Impact of excavation footage on vertical shaft lining deformation and surrounding rock stress in Xiyu conglomerate | Scientific Reports

Scientific Reports volume 14, Article number: 25659 (2024) Cite this article

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The Xiyu conglomerate, which is extensively distributed in Xinjiang, China, presents challenges for vertical shaft construction owing to its poor cementation and low strength. The selection of an appropriate footage length is paramount for ensuring safe construction. Based on the shaft pipeline construction project of the Xinlongkou Hydropower Station on the Kuitun River, this study investigated the impact of footage length on the stability of vertical shafts within the Xiyu conglomerate strata using finite element simulation and measurement data to analyze the lining displacement and change in stress in the surrounding rock. The results show that the excavation footage has little effect on the lining’s horizontal displacement during vertical shaft excavation. A mathematical model was developed to describe how the vertical displacement of the lining varies with the excavation footage and vertical shaft depth. Below a critical threshold, the stress in the surrounding rock cannot be effectively alleviated, leading to a concentration of stress; above that critical threshold, an excessively large excavation increases the load on the surrounding rock. Based on the simulation results and factors such as economic benefits, construction speed, and safety, an excavation footage of 4 m is judged to be appropriate.

The Xiyu conglomerate, also referred to as the western piedmont gravel layer, is extensively distributed across the Tarim Basin1,2, the northern foothills of the Kunlun Mountains3, and the piedmont basin at the southwestern base of the Tianshan Mountains4,5. It comprises a series of gray and gray-black, coarse-grained, thick-bedded, and inclined piedmont gravel-like rock formations, tens to thousands of meters thick, with an average thickness of approximately 2,000 m (Fig. 1)6. In recent years, a significant number of water conservation projects have been constructed in the Xiyu conglomerate. The unique characteristics of the formations, including their intricate material composition, inadequate cementation, low strength, and susceptibility to weathering, present a number of difficulties for the safe design, building, and operation of structures.

Xiyu conglomerate.

Vertical shafts are crucial for water diversion and transportation7,8,9. They are used extensively in the mining and transportation sectors, serving purposes such as smoke exhaust ventilation10,11,12,13,14,15, entry and exit passages16, and foundations for high-voltage transmission towers in mountainous regions17. The safety of vertical shafts is essential for their effective functioning. Improper design and construction of support structures can lead to structural damage, sudden water influx, water flooding, and uneven settlement of surrounding buildings and can have serious adverse effects on construction safety18. According to incomplete statistics, there have been numerous incidents of deformation and damage in vertical shafts in China, and the repair costs alone can reach hundreds of millions of dollars19,20. Fan et al.21 pointed out the characteristics of loose formations and weakly cemented formations, as well as the safety issues faced in constructing vertical wells in such formations. Pu et al.22 observed that shafts situated within formations characterized by geological weakness are predisposed to failures in support structures and collapses of the surrounding rock during excavation, mostly because of the surrounding rock’s poor strength and resistance to deformation. Within the geological milieu of the Xiyu conglomerate, which exhibits intricate physical characteristics, the stability of shafts has emerged as a critical determinant impacting the safety of water delivery23. Consequently, it is imperative to investigate the safety and stability of shafts in Xiyu conglomerate formations thoroughly.

