Mechanical method sinking well milling disturbance vertical shaft segment bearing characteristic test system and method

Abstract

The application discloses a mechanical sinking well milling and digging disturbance vertical shaft segment bearing characteristic test system and method, and the system comprises a test base, a soil body structure, a vertical shaft segment, a vertical shaft heading machine, a milling and digging following mechanism, a milling and digging force applying mechanism and a data monitoring system, the soil body structure comprises a silicone rubber leakage blocking and resistance reducing sleeve pipe, a soil body and a soil body sleeve, the test base is used for a base for bearing the soil body structure and a suspension mechanism for the vertical shaft segment, the milling and digging following mechanism comprises a vertical following trolley and a horizontal following trolley for following the position of a cutting drum, the milling and digging force applying mechanism comprises a force applying mechanism one for simulating horizontal component force of milling and digging force and a force applying mechanism two for simulating vertical component force of milling and digging force, and the data monitoring system is used for monitoring the force applying condition of the milling and digging force applying mechanism and the milling and digging stress condition of the vertical shaft segment to analyze bearing characteristics. The application has important significance for revealing the bearing mechanism of the suspended segment in the milling and digging process of the sinking well type vertical shaft heading machine.

Description

Technical Field

[0001] This invention relates to the field of shaft excavation, and in particular to a test system and method for testing the load-bearing characteristics of shaft segments disturbed by mechanical caisson milling. Background Technology

[0002] With the acceleration of urbanization and the extension of underground space development to deeper areas, the reliance on shaft structures in engineering fields such as urban rail transit, integrated pipe corridors, and deep energy reserves is becoming increasingly significant. As the core hub connecting the surface and underground space, the construction safety, stability, and efficiency of shafts directly determine the construction quality and operational life of the entire underground project.

[0003] Traditional shaft construction techniques, such as diaphragm walls and pile foundations, are increasingly limited by site and environmental protection requirements. With the development of mechanized shaft construction technology, caisson-type shaft boring machines (such as the SCJM method) have become the preferred equipment for ultra-deep shaft construction due to their high degree of mechanization and strong site adaptability. This method innovatively adopts non-drainage excavation technology, which can significantly reduce the cost of retaining structures and effectively reduce the impact on the surrounding environment, injecting new vitality into shaft construction.

[0004] The unique operating mode of the mechanical caisson process fundamentally differs the stress mechanism of its suspended segments from that of traditional caisson segments, shield tunnel segments, and jacking tunnel segments. Existing research systems are insufficient to meet the load-bearing characteristics requirements of this type of segment: on the one hand, mechanical caisson segments need to be assembled in a suspended state, and the surrounding rock constraints of the assembled segment structure change continuously during the sinking process, resulting in poor assembly stress stability; on the other hand, the caisson-type vertical shaft tunneling machine needs to be directly supported and fixed on the assembled segment structure to carry out milling operations. The cutting reaction force and torque generated during the milling process will be transmitted to the segments through the support system, forming dynamic disturbance loads; at the same time, the attitude adjustment (such as correction and leveling) during the sinking process will further cause the segments to bear uneven lateral forces and bending moments, exacerbating the stress complexity. Its special process results in the mechanical caisson suspending the segments being in a special stress environment of "dynamic disturbance load + unfixed surrounding rock constraint + multi-condition coupling", and existing stress theories and monitoring technologies for caissons, shield tunnels and pipe jacking segments cannot be directly applied.

[0005] Given the complexity of the stress on suspended segments in mechanical caisson construction and the gaps in existing research, current engineering practice relies heavily on empirical analogies for segment structure design, lacking a precise understanding of the actual load-bearing characteristics of segments under milling disturbance. Excessive design redundancy increases engineering costs; insufficient strength can easily lead to segment cracking, deformation, or even instability, seriously threatening construction safety. Therefore, developing a testing system and method capable of accurately simulating the milling disturbance process in mechanical caisson construction and testing the load-bearing characteristics of vertical shaft segments in real time is of significant theoretical and engineering guiding value for revealing the mechanical response laws of suspended segments under milling disturbance, optimizing segment structure design parameters, and ensuring the safety of mechanical caisson construction. Furthermore, it is a key technological support for promoting the application of mechanical caisson technology to deeper and more complex geological conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a test system and method for the bearing characteristics of shaft segments disturbed by mechanical milling in shaft tunneling, so as to simulate the milling process of shaft tunneling machine and the stress condition of the segments.

