岩土工程技术

2023, 37(3)

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2023, 37(3): 1-3.

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Current Research and Prospect on Cutter Wear of Tunnelling Boring Machine

Huang Dan, Ma Hao, Yang Xiaocong, Li Yuxuan, Zheng Zhijie

2023, 37(3): 253-261. doi: 10.3969/j.issn.1007-2993.2023.03.001

[Abstract](274) [FullText HTML] (48) [PDF 1070KB](43)

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With the development of machinery manufacturing technology and economy, more and more project of water conservancy, transportation and mines use full face tunnel boring machine (TBM) to excavate tunnels. The wear of TBM cutter has great influences on the tunnelling efficiency and costs. The study on cutter wear is significant to improve the wear resistance of cutter and the timeliness of wear monitoring, reasonably predict the tunnelling period and cost, and take effective measures to shorten the construction period and reduce the project cost. The research of the types, influencing factors, monitoring methods and prediction models of cutter wear are reviewed. The direction for further study on the cutter wear is provided.

Reactivation Deformation Mechanism of Ancient Landslide at a Hydropower Station in Southeast Asia

Xia Yuyun, Liu Min, Qiao Jianwei, Liu Zhenghong, Wang Ran, Zhou Renfei, Li Xinyang

2023, 37(3): 262-267. doi: 10.3969/j.issn.1007-2993.2023.03.002

[Abstract](96) [FullText HTML] (29) [PDF 5240KB](24)

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For an ancient landslide on the upstream right bank of a hydropower station in Southeast Asia, the geological characteristics, sliding zone characteristics, and deformation characteristics of the landslide were studied through drilling, geological investigation, and long-term monitoring, and the mechanism of reactivated ancient landslide was explored. The results indicate that: (1) Unloading at the foot of the slope and heavy rainfall are the main reasons for the reactivation of ancient landslides. (2) Road excavation leads to changes in the stress field, causing landslides to "revive" along the contact surface of shallow Quaternary slope deposits, slate, and sandstone, resulting in creep deformation towards the free surface. (3) The deformation of ancient landslides is positively correlated with rainfall. During the rainy season with high intensity rainfall, the displacement and deformation rate rapidly increase, and during the dry season without rainfall, the landslide is basically in a stable state. (4) The deep displacement monitoring data shows that there is no sudden change in displacement in the deep part of the ancient landslide, and rainfall has little effect on the deep displacement.

High and Low Combination Wall Reinforced Earth Retaining Wall Engineering Application Example in Qingdao

Zhang Jiqing, Sun Tao, Shao Changhua

2023, 37(3): 268-274. doi: 10.3969/j.issn.1007-2993.2023.03.003

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The situation, design idea, construction scheme and monitoring results of a high and low combination wall reinforced earth retaining wall project in Qingdao were introduced. The concrete split surface module wall was used in the lower part of the composite reinforced earth retaining wall, and the cast-in-situ concrete panel with reinforced earth bag wall was used in the upper part. The monitoring data show that the larger the deformation of the lower splitting module towards the outer wall, the tighter the geogrid tension; the higher the load and earth pressure of the upper wall are, the denser the reinforced earth is, and the greater the tensile force of the backpacking geogrid and reinforced bolt is. The displacement of the soil and the deformation of the retaining wall have a certain lag with the loading time, and the deformation tends to be stable after the gap between the upper geobag and the retaining wall is fully crowded. The displacement direction of the retaining wall is different from that of the conventional retaining wall. The practice proves that the composite wall reinforced earth retaining wall has the characteristics of reasonable structure, convenient construction and safe and reliable, which can provide reference for the design of similar projects.

Investigation of Low Frequency Debris Flow Gully in Dense Forest Area on Airborne LiDAR Technology

Wang Ping, Lai Anfeng

2023, 37(3): 275-283. doi: 10.3969/j.issn.1007-2993.2023.03.004

[Abstract](73) [FullText HTML] (90) [PDF 7527KB](20)

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Airborne LiDAR is an active scanning remote sensing technology. Its laser pulse signal can partially pass through the gap of multi-layer vegetation to the surface, and quickly obtain high-precision three-dimensional data and images of the surface after stripping the vegetation layer, so as to truly depict the landform contour and finely restore the surface features. The low-frequency debris flow gully has a long intermittent period and the surface vegetation is relatively lush. The commonly used remote sensing technologies such as optical image and InSAR have certain limitations on its interpretation. The pilot work of airborne LiDAR was carried out for the detailed investigation of geological disasters in Yantian District. The surface DEM data with a resolution of 0.2 m was extracted, and the fine mountain shadow image was generated. The remote sensing interpretation mark of debris flow airborne LiDAR image was preliminarily established. On this basis, 17 gullies were interpreted, and finally 4 low-frequency debris flow gullies were determined. Combined with the DEM image of airborne LiDAR, the morphological characteristics and material source distribution of debris flow gullies were investigated in detail, and the present activity of debris flow gully was preliminarily analyzed. Practice has proved that in areas with high vegetation coverage, the interpretability of airborne LiDAR images is significantly better than that of traditional optical remote sensing, and is suitable for early identification and follow-up investigation of hidden dangers of geological disasters such as debris flow.