The stability of vertical shaft linings affects the safety of subterranean spaces24, and the surrounding rock stress is a critical parameter in assessing lining design. When considering the safety of a vertical shaft, emphasis should be placed on analyzing changes in the lining displacement field and surrounding rock stress field. Galli et al.25 simulated excavation and lining processes using a three-dimensional finite element model. The outcomes showed how the lining elements and surrounding soil interacted. Zhang et al.26 used the FLAC3D numerical simulation program to investigate the deformation characteristics of the rock surrounding a vertical shaft and offered support for improving its stability. Construction efficiency should also be considered, and the length of the footage is an important factor. Given the geological conditions of the Xiyu conglomerate, excessive footage length may increase construction risks. Wang et al.27 utilized Abaqus to establish a numerical model and found that with smaller footage lengths, there is increased overall stress on both the lining and surrounding rock, requiring more construction steps and thereby adversely affecting the overall economic feasibility of the project. However, in environments with poor surrounding rock, it is advisable to reduce the footage length and strengthen deformation control and support measures. Chen et al.28 employed the “model null” command to model tunnel excavation, selecting various excavation footage lengths to simulate rock and soil, and analyzed the stress and deformation characteristics of the surrounding rock and support. The results showed that the stress in the surrounding rock was highly associated with the surrounding rock conditions and dependent on the interaction between the surrounding rock and the support. In cases of poor surrounding rock quality, fewer excavation steps result in a greater stress release. Conversely, when the rock quality is favorable, fewer excavation steps and enhanced stress release are more beneficial for optimizing the surrounding rock’s self-bearing capability. Yan29 analyzed settlement factors and revealed a relationship between the size of the excavation footage and settlement; a larger excavation footage corresponds to greater settlement. It is therefore necessary to investigate the characteristics of the surrounding rock before construction to select an appropriate excavation footage size.

Although previous studies provide guidance for the planning and construction of vertical shaft projects, research on the effects of excavation footage size on the surrounding rock stress and vertical shaft lining displacement for projects in complicated strata, such as the Xiyu conglomerate, is scarce. In this study, the construction project of a vertical shaft pipe in the Kuitun River Basin at the Xinlongkou Hydropower Station was the basis for employing numerical simulation to assess the effect of vertical shaft excavation footage on project stability. The deformation of the vertical shaft lining structure and variation in the surrounding rock stress during excavation were analyzed. We sought to consider economic benefits, construction speed, and safety in developing a scheme for selecting the optimal excavation footage size for vertical shafts in the western pebble stratum.

The pressure pipeline of the Xinlongkou Power Station constitutes a significant component of the Xinjiang Kuitun River water diversion project and serves as one of its main water diversion systems. The shaft’s deepest unidirectional excavation depth is in the western conglomerate formation, primarily comprising a vertical shaft and lower adits (Figs. 2 and 3). The excavation hole is 6.6 m in diameter and 192 m long. The length of the footage is 4 m. The vertical shaft structure from the pipeline outward is as follows: a steel pipe with an outer diameter of 4.1 m and a thickness of 5 cm, a 70-cm-thick C25-backfilled reinforced concrete section, a 45-cm-thick C30reinforced concrete primary lining, and a 10-cm-thick C30 shotcrete exterior. A cross section of the vertical shaft is shown in Fig. 4.

The geographical location of the Kuitun River. (Image by Arc GIS 10.5 (http://b.mtw.so/5W7kZ9) Generated, the map is sourced from: http://b.mtw.so/5yO7yF) (a) Map of China, (b) Xinjiang Uygur Autonomous Region, (c) Usu City, Kuitun City, and Huyanghe City, (d) Actual location map of Kuitun River.

3D planning of Xinlongkou power station. (a) Plan view, (b) Sectional view.

Cross-sectional view of vertical shaft.

The pressure steel pipe was monitored in four sections with an inductive displacement sensor and stress-free meter installed at elevations of 1208.34, 1125, 1075, and 1015.58 m (corresponding to excavation depths of 0, 80, 130, and 192 m). An automated monitoring system with data acquisition units was used to collect sensor data and transmit the data to a monitoring center station, as shown in Fig. 5.

Automated monitoring system.

The power station site is on the southern periphery of the Urumqi Mountain Front Depression, close to the Yilian Habirga anticline. The secondary and tertiary tectonic units are delimited by the Qingshuihezi fault. The front pool of the site lies on the northern side (footwall) of the Qingshuihezi Fault. The bedrock south of the fault is mostly exposed, and the rock mass is broken. To the north, it is covered by a fourth series of strata, and its structural features are unclear.

