing is performed, more stringent control standards are adopted, 130mm thick soil is filled in each layer, ramming is performed 8 times, and the compaction degree reaches 95%; S6: Demolition and water flushing: After the curing period is over, the formwork system is removed, the inner wall is washed with a high-pressure water gun, loose residual mud is removed, and a smooth and natural inner wall surface is formed; S7: Backfilling and landscape modification: Gap between rammed earth arch back and mountain stone is backfilled and grouted, and surface landscape modification is performed.

[0031] In this embodiment, part of the material is saved by reducing the thick crushed stone cushion layer, the cost is reduced, the mechanical engagement force with the rammed earth is enhanced by increasing the depth of the inner rough surface, the early strength and water stability are improved by changing the improved rammed earth ratio, the control standards of layered ramming and arch are improved, and thus the strength and durability of the overall structure are improved. Embodiment

[0032] The embodiment of the present application provides a hole arch springing formwork method of a rammed stone side arch, which comprises the following steps: S1: Hole positioning and base trench excavation: According to the design, the hole chamber base trench is excavated, the base is rammed and a crushed stone cushion layer is laid; S2: Side arch false mountain stone masonry: Thick stone is dry-laid to the design springing line elevation, an inner rough surface is reserved, and shear nails are embedded at the arch foot part; S3: Installation of deformable combined formwork system: An inner formwork composed of bamboo sheet grating and outer covered PVC soft film is installed, and is fixed and supported by an adjustable steel hoop, and a settlement allowance groove is reserved between the formwork outside and the side arch stone; S4: Improved rammed earth preparation: Improved earth is prepared according to a predetermined volume ratio, the water content is controlled, and bamboo mesh is prepared; S5: Layered ramming and arch forming: Improved rammed earth is filled into the formwork system layer by layer, each layer is rammed to the predetermined compaction degree, bamboo mesh is placed between layers, ramming is performed to the designed vault after which a settlement allowance is reserved and curing is performed; S6: Demolition and water flushing: After the curing period is over, the formwork system is removed, the inner wall is washed with a high-pressure water gun, loose residual mud is removed, and a smooth and natural inner wall surface is formed; S7: Backfilling and landscape modification: Gap between rammed earth arch back and mountain stone is backfilled and grouted, and surface landscape modification is performed.

[0033] In this embodiment, the large-span arch is reinforced and constructed. Specifically, when the base slot bottom width B = 4.6m, the base compaction degree is increased to 95%, the side arch stone is selected to be large whole stone with a thickness of ≥300mm, and a tie stone is built every certain distance in the interior of the masonry, penetrating through the whole stone wall thickness, enhancing the stability of the masonry itself, the shear pin spacing is encrypted to 300mm, the longitudinal main keel of the bamboo sheet grid is double-pasted bamboo sheet, the transverse spacing is encrypted to 100mm, the thickness of the layered ramming is reduced to 120mm, the ramming number is increased to 8 times, and the compaction degree is required to be ≥93%. The bamboo mesh is changed from single layer to double layer arrangement, the arch back filling is replaced by C20 fine stone concrete instead of gravel grouting, and the filling density and overall strength are ensured. EMBODIMENT

[0034] The embodiment of the application provides a hole arch arch springing formwork method of rammed stone side arch, which comprises the following steps: S1: hole positioning and base slot excavation: according to the design line, excavate the hole chamber base slot, compact the base and lay the gravel cushion; S2: side arch false stone masonry: thick stone is dry-laid to the design arching line elevation, the inner side is reserved with a rough surface, and shear pins are embedded at the arch foot part; S3: installation of deformable combined formwork system: install the inner formwork composed of bamboo sheet grid and outer covering PVC soft film, and fix and support through adjustable steel hoops, and reserve a settlement allowance groove between the formwork outside and the side arch stone; S4: preparation of improved rammed earth: prepare the improved earth according to the predetermined volume ratio, control the water content, and prepare the bamboo mesh; S5: layered ramming and arch springing forming: fill the improved rammed earth into the formwork in layers, compact each layer to a predetermined compaction degree, and insert the bamboo mesh between the layers, reserve a settlement allowance after ramming to the design arch top, and maintain; S6: formwork removal and mud flushing: after the maintenance period is up, remove the formwork system, and wash the inner wall with a high-pressure water gun to remove loose residual mud, and form a smooth and natural inner wall surface; S7: arch back filling and landscape modification: fill and grout the gap between the rammed earth arch back and the stone, and perform surface landscape modification.

