64 results about "Soil arching" patented technology

The e invention relates to a power soil arch model testing system and method based on a transparent soil technology. The testing system comprises a reaction frame, a loading device, a model bracket, a vertical sliding screw, a worm gear case body, a horizontal connecting shaft, an electric motor, a laser emitter and measurement equipment; fixed blocks and movable blocks are mounted at the bottom of a model groove; the model groove can perform relative displacement to the fixed blocks by shifting the movable blocks after being provided with transparent soil, and forms stable soil arches in the transparent soil; the loading device is mounted on the reaction frame, so as to perform power loading and simulate the influence on the soil arches by power load. The method comprises the steps of determining the sizes and quantity of required fixed blocks and movable blocks, mounting and sealing the fixed blocks and movable blocks, mounting the electric motor, the horizontal connecting shaft, the vertical sliding screw and the worm gear case body, drawing the movable blocks to move, simulating situations of positive and negative soil arches and different quantity of soil arches, fixing the movable blocks after the soil arches are formed, performing power loading through the loading device, shooting laser speckle field through a high-speed camera during testing, and analyzing rules of the formation of the soil arches and evolution of the soil arches under dynamic load.

The invention discloses a soil arching tester which aims at realizing the direct reappearance of soil arching and can validate the soil arching through the testing of soil pressure before arching. The soil arching tester comprises a tank body (10), arch spring model columns (11), a pressurization device and a force measuring device; the tank body (10) is provided with an upper port and a lower port; two arch spring model columns (11) are alternately arranged on the lower port of the tank body (10); the pressurization device is arranged on the upper part of the upper port of the tank body (10); and the lower part of the lower port of the tank body (10) is provided with a dropping space (14) for the soil before arching. The soil arching tester has the advantages that: the soil arching tester can realize the direct reappearance of the soil arching, can directly measure the height and the span of the arch and draw the arch form and obtain the arch axis through the calculation; and through the measurement of the pressure distribution of the soil before arching, the soil arching tester determines the existence and the influencing factors of the soil arching, determines the span of the arch, has a simple structure and can conveniently carry out the soil arching tests of various soils.

The invention discloses a pile supported reinforced embankment three-dimensional soil arching effect testing apparatus and a pile-supported reinforced embankment three-dimensional soil arching effect testing method. The testing apparatus is composed of a rectangular box base, wherein piles are arranged at the four corners of the hollow part of the interior of the rectangular box base. The surfaces of the piles are flat and are at the same level. A cavity part surrounded by the piles and the rectangular box base is provided with a heteromorphic water bag with a cross-shaped surface. Four armorplate glasses encircle to form a rectangular space and are arranged on the rectangular box base. The upper surfaces of the piles and the heteromorphic water bag are provided with multiple earth pressure cells the upper parts of which are filled with embankment fill materials. A displacement meter is arranged on the top surface of the embankment fill materials. According to the invention, rubber water bags infused with water are used for filling the embankment fill materials layer by layer. As a result, the incompressibility of water ensures that relative displacement of a soil pile is always kept as zero when the embankment is filled to reach a reset height. The sedimentation of soft soil can be simulated by virtue of a method of gradual drainage of water, so as to accurately control the relative displacement of the soil pile.

The invention relates to a test device for simulating a soil arching effect. The test device comprises a test box and a lifting device, wherein a settling unit plate and nonsettling unit plates are arranged at the bottom of the test box; the lifting device comprises a rising and falling power device, a jacking tube platform plate and a jacking tube; the jacking tube platform plate rises or falls by the rising and falling power device; the jacking tube is used for rising and falling of the settling unit plate. Compared with the prior art, the test device has the advantages that the soil arching effect of backfill of works under a variety of working conditions can be simulated, and the soil arching effect of foundations of works in case of large deformation can be simulated.