Foundation Force and Grouting Reinforcement of Central Separate Wall in Shallow Buried Multi-arch Tunnel

Tian Lulu, Zhang Zhi, Guo Yongfa

2023, 37(3): 284-290. doi: 10.3969/j.issn.1007-2993.2023.03.005

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In order to study the foundation deformation characteristics of the central separate wall of a shallow-buried multi-arch tunnel and the foundation grouting reinforcement method, the MIDAS/GTS software was used for numerical simulation calculation and analysis based on a proposed expressway multi-arch tunnel in Yunnan Province. The research results show that: (1) When the surrounding rock is good and the buried depth is small, the pressure distribution at the base of the central separate wall gradually changes from the “saddle-shaped” distribution to the “bell-shaped” distribution along with the construction process. The maximum base pressure appears at the toe of the right wall after the lining of the advance tunnel is poured. The foundation of the central separate wall is generally uplifted; (2) When the surrounding rock is poor or the buried depth is large, the pressure distribution at the base of the central separate wall is in a “saddle-shaped” distribution. The maximum base pressure appears at the middle right after the second lining of the rear tunnel is poured. The foundation of the central separate wall is generally in a state of settlement. (3) Through numerical analysis, the required bearing capacity of the partition wall foundation of the multi-arch tunnel under different burial depths and geological conditions is obtained. Combined with the current code and previous research results, a calculation method for the foundation bearing capacity of the central separate wall before and after the rock foundation reinforcement is proposed. The research results can provide reference for the design and construction of multi-arch tunnels.

Stability Analysis and Treatment Measures of Lujiawan Bridge Accumulation Landslide

Wei Dongxu, Wan Li, Liu Chuanli, Zheng Guosheng

2023, 37(3): 291-296. doi: 10.3969/j.issn.1007-2993.2023.03.006

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The slope structure of accumulation body in southwest mountainous area is generally loose, and its stability is low. Most of them are in the basic stable or critical sliding state. Under the conditions of rainfall, earthquake, construction and excavation, the slope is prone to instability due to excessive deformation. Taking Lujiawan Bridge landslide of Da-Yong Expressway as an example, the stability of Lujiawan Bridge landslide accumulation was analyzed by the transfer coefficient method and rigid body limit equilibrium method based on the geological background of stratum lithology, structures and hydrogeological conditions through geological mapping and exploration results, and the anti-slide pile+anchor bolt support treatment scheme was proposed. The numerical simulation of the reinforced slope was conducted using finite element software, and the results showed that the slope was a composite type, with long-term heavy rainfall water seeping underground. The terrain was affected by the free surface formed by engineering construction excavation, resulting in the instability of the slope. After calculation, the stability coefficient of the slope after comprehensive treatment is 1.2. The landslide monitoring data shows that the displacement of the slope after treatment converges rapidly and tends to stabilize, indicating the effectiveness of the landslide treatment plan. The results can provide reference for similar projects in the future.

Automatic Monitoring Method of Highway Tunnel Shaft Construction

Duan Xingming, Ran Hua, Wei Tong, Xie Jialin

2023, 37(3): 297-302. doi: 10.3969/j.issn.1007-2993.2023.03.007

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Monitoring and measurement in the construction of long tunnel shaft is the guarantee of construction safety. Due to the limitation of shaft structure and construction space, the operability of conventional monitoring means such as level and total station is inefficient for the section far from the working face, which makes the shaft construction monitoring a difficult problem. Based on the Taihe tunnel shaft project of Mo-Lin expressway, an automated monitoring and measurement method for shafts was studied. This method was applied to actual construction monitoring, and monitoring data during construction was analyzed. The precautions for monitoring and measurement were summarized. The research results have certain guiding significance for the monitoring and measurement of similar shaft excavation.