[0007] To address this, the present invention provides a mechanical method for testing the bearing capacity of disturbed shaft segments during milling and drilling. This system, characterized by comprising a test base, a soil structure, shaft segments, a shaft boring machine (TBM), a milling follower mechanism, a milling force application mechanism, and a data monitoring system, includes a silicone rubber leak-proof and drag-reducing sleeve, soil, and a soil sleeve arranged sequentially from the inside out outside the shaft segments. The test base serves as a base supporting the soil structure and a suspension mechanism for adjusting the height of the shaft segments within the soil structure. The milling follower mechanism includes a vertical follower trolley and a horizontal follower trolley. The vertical follower trolley follows the height of the cutting drum of the TBM, and the horizontal follower trolley follows the horizontal position of the cutting drum. Both trolleys can simultaneously rotate circumferentially around the shaft segments to follow the cutting drum. The milling orientation of the shaft is specified. The milling force application mechanism includes: a force application mechanism one for simulating the horizontal component of the milling force and a force application mechanism two for simulating the vertical component of the milling force. The force application mechanism one is mounted on a vertical following trolley and can move up and down. The force application mechanism two is mounted on a horizontal following trolley. The data monitoring system includes a combined sensor for monitoring the milling force of the shaft segments, a load sensor one for monitoring the force of the force application mechanism one and a load sensor two for monitoring the force of the force application mechanism two, and a load sensor three for monitoring the force of the telescopic boom of the shaft tunneling machine. During the shaft segment bearing characteristic test, the shaft tunneling machine and / or shaft segments are first adjusted according to the set test conditions. Then, the milling following system is adjusted. Then, the milling force application mechanism simulates the application of milling force to the cutting drum. Finally, the data monitoring system monitors the force of the shaft segments for bearing characteristic analysis.

[0008] According to another aspect of the present invention, a method for testing the bearing capacity characteristics of disturbed vertical shaft segments during mechanical caisson milling is provided. Using the aforementioned mechanical caisson milling disturbed vertical shaft segment bearing capacity testing system, the testing method includes: based on the characteristics of mechanical caisson milling construction, establishing test items for the stress influence on the segments, including milling force F1 influence test, milling radius R influence test, milling orientation β influence test, and excavation section height... The impact test, as well as the impact test of excavation depth H, is conducted by developing different test condition combinations through orthogonal or uniformity test methods. During the test under different test conditions, the monitoring values ​​of the combined sensor, load sensor one, load sensor two, and load sensor three are observed. The stress bearing characteristics of the shaft segments during the mechanical caisson milling process are obtained through the combination of test conditions.

[0009] This system can simulate the milling process of a shaft tunneling machine and the stress on the tunnel segments, and conduct in-depth research on the stress characteristics and variation law of the tunnel segment structure. It provides a solid theoretical basis and technical support for the optimized design of construction schemes, the rational selection of tunnel segment parameters, and the safety monitoring during construction, thereby effectively improving the safety, efficiency, and economy of shaft construction.

[0010] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0011] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0012] Figure 1 A schematic diagram of the mechanical method for testing the bearing capacity of shaft segments disturbed by milling and drilling, according to an embodiment of the present invention, is shown.

[0013] Figure 2 A schematic diagram of the structure of the test base according to an embodiment of the present invention is shown;

[0014] Figure 3 A schematic diagram of the soil structure according to an embodiment of the present invention is shown;

[0015] Figure 4 A schematic diagram of the base structure according to an embodiment of the present invention is shown;

[0016] Figure 5 A schematic diagram of the structure of a vertical shaft tunneling machine according to an embodiment of the present invention is shown;

[0017] Figure 6 A schematic diagram of the structure of the milling following mechanism and the milling force application mechanism according to an embodiment of the present invention is shown;

[0018] Figure 7 A schematic diagram of the strain gauge layout in a vertical shaft segment according to an embodiment of the present invention is shown;

[0019] Figure 8 A schematic diagram of the optical fiber layout in a vertical shaft segment according to an embodiment of the present invention is shown;

[0020] Figure 9 A flowchart of the mechanical method for testing the bearing capacity characteristics of shaft segments disturbed by milling in a caisson, according to an embodiment of the present invention, is shown.

[0021] Figure 10 A schematic diagram showing the excavation section height of the shaft boring machine according to an embodiment of the present invention is shown;

[0022] Figure 11 A schematic diagram of the milling force analysis of a vertical shaft tunneling machine according to an embodiment of the present invention is shown;

[0023] Figure 12 A schematic diagram of the milling orientation of a shaft tunneling machine according to an embodiment of the present invention is shown.

[0024] Explanation of reference numerals in the attached figures

[0025] 1. Test base; 11. Base; 12. Constraint threaded rod; 13. Circular steel plate; 14. Nut; 15. Steel wire rope; 111. Circular groove; 112. Intermediate step; 113. Base platform;

[0026] 2. Soil sleeve; 3. Soil; 31. Silty clay layer; 32. Unsaturated sand and gravel layer; 33. Saturated sand and gravel layer; 4. Shaft segment; 5. Silicone rubber leak-proof and drag-reducing sleeve;

[0027] 6. Shaft boring machine; 61. Support leg; 62. Support foot; 63. Telescopic boom; 64. Cutting drum; 631. Lateral telescopic boom; 632. Vertical telescopic boom;