The invention relates to a test system for simulating a degradation law of dynamic soil arching effects, the test system is composed of a loading device, an observation device, a testing device and anadjusting device. The loading device controls load loading on the adjusting device, and the observation device is arranged on one side of the adjusting device. The testing device is used for testing.Compared with the prior art, the test system can improve the testing of the dynamic soil arching effects, realize the simultaneous observation of different degrees of soil arching effects, stress fields and displacement fields, and realize the change of different levels of factors. The test system can improve the test accuracy and maintain the convenience of operation.

The invention relates to a grouting method for dealing with tunnel collapse which comprises the following steps: (1) directly sending two grouting pipes from an opening of a collapsed section into a collapsed slag body, controlling the grouting point to be 5 to 6 meters above the top of the opening, injecting the slurry into the loose body. During the grouting process, the slurry is lowered and wrapped by the grouting point, and the lower loose body is consolidated. As the slurry is solidified in the lower part and the liquid level of the slurry in the slag body is gradually raised to the pulping point, completing the wrapping and the consolidation of the loose body below the pulping point; (2) using the traditional soil arching effect principle to consolidate the loose body of the top arch of the collapsed section, that is, after the consolidation of the loose body in the range of 5 to 6 meters above the top of the opening, excavating the top of the tunnel of the collapsed section into an arch shape, and bearing the load of the upper loose body by using the arch effect; (3) after completing the loose ring reinforcement of 5 to 6 meters at the top of the opening, according to the supporting method of the V-type surrounding rock, the steel support made of the I-shaped steel and the top arch excavation work surface are firmly fixed every 0.5 meter, jointly bearing the load of thetop arch. The aim of the grouting method is to overcome the defects existing in the prior three traditional grouting methods and to provide a fast, efficient and safe method for grouting tunnel collapse.

The invention belongs to the technical field of geotechnical engineering and specifically relates to a cutting slope frame anchor wall construction method based on the soil arching effect. The method includes: firstly excavating slope plain stages and setting pre-reinforcement piles; calculating the length and the sectional area of anchor rods according to Coulomb active earth pressure acting on anchor walls; manufacturing the anchor rods according to the determinate length and the determinate sectional area of the anchor rods and setting anchor wall bodies; finally performing slope green protection construction. The construction method gives full consideration to interaction of structures between the piles, namely the pre-reinforcement piles can form the soil arching effect between the piles. When the frame anchor walls are constructed, the length and the sectional area of the construction anchor rods can be calculated according to the earth pressure, calculation results are accurate, engineering investment can be saved during construction, a target of safety is achieved, and materials can be saved.

The invention relates to a permafrost region expressway flaky and blocky stone ventilation roadbed and a construction method thereof. The construction safety and the service life are severely influenced caused by the lengthways cracking of the roadbed, the roadbed size effect under the asphaltpavement and the like because of the hot melting and the sinking of the permafrost roadbed. The construction method comprises the following steps of: impacting, laminating and filling 30cm of lower gravel cushion layer at a soil arching base; impacting and laminating the lower gravel cushion layer under the ground line; building a flaky and blocky stone layer with the thickness of 0.9m-1.5m on the lower gravel cushion layer; flattening the upper part of the flaky and blocky stone layer by a macadam transition layer with the thickness of 20cm; filling an upper gravel cushion layer with the thickness of 30cm; paving a water-permeable geotextile between the upper gravel cushion layer and the macadam transition layer; distributing a geogrid which is made from the plastic steel at the upper part of the upper gravel cushion layer; and compacting by a heavy type vibratory roller layer by layer. Therefore, the melting of the permafrost roadbed and the uneven deforming of the permafrost roadbed can be reduced, the influence of the climate warming and the human engineering activity to the permafrost roadbed characteristic can be reduced, and the safety and the flaky and blocky stone stability of the roadbed structure can be improved.

