A method for making a model for a model load test of a karst pile in an inclined stratified rock formation

Abstract

The application discloses a kind of karst pile model load test model manufacturing methods in inclined layered rock stratum, belong to the category of geotechnical test.The present application is used to make inclined rock stratum pile load test model, it is mainly aimed at the complex stratum of rock stratum occurrence not horizontal, by making inclined rock stratum and bonding each rock stratum, it is used for the rock foundation part of indoor model pile load test.Inclined rock stratum is made by the mold of rock stratum model box, rock stratum inclination model and foam model assembly, the geometric form of rock stratum inclination model determines the inclination of rock stratum.The present application provides a kind of test model manufacturing method for studying karst pile model load test in inclined layered rock stratum, and provides help for studying the bearing deformation characteristics and mechanism of pile in inclined layered rock stratum.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical testing, specifically relating to a method for fabricating a load test model for a karst foundation pile in inclined layered rock strata. Background Technology

[0002] Karst areas are widely distributed in my country. With rapid socio-economic development, the demand for infrastructure construction has increased significantly, and the construction of buildings and structures in karst regions is becoming increasingly common, placing higher demands on foundations (especially pile foundations). Rock-socketed piles, with their excellent bearing capacity, are widely used in karst areas. However, the geological conditions in karst areas are unique. Due to the influence of geological structures, the development of structural planes and joints in rock strata is chaotic, and horizontally dipping rock strata are relatively rare. Current research on rock-socketed piles mostly focuses on horizontal rock strata, rarely considering complex rock strata, and little is known about the bearing characteristics of pile foundations under inclined rock strata. Therefore, studying the bearing characteristics and mechanisms of karst pile foundations in inclined layered rock strata is crucial. This research can fill the gaps in the study of the bearing characteristics of pile foundations in complex rock strata in karst areas, providing a reference for pile foundation design in karst areas, and has significant practical significance and value.

[0003] This invention discloses a method for fabricating a load test model of karst foundation piles in inclined layered rock strata, providing a method for fabricating test models to study the load test of karst foundation piles in inclined layered rock strata, and helping to study the bearing deformation characteristics and mechanism of foundation piles in inclined layered rock strata. Summary of the Invention

[0004] The problem this invention aims to solve is the lack of methods for constructing inclined rock strata in existing indoor model test research. Therefore, it provides a method for constructing a load test model of karst foundation piles in inclined layered rock strata.

[0005] To solve the above problems, the present invention adopts the following technical solution: a method for making a load test model for karst foundation piles in inclined layered rock strata. For the construction of the rock strata portion of the indoor test model for the foundation piles, the rock strata are constructed using a layered casting method. The rock strata inclination angle is determined by fixing a rock strata inclination model with a predetermined angle to both sides of the rock strata model box, and then casting the mold. For the rock-embedded space of the karst caves, earth pressure boxes, and model piles, foam models are fixed at a certain angle to the predetermined positions of the mold, and then layered casting is performed. After the rock strata have cured, all the rock strata are placed into the test model box and bonded with plaster. During the bonding process, the karst caves are filled to a certain extent. Then, the earth pressure box and model piles are placed into the reserved rock-embedded space, and the gaps around the model piles are filled and the pile body of the model piles is fixed. Finally, soil is filled in and compacted.

[0006] Preferably, the rock strata are cast using a mold consisting of a rock strata model box and a rock strata dip angle model. By designing the dimensions of the rock strata model box and the rock strata dip angle model according to requirements, single-layer casting of rock strata or multi-layer casting of the same mold can be achieved (after the rock strata cast in the previous layer has reached a certain strength, the next layer of rock strata is cast on its upper surface).

[0007] Preferably, when casting multiple layers of inclined rock strata in the same mold, there are two scenarios: no pre-reserved space between rock strata and pre-reserved space (for embedding cavities and model piles). Casting without pre-reserved space: No Vaseline needs to be applied between rock strata; the next layer can be cast directly. No adhesive is needed to bond the rock strata, reducing the number of steps. Casting with pre-reserved space between rock strata: Vaseline needs to be applied between rock strata to allow for easy separation and removal of the foam model.