The geological profile of the shaft is illustrated in Fig. 6. The lithology of the rock surrounding the cave body is a Xiyu conglomerate of the Lower Pleistocene (Q1X). Based on observations during adit construction within the site area, the upper section consists of weakly cemented green-gray Xiyu conglomerate mudstone, which allowed rapid excavation progress with pneumatic picks. The upper tunnel walls exhibited relative stability with occasional localized block detachment. The excavation section of the tunnel sidewalls was relatively undulating, and the conditions for the cave formation were average. In contrast, the lower section features gray-white mudstone with calcium cementation, which resulted in slower excavation progress with pneumatic picks. The upper tunnel walls remained stable with a flat excavation section, intact particle concavities, and favorable cave formation conditions. Drawing from analogous engineering experiences, although the Xiyu conglomerate has a certain self-stabilization time, it was still necessary to closely monitor the stress in the surrounding rock to take appropriate support measures in a timely manner and ensure safety during construction.

Diagram of the geological profile.

The groundwater in the factory site area is categorized as pore diving and is primarily found within the Quaternary strata along the Kuitun River. It primarily receives replenishment from river water and atmospheric precipitation and flows downstream as subsurface flow. Groundwater was not detected in the borehole on the terrace during the investigation period. The groundwater level ranged from 947.4 to 964.1 m, lower than the riverbed water level, indicating that it is replenished by river water.

Numerous intricate factors come into play in vertical shaft construction, rendering a comprehensive numerical simulation of a circular vertical shaft highly challenging. To optimize the numerical model and guarantee the accuracy and efficiency of the computational output, the following assumptions were made:

Irrespective of actual undulations of layers in the horizontal plane each rock and soil layer within the calculation scope was assumed to be horizontally distributed, homogenous, and continuous and consist of isotropic deformable material.

The process of distributed excavation was achieved through software “passivation.”

During the initial stress stage, the displacement was reset to zero, and the sole consideration during the excavation stage was the effect of the foundation pit on the nearby rock and vertical shaft.

To assess the effects of shaft excavation on the surrounding rock in greater detail, the distance between the outermost boundary of the model and the perimeter of the foundation pit was set to three times the shaft diameter. To mitigate dimensional boundary effects on the results, the longitudinal depth was set to 1.5 times the excavation depth. Hence, the dimensions of the three-dimensional model were 30 m × 30 m × 288 m (length × width × height).

The Mohr–Coulomb model30, which is commonly used in geotechnical mechanics, was selected as the constitutive model because it represents the shear strength of geological materials simply and effectively31,32. Three-dimensional solid elements were employed to model the surrounding rock, and two-dimensional shell elements were used for the support structure. One-dimensional embeddable truss elements were employed to simulate the anchor rods, and the other structures were set as isotropic elastic materials for the nonlinear computations.

To balance model accuracy with computational time and cost, a hybrid tetrahedral and hexahedral mesh was generated using three-dimensional solid elements. The solid elements and supporting structure elements inside the shaft were divided into grids of 0.5 m, whereas the soil elements outside the pit had progressively sparser grids as the distance from the shaft increased. The total node count was 110,804, with 181,631 elements. The model is shown in Fig. 7.

Three-dimensional finite element model.

Based on geological survey data and field investigations, the vertical shaft’s segment ranging from 1,208.34 m to 1,138.62 m in elevation is located in the upper layer of the Xiyu conglomerate, while the segment from 1,138.62 m to 1,015.58 m in elevation is located in its lower layer. Both segments were categorized under the Quaternary System Lower Pleistocene Series Q1X. Based similar engineering experience and the results of elastic resistance coefficient testing, in situ deformation testing, and particle separation testing, recommended values for the primary physical and mechanical properties and geological parameters of the Xiyu conglomerate within the Quaternary System Lower Pleistocene Series are shown in Table 1.