[0028] 7. Milling follower mechanism; 71. Circular track one; 72. Circular track two; 73. Vertical track; 74. Translation track; 75. Circular monorail trolley one; 76. Circular monorail trolley two; 77. Circular monorail trolley three; 78. Vertical follower trolley; 79. Horizontal follower trolley; 781. Telescopic rod one; 782. Drill pressure pad one; 791. Telescopic rod two; 792. Drill pressure pad two; 74a. Bolt hole;

[0029] 8. Data monitoring system; 81. Strain gauge; 82. Fiber optic cable; 83. Load sensor three; 84. Load sensor one; 85. Load sensor two; 86. Pressure cell; 87. Inclinometer. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Combined with reference Figures 1 to 8 The mechanical method milling disturbance shaft segment bearing characteristic testing system of the present invention includes a test base 1, a soil sleeve 2, soil 3, shaft segment 4, a silicone rubber leak-proof and drag-reducing sleeve 5, a shaft tunneling machine 6, a milling follower mechanism 7, and a data monitoring system 8.

[0032] The soil sleeve 2 is fitted outside the silicone rubber leak-proof and friction-reducing sleeve 5, forming an annular cavity between them to hold the soil 3. The soil 3 inside the soil sleeve 2 consists of a silty clay layer 31, an unsaturated sand and gravel layer 32, and a saturated sand and gravel layer 33 from top to bottom. The silty clay layer 31 is filled with a mixture of silt and clay particles, the unsaturated sand and gravel layer 32 is filled with a mixture of gravel particles and sand particles, and the saturated sand and gravel layer 33 is filled with a mixture of gravel particles and sand particles. Water is filled between the solid particles in the saturated sand and gravel layer.

[0033] The shaft segment 4 is installed inside the soil sleeve 2, and the shaft segment 4 passes through the silty clay layer 31, the unsaturated sand and gravel layer 32 and the saturated sand and gravel layer 33 from top to bottom.

[0034] The aforementioned soil sleeve 2, soil 3, shaft segment 4, and silicone rubber leak-proof and drag-reducing sleeve 5 constitute the soil structure to simulate the on-site environment of the caisson.

[0035] The shaft tunneling machine 6 is equipped with three support legs 61, and the support feet 62 at the top of the support legs are supported inside the shaft segments. The lower part of the shaft tunneling machine is equipped with a telescopic arm 63 and a cutting drum 64.

[0036] The test base 1 includes a base 11, several threaded rods 12, a circular steel plate 13, a nut 14, and a wire rope 15. The threaded rods 12, the circular steel plate 13, the nut 14, and the wire rope 15 constitute a suspension mechanism.

[0037] The base 11 has threaded holes 114 around its perimeter for threaded connection of the constraint threaded rods 12. Several constraint threaded rods 12, for example, four to six constraint threaded rods, are arranged vertically along the circumference of the base.

[0038] The circular steel plate 13 is suspended above the base by these constraint threaded rods 12. Its placement posture is horizontal and it is fixed by the upper and lower nuts 14. The constraint height can be adjusted by the upper and lower nuts 14.

[0039] The base 11 has a circular groove 111. The inner and outer radii of the circular groove 111 are the same as the inner and outer radii of the soil sleeve 2. A sealing rubber ring (not shown in the figure) is provided at the bottom of the circular groove 111. The soil sleeve 2 is installed on the circular groove 111, and the sealing rubber ring is used to prevent soil leakage.

[0040] The base 11 has a stepped truncated cone of a certain depth at its center, consisting of a middle step 112 and a bottom platform 113. The size of the middle step 112 is the same as that of the silicone rubber leak-proof and friction-reducing sleeve 5. The bottom surface of the middle step 112 is covered with silicone rubber special double-sided adhesive (not shown in the figure) to bond with the silicone rubber leak-proof and friction-reducing adhesive, preventing soil leakage from the inside. The size of the bottom platform 113 is the same as that of the circumferential track 72, which is bolted to the bottom platform 113.

[0041] A circular steel plate 13 is suspended by several steel wire ropes 15 along its circumference. The lower ends of the steel wire ropes 15 are connected to the lower edge of the shaft segment 4, and together they suspend the shaft segment 4.

[0042] The soil sleeve 2 is a vertical cylindrical tube with open top and bottom, with a height of H and an outer diameter of D.

[0043] Soil 3 is laid in the annular cavity between soil sleeve 2 and silicone rubber leak-proof and drag-reducing sleeve 5, and is in the shape of a thick-walled cylinder. The outer wall of soil 3 is in close contact with soil sleeve 2, and the inner wall of soil 3 is in close contact with silicone rubber leak-proof and drag-reducing sleeve. Saturated sand and gravel layer, unsaturated sand and gravel layer and silty clay layer are sequentially filled in the annular cavity. The height of silty clay layer is H / 3, the height of unsaturated sand and gravel layer is H / 3, and the height of saturated sand and gravel layer is H / 3.