[0008] Preferably, the rock stratum dip model is a right-angled triangular prism or a square prism with a right-angled trapezoidal cross-section. The dip angle of the rock stratum depends on the angle of the right-angled triangle or right-angled trapezoidal cross-section of the prism (within the range of 0° to 90°). The right-angled triangular prism is used for casting longer rock strata, and the square prism with a right-angled trapezoidal cross-section is used for casting shorter rock strata (the rock stratum length mentioned above refers to the cross-sectional length of the rock stratum).

[0009] Preferably, the wire passes through the center of the foam model and is fixed to the center of the mold according to the inclination angle of the rock strata. The fixing end is pre-drilled with a hole, the angle between the hole and the mold is equal to the inclination angle of the rock strata, and the wire is inserted into the hole. The diameter of the hole is slightly larger than the diameter of the wire to ensure accurate angle measurement.

[0010] Preferably, the foam model has a certain strength, is not easily compressed, and can maintain its geometric shape during pouring, thereby ensuring the stability of the karst cave shape and the smooth embedding of subsequent model piles without displacement.

[0011] Preferably, grooves are left around the pile model for attaching strain gauges, and wires are led out from the pile end along the grooves on the pile side. The pile grooves are sealed with AB glue to maintain the integrity of the pile body.

[0012] The beneficial effects of the present invention are as follows: (1) The present invention is a method for making a load test model of karst foundation piles in inclined layered rock strata, including a test model box, a rock strata model box, a rock strata dip angle model, and a foam model. Unlike the existing indoor model test method for pouring horizontally dipping rock strata, the present invention can make complex inclined rock strata, which helps to study the bearing deformation characteristics and mechanism of foundation piles in inclined layered rock strata. (2) The present invention controls the geometric shape of the poured rock strata cross section by adjusting the cross-sectional angle of the rock strata dip angle model, and after bonding all the rock strata, a rock strata with a predetermined dip angle is formed. At the same time, the present invention can also control the geometric shape of the underlying karst cave by making different foam models, so as to achieve the diversity of karst cave morphology. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view of a karst foundation pile model in inclined layered rock strata provided by the present invention.

[0014] Figure 2a , Figure 2b and Figure 2c These are cross-sectional views of rock strata model boxes with different cross-sectional lengths provided by this invention.

[0015] Figure 3 This is a cross-sectional view of the pre-reserved rock stratum model pile embedded in the spatial rock stratum model box provided by the present invention.

[0016] Figure 4 This is a cross-sectional view of the rock stratum model box with reserved karst cave space provided by the present invention.

[0017] Figure 5 This is a front view of the model pile and earth pressure cell provided by the present invention.

[0018] In the diagram: 1. Model pile; 2. Soil layer; 3. Test model box; 4. Rock layer (401-416 are rock layer numbers); 5. Karst cave; 6. Soil pressure cell; 7. Strain gauge; 8. Rock layer dip model; 9. Rock layer model box; 10. Foam model; 11. Wire. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. This embodiment discloses a method for fabricating a load test model for a karst foundation pile model in inclined layered rock strata. The specific fabrication method is as follows.

[0020] S1: Based on the dimensions of the pile model load test, the rock strata are divided into layers with a certain dip angle and thickness, such as... Figure 1 As shown, 401-416 are the sequence numbers of each rock stratum.