Applied Research of Carrier Pile in Pebble Stratum in Caotang Area of Fengjie

Li Junshan, Guo Yu

2023, 37(3): 303-307. doi: 10.3969/j.issn.1007-2993.2023.03.008

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As a new form of pile foundation, carrier pile has been widely used in engineering in recent years. Its basic principle is to tamp the hole through column hammer and tamp the soil layer and filler below the pile end to form a composite bearing body, so as to greatly improve the vertical bearing capacity of single pile. At present, the carrier pile has achieved some research results in sandy soil, cohesive soil, silt and soft soil, but there is less research in pebble stratum. Taking the carrier pile project of a standard plant as an example, the design and construction of carrier pile in pebble stratum in Caotang area were studied, and the stress mechanism of carrier pile combined with the load test results was analyzed. The results show that the carrier pile using pebbles as the bearing layer has good applicability in the Caotang area of Fengjie. Static load tests and settlement observations indicate that the carrier pile has good bearing performance and is a safe and economic foundation form. the Q-s curve is generally of slow variation type, indicating that the stress form of carrier pile in pebble stratum is closer to that of end bearing pile. The applicability of carrier pile in pebble stratum is closely related to pebble composition and gradation. Large particle boulder in soil may hinder the tamping of column hammer. Pile test and advance geological drilling should be carried out before construction.

Construction Technology of PHC Tube-pile in Typical Thick-dense Sand Layer in Nanchang Area

Deng Meicheng, Cai Zhi, Liu Tao, Tian Jiancheng, Wei Haitao

2023, 37(3): 308-313. doi: 10.3969/j.issn.1007-2993.2023.03.009

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Based on the example of pile foundation in Nanchang, static penetration in-situ test was used to analyze the geological characteristics of typical thick-dense sand layers in the area. Based on theoretical calculations and on-site tests, the hammer sinking resistance of PHC pipe piles and the ultimate bearing capacity of a single pile were analyzed. Reasonable suggestions were proposed for the design and construction of engineering piles, and the construction process of hammer driving PHC pipe piles under this geological condition was summarized. The subsequent pile bearing capacity testing results show that the optimized and adjusted construction technology meets the engineering design requirements and has achieved good social and economic benefits, which can be promoted and applied in this area.

Testing and Analysis on the Quality Problems of CFG Pile Composite Foundation

Song Dechao, Zheng Yan, Chang Qinhui, Zhao Zhichao

2023, 37(3): 314-319. doi: 10.3969/j.issn.1007-2993.2023.03.010

[Abstract](173) [FullText HTML] (30) [PDF 1597KB](57)

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The stratum of a project site is mainly composed of silt, cohesive soil, and sandy soil, and the groundwater level is high. CFG pile composite foundation is designed. The test results of CFG pile composite foundation show that the bearing capacity of both single pile and composite foundation cannot meet the design requirements. The low strain method and core drilling method were used to detect and compare the quality problems, and the reasons for the quality problems were analyzed. High pressure jet grouting piles were used to reinforce the foundation, and the reinforced composite foundation was tested. The test results show that the bearing capacity of the composite foundation meets the design requirements. The observation results of building settlement indicate that the maximum settlement and overall inclination of the building meet the design and relevant specifications. It can provide reference for solving similar engineering quality problems.

Disease Detection of Loess Highway Slope Based on Point Cloud Data

Shao Jianhong, Zheng Wanpeng, Zhang Bin, Du Yuan, Wang Xingtao, Luan Jihao

2023, 37(3): 320-326. doi: 10.3969/j.issn.1007-2993.2023.03.011

[Abstract](118) [FullText HTML] (34) [PDF 2626KB](22)

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Slope inspection is one of the main works of highway operation and maintenance. In view of the limitation of manual inspection and monitoring, a highway slope inspection and monitoring method based on 3D reconstruction and point cloud analysis using unmanned aerial vehicle (UAV)-based oblique photography technique was proposed. The results show that the terrain data of research area could be obtained quickly by the unmanned aerial vehicle (UAV)-based oblique photography technique. Slope diseases including slope deformation, gully erosion and blockage of drainage ditch could be identified quantitatively by 3D model reconstruction and point cloud data analysis. The algorithm of point cloud data analysis has a great impact on the results. Compared with Cloud to Cloud comparison (C2C) algorithm and Multiscale Model to Model Cloud comparison (M3C2) algorithm, the algorithm of Cloud to Mesh comparison (C2M) is most suitable for the point cloud data analysis of highway slope disease identification. This method improves the efficiency of slope inspection and is an effective method to make up for the shortage of manual inspection.