The cross-sectional area of the vertical shaft is 25 m² < A = 34.21 m² < 100 m², based on the Technical Specification for Excavation of Underground Works on Hydraulic Structures (DL/T5099–2011) and the Code for Construction of Shafts and Roadway of Coal Mines (GB50511–2010). The vertical shaft is an excavation of a cavity within the range of the interrupted surface. The manual vertical shaft method was adopted for the segmented excavation, and temporary support was provided immediately after the excavation. The Xiyu conglomerate falls within rock layer Class IV, necessitating that the unsupported section’s height did not surpass 2 m. Therefore, each layer was equipped with eight \(\:{\Phi\:}\)25 anchor rods 4 m long and spaced 2 m apart. Details are provided in Tables 2 and 3. Excavation followed the “short footage” construction principle. Given the substantial excavation depth of the shaft for this project, the layering height range was set to 4–8 m, and in areas with high ground stress, the layering height was reduced. This study focused on excavation footages of 2, 3, 4, 6, and 8 m (corresponding to schemes F1–F5, respectively).

During excavation of the vertical shaft, there was still a construction load on the ground. Therefore, in the model, a 35-kPa load within a 3-m radius around the circular vertical shaft, as well as the self-weight of the soil, were included to reflect the effects of these vertical loads on the lateral pressure on the enclosure structure.

The boundary conditions of the model were set using the “automatic boundary generation” function in the software. Fixed constraints were used at the bottom of the model, X-direction constraints were used on the left and right ends, and Y-direction constraints were used on the front and rear ends.

The model adopted the construction stage analysis function in the MIADS/GTS NX 2019 (https://product.midasit.cn/index/products-GTS.asp) software and established corresponding analysis conditions through “activation” and “passivation” of corresponding units to simulate the process of vertical shaft excavation and support. The specific steps were as follows:

(1) A fixed length of the excavation footage was selected for modelling based on the size of the vertical shaft. (2) After the grid was generated, the grid quality was checked to ensure node coupling. (3) The shotcrete, primary lining, and secondary lining materials were defined using the “extraction” function, with the length consistent with the footage. (4) Boundary conditions and loads were applied. (5) An initial stress field was formed by activating the grid elements, loads, and boundary conditions of the soil and vertical shafts, and the displacement was reset. (6) The construction process was divided into multiple stages, each simulating excavation, support, and backfilling operations. Because lining construction needs to be performed after each soil excavation step in actual vertical shaft construction projects, soil excavation should be carried out first in one excavation step, followed by the anchor rod, shotcrete, and lining construction. After the completion of the primary lining construction, backfilling of the secondary lining should be performed from bottom to top.

Because excavation depths of 0, 24, 48, 72, 96, 120, 144, 168, and 192 are common multiples of excavation footages of 2, 3, 4, 6, and 8 m, we focused on how the lining displacement and stress in the surrounding rock change under those eight conditions in the simulation of the shaft excavation process.

As measurements were conducted after the completion of the shaft excavation, the simulation results corresponding to an excavation depth of 192 m were chosen for comparison. A scatter plot of the simulation results and corresponding measurements is shown in Fig. 8. It is evident that the horizontal displacement magnitude and the trend in the measured values were consistent with those of the calculated values. The coefficient of determination of R2 = 0.99869 indicates a strong linear relationship between the measured and calculated values and supports the validity and accuracy of the selected computational model, algorithms, and grid partitioning.

Comparison of measured and calculated horizontal displacement of shaft lining. (a) Diagonal diagram, (b) Histogram.

Figure 9 illustrates the variation in the horizontal displacement of the lining with excavation depth for different excavation footages post-excavation completion (horizontal displacement values are positive toward the inside of the vertical shaft and negative toward the outside of the vertical shaft). The numerical results are as follows: (1) The horizontal displacement of the shaft lining deforms toward the inner side of the vertical shaft, and the deformation of the shaft lining first increases and then decreases with increasing depth of the vertical shaft. (2) The horizontal displacement increases with increasing shaft depth. Because the construction of the shaft was completed at a depth of 192 m, the shaft approached stability and horizontal displacement near zero, with the maximum value observed at a shaft depth of 168 m. (3) The maximum horizontal displacement occurred under the F5 scheme and reached 2.44 mm. For vertical shaft depths in the ranges of 0–72 m and 168–192 m, the excavation footage had a negligible effect on the lining’s horizontal displacement. For vertical shaft depths in the range of 72 to 168 m, the effect of the excavation footage on the lining’s horizontal displacement was only 0.14 to 0.2 mm. This suggests that the horizontal displacement of the shaft lining is not significantly affected by the circular excavation footage during shaft excavation. (4) The five excavation footage schemes were categorized into two groups for analysis. Within the footage range of 2–3 m, the horizontal displacement of the lining decreased as the footage increased. Conversely, within the footage range of 4–8 m, the horizontal displacement increased with increasing footage.