[0021] S2: Determine the dimensions of the rock stratum model and the rock stratum dip angle model. Based on these dimensions, fabricate and assemble the mold. According to the experimental size requirements, mark the rock stratum layers on the inside of the mold and place the foam model. (For rock strata requiring space for model pile embedding or for karst caves, such as rock strata 401-403 and 405-408, use...) Figure 3 , Figure 4The mold shown has corners below the rock stratum dip angle model on the left and above the rock stratum dip angle model on the right, which are complementary to the rock stratum dip angle. Rock strata 404 and 409 are complete rock strata, and the mold shown in Figure b of Figure 2 is used for their construction. The rock mass at the lower left of rock stratum 410 occupies the bottom corner of the rock stratum model box at a right angle, and the mold shown in Figure a of Figure 2 is used for its construction. The cross-sectional lengths of rock strata 411-416 decrease gradually, and the mold shown in Figure c of Figure 2 is used for their construction. The length of the rock stratum dip angle model on the left side of this mold increases with the increase of the rock stratum number, but the acute angle on the far left remains unchanged.

[0022] S3: Apply Vaseline to the inside of the mold and the surface of the foam model. Pour the mixture into the mold until it reaches the rock stratification line inside the mold, then stop pouring. (During pouring, for rock strata requiring space for embedded model piles, and rock strata requiring space for karst caves, such as rock strata 401-403 and 405-408, use...) Figure 3 or Figure 4 As shown in the mold, after the lower rock layer is poured and cured, Vaseline is applied to the upper surface of the rock layer and the next rock layer is poured.

[0023] S4: After the pouring and curing are completed, place the rock layers and consider filling the karst caves in the test model box according to the rock layer number, and apply a layer of adhesive between the rock layers to bond them together.

[0024] S5: Place the earth pressure cell and the pre-fabricated model pile sequentially into the reserved space for the model pile embedding in the rock stratum. Adjust the positions of the earth pressure cell and the model pile. After stabilizing the pile, pour rock grout around the pile to fill the voids. Finally, fill the remaining space above the test model box with the soil layer to be used and compact it. Figure 1 As shown.

[0025] Materials and Connection Methods: The test model box, rock stratum model box, and rock stratum dip angle model are all made of wooden boards and secured with threaded nails for easy disassembly and replacement of the rock stratum dip angle model. The foam model is mainly made of polypropylene, which has a certain strength, is not easily compressed, and is lightweight, thus maintaining the tilt angle and spatial position well. When fixing the wire, holes are pre-drilled at the fixing end, and the angle between the small hole and the mold is equal to the rock stratum dip angle. The wire is inserted into the hole, and the diameter of the small hole should be slightly larger than the diameter of the wire to ensure accurate angle measurement. AB glue is used to fill the small hole to stabilize the angle of the wire.

Claims

1. A method for fabricating a load test model for karst foundation piles in inclined layered rock strata, characterized in that: For the fabrication of the rock strata portion of the indoor test model for foundation piles, the rock strata are constructed using a layered casting method. Rock strata inclination models with predetermined angles are fixed to both sides of the rock strata model box. The inclination angle of the rock strata ranges from 0° to 90°. The rock strata inclination models are either right-angled triangular prisms or quadrangular prisms with a right-angled trapezoidal cross-section, forming a mold. The mold is then cast, and Vaseline is applied between the rock strata to create the inclination angle. For the rock-embedded spaces of the karst caves, earth pressure cells, and model piles, foam models are fixed to predetermined positions on the mold using wire at angles from 0° to 90°. Layered casting is then performed, with the foam models pre-reserved for the karst caves and the rock-embedded spaces of the model piles. After the rock strata have cured, all the rock strata are placed into the test model box and bonded with plaster, filling the karst caves during the bonding process. The earth pressure cells and model piles are then placed into the pre-reserved rock-embedded spaces, and the gaps around the model piles are filled and the pile body is fixed. Finally, soil is filled and compacted.

2. The method for fabricating a load test model for karst foundation piles in inclined layered rock strata according to claim 1, characterized in that: When pouring the rock strata, the foam model reserves karst caves and rock-embedded spaces for model piles. The karst caves are filled with filler to simulate the on-site working conditions; the rock-embedded spaces of the model piles are used to place earth pressure cells and model piles.

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