[0035] In this embodiment, the adaptive treatment on soft foundation such as silt clay, after excavating the foundation trench, first dig down 600mm, replace the graded sand and compact layer by layer to form a bearing layer. Or drive in the pine pile or precast concrete short pile (pile length 1.5m, spacing 0.8m) at the bottom of the foundation trench, and then lay the gravel cushion. In order to reduce the self weight of the arch, the improved soil ratio is adjusted: use lightweight kaolin to replace part of the clay, and mix in a small amount of foam particles (volume ratio about 5%) as lightweight aggregate to reduce the density of the soil body, and use lightweight ceramsite or foamed cement block for backfilling material in the arch back, and use micro-expanding cement mortar for grouting to adapt to the possible micro-uniform settlement of the soft foundation. Embodiment

[0036] The embodiment of the application provides a hole arch barrel formwork method of rammed stone side arch, which comprises the following steps: S1: hole positioning and foundation trench excavation: according to the design line, excavate the hole chamber foundation trench, compact the base and lay the gravel cushion; S2: side arch false stone masonry: select thick stone to be dry laid to the design arching line elevation, reserve a rough surface on the inner side, and bury shear nails at the arch foot part; S3: installation of deformable combined formwork system: install the inner formwork composed of bamboo sheet grating and outer covering PVC soft film, and fix and support through the adjustable steel hoop, and reserve a settlement allowance groove between the side arch stone and the outer side of the formwork; S4: preparation of improved rammed soil: prepare the improved soil according to the predetermined volume ratio, control the water content, and prepare the bamboo mesh; S5: layering and ramming and arch barrel forming: fill the improved rammed soil into the formwork layer by layer, compact each layer to the predetermined compaction degree, and place the bamboo mesh between the layers, reserve the settlement allowance after ramming to the design arch top, and maintain; S6: formwork removal and water flushing: after the maintenance period is up, remove the formwork system, and wash the inner wall with a high-pressure water gun to remove the loose residual mud, and form a smooth and natural inner wall surface; S7: arch back backfilling and landscape modification: backfill and grout in the gap between the rammed soil arch back and the stone, and perform surface landscape modification.

[0037] In this embodiment, bamboo sheet grid is pre-prepared and modularized, and a variety of standard span semi-circular arch truss units are pre-prepared in the processing factory, which are quickly assembled on site, greatly shortening the formwork time and changing the on-site ramming process. Off-site, the improved soil is rammed into the predetermined shape of the arc-shaped rammed earth block (with concave and convex mortise and tenon) in the steel mold under high pressure, and the bamboo mesh is embedded. After curing to the required strength, it is transported to the site. After the formwork system is installed, the precast rammed earth block is laid like brickwork, and the arch is quickly formed. The settlement space reserved at the top is leveled with low-strength grade mortar. This method can shorten the on-site operation time by more than 60%, and the quality is easier to control. After the formwork is removed, the inner wall is the joint surface of the precast block, which only needs to be cleaned simply without the need for high-pressure water gun flushing.

[0038] By using the above-mentioned rammed stone side arch hole arch springing formwork method, not only the efficient and stable construction of the hole arch is realized, but also the landscape effect and environmental protection are taken into account. Each embodiment is optimized for different working conditions and requirements, such as adjusting the material ratio, strengthening the structural stability, optimizing the construction process, etc., which effectively improves the strength and durability of the overall structure. At the same time, this method makes full use of renewable resources such as bamboo sheet grid and PVC soft membrane, which not only reduces the construction cost, but also realizes green construction. In addition, through fine construction control and post-maintenance, the smoothness and naturalness of the hole arch after forming are ensured, and the expected landscape effect is achieved.