Curve showing the lining’s horizontal displacement with shaft depth under various excavation footage.

The correlation between the measured and calculated values of the vertical displacement of the shaft after excavation is shown in Fig. 10. The strength of the linear relationship is indicated by the R2 value of 0.99948, which meets the accuracy requirements.

Vertical displacement of shaft lining measured value and calculated value comparison diagram. (a) Diagonal diagram, (b) Histogram.

Figure 11 shows the vertical displacement curve of the shaft lining with respect to the depth of the shaft for various excavation footages after the excavation was completed. A negative vertical displacement value denotes settlement, and a positive value denotes rebound. Figure 11 shows that the displacement difference between the neighboring excavation footage decreases as the shaft becomes deeper and eventually tends to zero, showing a progressive decrease in the influence of the excavation footage on the vertical displacement. Figure 11 also shows that, as with the horizontal displacement, the vertical displacement decreased as the footage increased within the range of 2–3 m. The number of times the rock is disturbed will also increase, which will lead to the gradual accumulation of settlement. In the footing range of 4–8 m, the vertical displacement increases as the footage increases. An excessively large excavation results in short-term settlement greater than the accumulated settlement resulting from the disturbance of the surrounding rock excavation, as also reported in other research33. (3) The schemes can be ordered as follows in terms of the vertical displacement magnitude: F5 > F4 > F1 > F3 > F2. In the F5 scheme, the maximum settlement occurred at the wellhead, with a value of 28.06 mm.

Curve of vertical displacement of lining with depth of shaft under different excavation footage.

Before the excavation of a tunnel, the surrounding rock is in an initial stress state. Excavation of the tunnel destroys the balance of this initial state, resulting in tectonic stress release, stress redistribution34, and potentially surrounding rock property changes, tunnel section shrinkage, collapse, and instability35. The focus of research on the effects of excavation on the stability of a rock mass is the stress in the surrounding rock.

When a shaft is excavated in the conglomerate of the western region, basement uplift may occur with increasing depth. Basement uplift is dangerous for workers because it makes the excavation surface unstable and causes ground deformation, thus disrupting the stability of the surrounding ground36. Figure 12 illustrates the change in the surrounding rock’s vertical displacement during the excavation process. The figure illustrates the following. (1) The trend for each excavation curve is essentially the same. (2) The rebound magnitude increases with increasing excavation depth because the soil is under more stress as the excavation depth increases. Moreover, the supporting effect of groundwater on the soil may be weakened, and the soil will be destroyed by the structure, causing rearrangement and adjustment inside the soil, thereby increasing the rebound of the soil. (3) The vertical displacement of the lining and the rebound amount vary essentially identically with the excavation footage, with the maximum rebound of 3.04 mm occurring when the footage is 8 m.

Spring-back amount. (a) Footage of 2 m, (b) Footage of 3 m, (c) Footage of 4 m, (d) Footage of 6 m, (e) Footage of 8 m.

As the constitutive model of the surrounding rock is the Mohr-Coulomb model, the rock obeys the Mohr–Coulomb yield criterion:

where \(\:F\) is the yield condition function, \(\:q\) is the shear stress, \(\:p\) is the normal stress; \(\:\varphi\:\) is the friction angle, c is the cohesion, \(\:{R}_{mc}\) is a parameter that controls the shape of the yield surface in the π plane, and \(\:\varTheta\:\) is the polar angle.