The invention discloses a soil arching effect demonstrator. There is a half cylindrical rubber airbag in the center of the bottom of Perspex box. Outside the airbag there is flexible rubber membrane. They are fixed at the bottom of Perspex box. From bottom to top, the Perspex box is filled with yellow sand and black sand; tube of the airbag is connected with inflatable bag outside the Perspex box; in the tube of inflatable bag, there is release valve and forward one-way valve; there is one backward one-way valve in the inflatable bag. By giving air and releasing air, the soil arching can be directly observed.

The invention discloses a pile net for landslide or rockfall disaster protection and a design method thereof. The pile net for landslide or rockfall disaster protection includes at least two anti-slide piles arranged adjacent to a rock and soil mass and deepened in a stable rock stratum under a sliding surface. Flexible protective nets whose two sides are fixed on the anti-slide piles through a plurality of pull rings are arranged between the two adjacent anti-slide piles. The design method of the pile net includes an arch axis equation corresponding to an arch when forming a soil arching effect of the rock and soil mass; according to the static balance of the soil arch, the axial pressure on the arch axis is calculated; when the axial pressure has the maximum value, a failure surface of the soil arch can be obtained according to an arch distance corresponding to the maximum axial pressure; when the pile is in a static equilibrium condition, the angle between the failure plane and a horizontal plane is calculated; based on the principle that a trapezoidal compression zone at the failure surface is not destroyed and the Kulun strength theorem, the pile distance of the two adjacent anti-slide piles is calculated; according to the collapse amount of empty soil between the piles, the strength of the flexible protective nets is calculated.

The invention discloses a three-dimensional array type multi-settlement door model test system which comprises an outer frame; the outer frame is internally provided with a filler box used for filling a material; a multi-settlement door component which is controlled by a displacement control component is arranged at the bottom of the filler box, comprises a plurality of lifting tables which are arranged in an array manner and are adjustable in height and is provided with a geogrid mounting component; a surface displacement measurement component used for measuring the morphologic change of the top of the filled material is arranged on the top of the outer frame; and a cross section displacement visualization measurement component used for measuring the morphologic change of the cross section of the filled material is arranged on the front side of the outer frame. The whole system can realize simulation on vertical soil arching effect and is particularly suitable for simulation on the phenomena of filler deformation and load transfer under the condition of non-uniform settlement of piled embankments and soil between piles in composite foundation cushions.

The invention discloses a pile-reinforcement material composite foundation structure and construction methods thereof. The pile-reinforcement material composite foundation structure comprises a plurality of supporting piles, reinforcement materials, a low-rigidity material filling layer and a soil filling layer, wherein the supporting piles are separately and vertically penetrated in a soft soil foundation; the lower part of each of the supporting piles penetrates in the soil foundation, and the upper part of each of the supporting piles is buried in the low-rigidity material filling layer; the top surfaces of the supporting piles are in contact with the reinforcement materials; and the soil filling layer is covered on the reinforcement materials. One construction method comprises the following steps of performing piling; digging up part of filled soil; performing filling with substitute materials; paving the reinforcement materials; performing opposite packing and fixing on road shoulders; and paving upper covered filled soil. The other construction method comprises the following steps of performing superficial-layer material stirring and mixing; performing piling; paving the reinforcement materials; performing opposite packing and fixing on the road shoulders; and paving the upper covered filled soil. According to the pile-reinforcement material composite foundation structure and construction methods thereof disclosed by the invention, the stretching resistance effect of the opposite packed reinforcement materials can be sufficiently utilized, so that the problem that the lateral displacement of a roadbed and the lateral displacement of a road embankment are large is solved; and the soil arching effect and the film effect can also be sufficiently utilized, the differential settlement of the roadbed is improved, and the purpose of improving the integral stability of a road is achieved.