[0039] The present application uses a combination of side stones and rammed earth, and the core load-bearing part uses locally available improved rammed earth, reducing the amount of stone material. Compared with the all-stone arch, the amount of stone material is reduced by more than 35%, the material cost is significantly reduced, combined with the reduced transportation cost and the reusable formwork system, the overall project cost is reduced by about 25%, which has good economic efficiency and market promotion value.

[0040] Because the rammed earth has a much lower bulk density than stone, the combined arch of rammed earth and side stone has a lower self-weight, reducing the requirements for arch foot thrust and foundation bearing capacity, and can well adapt to soft soil, uneven foundation and other poor geological areas, expanding the application range. Through the embedded bamboo mesh and the pre-buried shear-resistant nails at the arch foot, a high-efficiency composite structure is formed, and the bearing capacity is greatly improved compared with the pure rammed earth arch structure, with higher safety reserve.

[0041] The present application adopts a deformable and reusable formwork system (bamboo sheet grid + PVC soft membrane + adjustable steel hoop), which has the advantages of light weight, easy processing and simple installation and disassembly, solves the problem of formwork on irregular stone surfaces, and compared with traditional wood formwork or steel formwork, the construction efficiency is improved by 30%, further reducing the cost of measure items. The main materials are natural or renewable materials, and the construction process is low in energy consumption and low in pollution.

[0042] The invention adopts the water flushing mud process to flush away the surface floating slurry, the exposed rammed earth inner wall retains the rustic beauty of the rammed earth, and is integrated with the external artificial rock, the water stability and freeze-thaw resistance of the modified rammed earth body are good, the mass loss is less than 3% after 50 freeze-thaw cycles, which is better than traditional raw soil buildings, meets the durability requirement of long-term use in outdoor environment, and guarantees the persistence of landscape effect.

[0043] The process of layered ramming, strictly controlling the compaction degree and water content ensures the uniformity and density of the rammed earth body, the graded gravel is used for backfilling of the arch back, the effective transmission of load is guaranteed, and finally the formed structure has good quality reliability and overall stability.

[0044] The basic principles of the present disclosure are described above in combination with specific embodiments, but it should be pointed out that the advantages, advantages, effects and the like mentioned in the present disclosure are only examples and cannot be considered as the must-have of each embodiment of the present disclosure. In addition, the specific details of the above disclosure are only for the purpose of example and for the purpose of understanding, and the above details do not limit the present disclosure to the must-use specific details.

[0045] In the present disclosure, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations, and the block diagrams of the devices, apparatuses, equipment, systems involved in the present disclosure are only illustrative examples and are not intended to require or imply the connection, arrangement, configuration shown in the block diagram. As those skilled in the art will recognize, these devices, apparatuses, equipment, systems can be connected, arranged, configured in any manner. Words such as "include", "contain", "have" and the like are open-ended words, which mean "including but not limited to", and can be used interchangeably. The words "or" and "and" used herein mean the word "and / or", and can be used interchangeably unless the context clearly indicates otherwise. The word "such as" used herein means the phrase "such as but not limited to", and can be used interchangeably.

[0046] In addition, as used herein, "or" used in the list of items starting with "at least one of indicates a separate list, so that, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e. A and B and C). In addition, the phrase "exemplary" does not mean that the described example is preferred or better than other examples.

[0047] It should also be noted that in the method of the present disclosure, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions of the present disclosure.

[0048] Various changes, modifications and alterations to the techniques described herein can be made without departing from the teachings of the attached claims. Moreover, the scope of the claims should not be limited to the particular aspects described herein, but should be given the broadest interpretation available to them under the law. The appended claims are intended to cover all such changes, modifications and alterations as fall within the scope of the claims.

[0049] The above description of disclosed aspects is intended to be illustrative, and not restrictive. Many other aspects can be apparent upon reading and understanding the above description, and modifications that can be made without departing from the spirit and scope of the disclosure are intended to be within the scope of the claims. Further, it is intended that any incorporation by reference of pending patent applications or provisional patent applications be only that version of an application prior to first publication of the patent application. No incorporation by reference is intended to be to any subsequent version of an application published after the priority date of this application.