[0044] The shaft segment 4 is set in a cylindrical space surrounded by the inner edge of the soil, with a height of H, an outer diameter of D / 2, and a thickness of D / 30. The upper edge of the shaft segment is D / 10~D / 5 above the stratum.

[0045] The silicone rubber leak-blocking and drag-reducing sleeve is a pre-formed solid rubber component. The base has a slot for fixing the silicone rubber leak-blocking and drag-reducing sleeve. It is fixed with double-sided adhesive and can simulate the action of drag-reducing mud and effectively prevent soil leakage.

[0046] In the shaft tunneling machine 6, the support leg 61 is fixedly connected to the shaft segment 4 through the support foot 62, thereby installing the shaft tunneling machine on the shaft segment 4. The center of the support foot is D / 4 away from the lower edge of the shaft tube.

[0047] The telescopic boom 63 consists of a horizontal telescopic boom 631 and a vertical telescopic boom 632. By extending and retracting the horizontal telescopic boom 631 and the vertical telescopic boom 632, the cutting drum 64 can be adjusted to cut the strata at different angles and different excavation depths.

[0048] The milling follower mechanism 7 includes two circumferential tracks (i.e., circumferential track 1 71 and circumferential track 2 72), one vertical track 73 and one translation track 74.

[0049] The circumferential track 71 is fixed to the inner wall of the shaft segment 4 by bolts, and the vertical distance from the center of the circumferential track 71 to the lower edge of the shaft segment 4 is D / 8.

[0050] The second circumferential track 72 is fixed to the base 11 by bolts. The vertical distance from the center of the second circumferential track 72 to the lower edge of the shaft segment 4 is D / 10.

[0051] Circular track 1 71 is equipped with circular monorail trolley 1 75, and circular track 2 72 is equipped with circular monorail trolley 2 76 and circular monorail trolley 3 77. Circular monorail trolley 1 is interlocked with circular track 1, and circular monorail trolleys 2 and 3 are interlocked with circular track 2. The three circular monorail trolleys can move on the circular tracks.

[0052] The vertical track 73 is bolted to the first circumferential monorail trolley 75 and the second circumferential monorail trolley 76. A vertical following trolley 78 is installed on the vertical track 73, and the vertical following trolley 78 can move up and down on the vertical track 73.

[0053] The translation track 74 is connected to the second circumferential monorail trolley 76 and the third circumferential monorail trolley 77 by bolts. The horizontal axis of the translation track 74 passes through the center of the second circumferential track 72. The translation track 74 can rotate around the vertical central axis on the second circumferential track 72. There is a horizontal following trolley 79 on the translation track 74. The horizontal following trolley 79 can move horizontally on the translation track 74.

[0054] The circumferential track 71, circumferential track 72, vertical track 73, and translation track 74 are made of steel rails.

[0055] The vertical shaft segment bearing capacity testing system of the present invention further includes a milling force application mechanism, which includes: a force application mechanism one for simulating the horizontal component of the milling force and a force application mechanism two for simulating the vertical component of the milling force.

[0056] The force-applying mechanism includes a telescopic rod 781 mounted on a vertical following trolley 78 and a drill pressure pad 782 mounted at the end of the telescopic rod 781. The axis of the telescopic rod 781 is arranged radially along the vertical shaft segment 4. A load sensor 84 is installed between the telescopic rod 781 and the drill pressure pad 782.

[0057] The second force-applying mechanism includes a telescopic rod 791 mounted on the horizontal following trolley 79 and a drill pressure pad 792 mounted on the upper end of the telescopic rod 791. The axis of the telescopic rod 791 is parallel to the vertical shaft segment 4. A load sensor 85 is installed between the telescopic rod 791 and the drill pressure pad 792.

[0058] The translation track 74 is also provided with a row of bolt holes 74a. The horizontal following trolley can be fixed to the bolt holes by bolts. The position of the bolt holes can control the contact position (i.e., milling radius) between the drill pressure pad and the cutting drum.

[0059] The data monitoring system 8 includes strain gauges 81, optical fibers 82, load sensor one 84, load sensor two 85, load sensor three 83, pressure cell 86, communication cables, and data acquisition unit.

[0060] Strain gauges 81 are arranged on the inner wall of the shaft segment. Two strain gauges are arranged near each support foot in a T-shape. One strain gauge is arranged close to the support foot along the circumference of the shaft segment, and the other strain gauge is arranged close to the support foot along the vertical direction of the shaft segment. At the middle position of the connected support feet, a strain gauge along the circumference of the shaft segment and a strain gauge along the vertical direction of the shaft segment are respectively arranged. In this way, the horizontal center lines of the six circumferentially arranged strain gauges are located in the same plane, and the horizontal center lines of the six vertically arranged strain gauges are also located in the same plane.