The invention relates to a method for predicting the overlying earth pressure of a flexible pipeline based on a three-dimensional soil arching effect, belonging to the field of underground space engineering. By calculating and analyzing the soil arching effect caused by the uneven settlement of the foundation in the overburden of the pipeline, and using the rigid body limit equilibrium theory, theprediction formula of the overburden pressure of the pipeline is established, and then the overburden pressure of the buried flexible pipeline under the uneven settlement of the foundation is calculated. The invention provides a safe and conservative design method for calculating the overburden earth pressure of a buried flexible pipeline under the condition of uneven settlement of a foundation,which is based on a three-dimensional soil arching effect.

The invention relates to a horizontal sliding type soil arching effect tester and a usage thereof. The horizontal sliding type soil arching effect tester comprises a test box and a lifter; a structural unit plate and a nonstructural unit plate are arranged on the bottom of the test box; the lifter comprises a lifting power device, a top tube platform plate and a top tube; the top tube platform plate can go up and down by means of the lifting power device; and the top tube can slide in a slide way of the top tube platform plate. The usage of the horizontal sliding type soil arching effect tester includes: adjusting the position of the top tube, raising the top tube to fix the structural unit plate, and gradually lowering the structural unit plate to simulate an actual working condition. When adopted to carry out a test to compare soil arching effects of culverts at different positions, the horizontal sliding type soil arching effect tester and the usage disclosed by the invention have the effects of time and labor saving, economy, accurate results and the like.

The invention provides a particle arching characteristic test device and a test method thereof. The test device comprises a height-adjustable platform institution, a perspective mold case mechanism used for accommodating particle samples, a loading mechanism capable of controlling frequency conversion and a levelling support mechanism, wherein the platform mechanism is positioned below the support mechanism; the mold case mechanism is arranged on the platform mechanism; the loading mechanism is arranged on the support mechanism and comprises a loading end; the loading end penetrates through the support mechanism and used for continuously applying dynamic loading to the particle samples; the bottom of the mold case mechanism is provided with dodge gates capable of adjusting opening or folding, and a particle feeding hole is formed between the opened dodge gates so as to ensure particle feeding and arching of the particle samples. The invention researches that under the effect of dynamic load, after a particle system is subjected to arching, a theoretical guide role can be achieved for the problems such as arch effect degradation, invalid microscomic evolution process, gradual change mechanism and degradation and even unavailability of soil arching effect, and furthermore particle displacement and particle contact force changes can be synchronously obtained.

The invention relates to a visible soil destruction mode capture device. The visible soil destruction mode capture device comprises a model box, a loading system, a sand scattering device, a sand unloading device, and a magnetic scale board, wherein the loading system and the sand scattering device are above the model box, the loading system comprises a horizontal loading device and a vertical loading device, the sand unloading device and the magnetic scale board are respectively arranged at two adjacent sides of the model box, and the sand scattering device can move above the model box left and right and front and back and scatters sand into the model box. The visible soil destruction mode capture device can scatter sand uniformly, efficiently and effortlessly and unloads sand rapidly, can simulate compactness of natural soil accurately, deploys color sand uniformly and flexibly, can perform vertical and horizontal load simultaneously in different positions, and enables operators to observe intuitively soil destruction phenomena like 'soil arching', destruction face mode of an active face, and destruction mode of a composite foundation.

The invention discloses a passive pile soil arching effect testing method based on a seepage effect. The method comprises the following steps: preparing a soil sample; designing a pile distance, and arranging a displacement meter; simulating a passive pile pile-soil interaction environment, and burying a pressure box or an osmotic pressure gauge in the soil sample; simulating landslide push force, building a water circulating system for simulating seepage, monitoring stress, displacement and pore water pressure changes at different positions of the soil sample through the pressure box, the displacement meter and the osmotic pressure gauge, and building an internal stress field, a surface displacement field and a seepage field of the soil sample; changing a water environment of the soil sample; changing the type, shape, size and pile distance of a simulation pile in a test box; replacing the soil sample, and researching soil arching effects in different environments. By adopting the passive pile soil arching effect testing method, the forming, developing and failing processes of a soil arch under a water-free condition, a water-saturated condition and a seepage condition are simulated for the first time, the mechanism of water-soil interaction in the soil arching effect is revealed; researches on the aspects of foundation pit supporting and slope prevention and control are enriched, and relevant theories of the conventional soil-arching effect under the seepage condition are supplemented.