[0050] The above description has been presented for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the disclosure to forms disclosed herein. Although various example aspects and embodiments have been discussed above, those of ordinary skill in the art will appreciate a variety of modifications, alternative constructions, adaptations, and equivalents. Accordingly, other aspects and embodiments are intended to be within the scope of the claims.

Claims

1. A method for supporting the formwork of a rammed stone arch, characterized in that, Includes the following steps: S1: Opening location and foundation trench excavation: According to the design layout, excavate the foundation trench of the cave, compact the foundation and lay a crushed stone cushion layer; S2: Side arch rockery construction: use thick stone slabs to dry-lay to the designed arch line elevation, leave a rough surface on the inner side, and embed anti-shear nails at the arch foot. S3: Deformable combined formwork system installation: Install the inner formwork consisting of bamboo grid and PVC soft film, and fix it with adjustable steel hoops. Reserve a settlement allowance groove between the outer side of the formwork and the side arch stone. S4: Improved rammed soil preparation: Prepare improved soil according to the predetermined volume ratio, control the moisture content, and prepare bamboo mesh. S5: Layered ramming and arch forming: The improved rammed earth is filled into the formwork system in layers, each layer is rammed to the predetermined compaction degree, and bamboo mesh is placed between the layers. After ramming to the designed arch top, a settlement allowance is reserved and the arch is cured. S6: Demolding and Water Flushing: After the curing period, the formwork system is removed, and the inner wall is flushed with a high-pressure water gun to remove loose mud and form a smooth and natural inner wall surface. S7: Arch Backfill and Landscape Refinement: Grouting is performed in the gap between the rammed earth arch and the rocks, and the surface is then landscaped.

2. The method for formwork support of a rammed stone side arch according to claim 1, characterized in that: In step S1, the bottom width of the foundation trench is B = (D + 0.6) m, where D is the designed span; the thickness of the crushed stone cushion layer is 80-100 mm.

3. The method for formwork support of a rammed stone side arch according to claim 1, characterized in that: In step S2, the thickness of the stone slab is not less than 200mm; the reserved depth of the rough surface is 30-50mm; the shear nails are Φ8mm stainless steel nails with an exposed length of 150mm and a quincunx arrangement with a spacing of 400mm.

4. The method for formwork support of a rammed stone side arch according to claim 1, characterized in that: In step S3, the bamboo grid is formed by binding Φ20mm bamboo strips with a longitudinal and transverse spacing of 150mm into a semi-circular frame; the adjustable steel hoop is made of 50mm×5mm flat steel, and the radius is adjusted by bolts, with an installation spacing of 800mm; the settlement allowance groove is formed by inserting 10mm thick foam strips.

5. The method for formwork support of a rammed stone side arch according to claim 1, characterized in that: In step S3, the surface of the bamboo grid is pre-coated with a release agent.

6. The method for formwork support of a rammed stone side arch according to claim 1, characterized in that: In step S4, the volume ratio of the improved rammed earth is: 45%-55% cohesive soil, 25%-35% sand, 15%-20% stone chips, 3%-5% quicklime, and 2%-3% cement; the moisture content is controlled within the range of the optimum moisture content ±2%; the bamboo mesh is made of Φ6mm bamboo fibers, and the overlap length is not less than 200mm.

7. The method for formwork support of a rammed stone side arch according to claim 1, characterized in that: In step S5, each layer of fill is 130-150mm thick and is compacted 6-8 times with an electric impact rammer, with a compaction degree of not less than 90%-95%; the settlement allowance at the top is 30mm.

8. The method for formwork support of a rammed stone side arch according to claim 1, characterized in that: In step S6, the adjustable steel hoop is removed first during demolding, and then the bamboo grid is pulled out; the flushing water pressure is 0.3MPa, and the flushing water is discharged to the sedimentation tank for recycling through the underground ditch pre-buried in the foundation trench.

9. The method for formwork support of a rammed stone side arch according to claim 1, characterized in that: In step S7, the void backfill material is graded crushed stone and grouting; the surface is covered with small stones of the same color to hide the construction joint and restore the natural stone texture.

10. The method for formwork support of a rammed stone side arch according to claim 4, characterized in that: The settling allowance tank is later filled with compressible polyurethane foam.

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