[0061] The data from strain gauge 81 is transmitted to a data acquisition unit (not shown in the figure) via a communication cable. These strain gauges measure the strain values ​​generated by the stress on the shaft segments. Then, the elastic modulus is determined based on the strength grade of the concrete in the shaft segments. According to Hooke's Law The stress values ​​at corresponding locations of the shaft segments were calculated. Through stress value Calculate the axial force and bending moment at the corresponding positions of the shaft segments.

[0062] Fiber 82 is pre-embedded inside the vertical shaft segment 4. Three test rings are arranged inside the vertical shaft segment, and each of the three rings is composed of a single fiber. The positions of the three fiber test rings are the support foot plane, a plane above the support foot, and a plane below the support foot, respectively. The length L of the fiber of the top ring from the fiber of the support foot plane is equal to the distance L of the fiber of the bottom ring from the fiber of the support foot plane, so as to monitor the stress deformation of the shaft during the entire test process.

[0063] Load sensor 1 84 is located on the right side of the adjustable track vertical following trolley, load sensor 2 85 is located on the upper side of the parallel trolley, and load sensor 3 83 is located inside the telescopic boom of the shaft tunneling machine.

[0064] The pressure box 86 is pre-embedded on the outer edge of the shaft segment 4, located on the outer edge where the support foot 62 contacts the shaft segment 4. The force-bearing surface of the pressure box 86 is flush with the outer surface of the shaft segment 4. It is used to measure the pressure of the silicone rubber leak-proof and drag-reducing sleeve on the outer wall of the shaft segment during the milling process. The data from the pressure box 86 is transmitted to the data acquisition unit via a communication cable.

[0065] The data monitoring system 8 also includes inclinometers 87 as attitude analysis components. Three inclinometers 87 are installed on the inner wall of the shaft segments 4 above the three support legs of the shaft boring machine. The three inclinometers 87 measure the tilt of the shaft segments caused by the shaft boring machine under stress. The data from the three inclinometers 87 are transmitted to the data acquisition unit via communication cables.

[0066] Referring to the figures, the mechanical method for testing the bearing capacity of disturbed vertical shaft segments during milling and drilling of a caisson according to the present invention includes the following steps S1 to S4.

[0067] S1. Precast shaft segments: Pressure boxes, optical fibers and communication cables are pre-embedded simultaneously when making shaft segments.

[0068] S2. Assemble the shaft segments: Install the shaft boring machine, circumferential track 1, and vertical track onto the shaft segments, and attach strain gauges at the same time. Connect the communication cable to the data acquisition unit.

[0069] S3. Set up the testing system: Install the soil sleeve, soil, shaft segments, silicone rubber leak-proof and drag-reducing sleeve, shaft excavator, and milling follower mechanism on the testing base, and at the same time set up a data monitoring system.

[0070] S4. Milling Disturbance Test: Based on the characteristics of mechanical caisson milling construction, determine the magnitude of different milling forces F1, milling radius R, milling orientation β, and excavation section height. And the impact of excavation depth H on the stress on the tunnel lining segments.

[0071] Different combinations of test conditions were developed using orthogonal or uniformity testing methods.

[0072] During the above tests, the values ​​of load sensor 1, load sensor 2, load sensor 3, pressure cell, strain gauge, and optical fiber were observed. By combining working conditions, the stress bearing characteristics of the vertical shaft caisson segments during the mechanical caisson milling process can be obtained.

[0073] Step S3 includes the following steps S31-S35.

[0074] S31. Install circumferential track two: Fix circumferential track two to the base with bolts.

[0075] S32. Install the soil sleeve: Install the sealing ring in the circular groove, and then place the soil sleeve, ensuring that it fits tightly with the sealing ring.

[0076] S33. Install silicone rubber leak-blocking and drag-reducing sleeve: Apply silicone rubber double-sided adhesive to the bottom of the center step to bond the silicone rubber leak-blocking and drag-reducing sleeve and the base.

[0077] S34. Filling: Fill the saturated sand and gravel layer, unsaturated sand and gravel layer, and silty clay layer in sequence.

[0078] S35. Install shaft segments: Slowly lower the shaft segments along the silicone rubber leak-proof and friction-reducing adhesive to the designated position. The lower edge of the shaft segments is lifted by steel wire rope to achieve suspension and fixation.

[0079] Step S4 specifically includes the following steps S41-S45.

[0080] S41. Milling Force F1 Influence Test: The loads of telescopic rod one and telescopic rod two are applied synchronously, and the resultant force of the two is along the direction of the telescopic arm. With other factors kept constant, the resultant force of the two is applied linearly to investigate the influence of milling force on the bearing characteristics of shaft segments.

[0081] S42. Milling radius R influence test: By changing the position of the horizontal following trolley, the influence of the milling radius R on the bearing characteristics of the vertical shaft segments can be investigated under different milling radii R while keeping other factors constant.