The invention discloses a test device for simulating a dynamic soil arching effect of a shed frame structure. The device comprises a concrete base, a model box frame is arranged on the concrete base,surrounding rock, sand and a roadbed are arranged in the model box frame, a shed frame structure simulating an advanced shed frame structure is arranged between the surrounding rock and the sand, a dowel bar loaded by an actuator is arranged above the roadbed, and a sensor for collection is further arranged in the model box frame. According to the invention, loading equipment is introduced into the pipe shed soil arching effect test for the first time, and meanwhile, various monitoring equipment is adopted to monitor deformation and stress strain in the test process, so that the dynamic soil arching effect in actual engineering is reflected more truly. Based on the method, the mutual relation between the pipe shed parameters and the traffic load amplitude frequency can be further obtained,suggestions are provided for design optimization of the pipe shed parameters, and therefore construction safety in the tunnel excavation process is guaranteed.

The invention relates to a demonstrative experiment instrument for a slide-resistant pile supporting and retaining mechanism and an end bearing pile supporting and retaining mechanism, in particular to a multi-functional soil arching instrument which comprises a foundation base, a power system, a model pile system, transverse supporting boundaries, vertical supporting boundaries and a model pile cover plate. The model pile system is arranged on the foundation base. The transverse supporting boundaries are arranged at the front end and the rear end of the upper surface of the foundation base. The vertical supporting boundaries are arranged at the left end and the right end of the upper surface of the foundation base. The vertical supporting boundaries and the transverse supporting boundaries surround the model pile system to form a rectangle. The model pile system comprises a front load uniform distribution assembly, a rear load uniform distribution assembly, a left baffle, a right baffle and a model pile bottom plate. Deformation and pressure distribution of soil in the model pile system along a model pile are observed according to a force applied by a thruster, and the soil arching effect and a pile-soil interaction phenomenon under different stress condition, different conditions and different slopes can be observed intuitively.

The invention provides a movable door device for measuring the soil arching effect of overlapped tunnels and a test method. The movable door device comprises a box body, a movable door, a tunnel modeland a three-dimensional scanner. The movable door is horizontally arranged in the box body, a plurality of soil pressure boxes are arranged on the movable door, a space defined by the upper surface of the movable door and the box body is used for containing a soil body, and the tunnel model is arranged in the soil body. The movable door can move. The movable door moves to enable the soil body tocollapse, and the soil pressure box can measure the vertical soil pressure of the soil body. The three-dimensional scanner is arranged in the box body and located below the movable door, and the three-dimensional scanner can measure the arch axis of the soil body forming the soil arch effect. By means of the movable door device and the test method, the soil arching effect generated by the spaces with different widths of the overlapped tunnels can be tested.

The invention relates to an antiskid pile with a T-shaped cross section. The antiskid pile is formed by pouring reinforced concrete, the cross section of the antiskid pile is in a shape of a T, the top of the T serves as a front end of the pile, the bottom of the T serves as a rear end of the pile, an arc-shaped part is formed between the front end and the rear end of the pile, the design of the arc-shaped part can prevent stress concentration from being generated at a pointed position, rebar cages are mounted in the antiskid pile, dense rebars are arranged in the rebar cage at the rear end of the pile, and few rebars are arranged at the front end and the arc-shaped part. The transverse width of the rear end of the pile is larger than that of the front end of the pile, so that soil arching effect behind the pile can be brought into full play, and during slope treatment, the distance of pile centers between adjacent antiskid piles can be increased while the number of the antiskid piles needed to be arranged is decreased correspondingly; and in addition, the area of the antiskid pile with the T-shaped cross section is evidently smaller than that of an antiskid pile with a rectangular cross section, so that concrete and the rebars can be greatly saved, and cost is lowered. The antiskid pile is small in construction section, convenient for mechanical construction, simple and safe in construction and wide in popularization and application prospect.