The tangential and normal forces on the structural plane of the surrounding rock can be determined using Eqs. (3) and (4), respectively:

The conditions for shear failure of structural plane are as follows:

where \(\:T\) is the tangential force, \(\:N\) is the normal force; \(\:{\sigma\:}_{1}\) is the maximum (first) principal stress, \(\:{\sigma\:}_{3}\) is the minimum (third) principal stress, \(\:{\varphi}_{j}\) is the internal friction angle of the structural plane, \(\:{C}_{j}\) is the cohesive force of structural plane, \(\:h\) is the depth, and \(\:\alpha\:\) is the angle between the structural plane and the horizontal plane.

Equations (3), (4), and (5) show that an increase in the maximum principal stress results in an increase in the tangential force of the structural plane, which increases the likelihood that the structural plane fails. Under the action of a tangential force, the upper half of the structural model slides along the structural plane. A normal displacement \(\:{\delta\:}_{n}\) in the direction of the minimum principal stress will also occur, in addition to the tangential displacement \(\:{\delta\:}_{\tau\:}\) in the direction of the maximum principal stress.

The variation curves of the maximum and minimum principal stresses of the surrounding rock with the excavation depth for various excavation footages, and the peak values are shown in Figs. 13 and 14, respectively (in which positive values indicate tension and negative values indicate compression). Figure 13 shows that (1) the maximum principal stress varies smoothly and that the compressive stress in the surrounding rock is significantly greater than the tensile stress; (2) the maximum value increases with excavation depth; and (3) for an excavation footage of 3 m, the maximum stress decreases abruptly at an excavation depth of 72 m. This may cause compression, slip, or fracture of the rock and soil. Figure 14 shows that the maximum value of the minimum principal stress hardly changes before an excavation depth of 96 m is reached and then changes significantly, increasing with increasing excavation depth.

The maximum value of the maximum principal stress of the surrounding rock under different excavation footage.

The surrounding rock’s least principal stress maximum value under various excavation footage.

The variation in the peak values of the maximum and minimum principal stresses with increasing footage was similar to that of the lining displacement. The excavation operations must be performed in a confined range when the excavation footage is inadequate, which restricts the release and dispersion of internal stress in the rock mass. Thus, the principal stress in the surrounding rock mass cannot be effectively alleviated, resulting in stress concentration and further increase. When the footage is in the range of 4–8 m, the principal stress in the surrounding rock mass increases with increasing footage. When the excavation footage is too large, the surrounding rock mass is subjected to greater stress transfer, and the load applied to the surrounding rock mass by the excavation project increases. Thus, the stress state inside the rock mass changes, and the principal stress increases.

Table 4 shows the maximum values of the first and third principal stresses of the surrounding rock following excavation. The F2 scheme results in a minimum principal stress of −10.399 MPa and a maximum principal stress of −3.203 MPa. The F3 scheme results in a minimum principal stress of −10.871 MPa and a maximum principal stress of −3.206 MPa. The ratios of stress for the F2 and F3 schemes are 0.308 and 0.295, respectively. Although the maximum and minimum principal stresses are expressed as F3 > F2, the ratio of the two is expressed as F3 < F2, which can prevent the structure from deforming and failing as a result of dilatancy in the butterfly plastic zone. The specific variation patterns for the two schemes are shown in Figs. 15 and 16. The difference in stress in the surrounding rock at the same depth is relatively small for the 3 m and 4 m footages. As the depth of the vertical shaft increases, the self-weight of the rock layer above the vertical shaft increases, leading to a gradual increase in stress in the surrounding rock. In addition, as the excavation depth increases, the stress on the surrounding rock gradually increases. However, the magnitude of the change is small, indicating that the support structure provided good protection.

Cloud diagram of maximum principal stress variation in surrounding rock. (a) Excavation of 24 m, (b) Excavation of 72 m, (c) Excavation of 120 m, (d) Excavation of 196 m.