[0082] S43. Milling orientation β influence test: Adjust the orientation of the translation track and keep other factors constant to explore the influence of milling orientation β on the bearing characteristics of shaft segments.

[0083] S44, excavation section height Impact Test: Changing the distance between the cutting roller and the lower edge of the caisson shaft affects the height of the excavated section. Adjustments were made to explore the height of the excavation section. The impact on the load-bearing characteristics of shaft segments.

[0084] S45, Excavation Depth H Influence Test: Shaft segments of different heights are inserted into the soil sleeve, and then soil of the corresponding height is filled in, so as to effectively control the excavation depth H and explore the influence of excavation depth H on the bearing characteristics of shaft segments.

[0085] The direction of the resultant force F1 exerted by telescopic boom 1 and telescopic boom 2 on the telescopic boom of the shaft boring machine is constant. The magnitude and direction of the resultant force F1 are as follows:

[0086] (1)

[0087] In the above formula, f1 is the force applied to the cutting drum by the first telescopic rod, in N; f2 is the force applied to the cutting drum by the second telescopic rod, in N; F1 is the resultant force applied to the telescopic boom of the shaft boring machine by the first and second telescopic rods, in N; h is the height of the telescopic boom along the vertical direction of the tunnel segment, in m; R is the milling radius, in m.

[0088] The telescopic boom is equipped with a load sensor, which can accurately measure the load value borne by the telescopic boom. The measured result can be directly compared with the pre-set design value F1 for verification.

[0089] Keeping other factors constant (milling radius R, milling orientation β, excavation section height) (Excavation depth H), the resultant force F1 is increased at a constant speed along the direction of the telescopic arm, the values ​​of each test element are monitored, and the influence of the load F1 on the vertical shaft segment stress state is studied.

[0090] In step S42, the distance between the bolt holes on the translation track and the center point of the shaft tunneling machine is the milling radius R, where R = 0 ~ D / 4. This distance is adjusted by adjusting the position of the bolt holes on the translation track of the horizontal following trolley.

[0091] Keeping other factors constant (milling force) Milling azimuth β, excavation section height In addition to the excavation depth H), the vertical following trolley position was kept fixed, and the position of the horizontal following trolley on the translation track was adjusted. The excavation radius R was set to D / 10, D / 5, 3D / 10, and 2D / 5 respectively. A total of 4 sets of comparative experiments were carried out to observe the values ​​of each test element and study the influence of the milling radius R of the shaft tunneling machine on the stress state of the shaft segments.

[0092] In step S43, the three circumferential monorail trolleys 1, 2, and 3 are precisely controlled to rotate between adjacent support legs, thereby driving the translation track to perform circular motion around the center of the circumferential track 2. The center angle between adjacent support legs of the shaft tunneling machine is 120°. The initial position of the translation track is directly below any support leg. Different milling orientations β will cause different forces at each support leg position. If the milling orientation β is biased to one side of any support leg, it may cause uneven stress distribution, forming an eccentric load, which will cause stress concentration in the tunnel segment and cracks. Therefore, according to the principle of symmetry, the milling orientation β is precisely controlled to 10°, 20°, 30°, 40°, 50°, and 60°, and a total of 6 sets of comparative experiments are carried out.

[0093] Furthermore, the translation track is rotated sequentially to the set angle, while keeping other factors constant (such as the magnitude of the milling force). Milling radius R, excavation section height In addition to the excavation depth H), the values ​​of each test element were observed to study the influence of the milling orientation β of the shaft tunneling machine on the stress state of the shaft segments.

[0094] In step S44, the position of the circular steel plate is adjusted by rotating the nut. Using the steel wire rope on the hoisting plate, the shaft segments are raised and lowered to adjust the distance between the cutting drum and the lower edge of the shaft segments. Based on the actual excavation height of the caisson-type shaft boring machine in on-site construction, several different excavation height ratios are designed in the experiment, including 1 / 3... 2 / 3 , 4 / 3 5 / 3 Five sets of comparative experiments were conducted.

[0095] Furthermore, adjust the height of the excavation section. Upon reaching the design height, while keeping other factors constant (such as the magnitude of the milling force)... The milling radius R, milling azimuth β, and excavation depth H were measured, and the values ​​of each test element were observed to study the excavation section height of the shaft boring machine. The impact on the stress state of shaft segments.

[0096] In step S45, shaft segments of different heights are installed inside the soil sleeve. The designed heights of the shaft segments are 1 / 5H, 2 / 5H, 3 / 5H, 4 / 5H, and H, respectively, and a total of 5 sets of comparative experiments are carried out.

[0097] Rotate the nut to adjust the lifting plate to the corresponding height. Then fill the soil so that the soil level is flush with the top of the shaft segments at different heights.

[0098] Furthermore, keeping other factors constant (milling force F1, milling radius R, milling orientation β, and excavation section height) ), observe the values ​​of each test element, and study the excavation section height of the shaft boring machine. The impact on the stress state of shaft segments.