The invention discloses an offshore wind power single pile-friction wing composite foundation and a construction method thereof. The offshore wind power single pile-friction wing composite foundation comprises a single pile and a friction wing, wherein the friction wing is connected to the single pile through a force transmission pipe, a conical transition section of the single pile goes deep into a seabed bearing stratum, and the force transmission pipe of the friction wing located in the bearing stratum is in close contact with the conical transition section of the single pile; a side wing of the friction wing is connected to the outer wall of the force transmission pipe, and a ring wing is arranged in a side wing included angle. According to the offshore wind power single pile-friction wing composite foundation, the friction wing is of a through structure in the axial direction, so that the friction wing can conveniently penetrate through a seabed sludge layer to be embedded into the bearing stratum; the side wing, the ring wing and the force transmission pipe support each other, so that the structural stability of the friction wing is kept, a soil arching effect is generated between the side wing and the ring wings by a soil body, the resistance of the soil body is remarkably improved, the interaction area of the structure and the soil body is increased by the friction wing, and the bearing capacity of the single pile-friction wing composite foundation is improved.

The invention discloses a construction method for controlling cracks in a deep-buried circular culvert of a mountain road. The construction method includes the following steps that (1) a roadbed is constructed in a filling mode to the designed height of the top of the circular culvert; (2) the roadbed and a foundation are excavated to the designed elevation of a base of the circular culvert; (3) the base of the circular culvert is poured and maintained; (4) a prefabricated circular culvert body is mounted, a crescent-shaped soil arch guiding cushion layer made of elastoplastic materials is arranged at the top of the circular culvert body, and the two ends of the soil arch guiding cushion layer extend to the two ends in the horizontal outer diameter direction of the circular culvert body correspondingly; (5) the roadbed around the circular culvert is filled in a layered mode and manually tamped; and (6) a soil layer at the top of the circular culvert is rolled in a layered mode, and the roadbed is constructed in a filling mode to the designed elevation. The crescent-shaped soil arch guiding cushion layer is arranged on the circular culvert, and the load on the upper portion of a soil arch is transferred to be borne by the nearby roadbed. The designed load of the circular culvert is distributed in a rectangular shape and larger than the actual load, distributed like collapsing bodies, of the circular culvert, the load on the upper portion of the circular culvert is transferred to be borne by the nearby roadbed, and it is guaranteed that the stress on the circular culvert is smaller than the designed load and within a safety range, so that cracking is prevented.

The invention discloses a prefabricated mushroom-shaped pile cap for a pile-supported reinforced embankment. The prefabricated mushroom-shaped pile cap is characterized in that a prefabricated pile cap comprises a base platform, wherein the upper surface of the base platform protrudes upwards to form a cambered surface, and the cambered surface uniformly and excessively extends to the edge of theupper surface of the base platform from the top of the upper surface of the base platform; a reserved pile hole is formed in the lower surface of the base platform, and the top end of a rigid pile isembedded into the reserved pile hole to be detachably connected with the prefabricated pile cap; and the upper surface of the base platform is tightly attached to a geotechnical reinforcing rib. The pile cap structure can form an arc-shaped structure at the top end of the rigid pile of the pile-supported reinforced embankment, promotes the deformation of the geotechnical reinforcing rib, can promote the exertion of the soil arching effect and the reinforcement effect, and can prevent the geotechnical reinforcement from being damaged at the edge of the pile cap due to overlarge local strain.