Influence of Tunnel Excavation on Valley Slope Deformation and Mechanical Characteristics of Lining Structure

Yang Zhijun, Liu Jingtang, Hu Jinxin, Hong Ming

2023, 37(3): 327-334. doi: 10.3969/j.issn.1007-2993.2023.03.012

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Based on the topography of the loess tunnel entrance through the valley, the finite element numerical calculation model was established, and the strength reduction method was used to analyze the influence of the left tunnel and the right tunnel on the stability of the valley slope, and the mechanical characteristics of tunnel lining structures under different construction schemes were further studied. The research results show that in the two construction schemes, the left tunnel excavation has a greater impact on the sliding surface and plastic zone of the slope, and has the greatest impact on the displacement of the slope toe. In addition, the tunnel excavation makes the lining structure of the leading hole more stressed, and the left tunnel excavation has a greater impact on the lining than the right tunnel excavation, but the left tunnel excavation is beneficial to the slope stability. Therefore, left tunnel excavation should be adopted in this type of unsymmetrial loading tunnel to reduce the disturbance to the slope by the tunnel excavation. At the same time, the design of the left and right tunnel lining should be strengthen according to the distribution pattern of the weak points on the inner side of the lining structure.

The Implementation of Automatic Test for the Dynamic Parameters of Model Foundation with Variable Disturbance

Chen Xiaofeng, Tan Rongwei, Yu Jian, Yi Qiutian

2023, 37(3): 335-341. doi: 10.3969/j.issn.1007-2993.2023.03.013

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If the test for dynamic parameters of model foundation with variable disturbance adopts manual methods to control the test process, collect vibration waveforms, and process the test data, the work efficiency is low and the labor intensity is large. Composed of a notebook computer and a data acquisition card, the automatic test instrument of the model foundation dynamic parameter with variable disturbance based on the virtual instrument scheme was provided. This instrument could control the vibration frequency of the mechanical exciter by controlling the frequency converter, and the vibration signal of the model foundation can be automatically collected according to the program setting, so as to realize the automation of the test process. The automatic test instrument have a simple device, and have advantages of highwork efficiency, high precision and good reliability, making the process of testing simple and efficient.

Influence of Foundation Pit Excavation and Building Loading on Nearby Subway Tunnel

Ma Qingxun, Zhang Xintao, Liu Yunxia

2023, 37(3): 342-347. doi: 10.3969/j.issn.1007-2993.2023.03.014

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Taking the project in the Tongzhou Canal Core area of Beijing as an example, the major impacts of deep and large foundation pit excavation, complex groundwater environment and super-high-rise building loading on the adjacent subway were analyzed, and concrete reinforcement measures and construction suggestions for the adjacent subway construction project were provided. The combined technique of numerical calculation and SFIA was used to analyze the subway deformation caused by upper structure loading, and compared with long-term settlement data. The engineering practice and monitoring results show that the reinforcement measures and construction suggestions can effectively control the influence of the project construction on the adjacent subway tunnel, the combined analysis technique of numerical calculation and SFIA can accurately and effectively predict the ground settlement and deformation, which could provide reference for similar projects.

Construction and Application of Immovable Cultural Relics Display System

Sun Yuanping

2023, 37(3): 348-351. doi: 10.3969/j.issn.1007-2993.2023.03.015

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It has become an important direction for the relic management and cultural tourism to manage and display immovable cultural relics in an information and intelligent way. It can realize the transformation of immovable cultural relic material resources to digital resources and make immovable cultural relics become the cultural resources that can be continuously excavated, transformed and utilized. The construction background, data acquisition, data processing methods, system architecture, logical structure, and system functions of an immovable cultural relics display system were introduced. Through the establishment of immovable cultural relics information database and its corresponding comprehensive management system, the digital management of immovable cultural relics is realized.

Stability Analysis of an Artificial Accumulation Slope of Substation

Li Congyun, Huang Xiao, Zhang Xue, Zhang Xiaochen, Wang Hanxun

2023, 37(3): 352-356. doi: 10.3969/j.issn.1007-2993.2023.03.016

[Abstract](93) [FullText HTML] (25) [PDF 1874KB](29)

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Taking the artificial accumulation slope of a substation site in Mentougou District, Beijing as the research object, based on investigation and test results, typical slope profiles were selected, and the stability of the slope under different working conditions was studied using the limit equilibrium method. Targeted prevention and control measures were proposed. The results indicate that under natural working conditions, both profiles 1-1 and 2-2 of the artificial accumulation slope are in a metastable-unstable state. Under the rainstorm condition, both profile 1-1 and profile 2-2 are in an unstable state, and the slope is in an unstable state as a whole. Based on the analysis results of slope stability and combined with the actual situation of the project, the pile plate retaining wall is determined as the optimized support plan for the artificially piled slope.