[0099] The above description is merely an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A mechanical method for testing the bearing capacity of shaft segments disturbed during milling and excavation, characterized in that, This includes the test base, soil structure, shaft segments, shaft boring machine, milling follower mechanism, milling force application mechanism, and data monitoring system. The soil structure includes, from the inside out, a silicone rubber leak-proof and drag-reducing sleeve, soil, and a soil sleeve arranged sequentially outside the shaft segments. The test base serves as a base to support the soil structure and a suspension mechanism for adjusting the height of the shaft segments within the soil structure. The milling following mechanism includes a vertical following trolley and a horizontal following trolley. The vertical following trolley is used to follow the height position of the cutting drum of the shaft boring machine, and the horizontal following trolley is used to follow the horizontal position of the cutting drum. Both can rotate simultaneously around the shaft segments to follow the milling orientation of the cutting drum. The milling force application mechanism includes: a first force application mechanism for simulating the horizontal component of the milling force and a second force application mechanism for simulating the vertical component of the milling force, wherein the first force application mechanism is mounted on a vertical following trolley and is capable of vertical movement, and the second force application mechanism is mounted on a horizontal following trolley. The data monitoring system includes a combined sensor for monitoring the stress on the segment milling of the shaft, a load sensor one for monitoring the stress on the first force-applying mechanism, a load sensor two for monitoring the stress on the second force-applying mechanism, and a load sensor three for monitoring the stress on the telescopic boom of the shaft boring machine. During the test of the bearing characteristics of shaft segments, the shaft boring machine and / or shaft segments are first adjusted according to the set test conditions. Then, the milling follow-up system is adjusted. Next, the milling force application mechanism simulates the application of milling force to the cutting drum. Finally, the data monitoring system monitors the stress on the shaft segments for bearing characteristic analysis. The milling following mechanism further includes a first circumferential track, a second circumferential track, a vertical track, and a translational track. The first circumferential track is fixed to the inner wall of the shaft segment by bolts, and the second circumferential track is fixed to the base by bolts. A first circumferential monorail trolley is mounted on the first circumferential track, and a second and a third circumferential monorail trolley are mounted on the second circumferential track. The first circumferential monorail trolley is interlocked with the first circumferential track, and the second and third circumferential monorail trolleys are interlocked with the second circumferential track. The three circumferential monorail trolleys can move on the circumferential tracks. The vertical track is bolted to the first and second circumferential monorail trolleys. The vertical following trolley is set on the vertical track and can move up and down on the vertical track. The translation track is connected to the circumferential monorail trolley two and the circumferential monorail trolley three by bolts. The horizontal axis of the translation track passes through the center of the circumferential track two. The translation track can rotate around the vertical central axis on the circumferential track two. The horizontal following trolley is set on the translation track and can move horizontally on the translation track.

2. The mechanical method milling and disturbing shaft segment bearing capacity testing system according to claim 1, characterized in that, The force application mechanism includes a telescopic rod mounted on a vertical following trolley and a drill pressure pad at the end of the telescopic rod, wherein the load sensor is disposed between the telescopic rod and the drill pressure pad. The second force-applying mechanism includes a telescopic rod 2 mounted on a horizontal following trolley and a drill pressure pad 2 mounted at the end of the telescopic rod 2, wherein the second load sensor is mounted between the telescopic rod 2 and the drill pressure pad 2.

3. The mechanical method milling and disturbing shaft segment bearing capacity testing system according to claim 1, characterized in that, The combined sensor includes strain gauges, a pressure cell, and optical fibers. The strain gauges are arranged on the inner wall of the shaft segment. A set of combined strain gauges is arranged near each support foot of the shaft boring machine and at the middle position of adjacent support feet. The combined strain gauge consists of two strain gauges arranged in a T-shape. The data of the strain gauges is transmitted to the data acquisition unit by communication cable. The pressure box is embedded in the outer edge of the shaft segment, located at the outer edge where the support foot contacts the shaft segment. The force-bearing surface of the pressure box is flush with the outer surface of the shaft segment. It is used to measure the pressure of the soil on the outer wall of the shaft segment during the milling process. The data from the pressure box is transmitted to the data acquisition unit via a communication cable. The optical fiber is embedded inside the vertical shaft segment. Three test rings are arranged inside the vertical shaft segment, and each test ring is composed of a single optical fiber. The positions of the three test rings are respectively the support foot plane, a plane above the support foot, and a plane below the support foot.

4. The mechanical method milling and disturbing shaft segment bearing capacity testing system according to claim 1, characterized in that, The data monitoring system also includes an inclinometer, which is installed on the inner wall of the shaft segment above the three support legs of the shaft tunneling machine.