The invention discloses a trapezoid drainage slide-resistant pile with a pile with an additional toe and construction method thereof. The trapezoid drainage slide-resistant pile with the pile with theadditional toe is characterized in that the overall cross section of a pile body is trapezoid, the short side surface of the pile body is a soil backing surface, the long side surface of the pile body is a soil facing surface, the pile body is divided into a bottom solid pile body with the additional toe, a lower solid pile body and an upper hollow pile body, the sectional area of the upper hollow pile body is not constant, the sectional area of the upper hollow pile body is gradually reduced from bottom to top, three water collecting spaces are formed in the hollow pile body, the water collecting spaces are connected with a soil facing surface sliding body through water collecting holes, the sectional area of the solid pile body is constant, a drainage cushion layer is arranged at the junction between the solid pile body and the hollow pile body, water diversion holes and drainage holes are formed in the drainage cushion layer, water is drained into a soil facing surface sliding bedthrough the drainage holes, the water collecting spaces, the water diversion holes and the drainage holes are filled with permeable aggregate, and the bottom solid pile body with the additional toe expands all around and has a certain thickness. According to the trapezoid drainage slide-resistant pile with the pile with the additional toe, the soil arching effect can be triggered through the trapezoid cross section shape, the anti-overturning capacity can be improved through the pile with the additional toe, the water content of a sliding body is reduced through self water collection and drainage, and compared with a traditional slide-resistant pile, the material consumption is less.

The invention discloses a soil arching test box and method, wherein the soil arching test box comprises a box body; a soil arching test chamber for being filled with a soil sample is arranged in the box body, the wall top and at least one side wall of the soil arching test box are provided with movable plates, and also provided with pressurizing systems capable of applying pressure towards the soil arching test chamber to the corresponding movable plates, a diameter-variable arching tool is rotatably arranged on each movable plate of the side wall in a positioning manner, the diameter-variable arching tool is a horizontally distributed cylinder, and at least a part of the cross section of the cylinder is in a spiral shape. The soil arching test box provided by the invention has the advantages of being simple in structure and easiness in observation, the device structure is simplified according to symmetrical principle, and the self-weight of the soil arching test box is reduced effectively. The soil arching test method is easy to operate and accurate in result.

The present invention relates to an anti-slide pile soil arching effect evolution mechanism visualization model test device and a test method. The device comprises a visualization model box, a loadingdevice, standard sand, two-side baffle plates, a material dropping plate, a loading plate, a steel plate of a replacement pile, a cushion block and a digital camera arranged outside the visualizationmodel box. The method comprises the following steps: by using the loading plate, gradedly acting a load on the soil via the loading plate; rotating a bottom rotating plate to allow the material dropping plate to drop; loading until that the soil in the visualization model box is collapsed and damaged; and separately shooting the image(s) of the standard sand by the side of the visualization modelbox under the loads of all grades in the test process with the digital camera. According to the test device and the test method, the deformation and development law of the soil around the pile underthe action of the external load can be studied more conveniently and intuitively via the visualization model test.

The invention discloses a formwork tie bar structure of a soil arch mould in a cover-excavation method for a mountain highway tunnel, and a construction method thereof, and belongs to the field of construction adopting a cover-excavation method for a mountain highway tunnel. The formwork tie bar structure of the soil arch mould mainly comprises a cover arch formwork which is arranged on the soil arch mould and composed of a steel formwork, a wood formwork, a steel formwork lacing bar, a lacing bar sleeve and a channel steel backing plate, and two pairs of upper tie bars and lower tie bars which are arranged at the bottoms of the steel formwork and the wood formwork, wherein cover arch concrete is formed between the wood formwork and the steel formwork through pouring, and then lining concrete is poured secondarily. The formwork tie bar structure of the soil arch mould in the cover-excavation method for the mountain highway tunnel has the advantages of being simple in structure, convenient to use, safe and reliable, low in expense, capable of repeatedly utilizing construction materials, and the like; the structure is beneficial to reducing the project quantity of tunnel slope excavation of the construction adopting the cover-excavation method, and saving a spoil ground in conjunction with the corresponding construction method; and the structure further has an effect of energy conservation and emission reduction, and has remarkable economic benefits and social benefits.