Application of Finite Element Analysis in Seepage and Anti-slip Stability of Tailings Pond

Ning Hao, Zhang Xiangyang, Mu Zongqi

2023, 37(3): 357-360. doi: 10.3969/j.issn.1007-2993.2023.03.017

[Abstract](114) [FullText HTML] (38) [PDF 1130KB](24)

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In the preliminary design of a proposed tailings pond, one-time dam construction is adopted, and the dam type is roller compacted earth rock dam. In order to evaluate the rationality of the design scheme and the safety of the tailings pond, the seepage and anti-slip stability of the tailings pond were calculated by the finite element method. The results show that the seepage control system adopted by the tailings dam can well meet the seepage control requirements. The HDPE geomembrane on the upstream side of the dam has played a good seepage interception effect, and the distribution law of the infiltration line in the reservoir is reasonable. At the same time, the drainage system designed for the downstream has played a good seepage effect. Under the three conditions of normal storage level, maximum flood level and earthquake, the sliding stability of the downstream slope of tailings dam meets the specification requirements, proving that the design scheme is reasonable and feasible.

Comparison and Analysis on Treatment Technology of Dredged Coral Sand Foundation

Sun Lanning, Wei Haitao

2023, 37(3): 361-364. doi: 10.3969/j.issn.1007-2993.2023.03.018

[Abstract](96) [FullText HTML] (21) [PDF 1730KB](22)

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The engineering characteristics of dredged coral sand were introduced, and the foundation treatment methods of airport runway in an island country were analyzed and selected. Based on the vibration compaction and impact compaction experiments, the vibration roller compaction method was selected by analyzing the influence depth and settlement variation. The project has been completed and achieved good technical and economic results, which can provide reference for similar projects.

Temperature Stress of Superlong Reinforced Concrete Slab Bracing in Foundation Pit Retaining Structure

Xu Guanyu, Chen Junsheng, Liu Zibing, Li Wei, Tan Yiwei

2023, 37(3): 365-372. doi: 10.3969/j.issn.1007-2993.2023.03.019

[Abstract](106) [FullText HTML] (39) [PDF 2562KB](28)

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The calculation theory of axial force of concrete support is introduced, and applied to the axial force monitoring arrangement and axial force conversion of a large foundation pit slab support. According to the monitoring data of axial force of foundation pit slab support, horizontal displacement of ground diaphragm wall and temperature, the influence of temperature change on axial force of ultra-long reinforced concrete slab support and deformation of envelope structure was studied. The variation law of plate support axial force and horizontal displacement of ground connecting wall with temperature was verified and predicted, and the following conclusions are drawn: (1) The axial force of slab support is consistent with the trend of temperature change. The higher the temperature is, the more significant the influence of temperature change on the axial force of slab support is. The increase of daily temperature difference on the axial force of beam support is up to 30%, indicating that temperature is the main reason for the axial force change of long slab support beam under stable supporting and excavation conditions. (2) The horizontal displacement of the diaphragm wall at the plate support has a good correlation with the temperature change, but with the increase of depth, the influence of temperature change on the horizontal displacement of the diaphragm wall is weakened.

Deep Foundation Pit Support and Groundwater Control Method in Soil Rock Combination Strata in Lanzhou Area

Guo Zhiyuan, Long Zhao, Cao Chengming, He Laping

2023, 37(3): 373-378. doi: 10.3969/j.issn.1007-2993.2023.03.020

[Abstract](135) [FullText HTML] (34) [PDF 1835KB](32)

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Lanzhou area is a typical valley basin landform with two mountains and one river, the upper part of the area is Quaternary loose deposits and the lower part is Neogene weathered bedrock. The basic distribution of soil-rock combination strata and the distribution of groundwater in Lanzhou area was introduced. According to the cementation degree, water permeability, and uniaxial saturated compressive strength characteristics of the lower weathered bedrock, the soil-rock combination strata was divided into two types, The upper part of one combination is a loose accumulation layer, and the lower part is a weakly permeable to moderately permeable sandstone. The upper part of the other combination is a loose accumulation layer, and the lower part is an impermeable sandstone. For two types of soil-rock combination strata with completely different properties, the selection of supporting structure and groundwater control system for deep foundation pit engineering was summarized, and a typical case of deep foundation pit design in two types of soil-rock combination strata was given which provides a good reference for the design and construction of deep foundation pit engineering in similar strata.

2023 Vol. 37, No. 3