5. A method for testing the bearing capacity of shaft segments disturbed by mechanical milling in caissons, characterized in that, The mechanical method for testing the bearing capacity of shaft segments disturbed by milling and drilling, according to any one of claims 1 to 4, comprises the following testing methods: Based on the characteristics of mechanical caisson milling construction, the established test items for the stress influence on tunnel segments include the milling force F1 influence test, the milling radius R influence test, the milling orientation β influence test, and the excavation section height test. Impact testing, and impact testing of excavation depth H. Different combinations of test conditions were developed using orthogonal or uniformity testing methods. During testing under different working conditions, the monitoring values ​​of the combined sensor, load sensor one, load sensor two, and load sensor three were observed. The stress bearing characteristics of the shaft segments during the mechanical caisson milling process were obtained through the combination of working conditions.

6. The method for testing the bearing capacity of shaft segments disturbed by mechanical milling in a caisson according to claim 5, characterized in that, In the milling force F1 influence test, the load is applied synchronously by force application mechanism one and force application mechanism two. The resultant force of the two is along the direction of the telescopic boom of the shaft tunneling machine. With other factors kept constant, the resultant force of the two is applied linearly to analyze the influence of milling force on the bearing characteristics of shaft segments. In the milling force F1 influence test, the direction of the resultant force applied by force-applying mechanism one and force-applying mechanism two to the telescopic boom of the shaft boring machine is constant, and the magnitude and direction of the resultant force are as follows: （1） In the above formula, f 1 The force applied to the cutting drum by the force-applying mechanism; f 2 The force applied to the cutting drum by the second force-applying mechanism; F 1 The resultant force applied by force-applying mechanism one and force-applying mechanism two to the telescopic boom of the shaft boring machine; h The height of the telescopic boom along the vertical direction of the tunnel segment; R The milling radius; The load value borne by the telescopic boom is measured using a load sensor, and the measured results are compared with the pre-set design value. F 1 Perform comparative calculations; Keeping other factors constant, let the combined force F 1 The load is increased at a constant speed along the direction of the telescopic boom, and the values ​​of each test element are monitored to analyze the magnitude of the load on the telescopic boom. F 1 The impact on the stress state of the shaft segments.

7. The method for testing the bearing capacity of shaft segments disturbed by mechanical milling in a caisson according to claim 6, characterized in that, In the test of the influence of milling radius R, the distance between the cutting drum and the center point of the shaft tunneling machine is the milling radius R. The milling radius R = 0~D / 4. The milling radius R is followed by adjusting the position of the horizontal following trolley in the radial direction of the caisson. Keeping other factors constant and maintaining the position of the vertical following trolley fixed, the position of the horizontal following trolley in the radial direction of the caisson is adjusted. The milling radius R is set to D / 10, D / 5, 3D / 10, and 2D / 5 respectively. Four sets of comparative experiments are carried out to observe the values ​​of each test element and analyze the influence of the milling radius R on the stress state of the vertical shaft segments.

8. The method for testing the bearing capacity of shaft segments disturbed by mechanical milling in a caisson according to claim 6, characterized in that, In the milling azimuth β influence test, the vertical following trolley and the horizontal following trolley were controlled to rotate around the shaft segment circumference between two adjacent support legs of the shaft tunneling machine. The center angle between the two adjacent support legs was 120°. The horizontal following trolley was located directly below any support leg. According to the principle of symmetry, the milling azimuth β was precisely controlled to 10°, 20°, 30°, 40°, 50°, and 60°. A total of 6 sets of comparative experiments were carried out. The horizontal following trolley is rotated sequentially to the set angle, while keeping other factors constant. The values ​​of each test element are observed to analyze the influence of the milling orientation β on the stress state of the shaft segments.

9. The method for testing the bearing capacity of shaft segments disturbed by mechanical milling in a caisson according to claim 6, characterized in that, In the test of the impact of the excavation section height ∆h, the vertical shaft segments were raised and lowered by a suspension mechanism to adjust the distance between the cutting drum and the lower edge of the vertical shaft segments. Based on the actual excavation section height of the caisson-type vertical shaft boring machine in on-site construction, several different excavation section height ratios were designed in the experiment, including 1 / 3. 2 / 3 , 4 / 3 5 / 3 A total of 5 sets of comparative experiments were conducted; Adjust the height of the excavation section Once the design height is reached, keeping other factors constant, observe the values ​​of each test element and analyze the excavation section height. The impact on the stress state of the shaft segments.

10. The method for testing the bearing capacity of shaft segments disturbed by mechanical milling in a caisson according to claim 6, characterized in that, In the test of the influence of excavation depth H, shaft segments of different heights were installed inside the soil sleeve. The designed heights of the shaft segments were 1 / 5H, 2 / 5H, 3 / 5H, 4 / 5H, and H. A total of 5 sets of comparative experiments were carried out. Adjust the suspension mechanism to the corresponding height, and then fill the soil so that the soil level is flush with the top of the shaft segments at different heights. Keeping other factors constant, observe the values ​​of each test element and analyze the excavation section height. The impact on the stress state of the shaft segments.

Images