Cloud diagram of minimum principal stress variation in surrounding rock. (a) Excavation of 24 m, (b) Excavation of 72 m, (c) Excavation of 120 m, (d) Excavation of 196 m.

A reasonable excavation footage is crucial vertical shaft construction efficiency and safety37. When the footage was 3 m, the horizontal and vertical displacements of the vertical shaft and the principal stress in the surrounding rock were the smallest and were close to those for a footage of 4 m. In actual engineering projects, excavation must consider not only safety factors but also the construction schedule and efficiency. The total length of the vertical shaft was fixed at 192 m. For an excavation footage of 4 m, 48 excavations are required, whereas 64 excavations are required for a footage of 3 m. Fewer excavations can significantly improve construction efficiency, reduce transition and preparation time between operations, and permit increasing the footage to meet the project schedule requirements, as a larger excavation footage means that each operation covers a larger area, which means that the project can be completed more quickly38.

This study considered the construction of the shaft pipeline of the Xinlongkou Hydropower Station for the purpose of examining how to improve the safety and stability of the construction of ultra-deep shafts in the Xiyu conglomerate area in China. The results of numerical simulation of the displacement of the shaft lining and the stress of the surrounding rock were compared with actual measurement data from the construction site. The conclusions are as follows.

The excavation footage had little effect on the horizontal displacement of the lining during the shaft excavation process, as indicated by the highest variation in the influence of the footage on the horizontal displacement being only 0.2 mm.

The variations in the horizontal displacement, vertical displacement, and rebound were consistent. When the excavation footage was less than 3 m, the displacements and rebound gradually decreased with increasing footage.

When the excavation footage was less than a certain value, the maximum stress in the surrounding rock stress decreased with increasing excavation footage. This is because when the excavation footage is too small, excavation work must be carried out within a narrow zone, limiting the release and distribution of internal stress in the rock mass and making it difficult to effectively relieve the principal stress in the surrounding rock mass. When the excavation footage is greater than a certain value, the stress in the surrounding rock increases with increasing footage because excessive footage increases the load applied to the surrounding rock mass, increasing the principal stress.

The analysis of the variation patterns of the vertical shaft displacement and surrounding rock stress showed that the values were the lowest at a footage of 3 m. However, to improve construction efficiency and meet schedule requirements, it is advisable to increase the excavation footage to 4 m.

The data sets used in the current study can be provided according to the reasonable requirements of the corresponding authors.

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This study was financially supported by the XPCC science and technology innovation talent project (2022CB002-05), XPCC financial science and technology program (2023AB060) and Shihezi University high-level talent research project (XJ2020005001).

College of Water Conservancy & Architectural Engineering, Shihezi University, Xinjiang, 832000, China

Hao Wu, Jin Jin, Kaiqiang Geng & Yu Qiao

Key Laboratory of Cold and Arid Regions Eco-Hydraulic Engineering of Xinjiang Production & Construction Corps, Shihezi, 832000, Xinjiang, China

Jin Jin & Kaiqiang Geng

Kuitun River Diversion Project Construction Management Bureau of the 7th Division of Xinjiang Production and Construction Corps, Kuitun, 833200, China

Jianren Sun

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H.W. (Hao Wu) participated in the conceptualization of the study and wrote the manuscript; H.W. (Hao Wu) and J.S (Jianren Sun) carried out numerical simulation and measured data acquisition; H.W. (Hao Wu) and Y.Q. (Yu Qiao) conducted a field investigation; J.J. (Jin Jin) and K.G. (Kaiqiang Geng) provided constructive advice to the article. All authors have read and agreed to the published version of the manuscript.

Correspondence to Jin Jin.

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Wu, H., Jin, J., Geng, K. et al. Impact of excavation footage on vertical shaft lining deformation and surrounding rock stress in Xiyu conglomerate. Sci Rep 14, 25659 (2024). https://doi.org/10.1038/s41598-024-77636-8

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Received: 29 April 2024

Accepted: 23 October 2024

Published: 27 October 2024

DOI: https://doi.org/10.1038/s41598-024-77636-8

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